American Philosophical Society. 539 



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 intervals of time, made by J. Mon- 

 tandon, of Washington, and which was capable of indicating the 

 sixtieth part of a second. Besides these, an apparatus for hearing 

 was roughly made on board the vessel, in imitation of that used 

 by CoUadon in the Lake of Geneva, and consisted of a stove- 

 pipe, 4§ 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 22nd 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. Patterson, 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 hear- 

 ing instruments was tested at the distance of about a quarter of a 

 mile. Both instruments performed less perfectly than was ex- 

 pected, the noise of the waves greatly interfering, in both with 

 the powers of hearing. In the trumpet-shaped apparatus, the ring- 

 ing 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 stiU 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 

 the 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 

 apparatus 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 contact with the surface of the water. In these experiments 

 the cone was placed at right angles to the stem, and the mouth di- 

 rected towards the sound. The distances were measured by the in- 

 terval elapsed between the observed flash and report of a pistol. At 

 the distance of 1400 feet, the conical instrument was found consi- 

 derably superior to the cylindrical, and at greater distances the su- 

 periority 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 

 lieard 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 sound was also wholly changed, and, from other 

 experiments, it appeared that the blow of a watchmaker's hammer 

 against a small bar of iron gave the same sharp tick as a licavy 

 blow against the large sliijj'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 



