Mendip Caving Group

What an exciting place Mendip is for cavers at the moment thanks to the Upper Flood Swallet breakthrough, the promising Stainsby's Shaft dig, and now the breakthrough in Charterhouse Cave.

Although I was a Charterhouse leader for many years I never went into the dig beyond Grotto of the Singing Stal. I am just sorry I will no longer fit down the narrow fissure near the entrance so, as with Upper Flood Swallet, I will have to rely on the chat and photos

Breakthrough by WCC in Charterhouse Cave

After 26 years of digging and over 125 working trips the Wessex Caving Club have finally got through the Charterhouse Cave boulder ruckle and have explored an estimated 300m of walking sized streamway. A sizeable inlet enters part way down the extension and it is believed that this water is probably the G.B. Cave stream. Work continues. The final section of the Charterhouse boulder ruckle is extremely unstable and makes the Upper Flood Swallet boulder choke look positively safe!

The hard-won and significant breakthrough took place in the boulder choke in Charterhouse Cave where, after 125 digging trips over 26 years, the Wessex digging team lead by Pete & Ali Moody and Pete Hann found about 300m of new passage, some of it well decorated, and added about 90m to the depth of the cave. The breakthrough was just in time for the MCG dinner and Pete Moody came along as Guest Speaker to describe the discoveries.

However, most Charterhouse leaders will not be taking trips into the new stuff for a little while. There is a gate at the beginning of the dig, beyond The Grotto of the Singing Stal and this will remain locked for some time, with trips being undertaken only with the diggers. The reasons for this are twofold: firstly the diggers will have the usual period of grace in which to complete exploration, surveying, photography, conservation work and scientific inspection. Secondly the breakthrough choke is in an extremely precarious state and time will be needed to analyse the extent of the danger that it poses and to undertake any stabilisation works that might be possible.

A week after the announcement of the breakthrough, the team was back in action and several new things came to light:

There is a hint, based on altimeter readings, that the cave is actually considerably deeper than was first thought. The diggers are making no claims as yet, that will wait until the high-grade survey can be done, but the possibility is that they have broken their own Mendip depth record (Longwood Swallet 575 feet) and have the first 600 feet deep Mendip cave.

Time will tell, but with this team anything is possible. However, the choke is still extremely nasty and still needs work.

This is the second significant breakthrough in the Cheddar catchment area in less than 2 years (the other being in Upper Flood Swallet).

MCG extend their congratulations to the WCC. The race is well and truly on for the 2008 digging barrel!

Hidden Earth

Upper Flood padlock

Biff and Doug have modified the Upper Flood Swallet lid to take the new security padlock. Leaders should note it is a close fit and a bit fiddly at first but once you find the knack it's ok.

There is currently a single new key in the Upper Flood Swallet key box - it has the Upper Flood Swallet key tag attached to it. Make sure you have the right key when going to the cave!

The new padlock has a detachable shackle. When the key is turned in the body of the padlock, the shackle drops out. It is important, when opening the lock, to hold onto this shackle so that it is not dropped down the entrance pipe.

The cave should be kept locked at all times. However, the lid is designed so that it can be opened from within without a key.

Charities and Public Benefit

From 1 April 2008 all charities must not only have 'charitable aims' but must also demonstrate that the aims are for the public benefit. MCG already satisfies the 'charitable aims' condition, but do we meet the 'public benefit' requirement?

Public benefit - It must be clear what benefits to the public arise from carrying out a charity's aims. Our aims as stated in the Constitution are: 'the furtherance of all aspects of the exploration, scientific study and conservation of caves and related features' This is evidenced by:

The benefits must be related to the aims (exploration, scientific study and conservation. Between our different activities, each of the aims is covered, not just some of the aims

Benefits must be balanced against any detriment or harm. Our activities are not detrimental (unless you count digging) and we do not have aims that are illegal or are a sham.

The beneficiaries must be appropriate to the aims. Membership is open to anyone over the age of 16 years with an interest in the objects of the Group. Persons aged under 16 years may be sponsored by a member and attend meetings as their guests. Members can bring accompanied guests to the cottage and use tackle etc for no further fee. The actual number of people who can benefit at any one time may be quite small (120 members) but anyone who could qualify for the benefit is eligible. The benefit may be to a 'section of the public' (cavers), rather than the public generally, but the restriction is reasonable and relevant to the charity's aims (caving carries a risk so restricting membership to over 16 is reasonable).

Where benefit is to a section of the public, the opportunity to benefit must not be unreasonably restricted by geographical or other restrictions; or by ability to pay any fees charged. Well, we are geographically limited to Mendip because that is where the caves are. But we have members throughout the UK.

Charities must not be seen as 'exclusive clubs' that only a few can join. MCG membership is open to anyone over the age of 16 years with an interest in the objects of the Group and persons aged under 16 years may be sponsored by a member and attend meetings as their guests. Charities can charge fees that more than cover the cost of their services or facilities, provided that the charges are reasonable and necessary to carry out the charity's aims.

Where the charging restricts the benefits only to people who can afford to pay the fees charged, this may result in the benefits not being available to a sufficient section of the public. Members in hardship can apply for a reduction in subs, and cottage fees are charged at cost.

People in poverty must not be excluded from the opportunity to benefit. �If we excluded people from the opportunity to benefit because they could not pay the fees, then our aims would not be for the public benefit. Trustees should think about other ways in which people who cannot afford those fees can benefit in some material way related to their charity's aims. Members experiencing financial hardship may apply annually to the committee for consideration of a reduced personal subscription. If people are unable to join because they cannot affords the subs, they may use the facilities (tackle, library) for no charge as the accompanied guest of a member.

Any private benefits must be incidental. Where people or organisations benefit from a charity, other than as a beneficiary, then those 'private' benefits must be incidental, and not a necessary result, or by-product, of carrying out the charity's aims. Where private benefits are more than incidental this might mean the organisation is set up for private, not public, benefit and so might not be charitable. Any fees paid for presenting lectures should continue to be donated to the Group!

Reporting on MCG's public benefit. We already explain our activities in the Trustees Annual Report to the Charity Commission but this information now needs to be set in the context of our aims to show how in practice the aims have been carried out for the public benefit. Trustees will also need to confirm that we have had regard to the public benefit guidance.

Assessment. The Charity Commission decide, based on our Trustees Annual Report, if we are failing to meet the public benefit requirement. If we are failing, the Commission advise on what needs to change in order to meet the requirement, and give clear reasons and advice on what happens if it is not possible to meet the requirement. We will be not be expected to make changes overnight and the Commission will take reasonable account of how much time and resources might be needed to make changes in order to meet the requirement. If we fall foul of a public benefit decision, we can seek a review of that decision using the review procedures and, if necessary, can make a further appeal to the Charity Tribunal and, ultimately, to the courts. Having said that, the committee believe we already meet the public benefit requirement.

Upper Flood Lectures

Tim Francis is continuing to give a series of Upper Flood presentations to external groups and events. The slides in the deck continually get updated so feel free to drop Tim a line if you need a copy for something, such as Julie's session at the Grampian. Where a fee is being paid Tim donates all monies to the digging fund, so its all in a good cause. Recently he has lectured at the annual AONB Mendip Wardens and volunteers dinner in the Burrington Inn. So that's to all the people who have an active interest in the above ground world of the Mendips and of course including the Charterhouse reserve. Next stop was the Subterranea Britannica spring day conference at Imperial College on Saturday 12th April. And there is a Wells Rotary Club meeting coming up as well.

Lost swallet

Following the breakthroughs in Charterhouse Cave and Upper Flood Swallet, there is much interest in the remaining gap between the Charterhouse area and Blackmoor Valley. There is always the possibility that the still-slumping sink in Velvet Bottom about 400m down-valley from the old�Mendip Adventure Base should also drop into something interesting. It took a large amount of water after the 1968�flood. Vegetation had been visibly sucked into the hole.

As a practical guide to its location, walk on down Velvet Bottom having passed the 'adventure centre' on your right, initially the path hugs the drystone wall to your left. After about 300m it veers a little to the right�toward the right-hand drystone wall, and then it is followed among banks of mining spoil. The valley bottom lowers on the left�to form an elongated flat-floored depression. The path continues alongside and to the right of�this depression. The slumping feature is clearly visible at the farthest down-valley south-easterly�point in the depression floor.

We first noticed this feature a few days after the 1968 flood. It was immediately impressive but the surrounding soil was like a squelchy�bog. Despite the presence of grass and other vegetation showing clearly that it had been sucked down�into the hole we didn't fancy 'doing' a bog, and shortly afterwards we began work on Upper Flood Swallet which was guaranteed 'real' cave. The prospects in and around Velvet Bottom had momentarily gone�crazy: Grebe (Middle Flood) Swallet looked interesting; Waterwheel (Lower Flood) Swallet was inviting. These two were tempting until we saw Upper Flood Swallet which simply demanded our attention. Manor Farm Swallet had been transformed. However, Velvet Bottom was our first love, so there we stayed.

Regardless of the foregoing, it would still be interesting for fresh eyes to look into Bone hole. It is an impressive site which may still hold possibilities. Anyone with half-an-hour to waste could also find peering into White Spot Cave in the Gorge�interesting if it is still accessible.

I believe the feature which is being discussed is the end of the trench which the 18thC miners dug when they were reworking the older waste which filled the original valley. The sediments in the central deepest part of the valley had the highest concentrations of lead. When the price of lead plummeted, the mining company dug out the best stuff before they went bust. I suspect all this info is in Stanton and Clarke's paper.

During the 1968 floods the water flowed (rushed) down the valley until it reached the end of the trench and then disappeared. Whether it went down a swallet or just drained to the bottom of the sediments to emerge further down the valley is unknown (but I suspect the latter). Note that the water didn't flow all the way down the valley on the surface but resurged just below Charterhouse 1 Floor (smelter). I don't know where it sank below the breached embankment of the horseshoe bend.

A feature which intrigues me is the kink in the wall which bounds the south side of Velvet Bottom. It can be seen on Bill Chadwick's website to the east of the end of the trench (GR approximately 4950 5495). Why is the kink there? Presumably the wall builders were avoiding something and (if I remember rightly) there does appear to be a depression on the south side of the wall.

Also, there is a leat and water channel which occur down-valley of the buddles associated with the Charterhouse 1 smelter. Could this have been channelling water to a swallet?

Swildons book review

Few and far between are the books on caving that have really grabbed me. I will always be a life-long advocate of 'Subterranean Climbers' by Pierre Chevalier. From a few weeks ago that tome will have a challenger. I had not been too much enthused by prior announcement of 'Swildon's Hole 100 Years of Exploration' by D.Irwin, A. Moody and A. Farrant; edited by J. Hanwell and R.Whitcombe (Wessex Cave Club, 2007). However, the published result attests to the success of this team.

Before I had read ten pages, I was warming to the narrative. The exploration story begins in 1901. I was only six months old when Sump One was first dived in 1936. Having been familiar with Swildon's Hole since my first visit to Mendip in 1953, I thought I more or less knew the story of its exploration. However, this book fills in gaps in my knowledge, which I never knew existed.

It was often the proud boast of cavers in the 1950s that they had done a 'Full Swildon's'; this was a trip to Sump Two, free-diving Sump One on the way. Today such a trip doesn't merit a mention because it is no longer done wearing linen boiler suits and woollen underwear. Using a carbide lamp didn't help much, either. I vividly remember finding several 'lost' stinkies during one particular passage of Sump One.

The narrative moves smoothly through the early phases of exploration, helped in no small measure by copious photos and survey extracts. Page design is easy on the eye, giving text and graphics room to advantageously complement each other.

It soon became obvious that putting down the book would be difficult. As soon as exploration moves beyond Tratman's Temple through the Forbidden Grotto and past the Blasted Boss, the story picks up great momentum as St Paul's and Paradise Regained and ultimately Swildon's Four are entered between 1953 - 1957. This was a period on Mendip when every caver and his dog were eager to lend a hand with the rapidly extending exploration.

Barriers, imagined or real simply melted away as individuals from any and every club were drawn into the effort. WSG played a leading role in the effort to reach Swildon's Four, notably as coordinators. If you wanted to join in on a working trip, all you needed to do was to approach Len Dawes in the Hunters' and offer your services. There were always 'sherpa' trips to join. Enthusiasm and a willingness to perform an allotted task were all that it required. Friendships were quickly formed and 'heroes' began to emerge as progress became increasingly distant and difficult.

The name of Dennis Kemp will forever be associated with Blue Pencil Passage. Miners-style belt-mounted electric lamps had now become the standard form of lighting. This permitted longer trips and exploration of some particularly wet and nasty places such as the Mud Sump. However, they made passing the original Blue Pencil Squeeze a trifle difficult.

With the discovery of Swildon's Four streamway, it was largely divers who took up the gauntlet of exploration. However, Paradise Regained continued to provide a source of new discoveries with such gems as Shatter Series, Double Trouble Series and South East Inlets. Eventually the exploration story begins to reflect the extremely demanding progress in such areas as Renascence Series, Watergate, Cowsh Aven Series and Passchendaele.

I was pleased to read that the last 2m of the Cowsh Aven climb was regarded as tricky - it was like emerging out into a funnel, with about as many obvious holds. The recently discovered link from Priddy Green Sink into Swildon's Four via Cowsh sounds well worth avoiding.

Just when you think the book cannot get much better; it does, when the folded Swildon's survey falls out at your feet. The geomorphology section is clearly written and well illustrated, but I mourn the loss of 'Old Red Sandstone' to 'Portishead Formation'.

For me personally the book is full of names and photos of people I remember so well and is a reminder of a golden age on Mendip. This book simply begs to be read by anyone interested in Mendip caving. There are many other caves which could benefit from such caring, detailed treatment.

Keys deposits

A deposit of �20 is required for any key loaned to casual callers to the Cottage. When giving out a key, take this deposit and agree how the borrower will a) return the key and b) collect the deposit.

Preferably, take a �20.00 note or cheque and hang it on the key hook, to be exchanged for the key on return.

If this is inconvenient (eg the key is to be returned at a time when the cottage may not be open) it is acceptable to take a cheque which can then be destroyed when the key is collected from the letterbox.

It is advisable to place a note on the key hook explaining which key has been taken and the arrangement for return of the deposit.

Yv'sdroppings

They words

If you missed they words in the back room of the Hunters, fear not. You can now Listen Again thanks to Thrupelite® (the sounds & sights of caving,�with the discomfort and effort involved carefully processed out in the laboratories)

Do you want to know how the bison bones got into Hunters Lodge Inn Sink? The bones are a source of much puzzlement but Thrupelite® has an elegant theory to explain their presence. This theory is supported by an exciting discovery made recently at the lower end of Cheddar Gorge

March 2008

From the Editor

It is pleasing to have so many keen and active new members. I look forward to hearing from them - it's always good to get new members' views on caving trips, social activities, and other Group goings on.

We still have three main projects on the go - Upper Flood Swallet, Stainsby's Shaft, and the search for the elusive Charnel Shaft. There is something that everybody can get involved in, whatever their abilities. May it ever be thus.

Preliminary geological observations in Upper Flood Swallet

February 2008

Recent library additions

Cave and Karst Science, Vol 33 No 2 (for 2006) has something of interest for the club's surveyors. An article by Mark Dougherty describes how binocular vision disorders can affect the accuracy of a survey, to the extent that a Grade 5 survey may not be achievable. Various techniques to eliminate these errors are explained and compared. Another meticulously researched article in this volume records the history and development of White Scar Cave in Yorkshire.

Tsingy: Stone Forest - Madagascar by David Wolozan and Olivier Grunewald. A large, glossy coffee table book about the Tsingyy de Bemaraha National Park. The photography is superb with images of plants, animals, insects and CAVES and CANYONS. None of the caves are named but perhaps members of MCG's expeditions to Madagascar in 1998 and 1999 will recognise some of them.

The Descent by Jeff Long (1999). One reviewer's comment - "Far fetched fiction of average quality" (donated)

Grotte Casteret, an Annotated and Illustrated Bibliography (BCRA Cave Studies Series 17) edited by David St.Pierre. (2007). Essential reading if you are planning a visit, or even if you have visited the cave in the past. Surveys, numerous photos and, of course, a large bibliography.

Fight for Life: The Neil Moss Story by David Webb, 2006. The tragic death of Neil Moss in Peak Cavern occurred at about the time I first became interested in caves so I found this DVD enthralling, but sad. The events are sensitively described by some of the people who were directly involved. Photography and press cuttings from the time are intermixed with film of modern cavers retracing the route to Moss Cavern.

The World of Caves by Tony Waltham, 1976. A classic caving book of the 1970s - surprised we didn't already have it in the library (donated)

Cave Geology by Arthur.N. Palmer,Cave Books, 2007. An excellent book, packed with information, and with numerous drawings and descriptively captioned black and white photos. It has a useful glossary, index and bibliography and brings together most of the cave related disciplines (except cave biology which is planned for a later book). As Chris Howes wrote in his review in Descent 198 "every caver can simply enjoy reading and learning at a level that might challenge what you thought you know"

The Netherworld of Mendip by E.A.Baker and H.E.Balch, 1907. We were fortunate to obtain this book at the recent auction of the late Dave Irwin's books and pictures. Its descriptive prose brings the caves to life. A classic that every Mendip caver should have read.

The Mine Explorer (The Journal of the Cumbria Amenity Trust, Vol 1, 1984). A nice little publication with articles and surveys of Coniston Copper Mines, Ding Dong shaft and Helvellyn Mine, amongst others (donated)

Clearwell Caves, Ancient Iron Mines by Ray Wright, (30pp) undated but probably the first Clearwell Caves guide to be produced (donated)

Call-out cards

Advance Notice of Annual General Meeting 05/04/08

The AGM of the Mendip Caving Group will be held at Nordrach Cottage on Saturday 5th April 2008 at 10.30am.

Nominations for Office and proposals to change the Constitution and Rules must be submitted in writing by first class post to the Hon. Secretary's home address with the signatures of full members proposing and seconding at least 25 days before the meeting (10th March). A nomination for Office must be accompanied by a signed agreement to stand for election by the nominee. Nominations are sought for all posts.

Dec 2007

From the editor

It is nearly the end of another year and another good one for MCG. There has been lots of interest throughout the year resulting in some good reports. The MCG Yahoo Newsgroup is an excellent source of information too and it covers so many areas of caving - a very useful tool for me as Editor. But more than that; even though I live 300 miles away from the general hub of activity, this huge conversation that everyone can have enables me to be a part of whatever is going on. I'd like to wish you all a great Christmas and a Happy New Year - and here's to another good year for MCG. Yvonne

A Soaking on Skye

By Julie Hesketh-Laird

This year's Grampian Speleological Group's Annual Dinner was held on Skye and never having been there, let alone caved there, I thought it definitely worth a look.

According to the GSG's "Caves of Skye, Occasional Publication no 7", there is a considerable outcrop of both Cambrian Durness Limestone and Jurassic Limestone. There are only 2 caves over 300m in length but from my now limited experience of what the area lacks in length, it certainly makes up in quality.

On a wet and windy Friday afternoon, we headed off towards Skye for the weekend. Skye is about four and a half hours drive from Edinburgh. Only the first 45 minutes is on motorway and soon the road is windy and the biggest hazard is the grazing deer! The Grampian had booked a hostel and restaurant just over the Skye Bridge for what was the best attended dinner ever in the club's history.

Saturday dawned, very wet and incredibly windy. Around 30 or so people went underground that day with a large group of us heading over to Spar Cave (the Cave of the Nursling), a sea cave just to the south of Elgol. For some strange reason I had thought that we would just ramble over a sandy beach and pop into a sea cave for 20 minutes or so and then head to the cafe in Elgol for tea. So I had taken just waterproofs, a helmet and a couple of torches. And a 4 year old girl. Hmm.

Following in the footsteps of Sir Walter Scott who wrote about the cave in his work "Lord of the Isles" in the early 19th century, we set off in the lashing, horizontal rain down a muddy footpath and onto a rocky beach. We reached the small headland to find the tide still high and the cave on the other side. Some brave soul traversed around the headland, above crashing waves and called the rest of us over as the tide was on its way down. Eva was just superb with Mark and Pete - Grampian lads - helping her across the sea-weedy traverse. A very slippery walk up the valley on the other side of the headland took us to the cave entrance and under a waterfall in full spate and into the cave itself. When Walter Scott visited the cave in 1814 he had to climb over a wall built across the entrance using a rope, but a later passing sailor fired a cannon at the wall, demolishing it. Remains of the wall across the head of the inlet still exist.

The cave itself is just spectacular with almost vertical sides. It is formed by the erosion of an igneous dyke from a calcareous sandstone bed. It is the most surprising of sea caves and completely unlike any other I have ever been in as it is just beautifully decorated. The passage is high and the floor muddy to begin with but as one progresses into the cave, the walls, floor and ceiling become sparkly and white and the passage climbs up over flow gours to a clear emerald green pool.

A good description of a tour of the cave in 1835 describes it well: "..when, becoming incrusted with this brilliant substance [spar], it suddenly passes over a high mound, on which its roof rests, supported by massy columns crowned by capitals of pendent icicles. From this majestic portal, a steep descent conducts to a pool of the clearest water. It is only within a few years, that this cave was brought to light. Its beauty and magnificence when first discovered - before it had been despoiled of its stalactitic decorations by the contemptible pilfering of inconsiderate travellers - is spoken of with rapture by those who enjoyed the singular good fortune of witnessing it. What a proof does the unobserved toil of Nature, constructing, during ages, a monument of its workmanship so splendid in the dark recesses of a rock, afford of the might and skill of the guiding hand of Him who directs her operations where no eye but His surveys them, as well as on those vast fields of space on which worlds may gaze with wonder and delight!"

Soaked to the skin (even through Gore-Tex!) we made our way back to the car and I took my shivering child off to the local village hall for a warming hot chocolate and a complete change of clothes. I am not sure the experience has exactly enthused her about caving but it doesn't seem to have put her off either (caving now equals chocolate in her mind!).

That evening, the GSG gathered for its usual excellent annual dinner and around 40 or so people gathered after to hear me give a presentation on Upper Flood Swallet and so an orderly queue of people wanting trips in the cave began to form!

Sunday dawned slightly brighter and we headed off to the Allt Nan Leac Valley and for the first time, the cloud had lifted to reveal just what a spectacular setting the caves of Skye are in with the Cuillins towering above the sea at Loch Slapin. A large group of us headed over to the Camas Malag Caves, one of the best fun caves I have done in a long time. Steve Birch, a local Skye caver treated us to a guided tour of a few of the caves of the Valley. A 15 minute coastal walk took us to a small depression where a healthy stream was flowing off the hill into a low cave entrance. I waved goodbye to Ross and Eva and disappeared into what I can only describe as a Yorkshire cave in miniature.

The cave winds its way downstream taking a peaty torrent of water past occasional oxbows and through deep wallows. An unusual feature which is common in Skye caves is the occurrence of igneous dykes protruding into the limestone. At one point, the granite forces the water back above ground for a few metres before the stream plunges back over a short pitch and underground once more. That gave just enough time to wave again to the family who were walking on the surface and head back into the lower cave. The short (around 200m or so) but superb trip ended when the walking height rifty passage opens out to a spectacular entrance on the cliff overlooking Loch Slapin.

We had just enough time to take in Beinn An Dubhaich Cave before we hit the long road back to Edinburgh. A 10 minute walk uphill from Camus Malag, this cave too has multiple entrances due to the water being forced above ground by igneous intrusions. The cave was reached by a slippery climb down a small tree into a shakehole with 2 passages off. The dry way led first into a canyon which we traversed for 25m or so to a climb into a deep pool and a sump. We returned via the much thinner bottom of the canyon and then set off to the very exciting wet passage. The wetsuit boys had little trouble at all navigating the absolute torrent in Waterfall Chamber. So fierce was the water there that it ripped my Petzl Tikka off my helmet, never to be seen again. I made a hasty retreat in the dark, groping my way up the turbulent cascade and inhaling the peaty water as I went. Fortunately the lads managed to find the extremely tight and wet furthest exit to the cave and we met up on the surface where I was relieved to breathe the sweet Skye air. The wet caves of Skye hold no hostages and are very serious undertakings in such wet weather!

Speaking of the weather, it looked as if it was about to break once more and so we headed quickly back to the beach car park where Ross and Eva had been playing in the rock pools. Alas, we didn't quite make it before the heavens opened once more and we struggled out of our sodden gear in a complete deluge ensuring we were damp and soggy for our long road trip home.

If you are ever on Skye for a holiday, DO pack your caving gear - you will be in for a wonderful treat - even if the weather is unkind to you as it was for us. The GSG occasional publication no 7 is all you need for a long weekend of absolutely superb caving. Haste ye there!

For the last few years, occasional articles have appeared in the BCRA caving journals describing experiments with electronic compass and clinometer technology. The goal is to produce a "total station" for cave surveying, a single instrument that at a push of a button will record all of the survey readings in one go. At the start of 2007, there seemed to be little progress in producing a device that was sufficiently accurate, let alone one that was compact, robust, affordable and suitable for mass production. Then, out of the blue, a GP from Lancashire, called Phil Underwood, published details of his prototype electronic compass and clinometer that met all of the above criteria [CREG 66]. He called the unit the Shetland Attack Pony, and was offering a unit for loan and in the future to build units and sell them at the realistic price of ?250.

Click to enlarge - Clino and SAP for size comparisson

The benefits of the SAP were immediately obvious. The unit is aimed using a laser pointer, so can be used at arms length. In constricted passages, taking sights with a traditional compass and clinometer can be almost impossible, and typically the quality of readings in such circumstances is very poor. With the SAP, it is as easy to use in a constricted passage as in a comfortable chamber.

As it happened, Mike Richardson and I had agreed to survey Upper Flood's notorious Boulder Choke just a few weeks before Phil's article was published. A trip with that objective had fortuitously been aborted due to a small mud-slump blocking the way. On seeing his article, I immediately wrote to Phil and he offered to loan me his unit. It finally arrived in time for the August member's weekend, and I managed to persuade Mike to take a day off work and make a long weekend of it to get the most out of the SAP.

Click to enlarge - Sample of the survey of Upper Flood boulder choke

We set out on the Friday to survey the Boulder Choke, considering this to be the easier trip physically, and so conserve our energy for a long surveying trip at the far end of Neverland on the Saturday. All our expectations of the SAP were fulfilled.

The first thing to point out is that Phil has put a tremendous amount of thought and design into the unit. It is indeed compact and very easy to use. It is microprocessor controlled, and so Phil has of course had to write the control software for the unit. In so doing, he has put in numerous additional features that give the SAP the feel of a professional production unit, rather than that of an experimenter's prototype. Snazzy features include:

Underground the unit performed faultlessly and lived up to all our expectations. Using the SAP for compass and clino, and my Bosch laser rangefinder for distance, it was not only a lot more comfortable to take measurements, but also very much faster. Indeed, even in the constricted Boulder Choke, we found that instead of Mike waiting for me to take all the measurements, I was now waiting for him to write them all down and sketch the passage. Taking readings was a joy. In the Boulder Choke, we surveyed 82m in 39 legs, an average leg length of 2.1m per leg, indicative of the small and convoluted dimensions of the Choke.

The next day, with the help of Julie Hesketh, we tackled the remaining 300m of Neverland beyond the Rope Climb. The survey trip for the first 400m of Neverland had taken 12 hours producing 41 legs (9.7m per leg). Braced for another long trip we set off ridiculously late, not making it underground until after mid-day. Thankfully, however, with slightly easier terrain and the benefit of the SAP, we polished off the survey in record time recording a massive 48 legs (6.3m per leg). We emerged from the cave just 7.5 hours later.

A couple of loop closures on the Saturday also established a survey accuracy of 1.6% for the SAP. In fact, compared to compass and clino under ideal conditions (<1%), this is not a great result, and not as good as Phil's published results (1%) [CSG 37], but it still represents a good overall accuracy, and one that is more than adequate for our current purposes.

So - should we all rush out and buy a SAP? Well, I have! But I would recommend caution, unless you have cash to burn. The potential problems with the SAP are as follows.

It is not waterproof or even water resistant. I "seal" mine with insulation tape to keep out the moisture, and open it and expose it to warm dry air after every trip.

It is fragile. While Phil has made it as robust as possible, a drop is likely to dislodge internal components (battery, etc), destroying the calibration. While recoverable, it will take an hour's intense work to re-calibrate.

My new unit has suffered a "system crash" while connected to my computer, requiring me to hard-reset the unit by disconnecting the battery. This is not a known fault, and may be a one off, but is indicative of the fact that this is a newly designed unit hand-built to order.

Any electronics equipment can only be expected to last for a few years before single components start to fail. Typically, individual components are only available for sale for a few short years, and maintaining old equipment can be very difficult. That said, we all have reliable radios, etc., that are 10 or 20 years old! The point really is that at ?250, one does need to consider replacement cost.

There is no guaranteed maintenance or warranty, relying only on the good will of Phil Underwood. Luckily, there is plenty of that, but my worry would come if too many people ask to buy a SAP and then swamp him with support issues. One option could be for Phil to offer the unit through a supplier, such as Firefly Electronics. In fact, there are currently a small number of inventors offering high-tech electronics including Scurion and Stenlight, not to mention more established manufacturers such as Speleo Technics and Petzl. At the other end of the extreme, Siemens has recently gone into a joint venture with Zaragoza University, Spain, to manufacture the next generation cave radio, the TEDRA!

Finally, I said at the start that the SAP is only almost the Holy Grail. What's missing? A built-in laser rangefinder of course. While these are available as separate units now for ?60, an integrated device would allow for all three readings to be taken at one go. Not only that, but LRUD data would also benefit from having accurate direction recorded, rather than the rather vague Left and Right, which also suffer from ambiguity in terms of left with-respect-to-which-direction? Furthermore, if the distance could also be recorded electronically together with the station number and directional information, then the occurrences of blunders could be reduced to almost never.

CGS 37, Calibrating a combined electronic compass/clinometer, Phil Underwood, 2007

Alfie

Sad to report that Stanley J Collins, better known as "Alfie" has died at the age of 82. Older members will remember him from the singing sessions at the Hunters in the 1960s.Author of 'The Spelaeodes', 'Reflections' and 'A Strange Device' and composer of many caving songs, he was guest speaker at one of our dinners where, in his inimitable style, he recited his "Nautical Narrative of Percy Pound"

Dave Irwin

BCRA Cave Technology Symposium 18-20 April 2008, Mendips

The 2008 BCRA Cave Technology Symposium will be held in the Mendips on 18-20 April 2008.

Organised by BCRA's Special Interest Groups: Cave Surveying Cave Radio & Electronics and Explosives Users.

This event will feature lectures and demonstrations on the Saturday (function room at the Hunters Lodge Inn), with field trips and classroom events on the Sunday (at Wessex Cave Club).

Longwood/August System - car parking

The owner of Lower Farm/Longwood Grange Farm requests that cavers and walkers do not park on the 'triangle' of grass just at the top of her drive, on the right hand side of the lane.

This piece of land is private and includes a grave. Please do not drop litter (or pee on the grass or in the hedge). Apparently, some of the crosses marking the grave have been removed by persons unknown.

Yv'sdropping

B**f: "I had a big bone." (adding as an afterthought: "But there wasn't much meat on it.")

Mendip Caving Group. UK Charity Number 270088. The object of the Group is, for the benefit of the public, the furtherance of all aspects of the exploration, scientific study and conservation of caves and related features. Membership shall be open to anyone over the age of 18 years with an interest in the objects of the Group.

Old news

April 2008

From the Editor

Breakthrough by WCC in Charterhouse Cave

Hidden Earth

Upper Flood padlock

Charities and Public Benefit

Upper Flood Lectures

Lost swallet

Swildons book review

Keys deposits

Yv'sdroppings

They words

March 2008

From the Editor

Preliminary geological observations in Upper Flood Swallet

February 2008

Recent library additions

Call-out cards

Advance Notice of Annual General Meeting 05/04/08

Dec 2007

From the editor

A Soaking on Skye

By Julie Hesketh-Laird

Shetland Attack Pony

by Ben Cooper

Alfie

Dave Irwin

BCRA Cave Technology Symposium 18-20 April 2008, Mendips

Longwood/August System - car parking

Yv'sdropping