128 The Rev. J. Bayma on Molecular Mechanics, [Feb. 11, 



I think, can be established by evident arguments drawn from various con- 

 siderations. 



1. All bodies consist of simple and unextended elements, the sum of 

 which constitute the absolute mass of the given body. The extension 

 itself, or volume, of the body is nothing but the extension of the space in- 

 cluded within the bounding surfaces of the body ; and the extension of space 

 is nothing but its capability of being passed through (percurribilitas) in any 

 direction by means of motion extending from any one point to any other. 



2. There is no such thing possible as matter materially and mathema- 

 tically continuous — that is to say, such that its parts touch each other with 

 true and perfect contact. There must be admitted indeed a continuity of 

 forces ready to act ; but this continuity is only virtual, not actual nor 

 formal. 



3. Simple elements cannot be at once attractive at greater, and repulsive 

 at less distances. To this extent at least Boscovich's theory must be 

 corrected. If an element is attractive at any distance, it will be so at all 

 distances ; and if it be repulsive at any distance, it will be repulsive at all 

 distances. This is proved from the very nature of matter, and perfectly 

 corresponds with the action of molecules and with universal attraction. 



4. Simple elements must not be confounded with the atoms of the chemist, 

 nor with the molecules of which bodies are composed. Molecules are, 

 according to their name, small extended masses, i. e. they imply volume ; 

 elements are indivisible points without extension. Again, molecules of what- 

 ever kind, even those of primitive bodies, are so many systems resulting 

 from elements acting on each other; consequently elements differ from 

 molecules as parts differ from the whole ; so that much may be said about 

 separate elements, which cannot be said of separate molecules or chemical 

 atoms, and vice versa. Element, molecule, body have the same relation 

 to each other in the physical order, that individual, family, state bear to 

 each other in the social order ; for a body results from molecules, and 

 molecules from elements holding together^mechanically, in a similar way to 

 that in which a state results from families, and families from individuals 

 bound together by social ties. 



So much regarding extension ; for I do not now intend to proceed to 

 the demonstration of these statements, but simply to put down what it is 

 I am prepared to prove. 



Inertia. — There would scarcely be any need of saying anything on this 

 head, were there not some, even learned men, who entertain false ideas 

 about it, and from not rightly understanding what is said of inertia by 

 physical philosophers, throw out ill-founded doubts, which do more harm 

 than good to science. I say, then, 



1 . Inertia implies two things : (a) that each element of matter is per- 

 fectly indifferent to receiving motion in any direction and of any intensity 

 from some external agent ; (b) that no element of matter can move itself 

 by any action of its own. 



