Subterranean Greenwich and Kent

Blackheath Cavern - the great column of 1794

2012-02-04T02:55:00.001Z

Until now the earliest account we had of the Cavern was Helme's 1800 description. But now we can go back even earlier - to 1794 - with John Bew's Ambulator or a pocket companion in a tour round London (plagiarised by Helme). Bew gives us a fascinating new feature to ponder, now lost or inaccessible: a great column 43 yards in circumference. If circular, that would give it a diameter of some 40 feet; columns of this size rarely collapse, so it's probably buried in choked passageway somewhere in the Cavern complex. A cropped copy of the wartime survey is shown below as a reminder that there were certainly no columns/pillars to be seen in 1939.

Blackheath Cavern: missing pieces of the puzzle

2012-02-02T07:41:00.002Z

Pinnock's 1833 The Guide to Knowledge¹ is a critically important account of the layout of the Cavern. During the first half of the 19th century access to the cavern was by a "flight of steep steps cut in the chalk for about forty feet." The first chamber encountered at the bottom of the steps was "about thirty-five feet in length, varying from fifteen to twenty feet in breadth, and about twelve feet high." What follows next in the account is extremely interesting, because it describes a small person-sized tunnel that is now lost:

"...the guide next took us through a narrow confined passage in the rock, which is about six feet high, from two to three feet wide, and extends in a winding direction for about twenty feet, and gradually declining for about three feet, brought us into the first portion of the large cavern represented as above [a well-known engraving of the main chamber]."

So the original staircase, the first chamber, and the small winding passage are all essentially lost/inaccessible - although in 1939 Legrand, Sutcliff and Gell clipped original parts of Cavern wall twice while sinking their shaft and driving their exploration tunnel from the bottom of the shaft towards the main chamber as we see it today:

"...at a depth of 32 feet, the floor of the excavation [ie the shaft] began to give way, the workmen finding themselves in a small cavity, which appeared from inscriptions found on the chalk to be part of a passage leading to the cavern." (Craske 1946)

"...about 57 feet horizontally from the foot of the shaft, the original tunnel was again encountered, very close to its point of entry to the main chamber." (Craske 1946)

Pinnock's small "winding" tunnel almost certainly still exists, because this type of small passage - with a great thickness of chalk above it - tends to be extremely strong and resistant to collapse. It's probably just choked with sand/chalk debris, and given time could be found. But it seems that the first chamber has collapsed - which may be related to the hole found during foundation works for the northern end of the Undercliff flats. Borehole No.2 drilled by LSG in 1939 may have passed right through the collapsed/choked remains of the first chamber, with the drill dropping through space for 18 inches after passing through a 3-foot thick chalk ceiling. The drill then proceeded through 20 feet of disturbed ground before hitting a firm chalk floor. However, the first chamber was said to be only 12 feet high, which doesn't tally.

There is a remarkable implication here. If the small winding person-sized passage was the only way into the main chamber, then how was mined chalk brought out? It would be like mining through a keyhole. No chalk mine we have ever examined has an arrangement like this, which raises a fundamental question: is the Blackheath Cavern actually a chalk mine?

Pinnock also hints at a lost chamber concealed behind a piece of stone in what we now call the Inner Chamber, next to the "Bar":

"...at the top, in the chalk, there is a large piece of stone which would almost seem to have been placed across the entrance to a fifth cavern; but as we were not prepared to remove the earth, this remains only a conjecture."

Very slowly the evidence seems to be nudging towards the seven "apartments" originally described by Helme in 1800 (even then major falls had already occurred, with two high domes in the Thanet Sand).

Click the images above for slightly larger versions

¹ Pinnock's account was later plagiarised almost verbatim by Dunkin in 1855.

The oldest known photograph of denehole exploration

2011-09-12T04:05:00.003+01:00

In this 1866 photo we see the father of denehole exploration, F.C.J. Spurrell, as a young man - indeed this is thought to be the only surviving image of him. The picture was taken at a noteworthy four-pillared denehole at Stankey, Bexley. Also present on this excursion is Sir John Maryon Wilson - underlining Sir John's considerable knowledge about deneholes located on his estate at Charlton and nearby at Hanging Wood.

Left to right: FJS [Spurrell senior], FS [Spurrell junior], AS [Alfred Spurrell], Capt. Popperwell, HS [Herbert Spurrell], and Sir John Maryon Wilson.

Click image for a slightly larger version (781 x 544)

Mr Brand's Cavern

2011-08-07T02:39:00.002+01:00

Chalk mining and sand extraction to the north side of the Blackheath Hill roadway was disrupted (although not stopped) in 1751 when "the Crown proceeded against Morden College, to restrain the trustees from granting leases to dig for sand and chalk under Maidenstone Hill". Leases previously granted (illegally as it turns out) to three enthusiastic excavators (Messrs Harding, Steers, and Hatch and Nightingale) had expired in 1734. Whether sand and chalk extraction continued after 1751 is unknown - it would have depended on how brazen and unscrupulous the diggers were, as well as exactly when the original leases granted by Sir William Boreman were shown in court to have been illegal. Ultimately it wasn't until 1771 that concrete legislation was enacted that explicitly stated "no sand or chalk [to be] carried off the waste".

Click for larger version (303k 856 x 1154)

The name of Steers always seems to be tied to the Blackheath Cavern, even though there is no documentary evidence whatsoever that the Steers family ever set foot in it. In any event the characteristics of the Blackheath Cavern galleries are those of two or three centuries earlier; it was already long disused in Steers' era . All that is certain is that Steers was fined for undermining the King's highway - no inference should be drawn from that regarding how prolific a tunneller he was. Harding or Hatch and Nightingale are just as likely to have been carving out galleries in the chalk without keeping any plans of their activities - the root of the problem we face today, exemplified by Winn's Chalk Mine, which is almost certainly the work of one of the three above-mentioned operators.

Galleries in the chalk were open in the vicinity of Maidenstone Hill before the rediscovery of the Blackheath Cavern; we know this because of the 1751 court case in which the Crown took action against Morden College; Mr Brand, for Morden College, suggested that the excavations under Maidenstone Hill "might puzzle future antiquaries". There is no evidence that he was referring specifically to the Blackheath Cavern, although if he was, that means that the Cavern was already open in 1751, thirty years before its official "rediscovery". Just how many times can the Cavern be rediscovered? It's just as likely that Brand was talking about other accessible chalk galleries nearby. Incidentally, there is a small chance that Brand's comment is from the 1771 Exchequer Court case, which nevertheless would still prove the existence of open chalk mine galleries nine years before the Cavern "rediscovery"; Hasted is frustatingly vague in the chronology.

Previous commentators have misread this page of Hasted, failing to notice that Brand's suggestion that the chalk excavations would puzzle future antiquaries was made at least nine years before the Cavern's 1780 "rediscovery" and probably thirty years before it. This is a critically important detail. Further research may be able to tighten up the exact date of Brand's statement.

The page above from Hasted mentions in passing the Commissioners of Greenwich Hospital asking the Crown Officers for help to prevent damage to the conduits on Primrose Hill (now Vanbrugh Hill) and Conduit Vale (now Hyde Vale) - both caused by ballast digging.

Well in the secret garden, Park Vista

2011-06-24T22:59:00.002+01:00

A well was recently found in the Dwarf Orchard (the walled garden adjacent to Park Vista). The photo below (photographer's name witheld, although the person was clearly of unusually tall stature - the wall just here is some 10 feet high) shows the general situation:

Graham Keevill of Keevill Heritage Consultancy has come to the rescue with some very clear photos of the well, both before opening and then looking down the shaft:

The well is 9-10m deep, with an internal diameter of 1.2m approx; the capping stone is 0.75m diameter with a bevelled edge plus two iron lifting rings¹.

¹ The Orchard, Greenwich Park: archaeological evaluation report. Keevill Heritage Consultancy, final issue 30 March 2010. Graham Keevill and Catherine Underwood.

The price of conduits

2011-06-06T03:17:00.000+01:00

A fascinating note of how much was being spent on the Greenwich Hospital conduits has come to light. Dated 1727, it concerns "Conduits and Aquaducts" (sic), giving a figure of just over £2,257 - a very substantial sum of money at the time. It's not known over what time period this expenditure occurred. Click image for a slightly larger version.

Stunning new conduit portal image discovered

2011-06-05T04:55:00.001+01:00

An incredible new image of a grand conduit portal has turned up. This is the first time either Per or I have ever seen this image, and we've been looking hard for 25 years. It's a major discovery, although we're not sure which conduit it is; much discussion will now take place. It might be the original entrance into the Hyde Vale Conduit, set into the pit alongside the Standard Reservoir Building. But right now we simply don't know. It's quite a grand portal - befitting a major conduit. I must admit I almost fell off my chair when I first saw this. It's an incredibly rare find. Click image for a slightly larger version.

Brick vault on Crooms Hill

2011-06-02T03:24:00.000+01:00

This 1871 drawing by Sir John Gilbert shows a semi-ruined building on Crooms Hill with 3 entrances to what appears to be a brick-arched vault running into the hillside. The location is possibly opposite the church, where the park wall diverges away from the road and goes behind Hillside. Click the image for a slightly larger version.

Network Rail - the reluctant elephant moves 1 centimetre

2011-06-02T01:33:00.002+01:00

A letter from Network rail's John Halsall (click for a larger version):

"...we do not consider there to be a material risk of failure of part of the tunnel lining without prior warning in the form of significant cracking of the tunnel wall."

How quickly would cracking of the tunnel wall be noticed? How often is the tunnel thoroughly inspected? It needs to be inspected daily until the exact location of the 1849 mine gallery is determined and the mine entered and surveyed.

"The drilling should establish if there is any evidence of the mine/cave referred to in the 1849 article beneath the tunnel wall or track at the location we agreed and whether or not it was filled adequately at the time."

I think "should" is rather optimistic, bearing in mind the limited depth and scope of the proposed investigation. This statement again confines itself to the 1849 article and ignores the possible existence of related unknown mine galleries elsewhere under the tunnel/s. Furthermore who is to judge what constitutes "filled adequately"? We suggest an independent engineer selected by ourselves and paid for by Network Rail.

Per von Scheibner has mentioned that the letter omits parts of their agreement, i.e. the depth (2 metres) & positioning of the boreholes (not just under the actual rails, but also between the rails & the tunnel walls on both sides of the rails at one metre intervals along the tunnel entrances on both sides).

Network Rail are - as I expected they would - doing the minimum they possibly can to investigate this issue. Furthermore the transparency of any investigations carried out by them (past, present or future) is open to question. Unfortunately I see a return to using the legislative brute force of Parliament and the House of Lords in order to make the obstinate elephant that is Network Rail move more than a centimetre towards fulfilling its duty of care to the travelling public.

Go on Network rail - surprise us: do some proper (and transparent) investigations, and do them now. Not in 6 months or a year. NOW.

New subsidence in Croom's Hill roadway - breaking news

2011-04-20T11:13:00.006+01:00

A hole has opened up in Croom's Hill roadway within the past hour (written at 10am Wed 20 April), very close to the church. Greenwich Council currently digging, Parks Police in attendance initially, may still be.

Good coverage by the Greenwich Phantom here:

http://www.thegreenwichphantom.co.uk/2011/04/hole-opens-in-crooms-hill/

Per examined the hole and considers it of little importance. The section of the Hyde Vale Conduit that runs nearby is in excellent condition and has not collapsed. Probably a minor washout immediately under the tarmac - not unusual around the neighbourhood.

Charlton Lane tunnel - a small investigation will be carried out

2011-04-19T01:49:00.001+01:00

Following a meeting between Per von Scheibner and Network Rail's John Halsall and two other senior NR figures, an agreement has been reached in principle whereby Network Rail will conduct a limited examination at the extremities of the Charlton Lane railway tunnel without closing the railway or lifting the tracks. Whether this will be sufficient to discover the chalk mine gallery known to be located under the trackbed remains to be seen.

It's a welcome step forward to investigate this most important issue.

HM Inspector of Railways - reckless and dangerous

2011-04-06T04:40:00.000+01:00

We have just received a letter from Simon d'Albertanson, HM Inspector of Railways, regarding the chalk mine gallery underneath the trackbed in the Charlton railway tunnel. The Inspector sides entirely with Network Rail, concluding that there is no significant danger to the travelling public - a breathtakingly reckless conclusion to arrive at given the concise account of 1849 and our advice on the matter (informed by 25 years investigating chalk mines). If this is considered libel, then perhaps that will lead to a healthy airing of the matter in front of a judge - who will doubtless have a more open mind than those inside the UK railway industry, who continue to display an institutionalised cavalier attitude to the safety of the travelling public.

The risk-based approach to management of railway safety has largely been imported into Network Rail by chairman Rick Haythornthwaite, who was formerly chair of the Risk & Regulatory Advisory Council. In his business model, the value of a human life is arrived at using a pocket calculator and a balance sheet. The Inspector of Railways sadly goes along with this sinister mathematical callousness, instead of displaying the refreshing scepticism so urgently needed to deal with a largely unaccountable and secret organisation such as Network Rail.

Here is a verbatim copy of the Inspector's letter:

29 March 2011

Dear Mr Clinton

Dangerous Tunnels in Charlton

Thank you for your correspondence on the Charlton Tunnels. I have inspected Network Rail’s recent examination records for this area for both the trackbed and the tunnels which might be affected by the presence of an underground chamber in this location. A review of the relevant available information recorded since 1849 does not indicate any structural issues which might indicate the presence of an underground chamber.

The report in the Kentish Mercury for 1849 therefore appears to be the only source for the presence of an underground chamber in the vicinity of the railway. The reference to the Hanging Woods indicates that the Tunnel referred to is Charlton Lane which appears to be confirmed by examination of maps of the time, however, the exact location of the ‘cave’ is uncertain. The article seems to suggest that the railway passes over the breadth of one of the chambers. Unfortunately, it does not say whether the chambers were subsequently filled in and there does not appear to be any other information relating to this. Network Rail’s tunnel management strategy for this tunnel considered the 1849 article and as you know some trial drillings have been carried out in the past to locate it without success.

In my view, Network Rail have carried out all actions that could reasonably be expected of them under Health and Safety Law to manage risk at Charlton Lane Tunnel, including the possibility of an unknown void beneath it which includes risk based periodic examination of the structure. If you have any further information which might assist them to locate the ‘cave’ referred to in the 1849 article I would ask you to let Network Rail know so that they can take this into account in their management strategy for the structure.

I am satisfied Network Rail have suitable measures in place for the examination and maintenance of the tunnel and therefore do not propose to take the matter further unless new information comes to light.

Yours sincerely

Simon d'Albertanson

Here is the reply I sent to Mr d'Albertanson:

Dear Mr d'Albertanson,

Thank you for your letter detailing your position and intent regarding the old mine gallery under the railway tunnel at Charlton.

Your decision is inevitably flawed by the narrow terms of reference within which HSE/ORR operates.

I was shocked by how closely you have aligned yourself with Network Rail's position. How many more people must die on the railways of Britain before a genuinely responsible safety culture is introduced? Your innuendo about the small-scale drillings that were conducted some years ago being somehow sufficient is very unfortunate.

There are basically two approaches to the Charlton mine gallery issue:

The Network Rail approach:

Risk-based approach. Risk defined by lack of subsidence in the tunnel/s and lack of information about the location of the mine gallery. The lack of information is used as a justification for inaction. Rejection of the notion that the 1849 mine gallery may be just a part of a much larger mine working, other galleries of which may also undermine the railway. Do nothing. Wait until a disaster happens before action is taken.

The safe and sensible approach:

Definite and concise historic reference to mine gallery underneath the railway tunnel discovered in 1849 archives. Suspicion that the mine gallery is an orphaned gallery from a much larger chalk mine. Thorough geotechnical investigation launched in both railway tunnels and section between tunnels to attempt to find the 1849 mine gallery. Once 1849 gallery is located, it is entered and the fallen sand at the end is dug away for a considerable distance (supporting the roof to protect workers) to prove whether it is an old slope-drift entrance to a single isolated adit in chalk, or connects to further mine passageway. Even if it is a single adit, the original quarry face must be traced and exposed to see if there are neighbouring individual adits also driven into the chalk. The overall aim is to locate any and all mine galleries under Hanging Wood, and carry out an accurate underground survey. Roof falls/blockages are plotted and appraised to see where more galleries may be located. Result: a thorough understanding of mining activity under Hanging Wood, and subsequent remedial action undertaken if necessary in certain sections of mine gallery. Travelling public and railway staff safeguarded to a very high degree of certainty when passing through the tunnels by train.

Even if the 1849 gallery has been safely locally filled directly beneath the trackbed in the past, its location must still be found and the mine gallery re-opened in order to explore the mine and search for additional galleries not found in 1849 which may undermine the railway at other unknown locations in or around Hanging Wood.

*Although I refer to the "1849 gallery" it may actually have been dug decades or even centuries before 1849.

==================================

I will continue to pursue other avenues in order to force Network Rail to launch a full and through geotechnical investigation monitored and evaluated by truly independent engineers who will report their findings to me and my colleague.

Regards,

Dominic Clinton

Yesterday I reviewed the official report into the Moorgate tube disaster of 28 February 1975, as well as looking through contemporary photographs of the rescue effort - much bravery was in evidence amid the harrowing crush of metal and human bodies. Forty-three people were killed at the scene, with several more dying later from their injuries. I'll be the first to admit that the circumstances are not the same as the Charlton tunnels, but it's clear that a disaster in a tunnel is something to be avoided at all costs; the pictures below speak for themselves.

It is not something to be risk-assessed on a pocket calculator.

Royal Hospital - 1700 groundwater level investigation

2011-03-16T12:50:00.000Z

An unusual early geotechnical investigation of about 1700 into groundwater levels at the river wall of the Royal Hospital (subsequently the Royal Naval College and now Greenwich University) shows test pits that prove water level.

↑ Click for a larger version (427k 1000 x 674)

Royal Hospital - King Charles Quarter - sewer mouth & cellarage

2011-03-16T08:59:00.001Z

Two beautiful 1700-ish drawings of the King Charles Quarter of the Royal Hospital (subsequently the Royal Naval College and now Greenwich University) have turned up. One shows a sewer mouth in the river wall (now obscured), the other a salami-style cut through the block including cellarage - of which there were thousands of square feet under all four blocks.

↑ Click for a larger version (630k 1000 x 881)

↑ Click for a larger version (627k 1000 x 825)

Maidenstone Hill - intriguing account of subsidence and passageway

2011-03-10T23:23:00.000Z

Robert Williams (80) wrote to the Kentish Mercury in 1933 after its coverage of the Trinity Grove subsidence. He recalled a major collapse that happened in the garden of a house at the Point Hill end of Maidenstone Hill when he was a child (the 1860s), well away from the known Cavern. His account is intriguing, though should be viewed with at least a little scepticism. The house number has been censored because we are still investigating. Click for a large version (529 x 1500 545k):

Blackheath Cavern - the Trinity Grove and Undercliff problems

2011-03-09T13:05:00.007Z

Our new overlay of the wartime plan of the Cavern's location onto a very modern (June 2010) OS map is the most accurate ever done.

The Kentish Mercury of January 27 1933 reported a subsidence in Trinity Grove, which is located between the Blackheath Cavern and an old quarry now partially occupied by a tennis court. Five families had to be evacuated. It's highly likely that there were walk-in mine entrances in this quarry which headed towards the Cavern, though any possible underground connection is pure speculation. But it suggests a risk to property in a broad zone from the tennis court right through to the cavern; the corridor of risk should perhaps be expanded somewhat north to include the fork of Trinity Street and Maidenstone Hill.

Undercliff, the block of flats at the junction of Blackheath Hill and Maidenstone Hill, is partially built on shallow foundations, but the northern half - closer to the Cavern - was piled because a hole was discovered during foundation works. The piled section of Undercliff is some 30m away from the wartime shaft dug by Legrand Sutcliff and Gell, yet not above any known section of the Cavern; the implication is that the Cavern originally extended further towards the roadway of Blackheath Hill than the galleries surveyed by LSG. This is consistent with early descriptions of rooms in the Cavern (with at least two collapse domes in the ceilings) that were not found by LSG, probably because they had already fallen in. In 1914 John Stone mentions: "There have of late years been several landslips in the neighbourhood of Blackheath Hill... a small one occurred a few months ago just behind Trinity Church." The church was located where Undercliff now stands, at the corner of the main road. It seems logical to conclude that the Undercliff hole and the 1914 subsidence were closely related due to their extreme proximity.

Here is the overlay, showing additionally the piled section of Undercliff and Trinity Grove (click for a larger version 1336 x 1308 760k):

In Trinity Grove house numbers 2-5 (numbers are consecutive in this street) were affected, with considerable subsidence of foundations and buckling of walls, doors not shutting, and windows shattering under pressure. The subsidence occurred over a number of hours during 20-21 January 1933. Water and gas mains were severed. No geotechnical investigation of any kind was carried out, and the houses were repaired - although the leaning out-of-vertical front wall of no 3 is very obvious when compared with the newly-rebuilt no 2 (blue door), whose brickwork is true to the plumb line.

Click for larger version (1000 x 750 692k)

At the same time there were more problems occurring just over the main road behind the Horse and Groom pub:

"It is a curious thing, however, that within two or three hundred yards of Trinity Grove is Harwich-place, where, a few days earlier, similar cracks were found in a number of houses.

Harwich-place is on the other side of Blackheath Hill, behind the Horse and Groom public house, and one of the householders here told the reporter that on Monday week cracks were noticed in the fabric of one of the houses. These seem to have spread quickly to the adjoining properties, and at first it was thought it would be necessary to evict the tenants on the ground that the condition of their homes was dangerous.

It is gathered that the necessity for this has been averted. Eight of the houses have been shored up, and it is understood that the tenants will now only be required to move to the backs of the houses while the repairs to the fronts are carried out."

Blackheath Hill 2002 - the boreholes

2011-03-09T12:33:00.006Z

A number of boreholes were carried out during 2002 on Blackheath Hill after the major subsidence that caused its closure. This plan of 10 May 2002 shows the 9 boreholes (click for a larger version 1059 x 1500 1.1 MB):

Results were generally inconclusive, with evidence of much disturbed ground. Borehole 3 was very interesting, however - located in the westbound roadway slightly downhill of the junction with Maidenstone Hill. A curious metal item was hit at 16.5m (54 feet) which could not be passed and indeed broke various drill bits. The driller's interpretation of this is that it was the roof of passageway. We believe this to be incorrect, and consider it to be metallic junk left on the floor of a mine passageway that subsequently became choked or collapsed. The depth to the floor of the supposed passageway would put the gallery on the same level as that of the Blackheath Cavern, although we are not suggesting there was ever a through trip possible underground between the two.

The driller describes it (quoted verbatim):

At 16.50m an obstruction was encountered. Various drill bits tryed + damaged. beleived to be metal. Possible roof of mine /Tunnel!!!

Here is the log sheet (click for a larger version 1066 x 1500 1.2MB):

Other interesting subsidences in the vicinity have come to light:

In 1974 Glennie House (on the south side of Blackheath Hill directly opposite the main 2002 roadway subsidence) had a sudden collapse of surrounding grounds.

In 1998 the Horse and Groom pub, downhill from Glennie House, suffered severe subsidence after a "sink hole" developed. It was subsequently closed after becoming structurally unsound.

Downhill from the Horse and Groom was Braid House, where a "sink hole" appeared during 1999/2000 - the hole was partly filled.

Downhill from Braid House, on the southern side of Blackheath Hill, is Robertson House. During 1999/2000 a "sink hole" appeared which caused 100mm of settlemnet of the flats - they have now been demolished.

"Sink holes" may well have been air pockets from collapsed mine galleries working their way up to the surface. What is certain is that Blackheath Hill is an area heavily undermined by old chalk mine galleries which are collapsing in a chaotic fashion; more collapses will surely happen in the future. A more systematic approach from local and central government is required to address the problem, which should include driving extensive underground headings to intercept unsurveyed/orphaned mine galleries.

Network Rail: the lies begin

2011-02-16T02:38:00.010Z

We received a letter from Network Rail dismissing the Charlton railway tunnel chalk mine as insignificant. The letter contains one fundamental lie which contradicts the historical fact. We will not allow Network Rail to re-write history, which is what they are trying to do.

Click each page for a large version:

In the letter James Pickard, Community Relations Advisor for L & SE states:

"The mines are recorded as being adjacent to the tunnel and not beneath it."

WRONG. The original article states (quoted verbatim):

"the workmen are now busily employed in shoring up a part of the roof of one of the chambers, the railway passing over its entire breath."

He states:

"Network Rail undertook a programme of trial drillings in the tunnels in 1985. No voids were found as a result of this drilling."

DISINGENUOUS. Our information suggests that those drillings were minor and conducted over a single weekend without closing the railway. This is completely insufficient. In any event I have one thing to say to that: show us the plans, or it didn't happen (and remember it may be a criminal offence to create fake plans in such safety-critical circumstances).

He states:

"Given that the mines were explored at the time of the construction of the railway, they would have been treated to the railway's specification."

RIDICULOUS. The "railway's specification" in 1849 was the ability to safely support a locomotive weighing around 24 tons, such as the Jenny Lind 2-2-2 class. Modern locomotives weigh up to 120 tons. In addition, whatever supports were placed in the mine gallery in 1849 may have deteriorated by now - their condition is entirely unknown.

He states:

"Given the level of exploration at the time the chances of unrecorded working beneath the railway is relatively low, however cannot be discounted entirely."

IGNORANT. The writer reveals his complete ignorance of chalk mining techniques. The roof fall at the end of the gallery was never dug through in 1849 to establish whether it was a slope drift entrance to the mine, or a further continuation of unsurveyed and unknown gallery which may have undermined the railway in another place.

He states:

"Many of our tunnels have large mineworkings in and around them (Box tunnel, Clay Cross tunnel etc), all of these are regularly checked and there is no immediate cause for concern at any location."

DISINGENUOUS. Box railway tunnel in Wiltshire is located underneath a large freestone mine, not above it, so the railway has nothing to subside into. At Clay Cross tunnel, coal was only discovered during the construction of the tunnel, and all subsequent mine workings were located so as not to interfere with the structural integrity of the tunnel. Clay Cross tunnel was driven in the late 1830s by George Stephenson, whose own Clay Cross Company carried out all subsequent mining activities. To suggest that Stephenson would have endangered his own tunnel (which cost the lives of 15 men to build) with his mining activities is absurd.

At Charlton, Network Rail continues to gamble with the safety of the travelling public and railway staff. They must stop lying and trying to re-write history: the facts are, as we have already said, undeniable and unequivocal:

↑ Click for a larger version (641k 825 x 1000)

James Pickard is just doing his job - which is to spin and distort information to the advantage of Network Rail. What is more interesting is the identity of the senior managers who approved this letter - they must be revealed and possibly even prosecuted for endangering the public and railway staff by hindering a safety investigation. However, we will be obtaining Counsel's Opinion on the possibility of a successful prosecution of James Pickard under Health and Safety legislation; he clearly and wilfully distorted a fundamental safety-related fact with intent to deceive. Under the circumstances that's an extremely serious matter. Network Rail have been tasked with looking after the safety of the travelling public, and to have that behaviour from one of their employees is outrageous. But outrageous behaviour is nothing new at Network Rail; they stand accused of supplying false information to the High Court during an injunction application in April 2010 to halt a strike¹. Previously in November 2003 Peter Bennett, Network Rail's head of human resources (more recently accused in Parliament of "presiding over a culture of fear and bullying"²) was under suspicion:

In November 2003, Mr. Bennett presided over Network Rail's so-called “Project Violet”. Almost overnight, some 600 employees, senior and long-serving managers among them, were dismissed and offered terms that in effect precluded them from voicing concerns in an employment tribunal, given the substantial settlements that were offered—settlements paid out of the taxpayer's pocket.²

More recently:

...in 2007 the company dismissed 247 employees, 38 of whom were covered by compromise agreements—that is, by confidentiality [gagging] clauses. The figures for 2008 were 270 and 57 respectively. In the past two years alone, 95 employees have been dismissed by the company, and the details of their settlements have been covered up. The number seems to have increased year on year.³

If you work for Network Rail (or used to work for them) and have confidential information about this situation (or indeed anything else relating to Network Rail) that you wish to discuss with us at Subterranean Greenwich, please feel free to contact us in absolute confidence. You may wish to discuss initially how best to bowdlerise (disguise the source) of your information before supplying us with that information. If it's difficult to bowdlerise it, then we can publish it in a more general form as deep background to the situation.

Because Network Rail are trying to avoid paying the several million pounds that a proper safety investigation would cost, we would be unsurprised if some level of informal intimidation was used against us. Anything of that nature will be immediately reported to the police, the ORR and the House of Commons Transport Select Committee.

To see the our original article on the Charlton railway tunnel cave please click here.

¹ http://www.socialistunity.com/?p=5557

² http://www.publications.parliament.uk/cgi-bin/newhtml_hl?DB=semukparl&STEMMER=en&WORDS=act&ALL=&ANY=&PHRASE=&CATEGORIES=&SIMPLE=Firearms%20act&SPEAKER=&COLOUR=red&STYLE=s&ANCHOR=90304h0009.htm_spmin0&URL=/pa/cm200809/cmhansrd/cm090304/halltext/90304h0009.htm

³ http://www.theyworkforyou.com/whall/?id=2009-03-04b.307.0

Remarkable new central London conduit plan of 1718

2011-01-18T12:13:00.009Z

As an example of a conduit system contemporary with Greenwich Hospital, this incredible plan from 1718 showing the huge conduit network of Hyde Park, St James's Park and the area of St Martins Lane/Charing Cross is relevant and important.

The network was probably mostly lead pipes, but almost certainly there were originally hundreds of feet of passageway in addition to the pipes, along with interesting cisterns and a multitude of conduit-related infrastructure. It's highly likely that some parts of the system still exist. Getting permission to do anything in the Royal Parks is usually almost impossible, so sadly the intransigence of the Royal Parks Agency will continue to stifle historical and archaeological investigation as it has done for decades.

These conduits are, however, much older than the 17th or even 16th centuries:

A Supply of water by conduit from this spot [a conduit memorial in Hyde Park] was granted to the abbey of Westminster with the Manor of Hyde by King Edward the Confessor. The Manor was resumed by the Crown in 1536 but the springs as a head and original fountain of water were preserved to the abbey by the charter of Queen Elizabeth in 1560.¹

Edward was the last of the Saxon kings² - allowing this conduit system to claim an antiquity of almost a thousand years. It therefore pre-dates most British mediaeval monastic systems, and knocks on the door of Saxon London (Lundenwic), whose focus had shifted a mile west of Roman Londinium to the Covent Garden area. The people of Lundenwic would certainly have been aware of the springs in what is now Hyde Park, and would probably have made efforts to bring the water eastwards to help supply the expanding town. It would not be surprising if there were remains of Saxon plumbing still intact under the lawns of Hyde Park.

↑ Click for a huge version (4.4MB 3968 x 2464)

¹ http://commons.wikimedia.org/wiki/File:Conduit_Hyde_Park.jpg

² Technically the last Saxon king was Edgar the Aetheling, who was proclaimed king briefly in late 1066, but was deposed after about eight weeks.

Charlton tunnel cave - a rail tragedy waiting to happen

2010-12-09T18:36:00.034Z

In 1849 a cave in chalk was discovered underneath the level of the railway line while excavating one of the tunnels underneath Maryon Wilson Park (between Charlton and Woolwich Dockyard stations). The railway passes across the entire breadth of one of the chambers, and the only work that was done to support the railway was described as "shoring up a part of the roof of one of the chambers." The current condition of that shoring is unknown, as is the exact location of the cave. Dozens of trains use this line every day, passing through the two short tunnels at up to 40mph. The vibration and weight will sooner or later cause a ground collapse inside the tunnel, causing derailment and a potentially extremely serious accident, perhaps involving localised complete internal collapse of the tunnel lining onto carriages.

The western tunnel is Charlton Lane Tunnel 154 yards.

The eastern tunnel is Mount Street Tunnel 121 yards.

It is not known which tunnel the cave is located in.

At the very least Network Rail must impose an immediate and strict speed limit through the tunnels of 5mph until thorough investigations can be carried out. "Thorough" means taking up all tracks through both tunnels and carrying out a tight 1m borehole grid until the cave is located. It must then be surveyed and made completely safe to modern civil engineering standards.

The article describing the cave appeared in the Kentish Mercury on Saturday March 24 1849. It provides unequivocal and undeniable evidence that the cave is located directly underneath the tracks currently in daily use. Not only is the condition of the 150-year-old shoring unknown, but also the condition of the chalk passageway (part of an unknown denehole or chalk mine) may well have deteriorated - galleries of this type have a hard enough time remaining in good condition without weight or vibration.

In the absence of knowledge about the current condition of the cave, this tunnel is a tragedy waiting to happen. Network Rail must act immediately.

↑ Click for a larger version (641k 825 x 1000)

Here is an exact transcript:

DISCOVERY OF A CAVE IN HANGING WOOD. -During the operations of the workmen on the North Kent line of the South Eastern railway, when tunnelling under the hanging woods, at Charlton, near Woolwich, they came upon a cave, of considerable dimensions, cut in the chalk and flint rocks. A great quantity of sand has fallen at one end, blocking up the side from which it has apparently been entered, and the workmen are now busily employed in shoring up a part of the roof of one of the chambers, the railway passing over its entire breath. Four chambers have been discovered, forming alternate recesses, from the main cave leading in a westerly direction. The roof of the cave is on a level with the line of railway, and the base 12 to 14 feet lower. The atmosphere in it is remarkably dry and pure, and presents a great contrast with the damp and close atmosphere experienced in passing along the tunnel to the extremity where the cave has been discovered. The men state they found a knife and a spoon on exploring it, and they turned their discovery to good account on Sunday, having lighted the whole of the tunnel with candles, and conducted visitors over the cave at the extremity, charging them 3d. for admission.

Is the cave a denehole or a chalk mine?

Deneholes are known to have existed at Hanging Wood. F.C.J. Spurrell notes the presence of deneholes at Charlton in the Archaeological Journal XXXVIII (1881):

In the direction of Charlton are some. The late Sir T. M[aryon] Wilson told me of several, and that one which fell in at the east end of his avenue was examined by him. He mentioned several which once existed at Hanging-wood

However, the description above of four chambers forming alternate recesses in a "main cave" steers my opinion slightly more towards this being an orphaned section of passageway from a chalk mine of unknown extent. This is a very important issue, because if this is a chalk mine, there may be further mine galleries under the railway that were not discovered while driving the tunnels in 1849. This aspect underlines the importance of using a tight borehole grid throughout both tunnels and the open section of track between them to locate any voids.

How old is the mine gallery?

The gallery was part of a disused mine working; it's impossible to say how many years before its rediscovery it was abandoned - maybe only 10-20 years, maybe 100+ years. If it is a denehole, then it may be up to 800 years old. The age of a chalk working doesn't necessarily predict its strength and stability - some of the Victorian workings under Alliance Road in Plumstead were highly dangerous, with numerous roof collapses occurring, wheras we have been in 700-year-old deneholes which are still in excellent condition. Whatever the age of the chalk working under the railway, it must be found and inspected.

After finding the mine working, then what happens?

The first question that must be asked is whether it's a denehole or part of a chalk mine. If it's a normal denehole, then it will be a self-contained working of a small size. If it's part of a pillar-and-stall mine working (similar to Chislehurst Caves), then the sand fill described as blocking one end of the gallery must be safely dug through, supporting the roof to protect the workers, to investigate if the gallery continues. The attitude must be to suspect that there are further unknown mine galleries under the railway line, and to search exhaustively to remove all doubt. It should be added that deneholes tend to occur in clusters, so there would still be a risk of other unknown deneholes nearby whose chambers might also undermine the railway.

What if boreholes in/between the tunnels find previously unknown galleries?

All new passageway must be entered and surveyed, and a complete plan drawn up of the mine working. If the working is very extensive, the most cost-effective solution is localised filling/strengthening near the railway, with permanent access points created which allow regular inspections of the rest of the mine to check for deterioration.

↑ The railway tunnels in about 1880 - click for a larger version (1.1Mb 1200 x 805)

↑ Click for a larger version (460k 1000 x 681)

↑ By 1746, huge sand and chalk pits were already cutting into the north east corner of Hanging Wood - demand from the growing military-industrial complex at the Dockyard and Arsenal was insatiable. Click for larger version (1.1mb 1332 x 1018)

↑ This 1790 panorama of the Dockyard, looking south, shows the Hanging Wood pits on the right, with further new pits opened directly behind the Dockyard. Click for larger version (613k 1798 x 343)

↑ Charlton Lane tunnel - click for a larger version (957k 1000 x 978)

↑ Mount Street tunnel - click for a larger version (900k 1000 x 990)

How much did railway locomotives weigh in the late 1840s?

The Jenny Lind, a highly successful and much-copied design of the late 1840s weighed only 24 tons.

Today the typical maximum single axle load on the North Kent lines is about 20 tons - not far off the entire weight of Jenny Lind, whose modest weight the 1849 shoring underneath the tunnel would have been designed to support. The individual bogies of new generation locomotives used on this line each weigh about 60 tonnes.

↑ A typical 2-2-2 design built in 1849 for the London, Brighton and South Coast Railway, the very same year that the Charlton tunnel cave was discovered. Click for a slightly larger version (221k 1055 x 593).

To expect the shoring under the tunnel to withstand present-day axle loads and bogie weights is insanely optimistic.

Blackheath Cavern: 1946 Craske report

2010-12-09T09:26:00.004Z

Full facsimile of the 1946 Craske report - a fairly accurate account of the Cavern. It suffers from the sweeping statement "no part of the cavern remained hidden" - a reference to the discrepancy between early descriptions mentioning seven apartments and later ones only four. Craske's assertion is contradicted by the three boreholes sunk by LeGrand, Sutcliff and Gell which all found firm evidence of further passageway that had either collapsed or been backfilled. Click any page to open a larger version with a height of 1200 and a file size of about 800K.

Woolwich 1963: hole in road eats truck

2010-12-08T07:43:00.002Z

At the beginning of April 1963 a huge hole opened up underneath a truck at the junction of Plumstead Road and Invermore Place in Woolwich; the cause was never fully established.

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Smugglers' tunnel at Woolwich Ferry

2010-12-08T07:05:00.002Z

In 1957 15 feet of passageway were discovered during foundation works at the garage/petrol station close to Woolwich Ferry; this was almost certainly a remnant of a much longer tunnel. The note "similar to a tunnel found before the war" doesn't clarify if it was the same tunnel but rediscovered for a second time, or something entirely separate. The 18th century decapitated model soldier is a nice find, probably intended to be a toy and discarded when broken - some things never change.

↑ Click for a larger version (349k 305 x 1500)

↑ The garage forecourt can be seen just left of centre. Click for a larger version (498k 1020 x 606)

An undercroft in Park Vista

2010-12-08T06:48:00.001Z

This antiquarian cutting describes an undercroft discovered in Park Vista, probably dating to about 1700. It spans two much more modern properties; we have examined both sides (a partition wall has been inserted underground to divide the space in line with the boundary). An interesting snippet is buried in the text: "Another resident of Greenwich had discovered the head of an old water conduit and traced an underground passage for 30ft." It's a frustratingly vague note.

↑ Click for a larger version (637k 437 x 1800)

Queen's House: culverts and air ducts

2010-10-26T04:15:00.005+01:00

During 1985 the Queen's House underwent considerable refurbishment, with an extensive culvert system being found along with a slightly later and quite unusual air duct system. This text is from the Museum of London (GRN85: Durnford, P, 1985 Queen’s House basements, archive report. MoL):

A watching brief took place in the N half of the basement during refurbishment of the 17th-century Queen's House. Doorways, sills and brick floors relating to the 17th-century building were revealed but the majority of the original levels seem to have been destroyed, probably in the early 18th century when an extensive drainage system was inserted. The drainage system consisted of brick-built ducts which drained to the NW of the building and the 'principal drains' of which formed an almost complete circuit. An air duct system, post-dating the drains, was also recorded; it was fed by a stoke pit found in one of the rooms close to the main entrance of the basement. It may be dated to the mid-late 18th century. By the early-mid 19th century, most of the drainage system had fallen out of use, its arched brick capping broken through and the ducts infilled. The air duct system had also been modified, if not abandoned. The disuse of these systems occurred at a time when the Royal Hospital School first occupied the house and made many alterations: some of the brick partition walls and other features of these alterations were located. A concrete floor (now removed) then covered most of the basement.

Site record: GRN85
Site name: Queen's House, National Maritime Museum
Site location: Romney Road, greenwich, SE10
Borough: greenwich
Year: 1985
Latitude: 51.4812822 Longitude: -0.0038444
TQ38527752
Organisation: HBMC
Type of fieldwork: watching brief
Archaeological periods: 17th century, 18th century, 19th century, 20th century

Conduit house at Queen Elizabeth's Oak - new photo

2010-10-21T04:31:00.017+01:00

A stunning new Victorian photo has just emerged that shows - partially but clearly - a conduit house close to Queen Elizabeth's Oak. The picture was buried amongst hundreds of National Maritime Museum seafaring photos, simply titled "Royal deer in Greenwich Park". The date could be anywhere during 1860-1890, because wet collodion plates continued largely unchanged during these three decades. Wet collodion can often be identified by the odd tonal rendition of colours - it does not give a panchromatic response as modern monochrome emulsions do. The tones of the seated woman's clothing are very strange, strongly suggesting this type of photography (unfortunately her head is lost by blur during the exposure of several seconds). This is significantly earlier than the bulk of historic photos of the park which were made possible by technological advances during 1900-1910. Look at the right hand edge of the photo:

↑ Click for a larger version (443k 1280 x 1259)

This may look like just a blurry old photo, but photographs of the conduit houses inside the park (many of which had been demolished by 1900) are vanishingly rare. Photography was still in its infancy at this time; the image above is a rare beast to stumble across.

East Lane Reservoir, Park Vista

2010-10-20T01:56:00.009+01:00

A large Tudor cistern - East Lane Reservoir - was originally located in what is now Park Vista, opposite the mouth of Feathers Place. A rather untidy patchwork of post-medieval houses, including a vicarage, now occupies this strip of land. With the kind permission of all the householders we have diligently searched for remains of the fabric of the conduit house - whose appearance we reliably know as early as 1670 - but without any success; rebuilding has simply been too extensive and invasive. Remains of an arched vault were seen in the roadway close to these properties during gas main repairs in the 1980s, though sadly no photographs were taken at the time.

The 1620 view towards the palace from the park just shows what must be the structure - there is some artistic licence used, but the four-gabled roof is still discernible:

The (approximately) 1670 view is a lot clearer:

Hawksmoor's drawing of 1720 shows the conduit house very well - he calls it Queen Elizabeth's Conduit. It appears to have been quite a substantial structure, and may well have been extremely similar to the lower Coombe Conduit House in West London that supplied Hampton Court Palace in Tudor times. A small stream of water issues from the front and dribbles into the road:

↑ Hawksmoor's drawing of 1720 - click for larger version (261k 1000 x 842)

↑ The lower house of Coombe Conduit, which supplied water to Hampton Court Palace in Tudor times; click for larger version (614k 768 x 1024). Photographer unknown - please contact me for a credit or deletion if it's you.

The arrangement of any associated subterranean vaults or passageway at the East Lane Reservoir is unknown, and it has yet to be proved that the brick vault seen in nearby roadworks was contemporaneous with the conduit house or simply redundant cellarage. It received water via lead pipes from conduits both inside the park and also to the east, outside the park walls.

The Admiralty survey of 1780 describes it thus:

an Building, but which is now converted into a stable, but appeared by the old surveys to have had a great reservoir in the loft of it, for all the waters in the east side of the park. This reservoir stood opposite the end of East Lane [now Feathers Place], and among other places afforded a supply of water to the yards and houses of the officers of His Majestys Works near the Crane

I'm not really convinced by the idea of a reservoir in the loft - ie the first floor (UK) or the second floor (USA). Until more contemporary evidence emerges, a high-level tank (probably lead-lined and constrained by masonry) will remain as pure speculation. A modestly-sized cubic tank with sides of 2m holds 8m³ of water, which weighs 8 tonnes. Increase the sides to 3m (27m³), and suddenly the weight increases to 27 tonnes. While the Tudor engineers could have built a structure strong enough to carry the weight, the idea of a "great reservoir" at first floor level seems slightly implausible; extensive use of a carefully-chosen building stone would have been required to withstand the weight, as seen in larger churches and cathedrals. Something like Hampton Court's Coombe Conduit seems more likely; water pressure up to first floor level in Placentia was mainly achieved by having conduit houses on the slopes of the park and adjacent hillsides at a higher level than the roof of the palace.

↑ Click for a larger version (491k 1024 x 609)

↑ Seen from the Thames, approx. 1755

SubG: approved by National Monuments Record

2010-10-13T05:14:00.002+01:00

Our coverage of the Hyde Vale Conduit has recently been accepted by the National Monuments Record and their website PastScape as an authoritative source of information. To see the record, please click here - you will need to scroll down and click the plus symbol next to "More information & sources". After many years of work in and around Greenwich, this is a small but significant acknowledgement of our efforts.

A 1905 cutting - Interesting Investigations

2010-10-07T14:34:00.002+01:00

An interesting 1905 newspaper cutting turned up recently - many thanks to Graham Dolan. Unusually, it describes the contemporary external appearance of the staircase access in Hyde Vale, which agrees with our photo discovery of the same that can be seen here. Stone's investigations are well known, but here we are given the identity of one of his co-explorers: the subterranean vicar Rev. S.M. Bardsley.

↑ Click to enlarge (122k 429 x 1051)

Miscellanea at the Royal Naval College

2010-10-02T03:22:00.014+01:00

↑ Click for larger version (550k 1012 x 597)

A diverse collection of items discovered during 1999-2008 are included in this round-up of subterranea from the former Royal Naval College, now Greenwich University. Although all the sections of passageway (we define passageway using the caving description - any subterranean space a human can move through) have been covered over with tarmac etc, it's nevertheless important to document them all. There is one outlying item located in Woolwich - number 7 in the list and citations below.

Many thanks to MOLA for allowing me to quote their text.

A 17th century truncated wall, running north-south was revealed, along with the 18th century foundations of the Queen Anne Quarter. Further 18th century walls and culvert were also observed.¹

The first watching brief involved the monitoring of a drainage trench on the east side of the Queen Mary Quarter. Part of a wall from the 17th century "Captain Guy’s House" was revealed, which had been truncated by the construction of the Queen Mary Block in 1698, the foundations of which were also exposed. Part of a 19th century culvert was also exposed.²

During the second watching brief six geotechnical test pits were monitored in the car park east of the Queen Mary Quarter. The remains of an 18th century culvert were excavated, overlain by 18th and 19th century demolition and dump layers.²

The watching brief took place in the courtyard of the complex, revealing fragmentary chalk foundations truncated by later culverts of 17th and 18th century date, and to the west of the building, wall footings of the 17th century overlaid by 18th century fills.³

The structural features revealed were all associated with the initial construction of the building between 1699 – 1708. Two such features were walls and the third was an internal cess pit, the first observed of this period in the Greenwich Hospital complex.⁴

At the eastern end of the trench was a deep late 17th century brick lined cess pit, almost certainly part of "Captain Sanderson’s House." At the western end of the trench was the corner of one of the large cess pits built in the 1730s to serve the Queen Mary Quarter.⁵

Most of the trenches have revealed recent made ground deposits. Brick foundations near the King Charles Quarter however, may be of 17th/18th century date. 19th century culverts were also present.⁶

The watching brief revealed the foundation walls of the Royal Dockyard buildings: the Engine House and Lathe Shop (area 1), the Iron Foundry (area 1), Boiler Makers (area 1) Punching and Pattern Shop (area 2), the Shop for Marine Engine (area 1) and tunnels which bisected the site.⁷

The major construction on the site was a large barrel vaulted cess chamber known to have been built for Greenwich Hospital in the 1730s. Retaining walls of the 19th century were the most recent features. Trench 2 revealed a number of fragmentary structures, layers and drains dating from the 17th to 19th centuries. Trench 3, to the north, was entirely taken up by another 18th century cess chamber.⁸

A large 19th century drain / tunnel was revealed near the west gate.⁹

Work continued from 2005. Excavations revealed the eastern end of the Chapel Royal of the Tudor Greenwich Palace, c. 1504. The chapel had a tiled floor and stone moulding on its walls and doorways. An integral drain was found below.¹⁰

Following earlier work in 2005, a watching brief was carried out on landscaping works on the lawns west of the King Charles and King William Quarters, on the car park east of the Queen Anne Quarter, and on four tree-planting trenches in the south-east corner of the site. During the stripping of the lawns, only two archaeological features were observed; At the eastern edge of the King Charles lawns a 19th century water tank was recorded, while along both sides of the N-S pathway, W of the King Charles Quarter, were traces of the original retaining walls. In the Queen Anne Outer Court, a brick and stone lined well (dated broadly to the 15th - 16th centuries?) had been truncated by a wall of early 18th century date.¹¹

During the evaluation four trenches were excavated. Trench 1, in the Regatta Café Courtyard, revealed natural gravels truncated by an undated E-W aligned linear feature containing a clay fill and covered by a thin silt layer. This layer was cut by an E-W aligned brick culvert of probable early 19th century date which was sealed by a clay layer beneath modern silt, rubble, and flagstone paving.¹²

¹ Data cable route, former Royal Naval College SE10 (RNV99) west TQ 3845 7784 east: TQ 3868 7799 MOLA (Julian Bowsher) watching brief January - July 1999 University of Greenwich RNV99

² Queen Mary Block, drain trench and car park, former Royal Naval College, Greenwich SE10 (RNM99) TQ 3867 7795 and TQ 3869 7792 MOLA (Julian Bowsher and Anthony Mackinder) watching briefs June-August 1999 DTZ Debenham Thorpe and Peter Brett Associates (on behalf of the University of Greenwich) RNM99

³ King Charles Quarter, Old Royal Naval College, Greenwich, SE10 (RNK00) TQ 3850 7793 MOLA (Julian Bowsher) evaluation and watching brief May-November 2000 Trinity College of Music and Greenwich Foundation RNK00

⁴ King William Quarter, Royal Naval College, Romney Road SE10 (RNO00) TQ 3860 7782 MOLA (Julian Bowsher) watching brief May-August 2000 University of Greenwich RNO00

⁵ Queen Mary Quarter and East Gate, former Royal Naval College SE10 (RNM99) TQ 3869 7792 MOLA (Julian Bowsher) excavation and watching brief November 1999- May 2000 The University of Greenwich RNM99

⁶ BT and Gas Trenches, Former Royal Naval College SE10 (RNY01) TQ 3850 7793 MOLA (Julian Bowsher) watching brief January 2001-ongoing The Greenwich Foundation for the Royal Naval College RNY01

⁷ Ruston Road/Woolwich Church Street Woolwich SE18 (WCS01) TQ 4230 7908 MOLA (Rosemary Joynson) watching brief July-August 2001 Countryside Properties WCS01

⁸ Greenwich Armoury, former Royal Naval College SE10 (KIC02) TQ 38468 77908 MOLA (Julian Bowsher) evaluation July 2002 Time Team / Greenwich Foundation KIC02

⁹ Thames Water trenches, former Royal Naval College SE10 (RNW00) TQ 38583 77924 MOLA (Julian Bowsher) watching brief April - September 2002 Greenwich Foundation RNW00

¹⁰ Queen Anne Outer Court, Old Royal Naval College, Greenwich SE10 (RND05) TQ 38651 78021 MOLA (Julian Bowsher) excavation September 2005-February 2006 The Greenwich Foundation for the Old Royal Naval College RND05

¹¹ Landscaping Works, Old Royal Naval College, Greenwich SE10 (RNE05) TQ 38560 77915 MOLA (Julian Bowsher) watching brief March 2007 Chris Blandford Associates on behalf of The Greenwich Foundation RNE05

¹² South West Wing, National Maritime Museum, Greenwich, SE10 (NAM08) TQ 38575 77581 MOLA (Agnieszka Bystron, Julian Bowsher) watching brief and evaluation April-May, August 2008 National Maritime Museum NAM08

The original block of URLs this material is derived from are these - choose your year from the menu and click GO:

Small cistern - Maidenstone Hill

2010-09-17T03:01:00.006+01:00

A small bottle-shaped cistern recently turned up at one of the older houses in Maidenstone Hill; smooth rendered inside, about 1m x 2m with a current depth of about 1.5m to the spoil heap. Age unknown (late Georgian?), probably with altered uses over the years - ie cistern then cess pit then rubbish pit. Extremely difficult to photograph inside without an ultra-wide-angle lens. At one end a 2 inch lead pipe leads in and dives down vertically into the spoil heap, destination unknown; at the other a 5 inch earthenware pipe enters, possibly for sewage.

I'm afraid it's not exactly a huge length of passageway or a vast cavern, but the lead pipe may lead back to something altogether much bigger and more exciting - like a conduit.

Two Blackheath Ice Houses

2010-09-13T08:35:00.017+01:00

Ice Houses are like buses here at SubG; you wait ages then two come along together. The two here are both on the West side of the heath, and only about 6 or 7 minutes walking time apart. It's quite likely they were constructed within a few years of each other, possibly even by the same builder. Both were almost certainly the typical half-buried egg shape with a double brick skin covered with a mound of earth; a brick drain at the base would have removed meltwater.

One was in the garden of a substantial 18th century villa on Dartmouth Row, close to Dartmouth House, and alas has now been destroyed and heavily built over. The other was located on a three acre plot of land leased by Lord Cardigan in 1758 from The Legge family, the Earl of Dartmouth and Viscount Lewisham. Its circular foundations were discovered many years ago in a garden on Eliot Vale and promptly misdiagnosed as a signalling beacon - with Tudor brickwork to boot - by someone clearly unversed in the principles of archaeology. Traces of the Eliot Vale ice house may still exist; we are in discussion with the relevant landowners to investigate the location.

You might also be interested in this post about the Brooklands Ice House in Blackheath, another 18th century example.

Watch out for idiosyncratic compass orientation in these plans...

↑ North is bottom left; click for larger version (496k 1000 x 674)

↑ North is at the bottom; click for larger version (572k 962 x 704)

Conduit engineering

2010-09-08T17:21:00.007+01:00

An accurate vintage cross-section through part of Queen Elizabeth's Conduit (near the old drinking fountain below Queen Elizabeth's Oak) - the open brickwork to allow water to percolate into the passage is clearly shown. The lead-lined gutter collected the water and passed it through a lead strainer to a settlement tank, from where it was piped down to the Royal Hospital.

↑ Click for a larger version (1.27MB 1500 x 1391) Image: London Borough of Greenwich Heritage Centre

Staircase into Hyde Vale Conduit - photo discovery

2010-09-08T00:18:00.023+01:00

Remarkable historic photos have come to light showing the archway which opened into the staircase of the Hyde Vale Conduit halfway along its length. The date is probably around 1900; a newly-discovered contemporary photographic view down the valley also shows the archway, with its light-toned stone plinth being easy to see. We had been hoping to unearth something like this for 25 years, and are delighted to finally publish these fascinating pictures for the first time ever.

Click here to see the main post about the Hyde Vale Conduit.

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Photos above by courtesy of London Borough of Greenwich Heritage Centre

Dartmouth Row - 18th century brick drain

2010-09-03T00:38:00.004+01:00

A vintage subterranean photo probably taken during the 1940s, showing an 18th century brick drain found in the garden of a house in Dartmouth Row. At the same property we examined a well with a short length of small passageway attached, but were unable to find the drain in the photo. The house number has been censored to protect the occupants from excessive public interest.

↑ Click for larger version (490k 800 x 857)

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Both photos Copyright: Trustees of the late Alan Roger Martin.

Admiralty Western Reservoir - revealed

2010-09-02T20:31:00.008+01:00

At the beginning of World War II the Admiralty Western Reservoir (the large subterranean structure a few metres uphill from the Standard Reservoir building) was opened for use as an air raid shelter. Here is a unique photo showing the works in progress:

Copyright: Trustees of the late Alan Roger Martin. Click for a large version (2.04MB 1500 x 1600)

Sayes Court mine, Deptford

2010-09-01T06:40:00.019+01:00

On John Evelyn's 1653 plan of Sayes Court in Deptford (Copyright © The British Library Board), there is a sand or gravel pit shown at the bottom right corner - with the entrance to a mine gallery clearly shown. To the untrained eye it may not look very clear, but once you understand the artistic conventions of the 17th century, it becomes obvious. Compare the method of showing the entrance with that used in the painting/plan (inset in second image) of Maze Hill mine - the technique is identical. Presumably it was a sand mine, as the alluvium which occurs in this area of the Thames valley is of little commercial value.

Our Correspondent "K" makes interesting points about the pit - that it already existed when Evelyn made the drawing, so predating 1653; also Evelyn's comment on the pit area: "an extravagant [=overgrown?^k] place mangled by digging gravell"

↑ Evelyn's plan of Sayes Court 1653 (Click for a large version 435k 1600 x 1387) - look in the bottom right corner, and you will see this:

↑ A closer view - inset shows the contemporary depiction of entrances at Maze Hill mine. Click for a slightly larger version 160k 494 x 464

The main objection to the mine existing is that today there appears to be insufficient vertical space between the high water mark of the Thames and the land surface to dig a mine gallery. However, that difficulty can be overcome by looking at the date of the plan - 1653 - during the LIA (Little Ice Age) when the average sea level was at least 25cm lower than it is today.

The Wikipedia article defines the LIA very well:

The Little Ice Age (LIA) was a period of cooling that occurred after a warmer era known as the Medieval Warm Period. While not a true ice age, the term was introduced into scientific literature by François E. Matthes in 1939. It is conventionally defined as a period extending from the 16th to the 19th centuries, though climatologists and historians working with local records no longer expect to agree on either the start or end dates of this period, which varied according to local conditions. It is generally agreed that there were three minima, beginning about 1650, about 1770, and 1850, each separated by intervals of slight warming.

↑ The fall in global sea level during the LIA is very clear.

Note that the plan was drawn in 1653 - coinciding exactly with the first Minima of the LIA, when sea levels would have been at their lowest.

If any of the gallery/mine still exists, it is now probably partially flooded and in a highly dangerous condition.

↑ The pit was on the south side of Leeway, which partially follows "the old watring pond" alongside the pit^k (click for a larger version 356k 659 x 610). The area shown in the bird's-eye view is still much the same now. It's the far corner of Convoys Wharf.^k

^k Words of Correspondent K

Mr Holmes and the subsiding lady

2010-08-27T03:38:00.065+01:00

I well remember the remarkable morning of Thursday April 12 1878, during which a gathering of eminent gentlemen assembled in the swirling mists of Blackheath to witness a singular scientific phenomenon. Having arrived early at the suburban hamlet of Blackheath on the 7.17 from Charing Cross, I ascended to the summit of the plateau, being immediately consumed by the fog and uncertain ground occasioned by centuries of gravel digging. That this place in recent memory had harboured vagabonds and highwaymen could not be doubted, and indeed a vintage yet effective pistol lurked in the folds of my greatcoat as a foil against such happenings. As I reached the crest of a particularly deep cavity, a disembodied voice shouted from my right.

"Mr Holmes, is it you? Mr Holmes?"

I recognised in a moment the commanding tones of Sir George Airy, the country's greatest astronomer, who had recently arrived after a short perambulation from his offices at the Royal Observatory a few furlongs distant. The gesticulating body was momentarily lost in the mists, reappearing sudddenly much nearer to me.

"Good Lord, man," he exclaimed through the high folded collars of his jacket, "how we can hope to find one another in this waste land is a mystery. Thank you for arriving at such short notice - we have found something most peculiar, and the cause at this moment is rather beyond our explanation, learned gentlemen as we are."

Taking out my pipe, which had a tendency to concentrate my thoughts, I replied, "Sir George, everything in nature can be explained if we can set our hands on the relevant information, however extraordinary events may be."

We shook hands warmly, and made all haste through the gorse bushes to a cluster of well-wrapped men standing in a circle around some noteworthy spectacle, as a group might worship a bonfire on an icy January night. But there were neither smoke nor flames, and as the group parted for us with welcome salutations, the object of their attention became immediately apparent: a fathomless cavity in the ground about seven feet in diameter, whose bottom could not be seen in the dim grey air that embraced us.

The above is my fanciful but not impossible dramatic reconstruction of the investigation into the Blackheath subsidences of 1878; the Mr Holmes in question is not the great detective (who did not appear in print until the publication of A Study in Scarlet in Beeton's Christmas Annual 1887), but Mr T.V. Holmes F.G.S. - an expert geologist of the time.

The Blackheath subsidences came to public attention when three occurred in fairly quick succession after the extreme rainfall of April 1878. T.V. Holmes is our guide (from The Engineer Feb/March 1881):

"During the night of Wednesday and the early morning of Thursday, April 11th and 12th, an extraordinary fall of rain visited the metropolis and its outskirts, causing an amount of distress from floods which appears scarcely ever to have been equalled in that part of the kingdom. The inundations were particularly severe in the valleys of the Ravensbourne and the Quaggy - a fact to which Sir Joseph Bazalgette bore witness in a report which he made as the engineer of the Metropolitan Board of Works. On the morning of Thursday a singular phenomenon presented itself on the broad open plateau of Blackheath. At a spot near the ride known as "Rotten Row," the earth was found to have sunk in to a depth of about 20ft., leaving what was described at the time as a "dangerous hole eight or nine yards in circumference." [location A on plan] The Metropolitan Board, who had jurisdiction over the heath, first of all placed a fence round the mouth of the shaft, and subsequently filled it in. The fence was then removed, and there was apparently an end of the matter. But early in November last another hole [location B] of a similar character opened in the Heath at a spot considerably to the westward of the first subsidence, and on the 19th of that month a third aperture [location c] presented itself, not far from the first. Parties residing in the neighbourhood began to think that these earth-falls were looking serious, as it was impossible to say where they might ultimately show themselves.

The aperture A is that which first appeared. It is situated about 250 yards from the nearest point of the park wall, close alongside of which runs the Charlton-road. Its position upon the Heath is very central, being about 370 yards E.S.E. from the large gates leading out of the park. The second aperture B is situated rather more than 600 yards distant from A, in a direction S.W. by W., while the third, C, is only about 110 yards from A, in a south-easterly direction. The subsidence A, being filled up, is not available for examination; but the committee have examined the fall C, with very interesting results. The subsidence was found to consist in the first place of a shaft, almost circular in form, being 7ft. 8in. in the longest diameter, and 6ft. 9in. in the shortest. The sides went down vertically to a depth of 18ft., and had all the appearance of a well, or artificial shaft. At the bottom was a heap of fallen earth, and when this was removed the sides were found to recede, the hole increasing in its diameter to about 14ft."

↑ The subsidence map updated by T.V. Holmes in 1907 with the line of the great sewer constructed under the heath; the sewer contractor provided important information about natural caves discovered in the chalk 100 feet below ground (see below). Click for a larger version (113k 1000 x 1053)

The Blackheath Subsidences Committee proposed many theories, mostly focussing on the action of natural groundwater, although some suggested collapsing denehole shafts. No firm conclusion was reached, but they were favourably disposed to the "hydro-geological" theory. T.V. Holmes curiously went on to state in a 1907 article that he thought the denehole theory was the best idea. He rejected the possibility of shallow mine galleries, despite the fact that sand mining had taken place on the heath in living memory at the time he was writing:

That a gallery was run in from one of the valleys in the side of the heath, or even from one of the pits which are to be found there, appears extremely unlikely.

A slightly bizarre illustration to show the cross section and scale of the subsidences appears in the Engineer article: a Victorian lady subsiding into the ground. What readers thought of this treatment is not known. The scale of the lady is woefully inaccurate; if the hole was 18ft. deep, that would make her about 20ft. tall.

↑ Click for a larger version (259k 1000 x 967)

Caves under the heath

Three very substantial natural caves in the chalk were encountered during the construction of the great sewer across the heath around 1903-4. Natural passageway was found near shafts 4 & 6 on the heath, as well as near the Mycenae Road shaft (see the plan of the heath further up this page for the line of the sewer). Bearing in mind that this was just one transect across the heath, it's safe to say that there must be dozens of similar cavities, some with active stream systems and others now dry (what cavers call "fossil" passageway). Chalk is a soluble rock, meaning that for the foreseeable future these caves will pose a hazard to human activity on and around the heath. The most likely cause for the majority of the Blackheath subsidences is voids from collapsed chalk caves migrating to the surface. The proven history of sand mining on the heath may also contribute occasional ground collapses due to the roof failure of shallow mine galleries; these collapses may be difficult to distinguish from voids that have migrated up from a much deeper level.

↑ Natural caves discovered under the heath; the diameter of the sewer is about 10 feet, which shows the scale of the cavities very well. Click for a larger version (2.28MB 3064 x 1090)

Blackheath subsidences historical round-up:

- November 12th (approx) 1798: "A singular accident happened last week at Blackheath. As a farmer and his son were conversing together in a field where a horse was feeding, on a sudden the animal sunk into the earth (hind feet first) to the depth of 15 feet, out of which he was dug, crushed to death. The cavity was only just sufficient to admit his body, the surrounding soil remaining firm."

- Transactions of the Geological Society of London Vol 4 1817: "In the year 1803, an extensive excavation which had formerly been made into these strata was laid open; it was supposed to extend to the chalk beneath, but the roof fell in and the passage became choaked [sic] up before it had been explored".

- John Winn (reminiscence given to Hart): "...about the year 1820 another place, not far from the large windmill near Whitfield's Mount, dropped down in the like manner to a great depth."

- [1876] "a strange subsidence occurred five years ago in Kidbrook Park Road, on the eastern border of Blackheath" Source: Popular Science Review, 1881, New series VOLUME V (volume XX of entire series)

- Thursday April 12 1878 - subsidence A

- Early November 1878 - subsidence B

- November 19 1878 - subsidence C

- F.C.J. Spurrell mentions in 1881 (Archaeological Journal XXXVIII) that other similar holes on the heath had been "behaving in a similar way; one of them was near "Washerwoman's Hole" [part of the heath adjacent to Royal Parade]. Some have been slipping gently for many years in the gravel pit near Whitfield's mound."

Blackheath Vale sand mine

2010-08-20T13:44:00.023+01:00

Blackheath Vale, formerly a modestly-sized gravel pit, boasted its own mini-sand mine, one gallery of which was open as recently as the late 1940s/early 1950s. Two witnesses - Bob Land and another gentleman - both independently remember the sand "cave". Their account appears in a brief correspondence in the Blackheath Bugle blog of January 5th 2009, and I reproduce the excerpt here with the kind permissions of both the Bugle and Bob Land:

Bob Land
March 25, 2009 at 4:59 pm

Peter,
Regards the ”bomb dump” in Blackheath Vale , I remember that as well, do you remember seeing a ”cave” in the sand , about half up the sheer wall on the Heath side of the Vale, we used to venture into it, but did not dare to go more than one or yards inside, afraid that the roof of the cave might collapse.

regards

Bob Land

--------------------

Peter C
March 26, 2009 at 12:28 pm

I do remember the sand cave. It was actually at ground level. It went in about 20 ft. (give or take because I was little at the time!) and then turned back on itself a few feet away. I seem to remember that you carried on and came out alongside the entrance but memories are hazy now. I do remember Miss Collins (the head mistress of All Saints school) telling us that it was a dangerous place.

↑Click for larger version (414k 1024 x 621)
Whether this mini-mine was contemporaneous with the late 18th century sand mine at Whitfield's Mount is unknown. It would be easy to write off the Blackheath Vale tunnel as the work of children or late Victorian amateurs, but the tradition of mining sand a stone's throw away as well as the substantial 20 feet of passageway suggest something more premeditated.

Could Goffers Road have mine galleries underneath it?

Yes - both at Blackheath Vale and up the road at Whitfield's Mount. Lewisham Council please take note.

But how can there be mine gallery below the level of both ponds (Hare & Billet and Whitfield's Mount)?

Because a water-resistant horizon (probably clayey) puddles the ponds that occur on the gravel. In Blackheath Vale you are walking around well below the level of the Hare & Billet pond. The same effect would have occurred at the Whitfield's Mount mine.

What action should Lewisham Council take?

Goffers Road is already partially protected from heavy vehicles by the width barrier at the top of the village. Installing temporary 7 feet width barriers at both the Blackheath Tea Hut and Hare & Billet entrances to Goffers Road would be prudent, pending a thorough investigation using traditional techniques like boreholes (drilled, not percussion method).

Winn's Chalk Mine, Blackheath Hill

2010-08-16T05:24:00.042+01:00

F.H. Hart, author of History of Lee and its neighbourhood (1892) gives us an account of a second chalk mine (ie NOT the Blackheath Cavern) at Blackheath Hill:

Mr John Winn, who then kept the Sun Inn, at the hill, informed us that about the year 1800 the earth dropped into an arched tunnel of chalk, north of the turnpike road, opposite these caverns, and that he and others went a great distance under the road, towards the Heath

Another account of the same date, extracted from the minutes of the New Cross Turnpike Trust Oct. 28th 1797, states:

It being stated to the meeting that within a few days past a great part of the Earth underneath the Road leading from Blackheath to the Limekilns on the North side had given way and with a part of the Road had fallen in a very considerable depth and that from the appearance of it more was likely to fall in owing to a large Cavern or Excavation beneath the Road, whereupon several of the trustees present went to the spot to view it and having seen the same and made Enquiry of some persons who were said to have explored the Excavation, it was proposed that a shaft or well should be dug in some part of it and the Cavity filled up with the earth from the adjoining Bank and be rammed in both perpendicularly and horizontally so as to make the whole solid and secure, but Mr. Driver and General Davis, two of the trustees present, offering to explore the excavation on Monday next, it was ordered that if upon Examination the plan proposed shall appear to be the most effective that it be carried into Execution, but at all events that immediate care be taken to prevent any accidents happening from the falling in of the Road and the Meeting agreed to adjourn...

Nov. 4th, 1797 General Davis and Mr. Driver reported that they had examined the Excavation under the Road leading from the Limekilns to Blackheath, that it runs in a southern Direction 33 ft. then turns south-west 33 feet 6 inches, then to the north north-west 47 feet to the centre of a part which rises higher than the rest in the form of a dome; that the average width is from 15 to 19 feet and about 12 feet on an average in height. They also reported that a shaft had been sunk at the Dome where the Earth was not more than 8 feet to the surface of the Road¹

↑ Reconstruction of the 1797 account; this is obviously not an isolated section of passageway, but part of a larger mine (click for a slightly larger version)

Remember that by 1800 the Blackheath Cavern had already been open for 20 years, and was being visited/used daily - there can be no doubt that what opened up was a different mine.

"North" of the turnpike road (Blackheath Hill) means on the same side as the Blackheath Cavern, although "opposite" implies it was on the other side of the road, which is puzzling. In any event, Winn had almost certainly been in the Blackheath Cavern, and well knew that the mine he entered via this ground collapse was not the same working. I suggested in my discussion of the Blackheath Cavern (here and here) that there is a missing mine in the vicinity of Maidenstone Hill; Winn's mine is a strong candidate.

Is Winn's mine the same as that explored by General Davis & Mr Driver? I'm not convinced it is. The survey by Davis and Driver can in no way be described as going "a great distance under the road, towards the heath".

Per von Scheibner was told a recollection that decades ago in the old pit on the South side of Blackheath Hill (bottom right of the aerial photo) there were blocked tunnel entrances; it's unclear what that reminiscence referred to.

↑ Blackheath Hill/Maidenstone Hill junction; click for a slightly larger version (373k 674 x 611)

This excellent 1823 map shows the area in question, but is of only limited help in unravelling the "north of the turnpike road, opposite these caverns" puzzle:
↑ Click for a larger version (483k 906 x 686)

What is most worrying is Winn's assertion (unique among the many historic reminiscences of the cavern) that "he and others went a great distance under the road, towards the Heath" - if he is referring to Blackheath Hill, then it opens the door to the possibility of more undiscovered galleries under the road in addition to the small one found after the 2002 collapse that simply connected open pits on each side of the road.

The investigation carried out after the 2002 roadway collapse is turning out to have been completely inadequate to address the issue of mining activity on Blackheath Hill. This inadequacy was made worse by the lack of subterranean exploration by mining historians - an experienced pair of eyes underground is everything. The agencies involved need to discuss with us a fresh schedule of investigations using proper techniques such as sinking shafts and driving headings underground (as was done at Plumstead in the 1950s) to intercept galleries. Keyhole surgery may be a good technique for humans, but for investigating chalk mines it's worse than useless.

¹ This information was quoted in the Records of the Chelsea Speleological Society, but unfortunately it was not quoted verbatim, leading to loss of accuracy in some details.

Whitfield's Mount Sand Mine, Blackheath

2010-08-16T04:49:00.046+01:00

It is absolutely certain that a sand mine once existed in Marr's Ravine, a long gravel pit located between Whitfield's Mount and Hare & Billet Pond. F.H. Hart, author of History of Lee and its neighbourhood (1892) personally inspected the tunnels:

The truth of this statement can be vouched for by the writer, he being one that entered this cavern at the end of the gravel pit, near the pond at the Mount ; it was then shown by a man from Lee, who charged 3d each for the use of candles. This cavern has fallen in on several occasions since that date, within the past 60 years, which the writer knows from experience.

Hart's location at the end of the gravel pit, near the pond at the Mount must refer to Marr's Ravine, an old pit that stretched down from the Mount to Hare and Billet pond; here it is, pictured in the 1890s or perhaps 1900-ish (it was filled and levelled in about 1903 with spoil from sewer digging) looking back towards the Hare and Billet:

↑ Click for a larger version (1.71MB 2000 x 1205)
A mine working on the heath was exposed by a subsidence in 1803 (see the note below from the Transactions of the Geological Society of London Vol 4 1817) - this is presumably the same one that Hart entered some years later, although it could have been elsewhere on the heath. Could the galleries have gone down to the chalk as suggested in the Geological Society excerpt? Highly unlikely, because when digging into the heath, copious quantities of water are encountered about 12m down, where it runs along the top of an impervious stratum, which would tend to inundate galleries dug below it. The chalk occurs much deeper at about about 30-35m.

↑ Note the description of an "extensive excavation". The Geological Society of London was not known for exaggeration but rather for stating unadorned scientific facts.

F.C.J. Spurrell also comments in 1881 (Archaeological Journal XXXVIII) - quoted in context with most relevant words in yellow:

The Times and local prints contain particulars of holes dropping in recently on Blackheath. They are discussed by Mr. T. V. Holmes and Mr. Lemon; three of them being partly visible in 1879. I can remember others, however, on the heath behaving in a similar way; one of them was near "Washerwoman's Hole" [part of the heath adjacent to Royal Parade]. Some have been slipping gently for many years in the gravel pit near Whitfield's mound

↑ The pit in 1805...

↑ Hart's location of the mine

In recent decades this mine has been very quiet, but nevertheless I would recommend that a closely-spaced borehole investigation is carried out in the pit and around its perimeter to ensure public safety; each bore should go down until the water-on-impervious horizon is encountered (typically about 12m across many areas of the heath).

↑ Click for a larger version (825k 1024 x 888)

Voyage into One Tree Hill Conduit

2010-07-08T02:24:00.028+01:00

Perhaps not quite Journey to the Centre of the Earth, but the One Tree Hill Conduit is still a nice little example of Hawksmoor's work. Here at Subterranean Greenwich we walk through walls effortlessly, as you will see below: a photo of the intact bricked-up entrance seen from inside.

Per von Scheibner takes up the story:

One Tree Hill is at the North-Eastern end of Greenwich Park. Set into the bottom of the mount, virtually facing the children’s playground is a bricked up doorway that has intrigued many a visitor. The bricks blocking the entrance appear to date from the same period as the opening arch and the elegant wall it is fitted into – but this impression is misleading; in the late 1970s this tunnel entrance was not yet bricked up and only a few metal bars blocked the way ahead.

↑ Inside the bricked-up entrance

What the frustrated explorer could see was a short, roughly two and a half metre long section of a tunnel leading straight into the hill. This visible section of the passage has an arched roof about 160 cm in height and about 1 metre in width, with a roughly square sump set into its flooring. The end of the culvert intercepts another tunnel, thus creating a T-junction. The eastern branch continues for a short distance and then turns by 90° to the south, thus running more or less directly underneath the gully that is visible to the east of footpath and steps leading up One Tree Hill. This 40 metre section of the passage slopes mildly upwards, gradually decreasing in height. It features several inspection shafts in its roof and is perfectly dry.

↑ The Eastern branch

Returning to the entrance passage, the western branch of the tunnel is about 50 meters long and somewhat higher than the entrance passage. It runs in a straight line along the bottom of One Tree Hill and still carries quite a bit of water. When it comes to an abrupt end the experienced explorer can’t help feeling that there should be more ... and there is. Some twenty years ago a dig exposed a Tudor tunnel that had been cut off by this 18th century structure. It ran from the western end of the present One Tree Hill Conduit in a north-westerly direction underneath the lawns towards the Vicarage – once the site of a reservoir building.

↑ The Western branch

Of all the conduits, this one is most eminently suited to being opened to the general public. The walk-in entrance and good condition of the brickwork mean that it is very safe; its limited length means that bad air would not be a problem. Quite a lot of tidying and internal cleaning needs to be done, but other than that and a very strong lockable door being installed, the cost would be trivial as part of the park's annual budget. As with the Coombe Conduit in South West London, there could be selected open days each year staffed by volunteers from local societies. Should more intensive usage be required, a modest entrance fee could be charged with almost daily opening during summer months and a paid guide/supervisor to lead the way.

The 1780 Admiralty Conduit Survey - full transcript

2010-07-02T11:28:00.019+01:00

For the first time ever, we publish our full transcript of the 1780 Admiralty Survey of the Greenwich Conduits. Deciphering the original copperplate handwriting was a major task; some of the words are illegible and cannot be surmised from the context. There is also some physical damage to the original.

There are 13 conduits mentioned, which may come as a shock to a few people - notably Simon Thurley, Chief Executive of English Heritage - who considers¹ that the EH survey of 2009 was an adequate investigation, even though it only covered 3 conduits (the contractor, Irriplan, failed to get into the extensive and ancient upper section of the Hyde Vale Conduit which we have been visiting for many years).

[Page 1]

The board having maturely and p- considered, the whole of the said papers, minutes, and maps, and the information arising therefrom, Resolved to take a survey thereof; and for that purpose, proceeded to the South Iron Gates, at the middle of the Hospital, entering from Romney Road. -

At this place, it appeared, that the leaden pipes, conducting the water into the Hospital, consisted of two large branches, one from the western parts of the park, and grounds more to the westward, without the park; but within the manor; the other, from the eastern parts of the park, and hills adjoining; Both which branches, are kept separate and distinct in their effect, unless where the difference of their level, in the several storys and higher parts of the Hospital, require a charge [change?] of these two supply water for that purpose; of which is effected, by opening and shutting distinct Cocks, at this place.

From this point, entering at the North Middle Gates of the Kings Garden, the Board proceeded to

[Page 2]

trace the course of the leaden branch of the western supply, from the information of the Clerk of the works, the plumber, and the turncocks.

Having proceeded cross the lawn, to the west side of the Kings House, the Great Pipe was found to cross the Court Yard; and, that there were the following branches taken out of it; to wit, one branch westward into a small garden, one other westward to the coach house and stables, one other eastward to a water closet in the middle of the Kings House; and one other eastward, passing along the south front of the said house, which supply a cistern near the ?, or from thence all the offices adjoining thereto

The Board then proceeded cross the park, in a south west direction, tracing the course of the Great Leaden Branch, which crosses the Square Lawn in the N. W. corner of the park, and about the middle thereof, affords by means of sidecock, (under lock and key,) a small supply into a trough, for the use of the deer.

The said Great Branch was then found to turn up the middle of the Western Walk, to the Great Cistern or Reservoir, commonly called

[Page 3]

the Standard Reservoir, which is built of stone & brick, lined with lead, & has a large brick building erected over it, all which was repaired, and the Cistern rebuilt of a larger size than formerly, at the expense of the Hospital about four years ago. From that level the water rises into the highest parts of the Hospital.

From this Standard Reservoir, which affords the largest supply of all the park waters.

The leaden pipes, which conduct water into it, were traced upwards in the following manner -

one leaden pipe comes from a Conduit Head on the face of the hill just above the reservoir 84 feet distant, which, for the sake of distinction, was called No.1 - This Conduit-head has a small receiver in it, and collects water from one brick drain underground, about 120 feet in length, which extends eastward, to the roots of a thorn tree, and also from one other brick drain underground, about 100 feet in length, extending south westward, in a curved direction, to a hollow in the ground. All which Conduit head lead pipe & brick drain were repaired and cleansed at the expense of the Hospital about 4 years ago.

Returning to the Standard Reservoir, one other Branch of Supply is a large leaden pipe, which lyes underground, was traced to a door in the face of the hill, at the end

[Page 4]

of a large brick arch, well constructed - Which arch passes from thence, out of the Park, under Croom hill, under the public highways to a hollow or valley, commonly called Sots Hole, or Conduit Vale, where it terminates at another door, and having several perpendicular shafts for air holes, at different distances, in the extent thereof - On the left hand side of the floor of this arch, the leaden pipe of supply above mentioned extends the whole length, and at the S. W. extremity of the said arch, turns suddenly to the left, and lyes in another smaller arch, which extends up the valley of Sots Hole to a Conduit head No.2 near the Horse Pond, on Blackheath, at the end of Chocolate Row; and which arch has one short square turning, and two small branches extending into the rising bank adjoining eastward, all underground.

The leaden branch of supply, in the said Drain, proceeds about half way only, up the valley of sots hole, and terminates at a dam cross the said brick drain, which stops and collects, all the several supplys from the springs in the bowels of the earth, and conducts the same collectively into the mouth of the said pipe.

[Page 5]

It appeared that all these several Drains, Conduit head and leaden pipe, were repaired and cleansed at the expense of the Hospital about 4 years ago -

It appeared also, by information from the papers above mentioned, that all the supply of water from this valley, were called or denominated by that of Croom hill Conduit-head; and prior to the year 1696, and before the large brick arch above mentioned, which passes thro' & underneath Croom hill, was constructed, had been conducted down the lower part of the said valley, thro' the lands of a Capn. Mason & Alice Cottle or Gottle widow, and joined another leaden branch of supply, hereinafter mentioned -

The Board then proceeded westward, to a point of land, being a part of Blackheath, known formerly by the name of Maiden Stone hill; and on the north side of the same, at the head of Gang Lane, surveyed one other Conduit-head, No.3; which commonly goes by the name of Gang Lane Conduit; and is called in one part of the Minutes, Foxes' Conduit.

[Page 6]

To supply this conduit head there is a brick arch underground, which passes towards the south, and seems to go into the said hill towards a small pool of water - But it appeared also, that there had been formerly, another Conduit head for the supply of ? of Gang Lane, more to the westward, and stood opposite to the workhouse (formerly the pest house,) with a brick drain to conduct water from it. but whether the said lastmentioned conduit and brick drain, has been rendered totally useless & taken away, by the digging the face of the hill, for sand gravel and chalk as was greatly practised, & complained of in former times by the Board; or lyes at this time, buried in the face of the hill, does not appear -

The said Conduit head No.3 appeared to be of very old construction, is out of repair, and contains water in it -

From this Conduit there is a leaden pipe 2 inches bore, which passes under the road of Gang Lane, and near to the north side of a small house, then thro' private garden grounds,

[Page 7]

down the hill, to the Grounds of Mr Oliver, From the fence on the west of his grounds, in the ? of the valley, it passes through his pasture land, and points directly to the Park and Hospital

On the south side of this large leaden pipe, there is a small branch of supply, to a trough in the corner of a field -

Nearer to the Mansion House there is another small pipe, ? ? to a cistern in the corner of the ? wall -

At a small distance from the south west corner of the said house, the large leaden pipe is discontinued, the old one having been taken up; and a small pipe of supply conducts the whole water, from thence to the north side of the said house, and serves the same, and the offices therof, with soft water.

It appeared by the testimony of the Clerk of the works, the Plumber, and turncocks, that instead of being discontinued, where it now is, did proceed further on towards the Park, and that the end of it was turned up above ground, at the south side of the said house, about 30 feet distant, about four years ago. And it also appeared from the ? and papers above mentioned, that the said large leaden

[Page 8]

branch, from Gang Lane Conduit No.3, was joined by the pipe from the Croom hill Conduit No.2, in the bottom of the valley, at or near the fence on the west side of Mr Oliviers Grounds, and jointly conveyed these waters into the Standard Reservoir in the Park from which ? ? house is very little distant -

It appeared also that as repairs or works ? ? have been done of late years to this last-mentioned Conduit No.3, or to the pipe of supply, at the expense of the Hospital; altho' it is mentioned in the minutes, to have been an object of care and attention in former times, and that a part of the supply for the old Palace and Offices, converted into an hospital, was derived from thence -

The Board, having spent many hours in this survey, adjourned the continuation thereof, until this day ? at two o'clock, to examine into the state of supplies of water, from the eastern parts of the park & c.

[Page 9]

Oct 14 1780

The board proceeded to the further part of the survey of the Conduits, pipes, and springheads; which was in part done on the ? ? For that purpose having repaired to the iron gate on the south side of the Hospital, the Board ascertained the situation of the Grea Leaden Pipe, which conducts the whole water collected from the springs on the East side of the park; and remarked that, after the said pipe turns to the east, within the iron fence of the Hospital, and proceeds to the distribution of the water, there is a small branch that goes from the said large pipe, cross Romney road and serves the lower part of the Kings garden, at or near the Hothouse -

The course of the said large leaden pipe, was then traced, through the Kings north gates, & cross the lawn, to the N. E. corner of the Kings House; and observation was made that there is a small leaden branch, in the middle of the lawn, which formerly served a round bain of water in the middle tthereof, and is now dead and useless -

The Great Leaden pipe was then found to cross the yard, (at 10 feet distance from the east end of the Kings House), where

[Page 10]

there is a firecock, and the water pipe is twisted and turned in an improper manner -

From thence the large leaden pipe, after crossing the other pipe of supply to the Hospital, which comes from the western large pipe to the reservoir of the kitchen ? of the Kings house, as mentioned in the former part of the survey, passes under the brick wall and into the park -

At a far distance from the south side of the brick wall, the said large leaden pipe (collecting all the waters from the east side of the park), divides into two parts; and the board proceeded trace the right hand branch pointing towards the south east -

After crossing the middle lawn, it was found to go through the trees to the receiver near the enclosed ground of the keepers lodge; Near to which the said pipe takes a small circuit to the east, and terminates at the said receiver -

This receiver, is a small square brick building, and is not a conduit nor a reservoir, for it receives the water by brick drains from several sprrings within the ? ground of the keepers lodge, and does not collect or retain any quantity of water for want of a cistern or reservoir to coontain the same; but, at particular times of the day or night, allows the overplus water to waste itself in the park, to the ? of the park habitat

[Page 11]

The said reservoir was denominated No.4; and the drain from it was found to proceed upwards to three several brick buildings, within the said fenced ground, which jointly afford a considerable supply of water, and were entitled No.5, No.6 & No.7

From the largest of the brick buildings, which contains a stair case, another large brick drain was found to proceed north east, out of the said fenced ground, and at a considerable distance, has a small square brick building, No.8, on the top of it, which serves for a shaft for air and access -

The said brick drain was then found to proceed eastward, and then terminates in a hollow, to the open air, having the end boarded up -

The whole of this last class of Conduits and spring heads, making the right hand branch of the eastern supply, were repaired, cleansed and put in proper order, by and at the expense of the Hospital, about 4 years ago -

It appeared that these parts were very ancient, and had been enlarged to their present extent, since the institution of the Hospital -

The Board then returned back to the south east corner of the Kings house, where the large leaden pipe divides in two parts as above mentioned -

The left hand branch, was found to run eastward along the White Rails, and under one of the posts, had been cut through, and turned up, by some [end of paper cut off]

[Page 12]

perhaps of what mischief they were then doing The said pipe then proceeds eastward, and opposite to the wicket going out of the park, it was found to have a stopcock upon it, which, being underground and unknown to any officer of the Hospital, prevented all supply of water from that quarter by its being found shut even if the water pipe need not been shut as above mentioned. A little further eastward a small side branch was found to go from the said great leaden branch, to the wicket aforesaid, and there supplys a small house, at the east gate of the Kings offices, and this passes on to other smaller offices, affords a supply of water to all persons in that neighbourhood who have obtained keys to a lock on the outside said gates; and which cock, passes thro' the wall from the pipe of supply abovementioned -

The great leaden pipe in the park was found to proceed a little further eastward to a place where the Clerk of the works of the Kings house, had lately as the Board were informed, put down a stop cock on the said pipe so as that the supply of water may be turned off at pleasure -

And that there was at the same time, a pipe of supply to put on the side ? to supply a cistern ? the inside of the ? of the said Clerk of the works, and from there a cock in the said garden had another in his kitchen -

The great leaden pipe was found to proceed from thence eastward, and to pass near an

[Page 13]

Building, but which is now converted into a stable, but appeared by the old surveys to have had a great reservoir in the loft of it, for all the waters in the east side of the park. This reservoir stood opposite the end of East Lane, and among other places afforded a supply of water to the yards and houses of the officers of His Majestys Works near the Crane, all which were granted to the Hospital by King George - -

At this place, there is a small pipe of supply, which serves a trough in the inside of the pale fence -

From thence the great leaden pipe was found to proceed still eastward, and ? there is, one small pipe of supply, which did serve a round basin, or fountain in the middle of the orchard, adjoining, but that the same is now dead and has not afforded supply for many years -

A little further eastward, the great leaden pipe aforesaid, turns through the trees to the south east, and at a certain place, divides again into 2 branches; one of which on the right hand, proceeds upwards in a diagonal line cross the lawn to a class of conduits on the north side of one tree Hill -

[Page 14]

At the east end of the avenue of trees, it receives a pipe of supply from the Conduit-head No.9, which conduit has a large brick drain, 50 feet in extent, toward the west, and another to the east, but turning round, passes afterwards to the south, into the side of the hill -

At the east end of the avenue aforesaid, the large leaden pipe has a branch of supply, from a Conduit head No.10 with a good supply of water from thence. This last conduit has a brick drain which passes underground a considerable way into the east side of the said hill -

At the east end of the avenue aforesaid, a pipe goes from the main leaden branch to a large brick building of a pyramidal form, entitled No.11, which building is nothing more than a receiver of a provisional supply from the main branch above mentioned, in case the supply of water, prove not sufficient, from a conduit head, No.12, standing a little up the hill to the south, and which conduit has a brick drain passing someway into the hill aforesaid -

In the receiver, No.11, there is only a small round basin, not capable of holding a quantity of water; and from thence a leaden pipe conveys the water to a house and garden in the north east

[Page 15]

corner of the Park, at the bottom of a piece of ground formerly the burying ground of the Hospital & which house was lately the residence of the Clerk of the Works of the Kings House -

The Board went from this part out of the Park, at the east wicket, cross Maze Hill, and proceeded to a Green Lane, commonly called Conduit Lane, and observed a spring on the west side of the said lane at the brow of the hill in the field possessed by Mr ? ? said to be the property of Morden College -

This spring produces a considerable quantity of water, and appears by the old survey to have been conducted in earthen pipes to the hobby stables belonging to the Crown, which stood near the Ballast quay now Crawleys Wharf and that it was called the Arundel conduit in the old survey aforesaid -

There are now no remains of brick although some is remembered to have been there, and the possibility of rendering is useful; is almost totally done away by the ground below having been cut down to an extreme depth for chalk, sand and gravel, as appears by the minutes -

The Board proceeded next to another Conduit-head in a piece of ground under Mr Wilkinson's house, in his possession and to the north of the same. This was entitled No.13, and appeared quite ruined, and choaked up. It was called Primrose Hill conduit, and has a drain which passes upwards to receive the water from the ground to the south, and it would appear, the leaden pipe went through the ground and yards of Mr Hatt (formerly Colonel Richards by the old survey) and after crossing the road of Maze Hill, passed into the east side of the

[Page 16]

Park, and proceeded on, towards the Kings House, and in the east lawn joined the leaden branch above mentioned, forming thereby, the left hand, or northern branch of the leaden pipe, which goes at present to the offices at the east gate of the Kings House, and went formerly into the reservoir opposite the end of East Lane -

Of the leaden pipe which conveyed the water from the Conduit, No.13, there appeared no remains, of it at present, except within the Park, and on the west side of the Hospitals old burying ground, at the wall of which it stops, and by a cock gives an occasional supply into the side of the leaden pipe which goes from the receiver No.11 into several parts of the garden and down to the house formerly possessed by the Clerk of the Kings Works, as above described -

The Board finished the survey at this place having gone over, and particularly examined, all the spring heads, and the present as well as ancient, method of conducting the waters therefrom, into the Ancient Palace, the Hospital, and the house of Officer belonging to the Crown -

Dominic Clinton and Per von Scheibner assert their moral right to be identified as the authors of this work.

¹ Personal correspondence

Conduits and a pyramid at One Tree Hill

2010-06-30T05:02:00.033+01:00

At the bottom of Maze Hill, just inside the park, we are presented with a complex array of conduits and water receivers, including a pond that no longer exists and a previously unknown pyramid by Nicholas Hawksmoor. The only visible remnant is the bricked-up entrance embraced by curving walls in the hillside, which is basically a small T-shaped conduit system which we have previously explored, surveyed and photographed (including a picture of the intact bricked-up entrance from inside - we have never found walls to be insuperable obstacles). A remarkable (and fragile) hand-coloured map in ink has recently come to light, which gives a highly accurate picture of the plumbing layout; its date is unknown. We publish a section of it here for the first time ever:

↑ Click for large version (624k 1000 x 915)

The Admiralty Survey of 1780 describes the (rather complicated) situation:

A little further eastward, the great leaden pipe aforesaid, turns through the trees to the south east, and at a certain place, divides again into 2 branches; one of which on the right hand, proceeds upwards in a diagonal line cross the lawn to a class of conduits on the north side of one tree Hill... At the east end of the avenue of trees, it receives a pipe of supply from the Conduit-head No.9, which conduit has a large brick drain, 50 feet in extent, toward the west, and another to the east, but turning round, passes afterwards to the south, into the side of the hill -

At the east end of the avenue aforesaid, the large leaden pipe has a branch of supply, from a Conduit head No.10 with a good supply of water from thence. This last conduit has a brick drain which passes underground a considerable way into the east side of the said hill -

At the east end of the avenue aforesaid, a pipe goes from the main leaden branch to a large brick building of a pyramidal form, entitled No.11, which building is nothing more than a receiver of a provisional supply from the main branch above mentioned, in case the supply of water, prove not sufficient, from a conduit head, No.12, standing a little up the hill to the south, and which conduit has a brick drain passing someway into the hill aforesaid -

In the receiver, No.11, there is only a small round basin, not capable of holding a quantity of water; and from thence a leaden pipe conveys the water to a house and garden in the north east...

The pyramidal structure is fascinating, especially given its antiquity; its demolition is scandalous. It is probably the square black structure with corner extensions on the plan above close to the roadway of Maze Hill, which is exactly at the location where Per von Scheibner discovered foundations some years ago. It should be thoroughly excavated, and if enough remains it should be fenced and an information board installed. Who designed it? Hawksmoor. He became Clerk of the Works at Greenwich in 1698, and began Castle Howard (with Vanbrugh) in 1699. Look at Castle Howard (first two photos) and his St Anne's Limehouse:

↑ First two photos provided by kind permission of yorkshirewalks.org Third photo author unknown (please contact me for a credit if it's yours).

↑ A map of 1827 shows three structures (arrowed) still standing, although how these relate to the plan above is uncertain.

Preserving the Greenwich Conduits

2010-06-25T07:21:00.018+01:00

The Greenwich Conduits urgently need to be conserved and preserved. They are a remarkable and fascinating piece of the heritage of Greenwich which for too long have been neglected by the Royal Parks and mostly ignored by English Heritage¹ in terms of their structural maintenance and inspection. This must all stop. Now. It's time for the Royal Parks and English Heritage to welcome us into a thorough programme which will conserve and preserve these subterranean waterways, as well as launching investigations inside the park to locate the older Tudor sections cut off by Hawksmoor. It's also time to open at least one of the conduits to the general public, as has been done at the Coombe Conduit near Hampton Court, which enjoys open days organised and staffed by Kingston Upon Thames Society with the full support of English Heritage. We are very confident that there would be considerable public interest in going underground in the park.

Conduits in Greenwich park - above, in excellent condition, and below, neglected but still standing.

The Government document PPS5 Planning for the Historic Environment: Historic Environment Planning Practice Guide contains a number of pertinent paragraphs that the Royal Parks would be well advised to learn from and act on:

6. People care about and want to conserve those elements of the historic environment that hold heritage value for them. Once they are lost, they cannot be replaced. People also want the historic environment to be a living and integral part of their local scene. That requires proactive and intelligent management of heritage assets. Sometimes change will be desirable to facilitate viable uses that can provide for their long term conservation.

10. A key feature of the PPS is its holistic approach to the historic environment. The elements of the historic environment that are worthy of consideration in planning matters are called ‘heritage assets’. This term embraces all manner of features, including: buildings, parks and gardens, standing, buried and submerged remains, areas, sites and landscapes, whether designated or not and whether or not capable of designation.

74. Local planning authorities, developers and other stakeholders with an interest in the historic environment will often find it useful and/or necessary to seek the advice of appropriately qualified and experienced individuals or organisations. This may be, for example: to inform the plan-making process, to provide advice on the significance of a heritage asset, or to undertake an archaeological survey.

Re: 74: Per von Scheibner and Dominic Clinton are an authoritative source of information about the conduits, having been investigating them for 25 years.

148. Good conservation of heritage assets is founded on appropriate routine management and maintenance. Such an approach will minimise the need for larger repairs or other interventions and will usually represent the most economical way of sustaining an asset.

Furthermore the RPA's own document TRP Corporate Plan 2009-11 contains the following clauses:

"We value the historic landscapes and buildings which we hold in trust for the nation"

"To conserve and [sic] the historic built environment of the Royal Parks"

Looking at the condition of some of the conduits in the park, there would seem to be scant evidence that these lofty aims are being achieved.

Failure by the Royal Parks to implement these key directives would amount to a rejection by them of some of the most fundamental parts of PPS5 as well as the TRP Corporate Plan.

¹ There is a brief account of the lower section of the Hyde Vale Conduit on the EH/NMR web site PastScape, along with general references to two other park conduits - those near Queen Elizabeth's Oak and one at One Tree Hill.

Cemetery Mine, Plumstead

2010-06-07T11:29:00.019+01:00

No comprehensive survey of the Cemetery Mine is known to exist; its general location was in the area of Rockcliffe Gardens, site of numerous ground collapses...

↑ Click for a larger version (617k 722 x 1000)

Small pieces of the mine were revealed by test headings dug underground by Legrand, Sutcliff and Gell (who incidentally also sank the new shaft that re-opened the Blackheath Cavern). The gardens were created in the 1950s after it was decided that this area of land was too dangerous to build on, although in 1987 a developer acquired the land with an intention to place a substantial housing development (Prestwood Close and Radnor Crescent) on this highly unstable piece of ground - a very unwise idea. The ensuing campaign by local people against the developer, under the guidance of Per von Scheibner, became known as the "Battle of Alliance Road", and featured extensive weekly coverage in local newspapers. The developer was ultimately forced to carry out a tight 1 metre borehole grid across the whole site during 1988, which revealed dozens of large voids - proving the existence both of large air pockets from collapsed galleries heading upwards as well as lost intact galleries. Extensive (and expensive) remedial work was carried out to stabilise the ground.

The residents of these new streets are now safe; however, outside the perimeter of the development, further voids and unsurveyed passageway probably still exist.

↑ Rockcliffe Gardens, showing mine features and collapse areas. Click for a large version (306k 1600 x 1126)

↑ The area of Rockcliffe Gardens, with voids ("V") discovered during borehole drilling in 1988; many more voids were subsequently discovered. Click for a large version (172k 1248 x 720)

The Stock Well, Greenwich

2010-05-29T12:42:00.007+01:00

Beryl Platts, resident of Crooms Hill, is the main witness to a collapse that happened just outside the entrance to Greenwich Theatre - there is little doubt that this well with passageway was closely related to the Stockwell, or may even have been it. Whether any of the structure described dates back to the time of Duke Humphrey is unknown.

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South Metropolitan Chalk Mine, Plumstead

2010-05-29T12:03:00.019+01:00

The South Metropolitan Mine was poorly worked and in places highly unstable, with a number of voids working their way up to the surface - with disastrous consequences for the houses in that section of Alliance Road. It was filled during the 1950s, although there were almost certainly some galleries that could not be reached because of roof falls, and these remain unfilled and unsafe.

↑ A nightmare of roof falls and partially flooded passageway. Click for a large version (1.84Mb 2500 x 1421)

↑On the left, South Metropolitan Mine, with Gregorys to the right of it. Click for a large version (3.55Mb 2500 x 1729)

↑ An extract from the original 1889 ground survey with the approximate location of some galleries added to the map in the 1950s. Click for a large version (4.1Mb 3488 x 2616)

Below: Borough Engineer George Helsdon working in the South Metropolitan Mine during the 1940s and 1950s, with general views of engineering work to stabilise the mine. Photos by courtesy of London Transport - click each image for a larger version.

George Helsdon again; two low-quality photos from newspapers of the time:

Gregorys chalk mine, Plumstead

2010-03-14T04:15:00.021Z

During the late 19th century in the neighbourhood of Kings Highway, Wickham Lane and Alliance Road in Plumstead lay three brickfields: Gregorys, Cemetery and the South Metropolitan. Each had its own substantial chalk mine, with many of the galleries being poorly constructed and highly dangerous to both those working underground and living/working above ground. A fourth mine, Dawsons, is reputed to exist slightly to the south of Gregorys, but has never been surveyed. The photo below shows Gregorys - skillfully worked passageway with a narrow profile; if all the mines had been this good, subsidence would not have been a problem at Plumstead.

The plan below of Gregorys (Alfred Gregory & Co) has never been published before; remember that it is/was surrounded by other huge mine workings whose galleries are not shown (although under 16-18 Villacourt Road an extremity of the South Metropolitan mine is plotted).

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After severe surface subsidence above the Cemetery and South Metropolitan mines, the "London County Council (Woolwich Subsidences) Act 1950" came into existence, which financed and managed the filling of all three mines. All the known galleries have now been filled, including Gregorys mine, which ironically was excellently worked with a probable further lifespan of 200-300 years. Many voids almost certainly still remain; time will tell if the associated air pockets continue to work their way up to the surface. The fact that money was wasted filling Gregorys demonstrates a complete lack of knowledge about chalk mining and a process driven by politics and public opinion rather than expert opinion.

The picture below shows the Wickham Lane brickfields about 1900 (look closely about 60 feet to the left of the base of the chimney, and you will see what appears to be a circular ground collapse crater):

↑Click for a large version (1.9Mb 2500x1974) Photo by Alan Gibbs

A 1958 article in London Transport Magazine discusses the South Metropolitan mine, part of which was located under the bus garage which formerly stood at the junction of Kings Highway and Wickham Lane:

Down the ladders of a dank shaft and into the eerie workings of a disused chalk mine went our somewhat apprehensive reporter. Dim electric light bulbs and the narrow beam of a hand lamp showed the way into a darkened gallery. It was an unusual expedition. Sixty feet above was Plumstead garage, with the buses coming and going as usual. Though new to our reporter, this inspection was a routine affair for the three men in his company. He was there to see an out-of-the-ordinary job which our civil engineers have been tackling for the past year. They are trying to trace and fill in a maze of chalk tunnels beneath the garage.

Before the days of lorries chalk for building was actually mined like coal, instead of quarried. But at the turn of the century easier transport made mining uneconomic at Plumstead, and the workings were abandoned. There have been serious subsidences in the vicinity over a long period, and five years ago London County Council, realising the danger of the mines, began finding and filling in the cavities. Last year their excavators discovered galleries leading under Plumstead garage and our engineers were called in.

Bore holes have been made in various places to test the solidity of the ground and several shafts have been found in and around the garage. Sixty feet below ground a heading, about 250 feet long, has been bored and this gives access to two old galleries. One cavern our men stumbled upon was large enough to take a bus! Several of the cavities have now been filled in. A mixture of pulverised fuel dust and water is pumped down and this eventually sets like cement.

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↑ Click for a larger version (958k 875 x 1500)

Both items above from the Kentish Independent about 1950.

The Co-op chalk mine, Abbey Wood

2010-03-14T02:07:00.009Z

In 1900 the Royal Arsenal Co-operative Society dug a substantial chalk mine in Federation Road, Abbey Wood, to supply lime and chalk for its new "affordable housing" development nearby.

As often happens on this blog, we give you material that has never been published before; the high-quality plan below shows the mine along with proposed works to convert it into an air-raid shelter:

Click for very large version (3.2Mb 2555 x 1475)

A publication by the society gives details of the works:

A shaft has been sunk from which chalk is being obtained for use as a foundation of the roads. From the shaft also a plentiful supply of water is obtained, which is used for the mixing of mortar and other manufacturing purposes.

A copy of RACS magazine noted that the hoist of the chalk pit was worked by a 16 horsepower engine which also drove other workshop equipment. It also mentions a mortar mill and lime kiln associated with the mine, and goes on to describe the mine in more detail:

The chalk pit descends 60ft perpendicularly, from that level four galleries extend horizontally about 100ft each, and from these the chalk is being continually raised. The water that percolates into the pit is pumped up and distributed where needed. Some of the chalk is... carted off on the tramlines for making the roads, but most of it is first burned in the lime kiln, then slaked, then mixed wth the fine sand, which by the way, overlies the chalk, to make the plaster for internal walls.

The mine was only active for about five years, which demonstrates the considerable length of passageway that can be created in a short span of time. It was thoroughly examined by Per von Scheibner in the late 1980s, which included extensive new photographic coverage.

The galleries were skillfully worked and shaped, with generous pillars left to support the land above. With regular inspections, this mine may well have a further 200+ years of life before complete filling becomes necessary, although localised repairs may be required periodically.

Blackheath Cavern - the boreholes

2010-02-07T01:04:00.015Z

As early as Autumn 1938 LeGrand, Sutcliff & Gell were working above the Blackheath Cavern. Albert Judd's letter, below, detailing the results of 3 boreholes, has never been published before (click each page for a slightly larger version):

The borehole numbers refer to stations No.1, No.2 and No.3 shown on the plan below. The exploration tunnel driven by LSG travels through a zone of choked and/or fallen passageway; the small hole which led to the rediscovery of the cavern was probably a void from a roof fall that allowed access to the galleries.

As I suggested in my main entry on the cavern here, there may well be further unsurveyed passageway in the vicinity of the exploration tunnel - a tight borehole grid would answer that question. Borehole No.2 is especially interesting - Judd writes that the boring tool dropped through space for a distance of 1'6" after passing through a 3' thickness of chalk (the ceiling of a choked gallery). The ground was disturbed until solid chalk (ie the floor of the gallery) was re-entered 20 feet further down.

Standard Reservoir - new plumbing plan

2010-02-07T00:20:00.005Z

A remarkable 1901 hand-drawn plan showing the plumbing of the Standard Reservoir has come to light; as far as we know it has never been published before. One of the branches supplied the swimming pool of the Naval College at the turn of the century - taking a dip would certainly have been a bracing experience, even at the height of summer. The big reservoir gains a name at last - "Admiralty Western Resevoir" (sic).

Greenwich Sand Mine

2010-01-27T07:40:00.011Z

In the neighbourhood of Hyde Vale is a small sand mine cut into the Thanet Sand, with passages varying between 4 and 8 feet high. Stone mentions it briefly in his survey of subterranean Greenwich, although his reference to a "perfect maze of tunnels" seems a bit overstated. However, the mine may once have been more extensive, although the design looks a bit amateurish from its layout. The sand may have been used for local glassmaking, although there is no direct evidence whatsoever to support this. The mine's age is unknown, and it suffers (as often with subterranean structures) from wild suggestions of great antiquity; it was rediscovered by Per von Scheibner in 1986.

From the entrance you descend a fight of stairs until you are standing on a floor some 20 feet below ground level. Originally three passages radiated off from this point, but a roof fall now blocks two galleries. However, small cross tunnels have been dug that allow you to circumnavigate the fall and enter the once-inaccessible passages. The total length of passageway is about 280 feet.

The Standard Conduit

2010-01-09T01:25:00.020Z

The Standard Conduit consists of 220 feet of passageway which fed a conduit house located 84 feet behind the Standard Reservoir building. That passageway is entirely separate from the Hyde Vale Conduit, and is several metres higher. The small conduit house of the Standard Conduit is shown on the 1894 OS map, although it disappears by 1914:

Countless writers and researchers over the years have confused or conflated the Standard Reservoir, the Standard Conduit and the Hyde Vale Conduit.

The Hyde Vale Conduit originally drained into the Standard Reservoir, which I found surprising because the Reservoir seems to be at a higher level than the floor of the Hyde Vale Conduit along which the original lead pipe/s ran. However, the 1780 survey is fairly clear on this point:

Returning to the Standard Reservoir, one other Branch of Supply is a large leaden pipe, which lyes underground, was traced to a door in the face of the hill, at the end of a large brick arch, well constructed - Which arch passes from thence, out of the Park, under Croom hill, under the public highways to a hollow or valley, commonly called Sots Hole, or Conduit Vale...

There is no entrance to passageway inside the Standard Reservoir building, which simply covers (albeit grandly) a large lead-lined cistern fed by at least 2 pipes uphill of it. The Hyde Vale conduit has its own entrance in the hollow nearby.

Immediately uphill from the Standard Reservoir building is a second (much bigger) underground reservoir fed by a pipe from the Standard Conduit (see map below); this was opened at the beginning of World War 2 for consideration as an air raid shelter. Again, there is no access to passageway from this structure.

The 1780 Admiralty Survey describes the Standard Conduit concisely:

...a Conduit Head on the face of the hill just above the reservoir 84 feet distant, which, for the sake of distinction, was called No.1 - This Conduit-head has a small receiver in it, and collects water from one brick drain underground, about 120 feet in length, which extends eastward, to the roots of a thorn tree, and also from one other brick drain underground, about 100 feet in length, extending south westward, in a curved direction, to a hollow in the ground.

The passageway of the Standard Conduit is almost certainly still there; it just needs re-opening. Half an hour's spade work would accomplish that, but unfortunately the Royal Parks have repeatedly refused any systematic investigation into the conduits, despite their considerable historic importance.

Lost railway tunnel Greenwich branch line

2009-12-18T00:22:00.011Z

For many years a lot of people have wanted to get into the lost railway tunnel used by the Greenwich branch line. Pictures of the Blackheath Hill bridge/tunnel have recently appeared, thanks to photographer Ian Mansfield - the man is a hero. However there is still much more tunnel waiting to be rediscovered; the full history of the railway is covered by Nick Catford here. Ian has given the pictures a CC license (Creative Commons), so non-commercial reproduction rights are fairly relaxed. Please Google CC if you're not sure.

Faces blurred for privacy. Click for large version 853k 1000x677

Click for large version 932k 1000x677

Click for large version 1.1Mb 1000x677

All photos above: Ian Mansfield - original set on Flickr here.

Point Hill Conduit House - watercolour

2009-12-12T00:17:00.026Z

The only known depiction of Point Hill Conduit House recently turned up. I puzzled over this somewhat unusual octagonal-vignetted picture for ages, because the perspective is difficult to interpret. The cylindrical design of the conduit house is clearly shown on early 19th century maps as seen below. Its sibling at the top of Hyde Vale may once have been a full cylinder, but rebuilt as partially square-sided. I think we can be fairly satisfied with an identification of this as the Point Hill Conduit House.

A charming watercolour - click for a slightly larger version (55k 560x404)

*UPDATE* A bigger version of the original has now become available, enabling us to look more closely at the conduit house (click for a larger version, 202K 614x412):

Click for a larger version (820k 1500 x 856)

The Travers map (1695) below marks a pair of heads labeled as No.2; the left of these - in what is now the road we know as Point Hill - is what is being discussed above. Also visible are three spring heads under the brow of the hill, which may have fed this conduit house. Incidentally it may be more correct to call this the Gang Lane conduit.

Flamsteed's Well

2009-11-28T03:29:00.121Z

Flamsteed's Well - a telescope located in a 100-foot deep brick-lined shaft on Observatory Hill - came into operation during or soon after November 1677; the lower 15 feet or so were unlined where the shaft entered chalk. After endlessly debating the available evidence in the manner of Sherlock Holmes, I have concluded that there is no irrefutable piece of information that can tell us when the shaft was originally constructed, and it could perhaps predate Duke Humphrey's activity on the site in the early 1430s. Even the idea that Flamsteed had the shaft specially sunk cannot be ruled out, although it would be bizarre for him not to mention it. The fact that it was not located on the "meridian" of the Octagon Room - which as convincingly proposed by Graham Dolan was the notional meridian of Flamsteed's era - carries little weight in the debate.

The original purpose of the shaft is obscure; rambling speculation is no substitute for hard historical evidence.

What we do know from contemporary illustrations is that a spiral staircase was installed, and the viewer reclined on a couch at the bottom to make celestial observations. As candles or oil lanterns were the light source, and ventilation was insufficient, air quality would have become very poor over a number of hours, with rising CO₂ and CO and falling O₂. Even if Flamsteed had extinguished his CO-producing yellow flame light source to achieve the desired dark viewing conditions, CO₂ would have continued to increase and O₂ to decrease. With daily use, the poor air would have lingered at the base of the shaft, eventually improving through barometric draughting if nobody went down. At ground level a small octagonal building kept the weather out and also probably housed the upper lens. In the first picture below (about 1680), this octagonal structure is clearly visible standing alone some distance to the right (South) of the observatory complex. The second and third pictures, which have a different viewpoint, put it more South East of the observatory.

Click for a large version (252k 1280x770)

A very similar version of the picture above; the vegetation is the main difference. (Mary Evans Picture Library)

↑ View from the roof of Flamsteed House; the well is at the bottom right corner. Click for a larger version (932k 1200 x 773)

↑ The plan that appears in Baily's 1835 biography of Flamsteed; this is supposedly an exact copy or replica of Flamsteed's own drawing. Click for a larger version (85k 580x669)

Visitors to the Observatory today will see a ring of bricks marking the supposed site of the well; the bricks mark the position of a rubble-filled unlined shaft discovered during an archaeological dig in 1965. The location of the well marked in Baily's plan of the Observatory (published 1835) fits closely (within a few metres) with this position when an overlay is done:

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In one bound this overlay makes a number of previous academic debates about the location of the well redundant, including the 1881 subsidence and the Lynn/Maunder letters.

The enormous difficulties with Flamsteed's well lead me to invoke the spirit of Sherlock Holmes. Ironically it's almost certain that Conan Doyle would have read Conrad's The Secret Agent of 1907, in which the character Verloc is tasked by Mr Vladimir (First Secretary in the embassy of a foreign country, by implication Russia) with blowing up Greenwich Observatory.

"You will not apply my precept," he said, shaking his head. "How often have I said to you that when you have eliminated the impossible, whatever remains, however improbable, must be the truth? We know that he did not come through the door, the window, or the chimney. We also know that he could not have been concealed in the room, as there is no concealment possible. When, then, did he come?"

(Sherlock Holmes The Sign of the Four)

Furthermore the two similar illustrations immediately above the plan also support the Baily location when perspective lines are projected, although the 1680 painting above them turns out to be very inaccurate - at least two different viewpoints have been combined into one image.

The absence of bricks in the shaft is extremely puzzling, unless of course they were salvaged. Why go to so much trouble? Because stripping the lining yielded around 7,500 bricks in good condition - a valuable commodity which could be used immediately (and conveniently) on site or stored until required. That number of bricks today (a reasonable quality facing brick) would cost in excess of £2,500 at your local builders merchant. The labour cost of stripping the bricks out of the shaft and then filling it would have been modest because labourers already employed within the park could have been used - much cheaper than bringing in an external contractor.

Here is a summary of the dig by F. Willmot of the Lewisham Natural History Society (my bolded text):

In 1965, the society learned of the efforts being made to locate the well, and examining the site, found that the contractors had uncovered a roughly circular, filled shaft, between 7 feet and 8 feet in diameter. This was near a spot indicated on a 19th century plan of the Observatory as being "site of Flamsteed's Well." At the request of the Ministry of Public Building and Works, the Society continued to remove the mixed infill of the "well," at the same time preserving its circular edge. At 24 feet below ground level, the Society reported to the Ministry that it would be unwise to continue deeper without further timbering.

No real evidence of any brick lining was found. No stratification existed within the well, the part examined having been filled in the 19th century. Traces of a hexagon shape within the infill of the circle of the well were noted, perhaps associated with a small six-sided building known to have capped the well in Flamsteed's time.

> The 19th century plan Willmot refers to is probably Airy's drawing, because Baily describes it (differently) as "The well, in which observations were sometimes made".

> The profile of Flamsteed's Well was circular, not hexagonal, with an octagonal structure built above it. Here's a small area of Flamsteed's own plan clearly showing the octagonal shape:

We are currently undertaking a thorough review of all archival material.

LATEST RESEARCH

>> The 1963 assertion by Laurie and Waters that "by the time Bradley became Astronomer Royal in 1742... [Flamsteed's] well telescope was filled in, having failed at an early date" is clearly impossible, because pottery dating a century later was found throughout the 24-foot depth of infill examined in the shaft. The shaft may well have been capped and covered over by 1742, but it had not yet been filled in.

>> A well was sunk in 1815, with a depth (according to what Airy was told) of 120 feet. But he points out that "the water proved bad and the well was covered in." Whether that means capped or actually filled in is open to question. We know the location of this later well to within several metres, and are investigating; it is/was located in the large garden below the Observatory.

Here are two excellent (and recent) aerial photos of the site which are very helpful in determining the viewpoints of the different historic illustrations (click each for the large version):

© National Maritime Museum

© National Maritime Museum

We have seen entrances to three culverts (17th or 18th century) at the Observatory, one bricked up and the other two choked to the roof with rubble - in addition to the remains of the covered way which led from the old Observatory to the new buildings. These culverts need to be opened up and properly surveyed/explored, as they are in the area of Flamsteed's Well. The well would certainly have made a wonderful soakaway or cess pit once it had become derelict. Opportunities for archaeological investigation at the Observatory over the years seem to have been sadly lacking.

Only two observations were ever recorded, in June and July 1679, suggesting that scientifically it was a failure, although the poor quality of the object lens (demonstrated in a 1956 test) may have been partly to blame. We know that it had become disused by 1737, because on November 3rd of that year the lens was presented to the Royal Society. The donor, James Hodgson, married Flamsteed's niece and went on to inherit some of his property; Hodgson was assistant at Greenwich 1696-1702.

↑ A contemporary cross-section through the "well". Note that the diameter of the octagon structure is smaller than that of the well; the octagon is positioned assymetrically, which would have meant that some type of bridging arrangement was needed for support. Click for larger versions (120k 187x800 & 103k 484x452 respectively)

↑ The site of the well (Nov 2009). Photographer unknown - if it's you, please contact me to be credited.

↑ Greenwich Castle, which stood on the site of the Royal Observatory, in its final incarnation during the mid 17th century.

A good analogue for Flamsteed's Well is the octagonal Vienna sewer kiosk seen in the 1949 movie "The Third Man" with Orson Welles and Joseph Cotten, which is the correct height of about 12 feet:

We have considerably more material than appears above, but are currently constrained by copyright issues; hopefully in due course much more will be added to this post.

Conduit Houses inside the park

2009-11-25T01:29:00.020Z

The earliest known depiction of a conduit house in Greenwich appears in van den Wyngaerde's panorama of Henry VIII's Palace of Placentia, drawn in 1558 when the palace was still at the zenith of its architectural maturity. The little house is hardly more than a scribble, yet definitely a structure of the correct size located in the right place - the hillside where both the Standard Conduit and the Snow Well (the ventilation shaft of an unknown conduit misnamed by Webster) are located. The Snow Well was a 30-foot deep well with passageway at the bottom heading in the direction of St Marys Gate, and is/was located in a tree-lined depression some 100 yards towards the Observatory from the standard; it must not be confused with the Hyde Vale conduit, which is quite separate.

Later conduit houses built in the era of the Royal Hospital frequently pop up in views of the park: several are shown below. Without any context it's usually very difficult to link them to particular conduit passageway or access points.

Do any of the conduit houses pictured above date from the Tudor era? Perhaps. What did Tudor conduit houses look like? Have a look at this photo set on Flickr.com of Coombe Conduit, which along with two other houses (Ivy Conduit and Gallows Conduit) supplied Hampton Court Palace from 3 miles away.

Woolwich Conduits

2009-11-24T04:11:00.005Z

Woolwich Arsenal had a substantial conduit system, upon which lavish sums were spent during the late 17th and early 18th centuries in a desperate effort to supply the huge demands of the military establishment. An infamous local gravel digger named Pattison was hauled in front of the local magistrate at one point after destroying part of the system and severely disrupting water flow. The main artery was called the Office Conduit (short for Office of Ordnance), and had a conduit house in Cholic Lane for many years; it's extremely frustrating that we never managed to find any of the passageway. Tower Place, the grand Tudor house that stood in the Arsenal, also had its own conduit - of unknown extent or location - although it may well have used the same spring source as the later system. Further reading on the Pattison case can be found in O. F. G. Hogg's excellent history of the Arsenal.

Rocque's map of the early 1740s clearly shows Cholic Lane and "The Spring Head". Click map for a big version (348k 654x891)

Hyde Vale Conduit

2009-11-20T01:08:00.068Z

Everyone seems to have heard of the Hyde Vale Conduit, but not many people have actually been in it. The passageway (which exceeds 1,400 feet in length) starts inside the park in a cellar-like structure...

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...near the Standard Reservoir building, and heads over towards the Ursuline Convent and school, passing under the roadway of Crooms Hill at a depth of some thirty feet. The height of this section can be described as lofty - about seven feet high, and wide enough for two people to pass without twisting sideways. Air shafts are encountered at regular intervals, including one that originally opened onto the sloping grass triangle in front of the convent - we surveyed and photographed a previously unknown high-level passage that leads off this shaft near ground level. This deep cut-through under Crooms Hill was probably constructed in 1696.

As the conduit nears Hyde Vale, the remains of a former entrance (via staircase) are encountered - the surface structure associated with this staircase can just be seen in a painting of Hyde Vale from around 1830 (click for a larger version 203k 1023 x 297):

↑ For more info on the staircase entrance, please see this post
Progress is now blocked by infill from modern-day electricity cable works. In the "upper" section beyond the blockage the passage is much lower and narrower, the arch having been decapitated and replaced with granite kerb stones. This was necessary when the roadway of Hyde Vale was constructed around 1834 (Henry S. Richardson's "Greenwich: its history, antiquities, improvements and public buildings", written in 1834, refers to "The new cut called Hyde Vale, leading from Royal Hill to Conduit Vale"¹). Conduit Vale was previously named Sot's Hole - and that old moniker had a number of tunnel legends associated with it... true legends as it turns out.

After continuing under Hyde Vale (with the curious muffled swooshing sounds of vehicles passing overhead), the arch returns, giving a ceiling height of five feet or so. A junction appears ahead, along with the sound of running water: to the right, the stumps of two blocked-off branches can be investigated, and to the left the way on is through a deep sump. At this junction the stream of water disappears into the floor down a steeply-sloping pipe, presumably into a deeper "modern" sewer. After a while the passage gets much lower, the fabric of the walls gets older (chalk blockwork in places), and marvellous mineralisation is encountered - stalactites and iron-stained flowstone on both walls and floors. By the end of the journey, the explorer has ascended some 50 feet from the point of origin in the cellar-like structure inside the park.

Above and below: under the upper section of the Hyde Vale roadway; note the chalk blockwork used in the walls to save bricks.

Uphill from the blocked branches, an isolated ancient section (early 1600s judging from the bricks) is located in the back garden of a house. This segment is filled with semi-liquid mud and dips down steeply in the uphill direction - some type of upside-down u-bend silt catch-pit design which has worked well. The downhill end of the segment is bricked up and also broken in from the surface. Removing the mud would be a Herculean task, with all of it having to be carried through the house in buckets over pristine carpets; there is no rear access at all. But if the mud could be removed, a good length of "brand new" old passageway would be revealed - the possibility is intriguing.

Above: the muddy isolated sump - digging (and pumping) could yield exciting new passageway

John Stone covered the Hyde Vale conduit quite well in his 1914 account of subterranean Greenwich; in modern times the late Dick Moy pioneered a full traverse of the passageway in the days when an uninterrupted journey was still possible. Dick kindly gave us the location of the access point in Hyde Vale - it seems to be one of those things that is handed down through the generations without ever being widely known. Should the conduit be opened to the public? Yes and no. The lower section is very safe, and definitely suitable. The much older upper wet section is really the domain of hardened well-equipped cavers, and would give the health and safety fascists in Greenwich Council an opportunity to spout their nonsense.

Above: two of Stone's photos, the upper image showing the view uphill through the sluice; the boards prevent the visitor sinking into 4-5 feet of mud.

What is No.2?

In 1776 (+/- a year) the Royal Hospital carried out a major programme of cleaning and repairing the 13 different conduits that supplied water to it; we know this because it is repeatedly referred to in the extensive 1780 Admiralty survey: "All which Conduit head lead pipe & brick drain were repaired and cleansed at the expense of the Hospital about 4 years ago." The stone disc set into the conduit building at the top of Hyde Vale showing "No.2" is simply for administrative purposes. With so many different heads and receivers, you have to know just which one you're talking about. The numbers start on the west side of the park, finishing with 13 near Maze Hill over to the east.

Here is the full description from 1780:

...a large brick arch, well constructed - Which arch passes from thence, out of the Park, under Croom hill, under the public highways to a hollow or valley, commonly called Sots Hole, or Conduit Vale, where it terminates at another door, and having several perpendicular shafts for air holes, at different distances, in the extent thereof - On the left hand side of the floor of this arch, the leaden pipe of supply above mentioned extends the whole length, and at the S. W. extremity of the said arch, turns suddenly to the left, and lyes in another smaller arch, which extends up the valley of Sots Hole to a Conduit head No.2 near the Horse Pond, on Blackheath, at the end of Chocolate Row; and which arch has one short square turning, and two small branches extending into the rising bank adjoining eastward, all underground.

The leaden branch of supply, in the said Drain, proceeds about half way only, up the valley of sots hole, and terminates at a dam cross the said brick drain, which stops and collects, all the several supplys from the springs in the bowels of the earth, and conducts the same collectively into the mouth of the said pipe.

Conduit water wasn't supposed to be free, although it was frequently intercepted en route - here's a bill (1 pound 5 shillings) for conduit water from the ledgers of the Hospital:

¹ Many thanks to Mike Leader (Governor Archivist, Blackheath Bluecoat School) for pointing this out.

The tunnels of Henry VIII's Placentia

2009-11-19T02:54:00.010Z

In the main quadrangle of the former Royal Hospital for Seamen, subsequently the Royal Naval College, now part of Greenwich University, stood Henry VIII's Palace of Placentia. There are remains of considerably earlier structures on the site dating back to the 14th century, and the first photo below shows a sewer from that pre-Tudor era revealed during the major excavation carried out by Philip Dixon in 1970-71. The second photo looks along a later sewer of Henrician vintage, originally about 3 feet high but now partially filled with silt. A larger sewer of more recent date (17th century) was also uncovered. The riverside entrances to all the sewers were blocked when a new river wall was built around 1700 for the Royal Hospital. For the subterranean enthusiast, these various tunnels span a wide time period, and present a miniature history of sewer design. Sadly none of them are currently accessible.

Maze Hill Conduit

2009-11-19T02:31:00.006Z

The only accessible section of this conduit is the entrance chamber, located in the back garden of a house in Maze Hill. The three-foot-high passageway exiting the chamber is bricked up after a foot or two - a small hole drilled through it yielded only earth, suggesting that the tunnel has at least been decapitated and filled, if not robbed out completely. The brickwork of the chamber is in very good condition, possibly having been repaired in the 19th century.

Maze Hill Mine

2009-11-19T01:27:00.007Z

The title above fails to identify this as either a sand or chalk mine - because we simply don't know. My view is that it is (or was, if it has been quarried away) a chalk mine behind Maze Hill station hard by the roadway of Maze Hill. Per considers it to be a sand mine on the hillside immediately beneath Vanbrugh Castle. For reasons of harmony between friends, I remain impartial on the issue. But the map/elevation, said to date from the 17th century, is unequivocal - there is a pit with entrances to three galleries clearly shown. Westcombe Manor House appears towards the top of the plan (ie East), the foundations of which have subsequently been located in an archaeological dig in the back garden of 66 Foyle Road. If the galleries are still there, then valuable property is inescapably undermined either way, and efforts must be made to locate the passageway. This is fact, not legend.

Blackheath Cavern

2009-11-19T00:24:00.082Z

↑ Click plan for a large version (792k 2000x1500)

The Blackheath Cavern - a chalk mine in Maidenstone Hill - has consumed many column inches over the years, mostly because of the notoriously decadent 19th century subterranean parties which took place in its lofty rooms. Whoever was originally responsible for digging the galleries clearly had no idea of the relatively safe and widely used method of pillar and stall mining, as seen at Chislehurst Caves, preferring instead to carve out a very wide individual main gallery with nothing to support the roof. The tiny passage that leads into the well chamber is most peculiar, and seems to have little to do with any known mining technique. The reason for this style of excavation is probably because the Cavern was dug before pillar and stall mining had become widespread, as we will see below.

Who dug the Cavern?

Most accounts pounce on the fact that the Steers family were associated with the site in the late 17th century, with punishment (a fine) being meted out in 1677 for undermining the Dover Road. However, there is no evidence whatsoever that the Steers dug the Cavern, and furthermore leases were granted to two other digging concerns in addition to Steers: Harding in 1663 and Hatch/Nightingale in 1683 (source: Hasted). The plan and mining methods employed in the Cavern bear no resemblance to a typical chalk mine of that time - such as the Outer Series at Chislehurst Caves. Chalk extraction at Blackheath Hill has been carried out for a long time, as Dr Christopher Phillpotts notes:

There were other limekilns to the east of Deptford at the west end of Blackheath, near the junction of Greenwich South Street and Blackheath Hill. These existed by 1432 and continued to operate into the sixteenth and seventeenth centuries.

The Cavern almost certainly predates the activities of the Steers era - we would be comfortable with a dating in the 15th or 16th century. But a new issue then arises - if the Steers dug a mine, where is it? There may well be a missing pillar and stall mine tucked away somewhere under Maidenstone Hill or nearby on the other side of the Dover Road.

The mine became inaccessible in 1839-40 - we know this because William Shoberl wrote in his 1840 A Summer's Day at Greenwich:

This cavern was, till very recently, open to public inspection for a trifling charge; but it is now closed, some parts having lately fallen in.

Although C.W. Craske, writing in 1946, is adamant that the cavern was closed because of the wild parties ("in either 1853 or 1854, orders were given for the Cavern to be closed") he doesn't provide evidence of that. It's just as likely that the galleries near to Maidenstone Hill were simply getting too dangerous, as suggested in the Shoberl account.

A description of partial roof falls, causing twin domes in the Thanet Sand, was given as early as 1808 in David Hughson's "History and description of the British metropolis and its neighbourhood, to thirty miles extent, from an actual perambulation" Vol V. He says:

The roof in two of those chambers has fallen in, probably from the chalk having been left too weak to support the sand forming the immediate superstratum, and which having partly fallen with each roof, has left a kind of dome of considerable height over both chambers

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Wartime re-opening

The Cavern was reopened by LeGrand, Sutcliff and Gell at the beginning of the Second World War for assessment as a possible air raid shelter; the photo below shows the sinking of the new wartime shaft in the back garden of a house in Maidenstone Hill.

The ground collapse of the Blackheath Hill roadway on 7 April 2002 was not a collapse of the known cavern, as can clearly be seen in the highly detailed wartime survey above. Without sinking a shaft and driving exploratory headings underground (which the investigating contractors failed to do), the cause may never be proved absolutely. The expensive microgravity survey below supposedly tells us where voids (shades of blue) are located - it's as clear as mud, to use a good old English saying. It basically tells us nothing about the location of passageway, and is totally pointless to anyone who knows anything about chalk mines. The only 100% reliable method of investigation is sending knowledgeable people underground to have a look and dig through falls where necessary, which is quite safe with the right equipment.

At the beginning of the investigation into the road collapse, cable percussion rigs were used - a very violent method of ground examination that can precipitate further collapses of mine galleries if they are present. This exemplifies the lack of knowledge about chalk mining displayed by the engineers who worked on the road.

↑ Click for a larger version.

David Jessop (Greenwich Council assistant director of transport and highways) said at the time of the road collapse: "Bearing in mind the recent subsidence and some of the recent investigations, I think it is prudent that the condition of the Blackheath Cavern and the extent of any workings in the immediate vicinity are thoroughly investigated." I don't see any thorough investigation. The "condition of the Blackheath Cavern" could only be assessed by re-opening it and allowing in experts such as ourselves, which hasn't happened.

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↑ The "Devil's head" carving - click for a larger version (622k 730 x 1000)

↑ Probably the earliest accurate plan of Maidenstone Hill - around 1750. A chalk pit is clearly shown close to the location of the cavern - though it is uncertain whether this was a Steers pit or an older disused working. Click for a large version (675k 2000x1552)

Perhaps the earliest reliable description of the cavern appears in Elizabeth Helme's colourful "Instructive Rambles in London and the adjacent villages", published in 1800 (quoted verbatim):

Having made a hasty meal they proceeded to view the curious cavern discovered in the year 1780, on the left side of the ascent to Blackheath; and having procured a guide, they entered it.

The guide led the way with a lanthorn, down a regular flight of steps composed of chalk, and at least fifty feet from the surface of the earth, at the entrance, and, as the guide informed them, at the extremity of the cavern 160 feet. They then reached the apartments, which are seven in number, and where the guide lighted up candles. Some of these apartments are from twelve to thirty-six feet wide each way, and have a communication with each other by arched avenues. The sides and roof of these are chalk, the bottom of sand: some of the apartments have large conical domes, upwards of thirty-six feet high, supported by columns of chalk, and in one of them is a well of very fine water, twenty-seven feet deep.

Charles and Mary were not soon weary of exploring this cavern: but Mr Richardson observing the latter shuddered, and complained of extreme cold, desired the guide to lead the way out.

"How amazingly curious !" said Mary, as they reached the top of the stairs, and again beheld the rays of the sun, which was setting as splendidly as possible, for the last of October, "yet how gladly do I again see the cheerful light ! I shall hereafter consider it with redoubled pleasure; for how dreadful must a dwelling be where it never enters !"

"Dreadful, indeed !" resumed her father.

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Where are the seven "apartments"?

Both the Helme (1800) and Hughson (1808) accounts above mention seven apartments. The wartime plan shows three, or perhaps four at most if you count the bar as a separate room, which is straining credibility. This is probably explained by final collapse of Hughson's two domed chambers, which had already lost their chalk ceiling in 1808. Air pockets from these two collapses may be slowly migrating to the surface, which could cause problems in the future.

You may also wish to take a look at the supplementary post on this topic, Blackheath Cavern - the boreholes.

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Brooklands Ice House, Blackheath

2009-09-21T13:38:00.015+01:00

The must-have accessory for every 18th century British stately home was an ice house. The ability to serve cold drinks to guests on a hot July day was a hugely important social statement, underlining a gentleman's wealth and prosperity - the wealth to pay labourers to build the structure and then nurture this much-prized resource. This classically-shaped house (missing its chopped-off entrance passage) was probably built by Gregory Page in 1723 at the same time as Wricklemarsh House, a substantial mansion located at the junction of Foxes Dale and Blackheath Park. The ice house itself was close to the ponds of Casterbridge Road, which would have provided a rich harvest of ice during January; sadly - and scandalously - now demolished. There was formerly an ice house in the grounds of Woodlands House in Westcombe Park; we managed to explore and photograph the entrance passage of this elusive structure, which is all that appears to remain. Photos of that passage will appear here in due course. Photograph c. 1939. Copyright: Trustees of the late Alan Roger Martin.

Turpin's Cave, Plumstead

2009-09-19T03:19:00.013+01:00

On the east side of the Wickham valley in Plumstead, at the edge of Bostall woods, lies a curious little chalk mine: Turpin's Cave. We can be fairly sure that Turpin was never in this cave - this wasn't his manor, and there is no record of him being here. Generations of children played in the cave, long before the modern era of health and safety fascism; many (now elderly) have fond memories of the place. Re-opening Turpins was a mammoth undertaking, using dozens of volunteers during a five-year dig in the late 1980s, and was ultimately successful. We eventually entered the right-hand gallery, which has had a big roof fall - the ceiling is a dome of Thanet sand exposed when the chalk fell down (a very long time ago). Inside you turn left and descend a sand slope into the smaller gallery, which is choked with sand - a hands-and-knees crawl with your back tickling the roof of the passage leads back towards the original face of the quarry. We didn't re-open the daylight entrance to this small gallery - it wasn't necessary to complete the survey, and there was obviously no way on. Despite our best efforts to secure the entrance, local children with formidable resources of power tools forced their way back in, and Greenwich Council ended up covering over the entrance again with many tons of sand.

Ifield chalk adits, Kent

2009-09-18T08:23:00.005+01:00

Back in Kent, a quick trip to Ifield chalk adits. Three galleries driven into the face of a small chalk quarry, not so far from the A2 (although the navigation required is somewhat Machiavellian). The main galleries are about 15 feet high, with two smaller cross-cuts to link all three. The quarry is in the middle of fields; it's easy to forget that Chislehurst Caves was once upon a time equally rural, not hemmed in by unaffordable housing for city workers.

Ware Chalk Mine, Herts

2009-09-18T07:34:00.008+01:00

A recent excursion outside our usual manors of interest took us to Hertfordshire. A few minutes' drive from Ware town centre is a nice little chalk mine dating from the early 19th century. As well as the usual work benches (giant chalk steps) that the miners stood on to reach the upper part of the gallery, there is a sudden floor drop in one alcove of about 14 feet; the unwary visitor with poor lighting risks a sudden lesson in the law of gravity.

About 500 feet of passageway altogether - small but pefectly formed. The roof is in good condition, unlike many chalk mines, although there is some evidence of frost action near the entrance - a few bales of straw would keep the inside cosy and stop the frost flaking on those long winter nights.

Every chalk mine is important and relevant - knowledge is cumulative.

Fan Museum Tunnel, Greenwich

2009-09-18T04:27:00.007+01:00

During the conversion of 10-12 Crooms Hill into the Fan Museum, builders exposed a short length of culvert related to a pair of old wells. Per went into the tiny passage - so narrow that there wasn't enough space to wear a helmet as it would have jammed against the walls - and emerged in a shallow well about 4 metres away. Somehow I managed to pass him a flash unit, and the resulting picture illustrates the cramped conditions quite well. The culvert is no longer accessible, and may even have been filled in by now.

Darenth Wood Denehole

2009-09-16T08:55:00.017+01:00

Dominic describes a solo trip into the Darenth Wood denehole
It's a grey day in the woods alongside the A2, quite close to the Dartford Tunnel. The funnel-shaped depression that forms one of the entrances to the Darenth Wood denehole lies at my feet. A muddy slide down the side of the 15 foot crater, and my body is halfway into the jaws of the earth; several hundred tons of chalk sit inches away from my chest.

I scramble all the way in, being careful not to touch the crumbly entrance area, and ease my way down into the spacious galleries, observing the classic double trefoil arrangement of the chambers. The smell is earthy and ancient - an aroma of passing centuries.

My breath smokes in the beam of the Oldham miners lamp, curling away in a faint draught. A few steps bring me to the bottom of the mossy shaft - the grey jagged circle of light looks back at me, illuminating old rope marks worn by countless baskets of chalk being hauled up centuries ago. After I complete my photography, I sit in quiet meditation for a while. Sounds of birdsong and distant traffic noise filter down, along with the skinny trees rattling against each other in the wind. The men's earthy banter as they hacked at the chalk long ago still echoes through the chambers - if you listen carefully.

Beneath the streets... with Dominic Clinton and Per von Scheibner

2009-09-13T02:18:00.035+01:00

An introduction to the blog
For well over 20 years Dominic Clinton and Per von Scheibner have been exploring, surveying and photographing the subterranean world beneath the streets of the London Borough of Greenwich, along with a few Kentish sites, notably the chalk mines of Chislehurst.

↑ Per von Scheibner in Ware Chalk Mine, Herts

↑ Dominic Clinton examining a pottery sherd underground during an expedition to Thailand

It's finally time to bring our huge archive to the general public. Without being immodest, it's fair to say that we know more about the dark labyrinths beneath the streets of Greenwich than anyone else alive - conduits, sewers, chalk mines, sand mines, deneholes and a host of other miscellaneous holes in the ground. Our excursions frequently take us into Kent, whose subterranea we jointly rule with other explorers and gurus.

↑ Per von Scheibner inspecting an 18th century tunnel in Maze Hill, Greenwich

Please note that all photos are strictly copyright. Exact locations have been witheld for reasons of safety, along with the fact that many entrances lie on private property. It's also a matter of conservation - some of the passages are tudor, and in a poor state of repair; they will not withstand the onslaught of intensive visiting.

The passage seen above (in Maze Hill) has rotten boards with the strength of a coffee-dunked digestive holding up the arch in a couple of places. It's part of a small network of early 18th century brick tunnels whose purpose is unfathomable - they are neither sewers or conduits. The height varies from about 4 feet down to 18 inches, with occasional deposits from visiting cats to welcome the visitor. A flat-out crawl with your helmet scraping the ceiling is required to reach the passage seen in the photo.