120 Dr. Young's Experiments and Inquiries 



nous : but it is not demonstrable that this circumstance would 

 affect the divergency of the motion, except at the instant of its 

 commencement, and perhaps not even then in a material 

 degree ; for, in general, the motion is communicated with a 

 very gradual increase of intensity. The subject, however, 

 deserves a more particular investigation; and, in order to obtain 

 a more solid foundation for the argument, it is proposed, as 

 soon as circumstances permit, to institute a course of experi- 

 ments for ascertaining, as accurately as possible, the different 

 strength of a sound once projected in a given direction, at dif- 

 ferent distances from the axis of its motion. 



VII. Of the Decay of Sound. 



Various opinions have been entertained respecting the decay 



of sound, M. De la Grange has published a calculation, by 



which its force is shown to decay nearly in the simple ratio of 



the distances; and M. Daniel Bernoulli's equations for the 



sounds of conical pipes lead to a similar conclusion. The same 



inference would follow from a completion of the reasoning of 



Dr. Helsham, Dr. Matthew Young, and Professor Venture 



It has been very elegantly demonstrated by Maclaurin, and 



may also be proved in a much more simple manner, that when 



motion is communicated through a series of elastic bodies 



increasing in magnitude, if the number of bodies be supposed 



infinitely great, and their difference infinitely small, the motion 



of the last will be to that of the first in the subduplicate ratio of 



their respective magnitudes ; and since, in the case of concentric 



spherical lamina? of air, the bulk increases in the duplicate ratio 



of the distance, the motion will in this case be directly, and the 



velocity inversely, as the distance. But, however true this may 



