torstai 14. huhtikuuta 2016

Akustinen vakoilu

The widespread sail of a ship, rendered concave by a gentle breeze, is also a good collector of sound.
It happened once on board a ship sailing along the coast of Brazil, far out of sight of land, that the persons walking on deck, when passing a particular spot, always heard very distinctly the sound of bells, varying as in human rejoicings. All on board came to listen, and were convinced, but the phenomenon was most mysterious.

Months afterwards it was ascertained, that at the time of observation the bells of the city of St. Salvador, on the Brazilian coast, had been ringing on the occasion of a festival — their sound, therefore, favoured by a gentle wind, had travelled over perhaps 100 miles of smooth water, and had been brought to a focus by the sail in the particular situation on the deck where it was listened to.

- Neil Arnott, 1829

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