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We are naturally pleased to publish this letter from our old friend 'Sett' especially as it says nice things about the B.B.  It is good to know that at least one club member reads it!

Dear Alfie,

The April B.B. is one of the best you have ever published.  However, there are several items which, in my opinion, justify comment - some briefly, some at greater length.  Let us discuss the shorter ones first.

What a well designed collection of articles on gorges!  I have always enjoyed open air caving and could, perhaps, point Kangy at some other worthwhile gorges in France.  I hope he will excuse me if it turns out that I am teaching my grandmother to suck eggs.

The gorge which goes from Le Rozier to Mayueis is one that he probably knows and is particularly spectacular when viewed from the platform above Grotte Dargilan.  Johnny Ifold might like to know that they now collect the post daily (in joke!)

Over in the Vercours (Esso map ref. V13 and 14) there are several notable gorges and cirques.  The Grands Goulets (not to be mistranslated!) used to be ignored by the locals.

Changing to your article on knots.  You are quite right to point out that the more vicious bends make a more anti-¬slip knot but generally weaken the system.  I doubt if this is as important with man-made fibres as with natural.  I have tried to tie the knot by the method shown, but I can't make it match the completed picture.  Perhaps you would like to check.  I wouldn't be surprised if one of our ex-navy members writes in to say that he has known this knot for years under another name.  If you don't get any response, try John Ransome.

There should be no trouble lifting a quarter of a ton with an ordinary caving or climbing rope.  A climbing rope in good condition will have a breaking strength of at least a ton and a half.  It needs to, to withstand the shock of a hundredweight and a half body falling from above a belay to end up suspended the same distance below. Any rope, stressed to this limit, should survive that particular episode but NEVER be used for climbing again.

Changing yet again to electronics for caving.  Like you, I too am on the fringe of electronics, although I try to keep in touch with modern developments.  The ideal one to one system is obtained by designing the receiver to be as quiet as possible and have a gain which just makes the background noise audible. (This does not apply to broad¬cast systems.)  Modern transistors and OP AMPS are infinitely quieter than some of the early transistors and should be seriously considered.  The U.S. Navy has worked underwater systems both with audio frequencies and with V.L.F. Carriers.  George Honey, who appeared to know what he was talking about, suggested a 150Hz carrier.

I have seriously considered organising a meeting (teach¬-in/seminar) on underground communication, but pressure of work puts this off until around or after the A.G.M. Perhaps we could sound out the electronics experts before and at that time to see if such an event was worthwhile and who could usefully attend.

Yours,
" Sett "

Editor's Note:     On knots, I believe that I said the knot has to be 'pushed together' to tighten it, as it is so non slip that it won't do this for itself.  You get slightly different looking versions according to how you do this, but topologically they are all the same knot. I have tried John Ransome, who does not know the knot.

CLANGS On B.B. 306 of this year's B.B., the clinometer was, of course, read to 10 MINUTES OF ARC not feet.  The confusion arose because the sign 10' is the same for both measurements!