Letter: Expensive wind-up

Sir: How did Jack Swigert use, in zero gravity, a Rolex GM1 Master to time the firing of Apollo 15's rockets ("Time bandits", 25 August)?

Fine though this watch is, it couldn't be done. This watch is an automatic, which relies on a gravity rota to wind its mechanism. As there's a distinct lack of gravity in space this type of watch wouldn't work in that environment.

It's more probable he used a wind-up Omega Seamaster. This was the watch of choice for Nasa during the 1960s.

BRIAN ATHERTON

Hoddesdon, Hertfordshire