No. 115
August 1957
Page 1
EDITORIAL Caving reports. Quite a few people must be wondering by now when, or even if, the next caving report is coming out, and what – apart from general slackness – is holding up the stuff which has been submitted for future reports. The original scheme was for such reports to be published whenever there seemed to be a need to record work which the club had done, and it was estimated that about two such reports per year would be about average. A fixed price of half a crown was also agreed upon. However, after the report on St. Cuthbert’s, the small size of the next reports has resulted in a new scheme of charging a price according to the length of the job, so that the next two will be a bit cheaper. Number 3, on the construction of lightweight caving ladders, is being prepared now and Number 4 will probably be cut before the end of the year. Prices and dates will be published in the B.B. later. “Alfie” _______________________________________________________________________________________
GENERAL NEWS July Committee Meeting Owing to holidays, attendance was low and not much new business was discussed. Apart from the progress on plans for the new hut and the electricity, the report from the analyst was discussed and a further report on the state of the drinking water was awaited. Progress is continuing on the redecoration of the women’s room. *
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Caving. The club G.B. day on the 29th June was taken advantage of by a party of 7 who had a pleasant cool 4 hours underground, away from the heat of the surface. Roy Bennett was in charge. The next date allocated for the B.E.C. to visit G.B. is the August Bank Holiday weekend. Cuthbert’s had a active month again, but to date no spectacular discoveries. Saturday, June 29th Coase managed to get Tom Radcliffe down for his first caving trip since he has been in Bristol. A visit to the Maypole series proved the reasonable access to this section of the cave. The so-called Upper Traverse Chamber Pitch needs in fact a 15’ ladder. The chain on the second pitch proved to be not so difficult as expected but all the same rather hard on the hands. A further 15’ ladder is need on the third Maypole Pitch pulled up from below on the Nylon line that is left there. (A correction to the last month’s account. It was incorrectly stated that the 20’ steel ladder was erected on the “last” Maypole Pitch. This should of course read “first”). On this same trip, a rawlbolt was fitted at the top of the big gour and a chain fixed to replace the “knobbly dog” previously used. On Sunday, 30th June, Norman Petty lead a party of six Sandhurst and two other B.E.C. members on a “tourist” trip. It was learnt that the Rabbit Warren extension was included and one Sandhurst type was persuaded to climb into the high level passage which didn’t go. The only snag was that he couldn’t bet back down and the rest of the party had to build them selves into a pyramid to rescue him! It is also reported that one member of this party through carelessness, broke off a number of fine stalagmites at the awkward ten foot climb. A great pity, will leaders of trips make sure that this sort of thing doesn’t happen again. Also, muddy hand prints have been planted on a number of stal. banks. The entrance to Harem Passage from the Railway Tunnel is one spot where with reasonable care, it is not necessary to touch the stal.
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On the 5th July, Chris Falshaw and T.S. Mills investigated a tributary passage between Pillar chamber and the Upper Mud Hall. Two hours work with a lump hammer and chisel were needed to remove the offending stal. The passage then lead into Pillar Chamber after thirteen feet. On the 7th July, Chris Falshaw and Steve took two Derbyshire climbing types on a semi-tourist trip. A short passage above the Plantation Junction was cleared of gravel, but nothing of interest was found. Further digging is required in this place. On the 15th July, Kangy King, George Honey and Chris Falshaw took six members of the Old Westonians round, into the furthest recesses of the Rabbit Warren. Here various small passages were penetrated for only a few feet. Work was started on the removal of a boulder choke on the upstream end of Continuation Chamber. The choke consists of round boulders, stal. and mud. The process of clearing from below is somewhat hazardous. Permission has now been obtained to dig Scramble Swallet, or Ramspit, and thus a large crowd assembled at the swallet on the 6th July to watch Bob Price and apprentice Gaff Fowler loose off deadly explosives in an attempt to remove several boulders, conveniently placed for them by Tony Rich. The entertainment was successful and club members were soon returning tn the Belfry removing earth and grass from their hair and replacing ears, nose and fingers etc. On the 13th and 14th, Kangy, George Honey and Chris Falshaw removed the debris from the blasting operation and continued digging at the end of the present cave. Good progress is being made in this hole. (The caving news was supplied by Don Coase and Chris Falshaw – Editor). _______________________________________________________________________________________
NOTICES & REMINDERS Caving Blackboard. It has been recently been brought to the notice of the Hon. Caving secretary that certain people (no names, no pack drill) are not filling in the details of their caving trips on the blackboard provided for this purpose in the Belfry. This board is for your safety and if you do have trouble down some hole it can mean you are found much sooner. It may appear a bit pointless when half a dozen people see you start off for Swildons, but perhaps they might go off somewhere else for the day and then go straight home. If M.R.O. have to start searching for you there are a large number of holes on Mendip and a glance at the board could save a lot of work and maybe your family a lot of needless anxiety.
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Drinking Water The second report from the Analyst has now been received. The drinking water pool is contaminated by surface contamination but the spring at Fair Lady Well is pure – probably as good of not better than tap water. The contamination occurs quite high up the steam and so if you want to draw water for drinking, the nearer you obtain it from Lady Well the safer you will be. _______________________________________________________________________________________
No. 115
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POET’S CORNER ……..A sonnet on the state of the Belfry lighting arrangements….. When Hunter’s lodge was lit by Calor gas Whose fragile mantles burnt with brilliance low When cavers scarce could see to drink their Bass Or sat in Silvie’s in the oil lamp’s glow, The Belfry – like some beacon in the night Shone out upon the startled countryside With lamps, electric, gleaming wondrous bright And flinging out their radiance far and wide. Now Mendip with Electric lighting shines The B.E.C., with ever cunning brain, Are working still on ultra-modern lines By using candles. They are first again! When Shepton have an atom powered car The Belfry will now have glow worms in a jar. “Alfie.” ______________________________________________________________________________________
A NEW ROMAN ROAD NEAR BRISTOL ………by Keith Gardner. With the discovery of the Roman town at Gatcombe, Long Ashton and the known numbers of Roman villas and minor farmsteads in the Bristol neighbourhood within the Bristol – Clevedon – Portishead triangle ever increasing, it becomes obvious that there must have been at least one main road connecting the district with the main network. An extensive occupational settlement is know to have existed at Sea Mills and this may possibly be identifies as ABONE referred to in the Antonine Itinerary. A study of aerial photographs backed up by field work revealed that one of the suspected roads ran north from Gatcombe towards Failand Farm, probably turning on the hill above the farm and proceeding via Abbot’s Leigh to the Avon bank opposite Sea Mills. Excavation at Abbot’s Leigh (ST/537738) confirmed its presence and also revealed a defended site with two levels of occupation connected with rough stone foundations. The lowest level contained native Iron Age pottery mixed with a little early Roman material together with a quantity of iron slag, bones, charcoal, a piece of coal and a pennanular brooch pin. This level was sealed by a rough floor, itself containing pottery, upon which was found pottery of the (early) third century. A lead pottery repair rivet and a lump of lead ore are being subjected to spectrographic analysis and it is hoped that the source of the coal may be identified by the N.B.C. Now how does this road fit in to the general system and does it connect with Mendip? To appreciate the situation it had better be explained that the district was for a time the Claudian frontier. The Charterhouse or Priddy lead mines were under imperial control within a couple of years of the Claudian invasion and Gloucester, possibly Sea Mills, Taunton and certainly Wivelscombe were advance frontier posts. These frontier posts and the Mendip mines were connected by East-West roads to the great Fosse Way which served as an arterial supply column for the frontier. When the Welsh frontier was pushed forward and the II Legion AUGUSTA moved its H.Q. from Glevum (Gloucester) to Isca Silurium (Caerlon) it seemed that a road parallel to the Fosse Way was constructed to feed the new frontier, running through Gloucester and Sea Mills. A ferry crossing the Avon would connect this with the newly discovered road to Gatcombe.
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A study of the 1” O.S. map shows a road and track alignment starting at Lulsgate Bottom (ST/514657) and going to Regilbury Court (ST/520630). Felton Hill may have been the junction between the Gatcombe road coming S.S.W. and one from Wraxall over Backwell Hill. This latter has yet to be proved but signs are promising. From Regilbury Court the road may have gone past the top of Harptree Hill where a straight alignment past Hunter’s Lodge to Rookham Hill (The old Bristol Road) would have served the St. Cuthbert’s settlement. Field work along these lines on Mendip would be a useful contribution that the B.E.C. could well undertake. _______________________________________________________________________________________
SWILDONS
FOUR
The following letter has recently been received from Dennis Kemp of behalf of the Westminster Speleological Group….. “Some members of our Group, with friends from other clubs, are actively engaged in the exploration of our dig at the bottom of Blue Pencil Passage, since the breakthrough three weeks ago. Some of the working parties have been inconvenienced by the great masses of spent carbide in the breakfast chamber at our base camp. It was found early in the exploration that carbide fumes tended to make working parties sick, for the circulation is very poor; and for over a year now, carbide has been banned on our trips and miner’s electric headsets are demanded. Please do not think it ingratious of us if we ask the members of your club, through you, to refrain from recharging carbide lamps anywhere in the Paradise System, until the present exhaustive phase of active exploration is finished. Should anyone wish to visit the new extension to the main Swildon’s streamway, there will be ample opportunity of joining one of the many working parties that are going down. The co-ordinator is Len Dawes, 113 Brooklands Avenue, Sidcup, Kent. Volunteers must use electrics for lighting and be prepared for some very tight squeezes. It is anticipated that working parties will be going down practically every weekend until mid-September.” I am sure that caving types will help Dennis by not leaving carbide around and some may be interested in joining working parties. We hope that Dennis may be able to send in an account of the new extension soon. _______________________________________________________________________________________
STEREOSCOPIC PHOTOGRAPHY ………by R.M. Wallis. Previous articles in the Belfry Bulletin dealt with both monochrome and colour photography in caves. Stereo work in only an extension of these but it is useless to take it up until you are really proficient at ordinary cave photography. Not only are there usual problems of cave photography to be overcome, but the additional ones posed by the new medium have also to be coped with. Apart from anything else, failure is twice as expensive.
No. 115
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We see in three dimensions because our two eyes see the scene before us from slightly two different angles. Our brain fuses these two images together and from them produces the effect of depth. In order to re-create the scene as we saw it, it is, in theory, only necessary to present to each eye a picture of the scene as that eye would have seen it. Our eyes are normally 2½” apart and view them with the correct eye; the sceneshould appear in its full 3-D glory. Naturally, things do not work out quite as simply as this, but the practice is not particularly difficult. Special stereoscopic cameras can be obtained, but they are, unfortunately, rather expensive. They have the advantage that they take both the pictures at the same time and ideally, when using one of them, anyone who can take ordinary snapshot can take good stereo pictures. Since both pictures are taken at the same time, moving subjects can be included. The two lenses in these cameras are, of course, at a fixed distance apart, and although for most purposes this is not a disadvantage, it is a real snag in cave photography. Cave subjects have the advantage that they are stationary and there is no reason why the two pictures should not be taken one after the other with as long as may be convenient between exposures. This naturally eliminates the necessity for using a special camera and, in fact, any camera which can be used successfully underground, can be used equally successfully for taking cave stereos. It is only necessary to make the first exposure, to move the camera sideways through a suitable distance and then make the second exposure. It must be obvious that insofar as colour cave pictures are superior to black and white ones, so colour stereos are equally superior. The combination of three dimensions and colour is just about the most complete re-creation of the original scene that we can achieve. All that is lacking is the cold and wet and these we can usually do without. A 35mm camera is thus probably the most suitable, not only on account of the lower cost of colour film in this size, but also owing to the wider choice of makes of colour film which are available for this size of camera. My personal choice has always bee Kodachrome Type A, which has invariably given satisfying results when using either Flashbulbs or Flashpowder as the illuminant, but naturally any other personal preference can be used equally well. In order to move the camera between the two exposures it is advisable to manufacture s small gadget although these can be purchased ready made if necessary. The commonest type of these consists of two plates, one fixed to the tripod and the other to the camera and connected together by a parallelogram linkage so that when the top plate is swung from one side tom the other, the camera is moved the desired distance. The disadvantage of this type is that it is difficult to arrange for variable separation. My own type consists of two plates which will slide one within the other and which can therefore be moved any distance between the smallest imaginable to about six inches. This range is amply sufficient for all cave work. These devices can be made out of almost all readily available materials – metal (preferably a rust resistant type) plastics or wood – and no doubt a suitable design will occur to the photographer. It is possible to dispense with this apparatus and to move the tripod bodily to one side, but this is definitely not to be recommended as it is then extremely difficult to ensure that the field of view is identical for the two exposures. Another method which has been suggested is to hold the camera first to one eye and then the other or alternatively, keeping it to the same eye band shifting the weight from one foot to the other between exposures. These methods are fairly satisfactory out of doors, but are unlikely to succeed in a cave. The technique of lighting the subject is essentially no different from that used when only a single picture is being taken and the same type of illuminant can be used. Flashbulbs are, however, to be preferred to flashpowder as there is then no necessity to wait while the fog created by the first flash disperses. As any cave photographer may well be aware, this can take a very considerable length of time and although the camera may be left in place while this happens, the use of flashpowder should normally be restricted to those places where it is known that the smoke will disperse fairly rapidly. On one occasion at least, I have had to abandon taking the second exposure when the fog was as thick as ever half an hour after the first flash. Admittedly this was a small chamber in a blind alley, but it is always advisable to leave very ample time between flashes as a trace of smoke can appreciably affect the second exposure, not only by softening the outlines of the more distant objects, but also by altering the colour balance. In one of my stereo pairs, a trace of smoke which was not apparent at the time, has caused the second exposure to be very much bluer than the first, though it must be admitted that this do not appear to detract from the effectiveness of the stereogram. For this reason, the use of flashbulbs is to be preferred; beware however, of the type of flashgun which is attached to the camera. Moving the position of the source of light between exposures is most undesirable as it alters the position of the shadows and can spoil otherwise an excellent picture.
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It may appear at first sight that almost any scene would make an effective stereo picture, but this is not, in fact, the case. Although the eyes are extremely efficient at location one body on front of, or behind another, they cannot locate accurately the position of an isolated object. It is, therefore, necessary to include in the picture a series of objects ranging from the fairly close foreground to the distance, so that the eyes can travel from one to the next, locating each in turn. In this connection, it is also important that the entire picture should be in focus; the technique of differential focus should never be used in stereo photography. Although we are unable to view a complete scene all at once, and therefore all of it except the part at which we are actually looking appears to be out of focus, the eyes can travel rapidly over the scene surveying all of it. To give a natural effect, they must be able to do this with the photographs which must therefore be sharp all over. It follows that if we wish to emphasise the importance of a particular object in the scene, this must be done by placing it suitably in the frame and if possible, by arranging subsidiary objects so as to make the eyes lead up to the main object. To be completed in next month’s Belfry Bulletin. Editor’s Note: For those who wish to refer to the previous articles which have appeared in the Belfry Bulletin on photography in caves, they are: “Starting Cave Photography” by D.A. Coase, published in Belfry Bulletin No. 39 for September 1950. “Colour Photography in Caves” by R.M. Wallis, published in Belfry Bulletin No .69 for May 1953. _______________________________________________________________________________________ Mendip Mining. The series of articles on this subject by Mervyn Hannam will be completed next month. _______________________________________________________________________________________ All contributions for the B.B. should be sent or given to any member of the Editorial Board, or the Club Secretary. Secretary.
R.J. Bagshaw, 56 Ponsford Road, Knowle, Bristol 4.
Editor.
S.J. Collins, 1 Kensington Place, Clifton, Bristol 8.