1823.] Royal Society. 301 



observations on the subject, which Col. Beaufoy, in the Annals 

 of Philosophy for Sept. 18l4, had recommended to be made in 

 England, Mr. G. had instituted at Madras. 



The observatory at Madras is peculiarly well adapted for the 

 requisite experiments and observations : it is situated in 

 80° 17' 21" E. long, and 13° 4' 9-1" N. lat. between Fort St. 

 George and the artillery cantonments at St. Thomas's Mount; 

 being distant from the former 13,932-g- feet, and from the latter 

 29,547 feet. These distances were determined by a precise 

 measurement, founded on part of Col. Lambton's Trigonometrical 

 Survey. 



At the Fort, as is usual in fortified places, a gun is fired morn- 

 ing and evening ; in the morning at day-light, and in the even- 

 ing at eight o'clock ; at the artillery cantonments, a gun is fired 

 at sun-rise and at sun-set. The guns are both 24 pounders, are 

 each charged with eight pounds of powder, and are pointed, 

 though not exactly to the observatory, yet very nearly in. its 

 direction. The distance of the Mount gun from the observatory 

 being about double that of the Fort gun, a good opportunity 

 was afforded of determining whether sound travels at the same 

 rate through paths of different length. 



The observations were made with Arnold's chronometers, 

 usually making 100 beats in 40 seconds ; sometimes there were 

 three observers, the author and two Bramin assistants at the 

 observatory, but more commonly there were only two. Each of 

 them began to count on seeing the flash of the gun, and ceased 

 on hearing its report ; and then wrote down his observation 

 without communicating it to the other ; the observations were 

 afterwards given to Mr. G. for registration. The states of the 

 barometer, thermometer, and hygrometer, the direction of the 

 wind, and the general state of the weather, were noticed at 

 the time of each observation. 



Mr. Goldingham gave, in eleven tables, the results of the 

 observations thus made ; from which it appears that the mean 

 velocity of sound, by the observations on the Fort gun, is 

 1 142-j-'^- feet per second ; and by those in the Mount gun 1 142 T 5 „- 

 feet ; the mean of both series being 1 142-pW feet per second : 

 so that the mean rate at which sound travels, as deduced from 

 these observations, is, almost precisely, that which Newton and 

 Halley have assigned. 



Mr. Goldingham's observations likewise show that the velo- 

 city of sound is considerably affected by the different states of 

 the atmosphere and of the weather, and by the wind, contrary 

 to whathasbeen asserted. The close agreement of the mean velo- 

 city by the Mount gun with that by the Fort gun evinces that 

 sound does travel equably through paths of different length. 

 The last table showed the mean velocity at Madras for each 

 month ; the velocity increases to a maximum at the middle of 



