JJQ TRANSMISSION OF SOUND THROUGH LONG TUBES. 



solid, to the difference 2*5" constantly observed between the 



arrival of the two sounds, we shall have the whole time of 



the transmission through the air equal to 2-76'. This time, 



calculated tVoin the length of the pipe, would have been 



2'79', as has jubt been seen; and the agreement between 



tliese numbers, which differ only 0"03", appears calculated 



to inspire some confidence in the results. 



Velocity in The time of transmission through the metal being 0'26", 



cast iron more vvhile that through air is 2 79"> it follows, that the transmis- 



thnn 10 times . . , _, , . • • ,,^ ^ .■ • i 



asgieatasLu s>o.n of sound: through cast iron is 10-5 times as quick as 



air. through air. If this estimation be not sufficiently exact 



to determine with precision the ratio of the velocities, it is 

 at least enough to show of what kind this ratio is, and what 

 idea we ought to'form of it. ,; 



Otherpheno. '" making these experiments we had an opportunity of 

 inena ob- observing several phenomena wortliy of remark with re- 

 **" ■ spect to the power with which sounds, even the faintest, 



are preserved and transmitted in tubes, to distances at 

 which we could scarcely suppose they would be perceptible. 

 Conretsation In our first experiments at the distance of I97 met, 

 easy through a |^215 yds.] we heard each other so well through the length 

 yards. of the pipe, that it was an inconvenience in the commence- 



ment, as the shghtest noise was transmitted from one ex- 

 tremity to the other. It was not necessary to speak into the 

 pipe to be heard, as common conversation two yards from 

 the end was transmitted through it clearly; and in writing 

 down my observations I asked Mr. Martin what it was 

 o'clock by his watch, as I would have done a person only 

 two paces from me. This mode of conversing with an 

 invisible neighbour is so singular, that we cannot avoid 

 being surprised, even though acquainted with the cause. 

 Speaking loud 1" ^^^^ experiments made by Messrs. Mai us and Bou- 

 heard 431 vard at the distance of 395 m. [431 yds,] they still heard 

 ^" '* each Other, but with much more difficulty. It was neces- 



sary to speak very loud, and frequently to desire a repeti- 

 At 1040 yds, ^'°^ ^^ *^'^"^ '^^^ been said. Finally, in the last experiment, 

 loud shouting which we tried at first together on a total length of 951 m, 

 bl^^nd^hc'' ['^40 yds.], the voice was scarcely to be heard when shout- 

 sound of the ing as loud as possible. The sounds of the bell and of the 

 hi.-n^crnot »ti<>ke of the hammer were no longer audible through the 



air. 



