Velocity of Sound. 137 
Mean height of 
Velocity in 
a Second. 
Barometer. |Thermometer.| Hygrometer. 
meet lt neeeetel © Dey: Feet. 
January ..... 30.124 79.05 6.2 1101 
February .... 30.126 78.84 a 1117 
30.072 82.30 1134 
30.031 85.79 1145 
29.892 88.11 1151 
29.907 87.10 1157 
29.914 86.65 1164 
29.931 85.02 1163 
September . .. 29.963 84.49 1152 
October 30.058 84.33 1128 
November .. . 30.125 81.35 1101 
December ... 30.087 79.37 1099 
These results serve, as far as they go, to confirm the suspicions 
which I have long entertained, that the velocity of sound is some- 
what different in different climates ; and that hygrometric changes 
have more influence than has usually been imputed to them by 
theorists. The velocity varies from 1099 to 1164 feet, while the 
barometric range does not exceed a quarter of an inch, and the 
thermometer varies only from about 78° to 88°. But the indications 
of hygrometric change are considerable, passing from 1 to nearly 
28 degrees. Unfortunately, however, we are not able to make such 
satisfactory deductions from these curious experiments as they 
might have furnished, had Mr. Goldingham described the con- 
struction of his hygrometer, and the fixed points, or the extent of 
its scale. 
Royal Military Academy, Nov. 8, 1823. 
Vol. II. Part I. Ss 
