NATUKAL PHILOSOPHY, 



I ULTIMATE CONSTITUTION OF MATTER. 



THIS is a subject which at present pre-eminently occupies the 

 attention of philosophers. The atoms of all solid, liquid, and 

 gaseous substances on earth are known to be in a state of con- 

 stant motion ; but what these atoms are is a mystery, as they are 

 much too small to be seen by the microscope. Some regard them 

 as small rigid pieces of matter ; others say that, however small we 

 suppose these to be, we may suppose the existence of other atoms 

 small enough to cut them ; others consider them as not matter at 

 all, but simply forces emanating from points; this is the prevail- 

 ing opinion among philosophers at present. Helmholtz has 

 proved mathematically that if a perfect fluid, destitute of viscosity 

 or fluid friction, were thrown into a state of vortex motion or 

 wirbel-bewegung ', it would preserve that motion and form to all 

 eternity, and if two such vortex rings were interlinked they could 

 never be separated from each other. Professor William Thomson, 

 in the " Proceedings of the Royal Society of Edinburgh," has re- 

 cently advanced the idea that probably Helmholtz's vortex rings 

 are the only true atoms, and he is now pursuing mathematical in- 

 vestigations on the subject ; his ideas are there illustrated by some 

 remarkable experiments with rings of smoke produced in air. 



MOLECULAR MOVEMENT IN SOLIDS. 



M. Tresca, by carefully oxidizing a section of a bar of appar- 

 ently homogeneous rolled iron, has proved that it is really a bun- 

 dle of minute fibres or filaments, each preserving its individuality 

 throughout the entire length, whatever distortions the bar may 

 have been submitted to. He thinks the rolling of iron something 

 analogous to the combing and carding of wool. This filamentous 

 structure, he says, will account for the different conducting 

 powers of sheet and bar iron for heat and electricity ; it also, he 

 believes, satisfactorily explains the transformation of fibrous into 

 crystalline iron in axles and other work exposed to continual 

 jarring. Sheet iron, he says, is made up of superposed distinct 

 sheets, the more or less perfect welding of which determines its 

 properties. 



In a general way he has shown that the molecules of solid sub- 

 stances possess the power of moving freely and independently, 

 like the molecules of liquids, and that the movements are governed 

 by the same laws, Mechanics 1 Magazine, June, 1867. 



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