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On the Constitution of Matter, by M. B. Pell, B.A., 

 Professor of Mathematics in the University of 

 Sydney, late Fellow of St. John's College, 

 Cambridge. 



[Bead, 6tli September, 1871.] 



In the following paper, an attempt is made to account for some 

 of tlie properties of matter upon mechanical principles. I 

 assume that solid bodies consist of isolated atoms, whose linear 

 magnitudes are so small compared with the distances between 

 them, that the atoms may be supposed incapable of giving or of re- 

 ceiving any energy except that of translation ; and that the mutual 

 action between two atoms is some function of their distance, and 

 acts in the line joining their centres of gravity. 



Some writers, whose opinions are entitled to much respect, 

 have expressed an entire want of faith in the theory of isolated 

 atoms acting upon one another at a distance ; and some even hold 

 that such a state of things is inconceivable. This is one of 

 those half metaphysical questions upon which perhaps no two 

 men would be found to be exactly agreed ; but to me it seems no 

 more difficult to conceive that atoms should have been created 

 with the property of acting upon one another at a distance, than it 

 is to conceive that they should have been created, or have in any 

 way come to exist, or to have any properties at all. It may be 

 that the bodies of the solar system do not act upon one another 

 directly, but they appear to do so, and we are contenb to assume, 

 provisionally at all events, that they do really so act. There 

 should be no difficulty then in making a similar supposition 

 respecting the atoms of which matter is assumed to consist. 



If matter does not consist of isolated atoms but is continuous, 

 any enquiry into its real nature would seem as hopeless as a 

 similar investigation respecting time or space. We could not 

 hope to give any explanation of the facts, for instance, that gold 

 is yellow and soft, and expands under the action of heat, except 

 that it consists of little bits, all of which possess those properties. 

 It will be time to confess that we are reduced to such a method 

 of accounting for the phenomena of nature, when every other 

 has been found to fail. 



I have endeavoured to assume as little aa possible respecting 

 the mutual action of two atoms, except that it must be such a 



