138 Remarks on Dr. Enfield’s Instotutes 
which is aay e to the ratio of the cube of the sine, instead 
of the sq But as the variation of the force deter- 
mined . eapetiieat differs totally both from the square 
and the cube, it would have pase better to erase the panes 
sition, than to attempt to amend it. 
Prop. 55. Schol. . The mode in which the constant ve- 
locity of sound is attempted to be explained, (which, like 
the rest of the scholium, is —- from Rowning,) is whol- 
fate erroneous? ieien we it easy to substitute an un- 
air is necessary to the existence of sound, of animal life, 
fire, and of explosion.” This, like several other statements 
scattered up and down the work in which chemical princi- 
ples are alluded to, needed, correction to render it accord- 
ant with the present state of our gegen on these sub- 
Phi ap experiments of Biot and Chladni shew: that 
eins thn Vs Fy ee 
and that it it may be conveyed tothe. organs of hearing with- 
out the spine of air, by forming a communication 
between the sounding body and the head by means of a 
solid conductor. —That fire and explosion require air for 
their existence, is true only in the most loose and popular 
sense of the terms. In particular, that the explosion of 
gunpowder cannot be effected in a vacuum, as is implied in 
one of the annexed. experiments, i isan entire mistake. <b 
The , on the barometer, t 
and steam-engine, are extremely defective in pointe of valu- 
able information, compared with what might have been said 
about them within the same limits, and in several respeets are 
calculated to leave erroneous impressions: but we must 
content ourselves with giving this we caution pe 
placing implicit confidence in them.{ 
* This. theoretical dotevesiuniiig insiy: be seen, Gregory's Mechanics, I. 
t Robins, Hutton’s Math. Dictionary, &c. 
+ It may be proper just to state, for the information of those who may 
ne oth th 10, in making loose esti- 
