OF ARTS AND SCIENCES. 401 



du pendule k reversion," would still apply to such a case ; but I am 

 unable to see upon what ground. 



Meantime, in tlie present state of the question, it appears to me that 

 we must appeal to direct experiment to determine the difference 

 between the time of oscillation on a stiff and on a flexible stand. Such 

 experiments were given by me in the paper above mentioned, and I 

 have since greatly multiplied experiments on a stiff stand, with the 

 general result there announced, namely that the difference is slightly 

 greater than my theory supposes (owing, perhaps, to neglecting the 

 energy of movement of the support), and not smaller, as M. Planta- 

 mour's views would require. 



VOL. XIII. (n. 8. v.) 26 



