of the Molecules of Solids. 109 



servable ; for an attempt to divide such a mass into two parts 

 would be resisted by the disinclination of the tops in the line of 

 division to be pushed to one side, involving, as this would, a 

 change of their planes of rotation, (b) Chemical action could 

 not take place, for there is no jostling of the tops one against 

 another ; and therefore if two such masses were placed in con- 

 tact, the tops in one would not mix with those in the other. 



(c) Nor would the mass transmit pressure equally iu all direc- 

 tions, as to do so would manifestly alter their planes of rotation. 



(d) Inertia would result from this state of things, just as cohe- 

 sion does, from the tendency of the molecules to preserve their 

 respective planes of rotation. The gyroscope illustrates this 

 well, resisting (save in directions parallel to the axis) motion 

 from the hand when taken up, and being superior to gravity 

 so long as in rapid rotation. A system of such tops, therefore, 

 would resist motion in all directions. 



Now extending the idea from tops to molecules, and from the 

 comparatively slow motion of the gyroscope to the infinitely 

 rapid motion which we attribute to molecules, these results 

 would increase very greatly in intensity, depending, as they do, 

 on the velocity of rotation much more than on the weight of the 

 moving body ; so that the hypothesis in the case of the tops 

 becomes a fact in the case of the molecules, and external forces 

 become so relatively insignificant as to have no effect; and 

 this view is in accordance with the variations of these effects in 

 different bodies, which we may consider as varying with their 

 molecular velocities. If this statement should seem at variance 

 with the effect of gravity and other external forces on matter, it 

 need only be remarked that, under ordinary circumstances, the 

 axes of rotation of the molecules in a body are in every con- 

 ceivable plane, and therefore their motions tend to neutralize 

 one another's effects in their result as a whole. 



At this point, then, only two assumptions concerning matter 

 are made ; that it consists of spherical or spheroidal molecules, 

 and that these in solids rotate round their own axes. The for- 

 mer is still only an hypothesis in the case of liquids and gases ; 

 it is with the second that this paper deals, with the view of 

 removing it from the region of opinion to that of fact. Hitherto 

 confirmatory evidence alone has been alleged, we may now pro- 

 ceed to more direct proof. 



It was stated that under ordinary circumstances the axes of 

 rotation of its molecules being in all planes, a body as a whole 

 does not resist external forces as its molecules do. A crucial 

 test, then, of the theory may be found, if by any means we can 

 cause a parallelism of these axes in a body. We have only to 

 resort to any molecular polarizing force, such as magnetism or 



