372 Professor Airy on certain Conditions, §fc. 



To find the increase from one vibration to another we must 



take the integral between two vahies of t differing by —f= : and 



1 i_x • ^ ^t- • TT.rtfi- sin c>ye 



thus we obtani lor the mcrease • 



e 



I shall not occupy the time of the Society by a discussion 

 of the different values of the increase corresponding to different 

 values of c : I shall only remark that if c ^e be less than tt, the 

 arc of vibration increases continually. Nor shall I consider the 

 cases in which c is supposed to be a function of the position or 

 velocity of the vibrating body (which possibly might better re- 

 present the circumstances that originally suggested this investi- 

 gation.) My object is gained if I have called the attention of 

 the Society to a law hitherto (1 believe) unnoticed, but not un- 

 fruitful in practical applications. 



G. B. AIRY 



OBSBRVATORy, Dec. 13, 1829. 



