414 



Dr. Gregory on the Velocity of Sound. 



will not proportionally affect the velocity of sound ? and if so, 

 how are the modifications to be appreciated ? 



To the experimental solution of some of these inquiries I 

 hope to devote myself at no very remote period : but others 

 of them, it is evident can only be satisfactorily answered, if 

 ever, by means of a cautious classification of skilful experi- 

 ments made by various philosophers in different parts of" the 

 globe. 



Royal Military Academy, Woolwich, OLINTHUS GREGORY. 



Oct. 25, 1823. 



P.S. Since the above paper was drawn up, a friend lias 

 favoured me with the perusal of Mr. Goldingham's account 

 of his experiments in reference to the velocity of sound, made 

 at Madras. From this very interesting dissertation I shall 

 venture to transcribe the following table of the mean motion 

 of sound for each month of the year at Madras. 



These results serve, as far as they go, to confirm the sus- 

 picions which I have long entertained, that the velocity of 

 sound is somewhat 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 1 164 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. Un- 

 fortunately, 



