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EXPLANATIONS. 



axis being introduced through the box, with a small disk - 

 upon it, so arranged that its centre is coincident with the 

 centre of the globe of oil, we turn the axis at a slow rate, 

 and thus set the oil sphere into rotation. " We then 

 presently see the sphere flatten a t its poles and swell out 

 at its equator, and we thus realize, on a small scale, an 

 effect which is Sdmitted to have taken place in the plan- 

 ets." The spherifying forces are of different natures, 

 that of molecular attraction in the case of the oil, and of 

 universal attraction in that of the planet, but the results 

 are " analogous, if not identical." Quickening the ro- 

 tation makes the figure more oblately spheroidal. When 

 it comes to be so quick as two or three turns in a second, 

 " the liquid sphere first takes rapidly its maximum of 

 flattening, then becomes hollow above and below, around 

 the axis of rotation, stretching out continually in a hori- 

 zontal direction, and finally, abandoning the disk, is trans, 

 formed into a perfectly regular ring." At first this re- 

 mains connected with the disk by a thin pellicle of oil ; 

 but on the disk being stopped this breaks and disappears, 

 and the ring becomes completely disengaged. The only 

 observable difference between the latter and the ring of 

 Saturn is, that it is rounded, instead of being flattened ; 

 but this is accounted for in a satisfactory way. 



A little after the stoppage of the rotatory motion of the 

 disk, the ring of oil, losing its own motion, gathers once 

 more into a sphere. If, however, a smaller disk be used, 

 and its rotation continued after the separation of the ring, 

 rotatory motion and centrifugal force will be generated in 

 the alcoholic fluid, and the oil ring, thus prevented from 

 returning into the globular form, divides itself into " sev- 

 eral isolated masses, each of which immediately takes the 

 globular form." These are " almost always seen to as- 

 sume, at the instant of their formation, a movement of ro- 

 tation upon themselves — a movement which constantly 

 takes place in the same direction as that of the ring. 

 Moreover, as the ring, at the instant of its rupture, had 

 still a remainder of velocity, the spheres to which it has 

 given birth tend to fly off at a tangent; but as, on the 

 other side, the disk, turning in the alcoholic liquor, has 

 impressed on this a movement of rotation, the spheres 

 are especially carried along by this last movement, and 

 revolve for some time round the disk Those which re- 

 volve at the same time upon themselves, consequently, 



