▼OL. v.] PHILOSOPHICAL TRANSACTIONS. 537 



Principiorum falsitas ostenditur, ipsiusque errores ac paralogismi ad oculum de- 

 monstrantur ac refutantur, a Francisco Wilhelmo Libero Barone de Nuland, 

 &c. Hagac Comitis, 1669, in 12mo. 



Though the author of this small treatise lays down an hypothesis of natural 

 philosophy, yet will he not be understood to be resolved to adhere unchange- 

 ably to it, but rather judges it more useful to employ great care and much time 

 in observing the effects of nature ; highly commending for that method the two 

 lately founded philosophical academies in England and France, which by obser- 

 vations and experiments, faithfully made, labour to attain the knowledge of 

 truth. 



Concerning M. Descartes, though our author professes a high esteem for his 

 ingenuity, yet is he of opinion, that the fondness which that great man had for 

 his system of the world, so blinded him, that he could not see his errors in its 

 contrivance. 



III. A Discourse concerning Local Motion, from the French. London, 

 1670, in 12mo. 



This discourse undertakes to demonstrate the laws of motion, and to prove 

 that, of the seven rules delivered by Descartes on this subject, he has mistaken 

 six. In doing which the author particularly insists on considering the commu- 

 nication of motion in percussions; declaring, that, though this subject has been 

 handled by very eminent men, yet he takes it otherwise in hand than they have 

 done, forasmuch as, without making any particular hypothesis, he makes it his 

 business to search into the very sources of nature, the causes of all the effects 

 we find in mptions, and undertakes to give the demonstrations of them. He is 

 not ignorant of what has been lately published by some famous mathematicians 

 of the Royal Academies of London and Paris. Neither does he contest with 

 those persons about that which they pretend to, of having found the secret of 

 the laws of motion. He only says, that it is now three years since he published 

 what he delivers in this discourse; and that, his rules being compared with theirs, 

 there may possibly be found conformity enough to make men believe, that he 

 has lighted together with them upon the truth, but that yet there will always be 

 found difference enough to make men judge, that he has not learnt it from 

 them. Besides, says he, they have done no more than merely proposed their 

 rules without proving them ; whereas he undertakes to demonstrate all those he 

 advances. 



The chief heads explained in this discourse are, that, 1. A body is in itself in- 

 different to rest or motion. 2. If a body be once at rest, it will ever remain 

 therein. 3. And if it be once in motion, it continues to move always. 4. That 

 rest is not a mere negation; and that there is as much positive action in rest as 



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