12 



*' If, then, these observations may be accepted to be good for any 

 part of space, we may, and indeed must, expect celestial pheno- 

 mena which can be traced to meteorites in all parts of space. 



" In spite of the difficulties which attend the observations neces- 

 sary to determine the velocity of meteors entering our atmosphere, 

 many observations have been made, from which it may be 

 gathered that the velocity is rarely under ten miles a second or 

 over 40 or 50. It is known that the velocities of some meteor- 

 swarms are very different from those of others. Professor Newton, 

 our highest authority on this subject, is prepared to consider that 

 the average velocity may be taken to be 30 miles a second." 



Thus meteorites are as far as we know the most universally dis- 

 tributed bodies in space, an 1 may reasonably be expected to play 

 no inconsiderable part in the economy of nature. We must 

 remember, too, that as the whole solar system is in perpetual 

 onward, as well ab rotatory motion, the earth can never twice 

 occupy the same space ; so it is fair to suppose that every part of 

 infinite space is equally full of meteorites as that we have already 

 passed through. 



The existence of enormous numbers of meteors pervading space 

 being proved, their tendency to collect in swarms within which the 

 tendency to collision will be greater than in the surrounding space 

 may be taken for granted ; what then would be the effect of such 

 collisions. Here again, I will quote Lockyer's own words : " The 

 question of what must happen to the meteorites themselves in 

 consequence of this system of collisions is worth going into 

 thoroughly. 



"As 30 miles per second is a very frequent value obtained for 

 the velocity of meteorites when they enter our atmosphere, it is 

 possible to compare temperatures brought about by collisions with 

 those produced by passage through our atmosphere. Two masses 

 of meteoric iron meeting each other in space would probably, if 

 moving with a certain velocity, be formed into a pasty conjoined 

 mass, and this process might go on until an iron of large dimen- 

 sions was formed, and the various meteorites thus welded together 

 would present in time a very fragmentary appearance. While 

 irons were thus increasing in size, collisions with smaller 

 meteorites would be attended with very local increases of tem- 

 perature, perhaps sufficient to volatilize the surface or allow it to 

 be indented, and in this manner the well-known " thumb marks " 

 receive explanation. 



" These operations of nature might go on either in free space, or 

 in the head of a comet, or in meteor-swarms. They probably 

 cause the appearance oi the so-called new stars, and in these 

 various circumstances the rate of subsequent cooling would of 



