METEORS AND AEROLITES. 285 



some of them seemingly lost, and the orbits of others altered 

 by their approach to the greater planets ; one or two of short 

 periods of revolution, and affording proof, by the successive 

 abridgement of these periods, of a resisting medium through 

 which they are moving in their orbits. While contemplating 

 space as thus occupied by so many forms of matter, in such 

 various degrees of concentration, yet all in constant motion, 

 we cannot but suppose that portions of matter still smaller or 

 more attenuated may be in movement around us ; apparent 

 only when they come into such contiguity to the earth as to 

 be deflected, or rendered luminous, by its influence. Meteoric 

 stones, we have already seen, are proved to come from beyond 

 the limits of our atmosphere and to enter it with vast velocity. 

 Numerous and exact observations have proved the same to be 

 equally true in the case of shooting-stars and meteoric globes 

 of light. Here then we have a bond of connection, associating 

 these phenomena under certain common physical forces ; 

 while yet leaving ample room for those causes of diversity on 

 which depend the aspects of the different classes of meteors, 

 as well as the individual character of each. Matter in one 

 form or other, variously revolving in the space through which 

 our own globe is moving, is the element with which our 

 enquiry has to occupy itself. 



We refer here to the movement of the earth, as well as of 

 these fragmentary or nebulous matters, because both must be 

 supposed concerned in the results. Perhaps some of our 

 readers, even though not wholly unfamiliar with these subjects, 

 may acquiesce in our reminding them, that the globe on 

 which we dwell is at every moment submitted to three sepa- 

 rate but simultaneous motions ; of rotation round its axis 



revolution round the Sun and lastly, that vast and mys- 

 terious movement by which it is carried, with the Sun and 

 entire planetary system, through unknown regions of space ; 



whether as the portion of an orbit round some remote 



