Velocity of Sound. 405 



Six rounds fired. Interval of passage of sound from 

 Shooter's Hill to Charlton Lane, 5"*9, 6"*0, 5"'9, 6"*0, 6"*0, 

 6"*0, their mean 5"'9%, distance 6550. 



-^~ = 1098 feet, velocity of sound; therm. 33°. 

 59 T 



Same day, January 9, half-past 12, barom. 29*86 inches; 

 Fahr. therm. 33° ; weather dry, wind scarcely perceptible. 

 Six rounds fh*ed. Result in reference to one, very doubtful. 

 Intervals of passage of sound from Shooter's Hill to Kid- 

 brook Lane, were 7"*95, 8"*0, 8"*0, 8"*0, 8"*05 ; their mean 

 8". Distance 8820 feet. 



— £— = 1102^ feet, velocity of sound ; therm. 33°. 



Same day, January 9, quarter past 1 PM., barom. 29*82 

 inches; Fahr. therm. 33°; weather dry, wind scarcely per- 

 ceptible. Five rounds fired ; intervals of the passage of sound 

 between the stations at Shooter's Hill and Blackheath, 

 12''-2, 12"-25, 12"*3, 12''*24, 12"*26; mean 12"*25, distance 

 1 3440 feet. 



•^J^- = 1097 feet, velocity of sound; therm. 33°. 



£ (1098 + 1102i+ 1097) = 1099£ feet, mean velocity from the 

 sixteen rounds ; therm. 33°. 



Monday, February 17, noon. Barom. 29*98 inches ; Fahr. 

 therm. 35°. Air humid, but neither rain nor sleet ; very gen- 

 tle wind N.E. by E. Employed bells on the mortar-range on 

 Woolwich Common, lying nearly north and south. 



A bell rung at the north station, was heard by a soldier at 

 the south station, who immediately rang another bell, having 

 his arm elevated for the purpose. I stood by the soldier who 

 rang the first bell, and measured the interval of time between 

 the sound of the first bell, and the sound of the second bell 

 when transmitted from the other station. 



By several preceding experiments, I estimated the time 

 which elapsed between the moment when the man with the 

 second bell heard the sound from the other, and struck the 

 clapper against his own bell, finding it to be one-fifth of a se- 

 cond; this, therefore, I deducted from the intervals which 

 marked the passage of sound, before I recorded them, as be- 

 low. 



Distance between the two bells 1350 feet; whole distance 

 traversed by the sound 2700 feet. Intervals elapsed (cor- 

 rected as above) in five experiments; 2"*5, 2"*48, 2"*44, 

 2"-46, 2"*42 ; mean 2 "*46. 



-|f^ = 1098 feet, velocity of sound; therm. 35°. 



Same 



