Miseatlanie. 161 
22d to 25th, 1838, with the view of. Pesetiitinting the depth of the sea by 
the echo.” 
This paper, which was not offered for publication in the Society’s 
Transactions, states that the generally received notions in regard to the 
intensity of sound in water, and the distance to which it is conveyed, had 
suggested to Mr. Botinycastle, some years ago, the idea that an audible ; 
echo might be returned from the bottom of the sea, and the depth be thus 
ascertained from the known velocity of sound in water. The probability ei: _* 
of this view was deemed at least sufficient to justify an experiment; and 
accordingly the Navy Commissioners authorized the construction of the a 
necessary apparatus, and Captain Gedney, of the U. S. Brig Washington, “Me 
attached to the coast survey, volunteered his services and the use of hi Pr 
vessel, and authority to this effect was liberally granted by the ary 
of the Treasury, Mr. Woodbury. an 
The apparatus, which is fully described in Mr. Bonnycastle’s paper, 
consisted, first, of a petard or chamber of cast iron, 2} inches in diam- 
eter and 5} inches long, with suitable arrangements for firing gunpowder 
in it under water; secondly, of a tin tube, 8 feet long and 12 inches in 
diameter, tarnfuated at one end by a conical trumpet-mouth, of which 
the diameter of the base was 20 inches, and the height of the axis 10 
inches ; ; thirdly, of a very sensible instrument for measuring small inter- 
vals of time, made by J. Montandon of Washington, and which was ca- 
pable of indicating the sixtieth part of a second. Besides these, an ap- 
paratus for hearing was roughly made on board the vessel, in imitation of 
that used by Colladon in the Lake of Geneva, and consisted of a stove- 
pipe, 41 inches in diameter, closed at one end, and capable of being 
plunged four feet in the water. The ship’s bell was also unhung, and an 
'_ arrangement made for ringing it under water. | 
On the 22d of August, the brig left New York, and in the evening the 
experiments were commenced. In these, Mr. Bonnycastle was assisted 
by the commander and officers of the vessel, and by Dr. Robert M. Pat- 
terson, who had been invited to make one of the party. 
Tn the first experiments, the bell was plunged about a fathom under 
water and kept ringing, while the operation of the two hearing instru- 
ments was tested at the distance of about a quarter of a mile. Both in- 
struments performed less perfectly than was expected ; the noise of the 
Waves greatly interfering, in both, with the powers of hearing. In the 
at: n of the metal, from the blow of the 
sub wooden casing; but, as it was 
_ water in the tube was found to 
t the sound of the bell was better 
as at the distance of a quarter of a mile 
= 4 shurp tap, about the loudness of that occasioned by 
gegen sates, 21 
efaekt: 
_ * if 2 3 
: a * 
Br) f m 
