26 THE PROGRESS AND SPIRIT OF 



in excentric orbits between Mars and Jupiter; of those 

 meteors, some of which have lately been recognised as pe- 

 riodical in occurrence ; and of the aerolites, which impinge in 

 mass upon the earth, can hardly fail to settle the questions 

 as to the occupation of planetary space to which we have 

 already alluded. How curious, for example, the inference to 

 be drawn from the composition of these falling stones, brought 

 to us undoubtedly from far beyond our own atmosphere, or, 

 as Laplace boldly phrases his belief, 'des profondeurs de 

 Tespace celeste ! ' Of the various ingredients they are found 

 to contain, every one is familiar to us upon the surface of 

 the earth we inhabit. They represent, indeed, fully one- 

 third of those forms of matter which are still simple or 

 elementary to our knowledge; though under different aspects 

 and forms of combination. Here then we have a sort of 

 material ingress into the regions of interplanetary space; 

 and presumption as to a common origin, though under 

 different modes of aggregation, not merely of those frag- 

 mentary masses which casually reach us, but of the great 

 planets also, which move with ourselves in orderly and 

 determined course around the sun. 



We are tempted to add one or two other instances here, 

 illustrating the manner in which modern science resting 

 upon the uniformity of laws, whatever the scale of their 

 operation has brought evidence to bear upon these vast 

 astronomical questions from the most minute manipulations 

 with matter here below. The happy idea occurred to M. 

 Plateau of Grhent of suspending globules of oil within water, 

 rendered exactly of the same specific gravity by addition of 

 alcohol, so that the globules should be wholly exempt from 

 the action of gravity or other extrinsic force, and free to 

 take any position or motions impresed upon them. By 

 means of a small metallic disk and wires, rotatory move- 

 ments of various velocity and direction were produced in the 



