Velocity of Sound. 403 



I employed no hygrometer (much as I wished it) ; for as 

 yet I am not acquainted with any in whose results I should 

 be inclined to confide. With regard to the distances between 

 the stations at which the sound was emitted and heard, they 

 were in some cases taken from the Ordnance Map of Kent, 

 and verified by new operations ; in others they were deter- 

 mined by actual and careful measurement : in others by tri- 

 gonometrical operations with accurate instruments. The 

 whole were conducted with care; and it would be useless to 

 enter into the detail of them. 



Friday, Jail. 3, 1824. — A nmsquet was fired from the bat- 

 tery near the Royal Artillery Barracks, and the interval of 

 time between the flash and sound was observed at two dif- 

 ferent distances on the mortar-range, direction nearly north 

 and south. 



January 3, half-past 2 P.M., barom. 29*7 inches, Fahr. 

 therm. 45°, rather moist atmosphere, but no rain ; very gentle 

 wind blowing in direction nearly perpendicular to that of the 

 range. 



Distance from musquet to my station 3600 feet. Six rounds 

 fired : in one the interval of time employed by the sound in 

 passing over the 3600 feet was doubtful : in the other five the 

 intervals were 3"*25, 3" - 3, 3"*25, 3"'2, 3"*26, the mean of these 

 is 3"-252. 



^— - =1107 feet, velocity of sound; therm. 45°. 



Same day, 3 o'clock P.M., barom. 29*64 inches, Fahr. 

 therm. 45° ; atmosphere, wind and weather as before. 



Distance from musquet to station 3600 feet. Five rounds 

 fired ; intervals 3 "'2, 3"% 3"*3, 3"'3, 3"-25 ; their mean 3"-25. 



— — - =1108 feet, velocity of sound; therm. 45°. 



Same day, half-past 3 P.M., barom. 29*64 inches, Fahr. 

 therm. 45° ; atmosphere, wind and weather as before. 



Distance from musquet to station 2100 feet. Eight rounds 

 fired. Interval between flash and report in one case doubt- 

 ful: the others were 1"*88, 1"*88, l"-9, 1"*9, 1"*9, 1"*9, 1"*91 ; 

 the mean 1"*896. 



— — = 1108 feet, velocity of sound; therm. 45°. 



Thursday, Jan. 9, three quarters past 7 P.M. dark, but 

 clear, star-light, frosty night. Barom. 29*82 inches, Fahr., 

 therm. 27°. Dry ; no wind. Musquets fired from the battery, 

 as before, distance 3600 feet. 



Six rounds fired, one doubtful. The other intervals be- 

 3 E 2 tween 



