282 CONTINUOUS VIBRATORY MOVEMENT OF 



world is composed of objects which we know only by the impressions they pi-o- 

 duce on our senses. Matter is the unknown principle of which they are formed, 

 the cause of the properties which they manifest, and of the sensations wliich 

 reveal them to us. But when we wish to study an "object, it is proper to com- 

 mence by defmina^ it; we should therefore ask ourselves, first of all, what is the 

 true constitution of matter? 



In considering the scale of magnitudes and the extreme divisibility of bodies, 

 Ave find that we can form two hypotheses on the constitution of matter. We may 

 admit that it is divisible to infinity, and consequently conceive of a body as a 

 continuous mass, as a veritable geometric solid ; or again, we may suppose that 

 by continuing to divide more and more the fragments of a body, we shall arrive 

 at an ultimate particle — an atom. On this last hypothesis, matter would be but 

 an assemblage of atoms, grouped in distinct elementary molecules, placed one 

 beside another without touching, and endowed with the faculty of approaching 

 to or withdrawing from one another. 



If we inteiTogate chemistry before making a choice between these two 

 hypotheses, it will reply that if matter is continuous, that is to say, not capable 

 of beinti- resolved into indivisible elements, the idea of chemical combinations 

 becomes essentially obscure. On the contrary, all the known laws of combina- 

 tion become evident conserpiences, logical corollaries of the hypothesis which 

 considers matter as formed by the union of a great number of small indivisible 

 masses; it is easy, in etlect, "to comprehend that the atoms of two simple bodies 

 may, in uniting, form mixed molecules and give rise to new bodies. 



Tlie propagation of heat and of light in the Torricellian vacuum and in the 

 planetary spaces, compels us to admit the existence of another highly subtle 

 species of matter, infinitely more diffused and universal than ponderable matter, 

 and which we are led to consider as the })rincipal agent of physical nature. 



We shall endeavor to prove, on this fjccasion, that movement is a fundamental 

 property of matter in whatsoever state it exists, ponderable or imponderable ; 

 and if movement exists to-day in all the particles of matter, it has, of necessity, 

 always existed. Without movem(;nt it is impossible for our mind to conceive 

 any modification whatever in the state of things. No action of bodies can be 

 manifested without our being able to afiirm that this action consists in a particular 

 mode of movement. We shall proceed, as those who transport themselves to 

 some elevation in order to embrace the view of a vast region, to cast a compre- 

 hensive glance on the phenomena offering more particularly the proof of the 

 interior movement which constantly animates the molecules. Let us remark at 

 once, that this movement is for us an ultimate fact, of which as yet we know not 

 the reason. 



Celestial mechanics has explained all the perturbations of the movement of 

 the planets, by admitting the necessary presence of unknown orbs at the limits 

 of the solar system; observation has verified the existence of those bodies. 

 Thanks to numerous and complete verifications of this kind, mechanics has suc- 

 ceeded in rendering extremely probable, not to say absolutely certain, the prin- 

 ciple of gravitation, and in establishing in a definitive manner the law of New- 

 ton. The law of continuity in nature forces us to admit that the same principle 

 extends to all. that exists ; it governs the constitution and movements of celestial 

 bodies; it binds the satellites to their planets and the planets to the sun; it con- 

 trols all the bodies which revolve one around another within a determinate radius ; 

 it also acts on each molecule, on each atom, at minute distances which escape our 

 gross senses and all our means of direct observation. 



[The name gravitation has been given to that force or tendency of masses to 

 approach each other with an intensity which varies inversely as the square of the 

 distance and directly as the quantity of matter. The force which acts between 

 the particles, though perhaps of the same character, is governed by a different 

 lav,', and hence has received a different name, that of cohesion. — J. H.J 



