jumarn.

1966 Climbers' Club Jrnl. 77 Somebody spotted him dangling from his Jumars, half-way down one of the fixed ropes.

1968 P. Crew Encycl. Dict. Mountaineering 73/1 Jumars are the most effective device for prusiking, but they have the disadvantage of not working well on iced ropes.

1971 C. Bonington Annapurna South Face viii. 90 Once the ropes are in place, the climbers no longer move roped together, but simply clip onto the rope, using on the upward sections a device called a jumar clamp. This is a metal handle, with a knurled lever which is fitted over the rope. It works on a ratchet principle, sliding easily up the rope, but biting into it when put under tension.

1971 D. Haston in C. Bonington Annaourna South Face xvii. 214 The sun was two hours away from the gully when we started the upward jumar.

1972 D. Haston In High Places 2 Onward, outward, creeping on jumars and rimed ropes. It is cold... Dachstein-mitted hands freeze in jumar clutch.

1969 Sunday Times 16 Feb. (Colour Suppl.) 38/3 I dreamed that I was on the ropes setting off for the summit by myself and I was jumaring all night without getting anywhere.

1972 D. Haston In High Places ix. 104 The hook fitted, a quick move, and I was up. Mick jumared and I pushed on again.

1971 C. Bonington Annapurna South Face xi. 125 This was the first time that this type of free jumaring had ever been necessary at this altitude in the Himalayas.

1973 C. Bonington Next Horizon ix. 141 Later, I learned that an essential precaution for any jumaring is to tie a knot in the rope, so that if the jumars do slip on the rope, you don't slide straight off the end.