162 Miscellanies. 
striking the back of a penknife against an iron wire: at the distance of a 
mile the sound was no longer audible 
In the second experiments, the mouth of the cone, in the trumpet ap- 
paratus, was closed with a plate of thick tin, and both instruments were 
protected by a parcelling of old canvas and rope-yarn, at the part in con- 
tact with the surface of the water. In these experiments the cone was 
placed at right angles to the stem, and the mouth directed toward the 
sound. The distances were measured by the interval elapsed between 
the observed flash and report of a pistol. At the distance of 1400 feet, 
_ the conical instrument was found considerably superior to the cylindrical, 
_ and at greater distances the superiority became so decided, that the latter 
was abandoned in all subsequent experiments. At the distance of 5270 
feet, the bell was heard with such distinctness as left no doubt that it 
could have been heard half a mile further. 
The sounds are stated in the paper to have been less intense than those 
in air, and seemed to be conveyed to less distances. The character of 
the soul was also wholly changed, and, from other experiments, it ap- 
peared that the blow of a watchmaker’s hammer against a small bar of 
iron gave the same sharp tick as a heavy blow against the large ship's 
bell. It is well known that Franklin heard the sound of two stones 
struck together under water at half a mile distance; yet two of the boat's 
crew, who plunged their heads below the water, when at a somewhat Jess 
distance from the bell, were unable to hear its sound. 
On the 24th of August, the vessel having proceeded to the Gulf Stream, 
experiments were made with the view for which the voyage was under- 
taken; that is, to ascertain whether an echo would be returned, through 
water, from the bottom of the sea. Some difficulties were at first pre- 
sented in exploding the gun under water, but these were at length over- 
come. The hearing-tube was ballasted so as to sink vertically in the 
water. The observers then went, with this instrument, to a distance of 
about 150 yards from the vessel, and the petard was lowered over the 
stern, about three fathoms under water, and fired. The sound of the 
explosion, as heard by Mr. Bonnycastle, was two sharp distinct taps, at an 
interval of about one third of a second. T'wo sounds, with the same im 
terval, were also clearly heard on board the brig; but the character of the. 
sounds was different, and each was secon by a slight shock. 
Supposing the second sound to be the echo of the first from the bottom 
of the sea, the depth should have been about 160 fathoms. 
To ascertain the real depth, the sounding was made by the ordinary 
method, but with a lead of 75 pounds weight, and bottom was distinctly 
felt at 550 fathoms, or five furlongs. The second sound could not, there 
fore, have been the echo of the first; and this was proved, on the follow-. 
ing day, by repeating the experiment in four fathom water, when 
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