1G CONVERSION OF MOTION. 



case would appear to have been as follows : Are heat, 

 light, electricity, &c., material bodies? If they are 

 material bodies and heat, for example, is the cause of 

 motion must not the calorific matter move itself or if 

 it be not self-moving, by what is it moved ? If heat is 

 material, and the primary cause of motion, then matter 

 must have an innate power of moving ; it can convert 

 itself into active force, or be at once a cause and an 

 effect, which can scarcely be regarded as a logical 

 deduction. 



We move a particle of matter, and heat is manifested ; 

 the force being continued, light, electricity, and chemi- 

 cal action result ; all, as appears from a limited view of 



the exertion of opposing force, and thereby to maintain equilibrium ; 

 or, 2ndly, to produce motion in matter, 



" Matter, or that whatever it be of which all the objects in nature 

 which manifest themselves directly to our senses consist, presents 

 us witli two general qualities, which at first sight appear to 

 stand in contradiction to each other activity and inertness. 

 Its activity is proved by its power of spontaneously setting other 

 matter in* motion, and of itself obeying their mutual impulse, 

 and moving under the influence of its own and other force ; 

 inertness, in refusing to move unless obliged to do so by a force 

 impressed externally, or mutually exerted between itself and 

 other matter, and by persisting in its state of motion or rest 

 unless disturbed by some external cause. Yet, in reality, this 

 contradiction is only apparent. Force being the cause, and 

 motion the effect produced by it on matter, to say that matter is 

 inert, or has inertia, as it is termed, is only to say that the cause 

 is expended in producing its effect, and that the same cause 

 cannot (without renewal) produce double or triple its own proper 

 effect. In this point of view, equilibrium may be conceived as a 

 continual production of two opposite effects, each, undoing at 

 every instant what the other has done/'? See continuation of 

 the argument in Herschel's Discourse on the Study of Natural 

 Philosophy, page 223. 



In the Edinburgh New Philosophical Journal, vol. xlv., will be 

 found a paper by Dr Robert Brown " Of the sources of motions 

 upon the Earth, and of the means by which they are sustained," 

 which will well repay an attentive perusal, as pointing to a class 

 of investigation of the highest order, and containing deductions of 

 the most philosophic description. 



