190 On the Measure of 
corpora non sunt perfecte elastica, aliqua pars 
Viriwm vivarum, que periisse videtur, consu- 
mitur in Compressione corporum, quando per- 
fecte se non restituunt; a’ quo autem nunc 
abstrahimus, concipientes, compressionem 
illam esse similem compressioni elastri, quod 
post tensionem factam impediretur ab aliquo 
retinaculo, quo minus se rursus dilatare posset, 
et sic non redderet, sed in se retineret vim 
vivam, quam a corpore incurrente accepisset : 
unde nihil viriuni periret, etsi periisse vide- 
retur.” * 
From this passage, and from various other 
passages in his works, relating to the doctrine 
** de conservatione virium vivarum,” it ap- 
pears, that Bernoulli thought it necessary to 
maintain that no force could be lost, and that 
even in the collision of nonelastic bodies he 
considered the change of figure to be such, 
that the force which had been expended in 
producing it might be recovered by the resto- 
ration of the figure, or by. some other means. 
Why he considered it incumbent upon him to 
maintain such opinions, or upon what founda- 
tion he understood them to rest, it is hard to 
gay. Experience furnishes us with nothing 
which can justify the conclusion that the force 
* Bernoulli’s works, Vol. iii. p. 243. 
