248 
MOVtNG FORCE. 
('n^es of diffi-iiniforme 1 pied en 1 minnle, parcourra 2 pleda en 2 minutes/ 
docfrines of*^ infinite de pieds en une infinite egale de minutes ; il a en 
moving force, soi de qnoi se mouvoir elernelJement, quoique sa force soil finie, 
il faut seulement qu’il ne rencontre point d’obstacles. Je sup- 
pose cette force telle que quandil se sera rafi pendant 1 minute, 
tofijonrs appliqne ^ un ressort qu’il fermera ^ la fin, et clont Ja 
base, qui repond ^ I’ouverture qu’il aura efie d’abord, ait etc 
de 1 pied, cette force soil entierement ccnsura6e, et je suppose 
eiisnite qu’au lien de ce ressort on kvi en donne k fermer deux 
consccutifs egaux ^ celui-B. Il ne peut Ics fermer sans les 
appliquer tous deux Ton contre I’autre, sans reduire'a rien leur 
base commune double de la premierej c’est-a-dire, sans pa'rcou* ‘ 
rif un espace de 2 pieds. Greet espace, il fie le peut paircourir 
qtt’en 2 minutes, done dans la primiere minute il 'ne peu/avoir 
fermc qn’i de tni chacun des deux ressorts,’iet a la fin de'^ la' se- 
conde il les aura entierement fermes tous et sa force sera 
consumee.’ 
Mr. Maclaurin has given, in his Treatise Of Fluxions, page 
431, some ingenious solutions of the problems where two or 
rrtore bodies at rest are struck at the same instant by another 
body moving with a given velocity in a git^en direction, 'it is 
remarkable, however, that the consideration of the time was ' 
omitted by him in the same way that it was omitted by M. Ber- 
noulli j although the oversight of the laftef had been pointed 
out by Mr. Robins fourteen years before Mr. Maclaurin pub- ’ 
lihihed his solntions j which appear to be defective also in the 
following respect. The resulting mdtiiins are first given on the 
supposition, that the bodies are hard and nonelastic, and from 
these results are deduced the motions which are supposed to 
result from the collision of elastic bodies. But M. D'Alembert 
has shown, that in all cases where the bodies which are struck 
are not equal to each other, and similarly silnated with respect 
tO' the direction of the striking body, the supposition of hard 
bodies leads to erroneous results with respect to elastic ones*. 
* Traite dc Dynamiqnr, p, 234 — 5. 
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