VOL. IX.] PHILOSOPHICAL TRANSACTIONS. 203 



found in the royal library at Paris, where the French Academy hold their ordi- 

 nary meetings. 



II. Authonii le Grand Dissertatio de Carentia Sensiis et Cognitionis in Brutis: 

 Lond. 1671. 



The author of this tract, consonantly to the Cartesian principle, places the 

 life of animals in the continued motion of the blood. And then declares his 

 opinion that matter is incapable of perception ; as also that cogitation cannot be 

 truly affirmed of extension, neither as an essential part, nor as a property, nor 

 as a mode thereof: against Mr. Hobbes, who undertakes to maintain cogitation 

 to be a corporeal motion ; and likewise showing, against Gassendi, that it is 

 improbable that sense should arise from insensible things. 



M. Leibnitz on his Portable Watches. N° 113, p. 285. 



The principle I thought on some years ago, for making exact portable 

 watches, is altogether different from that which consists in an equal duration of 

 unequal vibrations of pendulums or springs, applied to watches by M. Huygens, 

 with such general applause ; this depending upon a physical observation ; but 

 mine being grounded on a mere mechanical reflexion, which is easy enough, 

 and whereof the reason and demonstration itself are manifest to our senses, 

 which have not been noticed, for want of the art of combination, the use of 

 which is far more general than that of algebra. For having considered with 

 myself, that a spring being bent to the same degree, will always unbend itself 

 in the same time, provided it find the same freedom of unbending itself sud- 

 denly : I inferred from thence, that there might be employed two such, one of 

 which should play, while the first mover of the watch should bend the other 

 again ; since it will be no matter in this way, whether it bend again more or less 

 speedily, provided it bend only again before the other have done unbending 

 itself; and consequently, the one delivering the other at the end of its motion, 

 this play will always continue uniform, and so by letting go, at every turn or 

 period of these two springs, a tooth of a wheel carried about by the ordinary 

 motion, which counts seconds, or other parts of time equal to the periods, we 

 shall have such a watch as is desired by us. 



These thoughts I have executed in the following manner : — Let AB be one 

 of the watch-plates, (fig. 19, pi. 8) ; C and M two indented barrels, wherein the 

 small springs are enclosed. The teeth of the barrels catch those of the pinions 

 d, d, which carry the balances e, e; and other teeth of the said barrels are 

 caught by those of the interrupted wheel FG. Now let us imagine, that this 

 wheel FG, being moved towards HF, by the force of the first mover of the 

 watch, and turning the barrel C, bends the spring enclosed in it, and stops with 



D D 2 



