THEIR ARRANGEMENTS AND FORMATION. 13 



a common revolutionary motion, linked inextricably with 

 each other, though it might be at sufficient distances to allow 

 of each body having afterwards its attendant planets. Such a 

 phenomenon is occasionally realized to us on the surface of a 

 river flowing between irregular banks. There we not only 

 see single dimples rotating and passing onward, results of 

 that obliquity in the meeting of currents which is thought to 

 have set solar systems in motion, but often two or more of 

 these dynamic microcosms will come within a range of 

 mutual influence, and go on wheeling around each other. 

 These fantastic eddies, which the musing poet will sometimes 

 watch abstractedly for an hour, little thinking of the laws 

 which produce and connect them, form an illustration of the 

 mechanism of binary and ternary stars, and bring an unex- 

 pected aid to a hypothesis of the history of the heavenly 

 spaces. 



A remarkable approximation has also been made to what 

 may be called an experimental verification of this cosmogony, 

 by a living professor, M. Plateau, of Ghent. Divested of 

 technical terms, the experiment was nearly as follows : 

 Placing a mixture of water and alcohol in a glass box, and 

 therein a small quantity of olive oil of density precisely equal 

 to the mixture, we have in the latter a liquid mass relieved 

 from the operation of gravity, and free to take the exterior 

 form given by the forces which may act upon it. In point of 

 fact, the oil, by virtue of the law of molecular attraction, in- 

 stantly takes a globular form. A vertical axis being intro- 

 duced through the box, with a small disc 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 

 in rotation. " We then presently see the sphere flatten at 

 its poles and swell out at its equator, and thus realize on a small 

 scale an effect which is admitted to have taken place in the 

 planets." 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 rotation makes the figure 

 more oblately spheroidal. When it comes to be so quick as 



