TRANSMISSION OP SOtJND THttfeftJeH LONG TUBES. J07 



kngth of 394*55 met. [431' 184 yds]. At this distance the length of 431 

 time of transmission through air would be ri58" by ^^"^ *" 

 calculation, supposing the temperature still 11° [51'8° F.]. 

 The interval between the two sounds, deduced from 64 ^"'^""val, 

 experiments, was found to be 0*81". The difference T'nie of trans- 

 , , ,, 1 • /> ••11 rnission 



theretore, or 0*348 , was the time or transmission through ihroueh the 

 the solid. This appears much too great, if we coin- solid. 

 pare it with the preceding experiments, and on those j'^^PP^'"'^"*" 

 that follow, which were made on nearly triple the leni^th. great. 

 The latter would not permit us to suppose a longer 

 time than 0*125" for the transmission through the solid, 

 wl)ich would give an errour of 0'223" in the observa- 

 tion. But, beside that It is extremely difficult to answer for 

 such quantities,' when the instant of observation does not 

 coincide exactly with a beat of the watch, it must be re- 

 marked, that the whole length of the pipe might be far 

 from being at the same temperature, which might occasion 

 currents of air, that would influence the velocity of the 

 sound. For instance, in the present case, if we were to 

 admit the transmission of sound through air as it results 

 from the observations of the chronometer made by Messrs. 

 Martin and Bouvard at the points of departure and arrival, 

 it would be found eqnal only to 1*07", or 0*088" less than the 

 truth, which gives 0-2()" ibr the time of the transmission 

 of the sound through the solid; and the excess of this 

 result over those that follow, being no more than 0*135", is 

 more easily reconcilable with errours of observation. 



- Finally, the txperiments now to be related were made by 3dset of expe. 

 Mr. Martin and myself, on a series of 37S cylinders, which, [""^"^5, on a 

 vtrith their joints, formed a length of 951*25 m. [1039*575 yds] yards nearly. 

 of which the joints alone occupy 5'6lm. [6*131 yds]. I 

 satisfied myself at different times, and by more than 200 

 experiments, either with the hammer or the bell, that the 

 interval between the two, sounds transmitted by the metal 

 and by the air, was exactly 2*5"; and I found no sensible 

 variation in this auaotity. I made Mr. Martin observe the 

 interval alsOj without letting hioi know my results, and hef 

 found the same. Now, at the distance of 951*25 met; Interval. 

 [1039*575 yds], the temperature bein^ 11^ [51*8°.F.], the 



time 



