Boredom underground is not only tedious, it can be a killer ; muscles and brain seize up and then where are you? Incorporation into flowstone is a slow and dreadful way to shuffle off this mortal coil; so unwind those sprightly limbs, put your mind into gear - play ENGINES!!

Start with an easy one: SINGLE CYLINDER TWO STROKE (see fig. 1) Put hands over head, leaving about 1" gap (cylinder head), bend knees, lowering head (piston), keeping cylinder head in place. Unbend knees (compression stroke). At top dead centre (head nearest hands), shout "BANG !!" (ignition). Repeat sequence till satisfied. The more co~ordinated caver may care to try snapping his fingers just before shouting BANG!! to simulate the action of a sparkplug.

Got it? Good. Now gather several friends together, if you've still got any after shoutiug BANG!! for several minutes, and be a multicylinder engine. If playing a twin, remember, one is at the bottom while the other is BANG!!ing. Triples (120 degree crankshaft) are more tricky.

Now the real stuff - FOUR STROKE. (see fig. 2) Position yourself as for the two stroke and proceed as follows: Inlet stroke: Piston down, inlet valve open (left hand flaps down). Compression stroke: Piston up, inlet valve shut (left hand back up). Ignition: "BANG!!" Power stroke: Piston down, both hands up. Exhaust stroke: Piston up, exhaust valve open (right hand flaps down). Close exuaust valve. Repeat sequence till satisfied. Try again; you might get it after two or three tries. Don't move your arms - only the valves.

Now gather your fellow cylinders together and try a few nultis. There are two sorts of (easy) twins:

360 degree:

player 1 Inlet/compression/power/exhaust
player 2 Power/exhaust/inlet/compression

180 degree:

player 1 Inlet/compression/power/exhaust
player 2 Exhaust/inlet/compression/power

Now You're getting the idea, get a few workshop manuals together and try flat twins (eg. 2CV) or V twins (eg. Harleys [lust] or Moto Guzzis [likewise]). Then progress to triples and fours and - foaming at the mouth now - V6's and rotary engines and .....

Well, there should be enough here to keep you poor suffering souls warm deep in the bowels of the earth. All you need is a little co-ordination. Off you go now, kiddies, have fun (All right, officer, I'll come quietly).

Steve Roberts