METEORS AND AEROLITES. 309 



has been made (and this by more than one philosopher of the 

 day) to reach another inference, founded on the laws which 

 govern matter and forces on our own globe. The Sun is 

 ever radiating into space, from each point in its vast circum- 

 ference, an amount of heat hardly to be estimated by 

 numbers or thought. How is this loss (for so upon every theory 

 of Heat we must call it) to be repaired ? It is difficult to 

 conceive any other source of supply than from this very 

 surrounding space, which contains, as we have seen, matter 

 of different kinds, capable of being attracted to the planetary 

 bodies of our system. Every sudden impact of matter upon 

 matter evolves heat, and this in proportion to the violence 

 of the impulse. The hypothesis in question, adopting the 

 estimate of 300 miles a second as the final velocity of a body 

 falling on the Sun, supposes that an amount of Heat may 

 be thus generated, sufficient to repair the waste ever going 

 on. It is a theory, we are bound to say, sanctioned rather by 

 the want of any other plausible explanation than by its own 

 intrinsic evidence. But it may fitly be mentioned in con- 

 nection with the subject of Meteorites, and as illustrating 

 the arduous speculations of the philosophers of our day. 



