Page:The evolution of worlds - Lowell.djvu/64

40 Thus meteorites and shooting-stars are kin, and from the fact that they are pursuing orbits not very unlike our own we get our initial hint of a community of origin. Indeed, they are the little bricks out of which the whole structure of our solar system was built up. What we encounter to-day are the left-over fragments of what once was, the fraction that has not as yet been swept up by the larger bodies. And this is why these latter-day survivors move, as a rule, direct. To run counter to the consensus of trend is to be subjected to greater chance of extermination. Those that did so have already been weeded out.

From the behavior of meteorites we proceed to scan their appearance. And here we notice some further telltale facts about them. Their conduct informed us of their relationship, their character bespeaks their parentage.

Most meteorites are stones, but one or two per cent are nearly pure iron mixed with nickel. When picked up, they are usually covered with a glossy thin black crust. This overcoat they have put on in coming through our air. Air-begotten, too, are the holes with which many of them are pitted. For entering our atmosphere with their speed in space is equivalent to immersing them suddenly in a blowpipe flame of several thousand degrees Fahrenheit. Thus their surface is burnt and fused to a cinder. Yet in spite of