124 Dr. Grecgory on the 
continuation of the western wall of Greenwich Park towards the 
windmills. These three stations are probably 200 feet above the 
high water-mark in the Thames at Woolwich; and the statien at 
which the gun was placed is still more elevated. 
The distances, as accurately measured, were, from the Shooter’s 
Hill station to that in Charlton Lane 6550 feet; from Shooter's 
Hill to that in Kidbrook Lane 8820 feet ; from the Shooter’s Hill 
station to that on Blackheath, 13440 feet. 
The gun employed was a six pounder, the charge of powder 
eight ounces. The serjeant-major who remained at the gun, was 
directed to order the men to commence firing at a certain minute 
by his watch, (which was previously made to agree with mine) 
and then to fire regularly a certain number of rounds at intervals 
of two minutes ;: this was the practice throughout the experiments, 
the gun was always pointed towards me, at a very small elevation, 
except. it be otherwise expressed. 
January 9th, noon. Barom. 29.92 inches; Fahr. therm. 33° ; wea- 
ther dry, wind scarcely perceptible, a clear cloudless frosty day. 
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”.92, distance 6550, 
6550 5 
Fae 1098 feet, velocity of sound; therm. 33°. 
Same day, January 9, half past 12, barom. 29.86 inches; Fahr. 
therm. 33°; weather dry, wind scarcely perceptible. Six rounds 
fired. Result in reference to one, very doubtful. Intervals of pas- 
sage of sound from Shooter’s Hill to Kidbrook Lane, were 7”.95, 
8”.0. 8”.0, 8.0, 8”.05; their mean 8’. Distance 8820 feet, 
8820 ; 
—g = 1102; feet, velocity of sound; therm. 33°. 
Same day, January 9, quarter past 1, Pp. M. barom. 29.82 inches ; 
Fahr. therm. 33°; weather dry, wind scarcely perceptible. Five 
