Velocity of Sound. 126 
rounds fired, intervals of the passage of sound between the stations 
at Shooter’s Hill and Blackheath, 12”.2, 12”.25, 123, 12’.24, 12”26; 
mean 12”.25, distance 13440 feet, 
13440 
122 
+ (1098 + 11024 + 1097) = 1099: feet, mean velocity from the sixteen 
rounds ; therm. 33°. 
Monday, February 17, noon. Barometer 29.98 inches; Fahr. 
therm. 35°. Air humid; but neither rain nor sleet; very gentle 
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 trans- 
mitted from the other station. 
By several preceding experiments, I estimated the time which 
=1097 feet, velocity of sound; therm. 33°. 
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 second, this, therefore, 
I deducted from the intervals which marked the passage of sound, 
before I recorded them, as below. 
Distance between the two bells 1350 feet; whole distance tra- 
versed by the sound 2700 feet. Intervals elapsed (corrected as 
above) in five experiments ; 2”.5, 2’.48, 2”.44, 2.46, 2”.42 ; mean 2".46, 
2700 
2.40 
Same day, quarter past 12, barom. therm. wind and weather as 
before. 
Distance between the two bells 1650 feet; whole distance 3300 
feet. Intervals elapsed in four experiments; 3”.0, 3”.0, 3.0, 3”.0, 
= 1098 feet, velocity of sound; therm. 35°. 
