Velocity of Sound. 123 
Interval between flash and report in one case doubtful: the others 
were 1.88, 1”.88, 1”.9, 1.9, 1.9, 1.9, 1.91; the mean 1’.896, 
2100 
1.896 
Thursday, January 9, three quarters past 7, Pp. 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 between 
observing the flash and hearing the report, were 3”.25, 3’.28, 3.3, 
3”.3, 3”32; mean 3”.29, 
3600 
3.29 
The sound of the same charge, fired from the same musquet, 
= 1108 feet, velocity of sound; therm. 45°. 
= 1094.2 feet, velocity of sound; therm. 27’. 
was heard much more intensely, on this clear frosty night than in 
the day-time of January 3, at the same distance 3600 feet. 
Same day, January 9. Being anxious to extend the experi- 
ments to greater distances, I had previously applied to General 
Ramsey, of the Royal Artillery, the Commandant of the Garrison 
here, for the use of cannons as well as musquets, these, with his 
accustomed courtesy and kindness, he immediately ordered to be 
at my disposal, whenever I should need them in the course of my 
experiments. 
On the morning of this day, therefore, I chose a station for the 
gun, on the side of Shooter’s Hill, between Severn-Droog Castle 
and the 8 mile-stone on the Dover road. I selected three other 
stations from which the gun could be seen with a good Theodolite 
telescope; one of these was at the entrance of the lane turning 
from the Dover road to Charlton, between ‘‘the Sun in the Sands,” 
and the 7 mile-stone; the second in the Kidbrook Lane which 
turns off from the Dover road between the 6 mile-stone and ‘the 
San in the Sands;” and the third on Blackheath, nearly in a 
Q2 
