THE FLIGHT OF A METEOR 



27 



we have said, it is blown away just as 

 soon as fusion occurs. 



Let us turn a hot Wast or even a very 

 hot flame upon a piece of ice. Water 

 forms rapidly and is blown off the ice 

 but what remains is none the loss ice to 

 the end of the process. Ice is not com- 

 bustible. Let us then subject a ball of 

 wax to a forcible oxygen jet at high 

 temperature. The wax will burn out- 

 side, melt rapidly, and as soon as 

 melted, blow away, leaving a rapidly 

 diminishing body of wax to the last. 



An instantaneous vaporization of the 

 whole mass of a large iron meteor is 

 therefore not possible. Such a meteor, 

 on entering our thin upper air, will 

 condense the gases immediately in 

 front of it, increasing their tempera- 

 ture and bringing the oxygen to a 

 density at which the combustion of the 

 outer skin of the moving mass begins. 



If the initial velocity be extremely 

 high, the resistance as it reaches the 

 denser air may rise sufficiently to crush 

 or fracture the mass. The smaller frag- 

 ments will now burn and the rate of 

 wastage by combustion be greatly in- 

 creased by the fracturing, exposing a 

 much more extended surface to burning 

 or oxidation. If the flight is long 

 enough, most, if not all, of the frag- 

 ments may be consumed before reaching 

 ground. But if the velocity is not high 

 enough to cause such extensive and 

 complete fracturing the mass may not 

 break at all — or the fracturing soon 

 ceases and the remaining mass is 

 merely diminished by combustion and 

 fusion with the continual cleansing of 

 the surface of fused products due to the 

 rush of gas past the meteor. When the 

 mass has a size suflicient, it may endure 

 the rapid waste by oxidation and a con- 

 siderable fraction of it reach the earth 

 in a solid and comparatively cold con- 

 dition, embedding itself in the ground. 



Many fall into the sea. It would seem 

 that a mass which has so survived will, 

 in reaching the ground, have lost so 

 much velocity that its striking speed 

 will not necessarily be high as com- 

 pared with that of a projectile from a 

 high-powered gun. It will not be hot 

 except as to a thin layer on its outer 

 surface. Meteors rarely descend in ver- 

 tical paths. Passing in a course more 

 or less horizontal or much inclined to 

 the vertical, they traverse many miles 

 of dense air, and their form being usu- 

 ally very irregular, they meet with an 

 enormous retardation as compared with 

 the flight of a well-shaped cannon shot. 

 When fragments are broken off they are 

 poor projectiles and are retarded rap- 

 idly. 



Iron meteors of round or nearly 

 spherical outline are more likely to be 

 gradually retarded than to undergo 

 fracture unless their velocities are ex- 

 treme. 



The slower moving iron meteorites of 

 any considerable size are almost sure to 

 survive their flight and fall to earth, 

 having undergone a wastage by combus- 

 tion, not, however, constituting a high 

 percentage of the total mass. 



The greater number of the meteors 

 reaching our air are naturally small, 

 and are disintegrated or burned com- 

 pletely during flight. Others much 

 larger have in many cases come to earth 

 either entire or in fragments. There is 

 no limit to their possible size so far as 

 known, but evidently meteors weighing 

 many tons are very rare. The great 

 crater known as the "Meteor Crater,*' 

 formerly Coon Butte in Arizona, a few 

 miles west of Winslow, is by far the 

 largest excavation known as attributa- 

 l)le to the fall of a meteorite, or perhaps 

 a cluster of them. 



It is about forty-five hundred feet in 

 dinmoter and six hundred feet deep. It 



