At the place where we were camped a remarkable echo could be heard (one so remarkable that if it could be heard in this country it would draw crowds for its own sake); I believe it came from the cliffs of the Dent d'Herens. It was a favourite amusement with us to shout to rouse this echo, which repeated any sharp cry, in a very distinct manner, several times, after the lapse of something like a dozen seconds. The thunderstorm lasted nearly two hours, and raged at times with great fury; and the prolonged rollings from the surrounding mountains, after one flash, had not usually ceased before another set of echoes took up the discourse, and maintained the reverberations without a break. Occasionally there was a pause, interrupted presently by a single clap, the accompaniment of a single discharge, and after such times I could recognise the echoes from the Dent d'Herens by their peculiar repetitions, and by the length of time which had passed since the reports had occurred of which they were the echoes.
If I had been unaware of the existence of this echo, I should have supposed that the resounds were original reports of explosions which had been unnoticed, since in intensity they were scarcely distinguishable from the true thunder; which, during this storm, seemed to me, upon every occasion, to consist of a single, harsh, instantaneous sound.[1]
Or if, instead of being placed at a distance of less than a thousand feet from the points of explosion (and consequently hearing the report almost in the same moment as we saw the flash, and
- ↑ The same has seemed to me to be the case at all times when I have been close to the points of explosion. There has been always a distinct interval between the first explosion and the rolling sounds and secondary explosions which I have believed to be merely echoes; but it has never been possible (except in the above-mentioned case) to identify them as such.
Others have observed the same. "The geologist, Professor Theobald, of Chur, who was in the Solferino storm, between the Tschiertscher and Urden Alp, in the electric clouds, says that the peals were short, like cannon shots, but of a clearer, more cracking tone, and that the rolling of the thunder was only heard further on." Berlepsch's Alps, English cd., p. 133.
