92 M. Daniel Colladon’s Lxperiments on the Production 
This experiment was tried in 1838 on the coast of the 
United States of America, by order of the Admiralty, by Mr 
C. Bonnycastl , a professor in the University of Virginia. A 
notice of these experiments appeared in the 316th Number of 
the Journal of the Institute, p. 25.* 
Mr Bonnycastle’s Memoir contains an assertion which ap- 
pears to me to be opposed to the results I obtained in 1826, 
the details of which are inserted in the Annales de Physique 
for 1827, and in the 5th volume of the Memoirs of the Insti- 
tute. The American professor has concluded, from his ex- 
periments, that sound is better heard in air than in water, 
and he indicates the distance of from 8000 to 10,000 feet as 
the limit beyond which the sound of a bell under water could 
not be heard. The instrument which Mr Bonnycastle em- 
ployed was evidently very defective, for, in my experiments 
in the month of November 1826, using a bell weighing 65 
kilogrammes, I could transmit the sound, notwithstanding the 
noise of pretty considerable waves, to the distance of 13.500 
metres. J 
When we listen close at hand, in the water and in the air, 
to the sound of a stroke on a sonorous body partially plunged 
in water, using a hydro-acoustic apparatus similar to that de- 
scribed and figured in the 6th volume of the Savants étrangers, 
we distinctly hear two sounds; the first, conveyed by the 
water, is shortest, and appears less intense than the second, 
transmitted by the air ; but in proportion as we recede, the re- 
lation of the two intensities varies, and at a sufficient dis- 
tance the noise heard in the water is much more intense than 
that perceived in the air; and by still further increasing the 
distance, we continue to hear distinctly the sound in the water, 
even when it is impossible to hear any sound transmitted by 
the air, and that in perfectly calm weather and during the 
silence of the night. a 
When we strike, with equal force, a bell, alternately placed 
under water and out of it, we obtain results in every respect 
like the preceding. 
In the air, it is difficult to increase to any great extent the 
intensity of the collected sounds; the instrument I have de- 
* See Bibl. Univ. August 1839 (vol. xxii.), p. 380. 
