The experiences during ascents of the highest mountains are
contradictory. Saussure describes the sounds on the top of Mont Blanc
as remarkably weak: a pistol-shot made no more noise than an ordinary
Chinese cracker, and the popping of a bottle of champagne was scarcely
audible. Yet Martius, in the same situation, was able to distinguish
the voices of the guides at a distance of 1340 feet, and to hear the
tapping of a lead pencil upon a metallic surface at a distance of from
75 to 100 feet.
MM Wertheim and Breguet have propagated sound over the wire of an
electric telegraph at the rate of 11,454 feet per second.