340 . Mr. smeaton’s Fundamental Experiments 
be the lame in both, viz. one half of the velocity of the origi- 
nal firiking body. 
Here is therefore the affumption of a principle, which in 
reality is proved by no experiment, nor by any fair dedudlion 
of reafon that I know of, viz. that the velocity of non-elaflic 
hard bodies after the ftroke mu ft: be the fame as that refulting 
from the ftroke of non-elaflic [oft bodies; and the queflion 
now is, whether it is true or not ? 
Here it may be very properly afked, what ill effedls can 
refult to practical men, it philolophers fhould reafon wrong 
concerning the effects of what does not exift in nature, fince 
the practical men can have no fuch materials to work upon, or 
misjudge of? But it is anfwered, that they who infer an equa- 
lity of effects between the tw r o lorts, may from thence be 
milled themfelves, and in confequence miflead practical men 
in their reafonings and conclulions concerning the fort with 
which they have abundant concern, to w r it, the non-elaflic 
foft bodies , of which water is one, which they have much to 
do with in their daily practice. 
Previous to the trying my experiment on mills I never had 
doubted the truth of the dodtrine, that the fame velocity re- 
iulted from the ftroke of both forts of non-elaflic bodies; but 
the trial of thofe experiments made me clearly fee at leaf! the 
inconclufivenefs, if not the falfity of that doctrine : becaufe I 
found a refult which I did not expedl to have arifen from either 
lort ; and for the which, when it appeared from experiment, I 
could fee a fubftantial reafon why it fhould take place in one 
lort, and that it was impollible that it could take place in the 
other ; for if it did, the bodies could not have been perfedtly 
hard , which would be contrary to the hypothecs. Of this 
dedudlion I have given notice in my faid tradl on mills, pub- 
lifhed 
