Miscellanies. 161 



22d to 25th, 1838, with the view of determining 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. Bonnycastle, 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 

 of this view was deemed at least sufficient to justify an experiment ; and 

 accordingly the Navy Commissioners authorized the construction of the 

 necessary apparatus, and Captain Gedney, of the U. S. Brig Washington, 

 attached to the coast survey, volunteered his services and the use of his 

 vessel, and authority to this effect was liberally granted by the Secretary 

 of the Treasury, Mr. Woodbury. 



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 1] inches in 

 diameter, terminated 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. 



In 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 

 trumpet-shaped apparatus, the ringing of the metal, from the blow of the 

 waves, was partly guarded against by a wooden casing ; but, as it was 

 open at both ends, the oscillation of the water in the tube was found to 

 be a still greater inconvenience, so that the sound of the bell was better 

 heard with the cylindrical tube. At the distance of a quarter of a mile 

 this sound was a sharp tap, about the loudness of that occasioned by 



Vol. sxxviii, No. 1.— Oct.-Dec. 1839. 21 



