148 Notices respect'wg New Books. 



their states of motion when acting on our organs of sense, 

 or upon other matter, and which are not susceptible of 

 being confined. It cannot be doubled that there is matter 

 in motion in space, between the siin and the stars and our 

 globe, though it is a subject of di'^cussion whether sue- 

 cessions of particles be emitted from these heavenly bodies, 

 or motions communicated by them, to particles in theit' 

 vicinity, and transmitted bv successive impulses to other 

 particles. Eiheredl matter differs cither in its nature or in its 

 aflections by motit)n ; tor it produces diHcrent effects; foi* 

 instance, as radiant heat, and as different kinds of light." 



After brieflv stating the laws of gravitation and cohesion, 

 the Professor rebuts the notion entertained last century, 

 respecting an instrument of attraction or some unknown 

 matter which serves to impel bodies to each other. He 

 adds, "there is no ground for supposing that matter can- 

 not act at a distance [that is, in a vacuum], and it is absolutely 

 necessary for the explanation of the planetary motions, to 

 suppose space in the universe void of matter.'' This de- 

 finition of attraction gives to matter an occult quality, 

 more difficult to conceive, more incredible, than all the 

 speculations about spirit which have hitherto appeared. 

 To suppose that two inanimate and naturallv inert bodies 

 can act on each other at a distance and in a vacuum, does 

 not convey any satisfactory knowledge to the mind, and 

 gives to such matter something like mtelligence ox inttU 

 lect ; but if we suppose the attraction of bodies to be ef- 

 fected by some conductinii or connecting medium, by a 

 very attenuated atmosphere, for instance, we at least adhere 

 to experience and the mechanical laws of matter, without 

 any extravagant or incredible suppositions. 

 . Among the qualities of matter, the Professor introduces 

 heat, or what he calls " calorific repulsion." He illustrates 

 the contmon effects of calorie on matter by reference to 

 numerous experiments, and thus proceeds to state his no-, 

 vel doctrine respecting the non-cxistence of caloric or mat- 

 ter of heal. 



*' Heat, or the power of repulsion, may be considered as 

 the antagonist power to the aliraciitm of cohesion, the one 

 tending to separate, the other to unite the parts of bodies ; 

 and the forms of bodies depend upon their respective 

 agencies. In solids, the attractive force predominates over 

 the repulsive ; in fluids and in elastic fluids they may be 

 regarded as in different states of equilibrium ; and in ethereal 

 substances the repulsive must be considered as predomi- 

 nating over and destroying the attractive force. 



««Air 





