3i6 



NATURE 



\Feb. 6, 1879 



meteor's path. These are all supposed to come from the 

 meteor. Some were picked up on the surface of the 

 frozen ground. One was found on the top of a snow- 

 bank, and about forty feet away were marks of a place 

 where it had first struck the ground. Some were ploughed 

 up in the spring. The two largest found, of 74 lbs. and 

 48 lbs., fell by the roadside, and a law-suit to settle whether 

 they were the property of the finder as being wild game, 

 or of the owner of the lands adjacent as being real estate, 

 was decided in favour of the owner of the land. 



No one saw this stone come from that meteor. But in 

 many cases peculiar stones very like to this one have 

 been seen to fall from meteors, and this is one of a group 

 of about twenty stones belonging to Yale College which 

 were gathered at the places and directly after the time of 

 the fall. They are in the Peabody Museum in a case by 

 themselves, and are about one-tenth of all that has been 

 found. 



But though we have no eye-witnesses to speak of its 

 fall and finding, the stone as we look at it tells its own 

 story. This rounded side is not waterworn. From your 

 seats you cannot see them, but over these rounded hills 

 -and down these valleys run streaks showing that melted 

 matter has flowed over them. On two of the smaller 

 sides is collected a real lava deposit, giving in smallest 

 miniature the twisted gnarled forms that some of you 

 have possibly seen in the large lava beds at the foot of 

 the cone of Vesuvius. This other surface had just begun 

 to be melted, as though the fracture that formed it had 

 been made late in the meteor's flight. This larger face 

 is only smoked, and we might even doubt wheUier the 

 stone had not been broken here after its fall. But the 

 rounded edges of the thin black crust at the angles of 

 the stone show clearly that, except perhaps at some of 

 the corners, the stone was in its present shape when it 

 struck the ground. 



Now what caused that brilliant light, that terrific ex- 

 plosion which was heard for forty miles around, that rain 

 of stones ? The only explanation which we can admit is 

 that a stone weighing not less than 800 lbs. — how much 

 more we know not— perhaps two, perhaps fifty times as 

 much, came into the air from without. 



What ought to happen upon the passage of such a 

 stone through the air ? At the height of thirty to eighty 

 miles, the region where the meteor-tracks are most fre- 

 quently seen, the air is very rare, rarer than in the so- 

 called vacuum of an air-pump. Yet the rapid velocity of 

 the stone condenses the air in front of it. If we admit 

 the truth of the kinetic theory of gases we must regard 

 the molecules of air as in rapid motion, each molecule 

 driven this way or that, coming in contact with and 

 bounding back from other molecules. The average 

 velocity of these dancing molecules of air at usual tem- 

 peratures is a fraction of a mile per second. They there- 

 fore bound back from any heavy body that moves only a 

 few himdred feet per second, only slightly checking its 

 velocity. But the air is here met by a stone moving, say, 

 fifty times as fast as the average molecule. The mole- 

 cules are driven together beyond the possibility of getting 

 away, until the temperature of the air is raised enor- 

 mously. Probably the air is liquefied by the pressure, 

 and then pushed aside by main force till the meteor has 

 passed, when it is driven back again into the vacuum 

 behind, giving us a flame shaped like that of a candle. 



What effect has all this on the stone ? // is solid and 

 firm, as you see, and can withstand not a little pressure. 

 It is not, therefore, heated within ; but on the outside it 

 is in contact with, or rather rubbed hard against, an in- 

 tensely hot stratum of air. It is therefore melted off 

 just as a piece of tallow would be melted if drawn across 

 a white hot iron. There is no time for the heat to pass 

 by conduction deep into the stone. The melted matter 

 is wiped off by the air. A part clings to these hinder 

 faces of the stone, but the far greater portion helps to 



make up the meteor's train. It is scattered in eddying 

 currents in a long, narrow, whitish cloud, at first straight, 

 then twisted. That cloud broadens and floats away in 

 contorted forms, remaining visible sometimes a second, 

 sometimes an hour even. The pressure and the heat 

 generally keep cracking the stone, just as any stone is 

 cracked by pressure or when thrown into a hot fire. 

 Parts may survive this treatment and reach the ground. 

 Those who have picked them up as they fell have 

 generally said they were hot, as they must be on the out- 

 side. But some have been found, it is said, that were 

 very cold. This, too, we may well believe, for they should 

 retain in their interior the intense cold of space. 



This stone in my hand shows the breaking up, one 

 fracture being very clearly more recent than another, 

 and if you were near me you might even see fractures 

 that were begun but not ended when the stone reached 

 the ground. 



We often see this breaking up. On the wall is a pic- 

 ture of the principal explosion of the Iowa meteor, as 

 given by one who saw it, representing, it may be, the 

 cracking when this fragment was broken off from the 

 main mass. There is also one of a meteor seen in Greece 

 in 1863 by Dr. Schmidt. He was standing on the roof 

 of his house in Athens when he caught sight of a magni- 

 ficent fireball, moving so slowly that he was able to turn 

 his telescope upon it. The head had two main parts, 

 which were chased by a motley troop of followers, each 

 drawing a bright line on the sky, all of which, at a dis- 

 tance of three or four degrees, melted into a reddish 

 cloud of light. Often a meteor is to the naked eye made 

 up of a group of smaller ones, the whole being like a 

 flock of birds. 



I have traced back the history of this stone to its 

 entrance into the air on February 12, 1875, when it was 

 part of a mass not less than two feet, and I suspect not 

 more than ten feet each way. It looked larger, but men 

 saw the flame around the stone, not the stone itself. By 

 itself, and strictly taken, this history has gaps ; but taken 

 along with the history of like stones and meteors that are 

 numerous in the records of science, the story is easily 

 filled out as I have given it above. No scientific man to- 

 day would question it. 



The next step in my argument, though admitted by 

 most, is not admitted by all of those whose opinions in 

 this matter are entitled to special respect. I am not 

 aware, however, that anybody has given any formal 

 reasoning against it. I claim that between this stone- 

 producing meteor of Iowa and the faintest shooting-star 

 which you can see on a clear night in a telescope there is 

 no essential difference as to astronomical character. In 

 all their characteristic phenomena there is a regular 

 gradation in the meteors from one end of the line ito the 

 other. They differ in bigness, but in their astronomical 

 relations we cannot divide them into groups. They are 

 all similar members of the solar system. 



To prove this we must of necessity rehearse the points 

 in which the large and small meteors are alike and 

 unlike. 



First. They are all solid bodies. The Iowa meteor sent 

 down these stones, and we know that they are solid. This 

 other stone which I show you is one of about 4,000 which 

 fell from a meteor in Poland in 1868, and this you can 

 see is solid. In the Peabody Museum is a goodly collec- 

 tion of such stones from other meteors. 



A year ago last December, early on the evening of the 

 2 1 St, a meteor entered the air sixty miles or more in 

 height over the north-west corner of the Indian Territory, 

 or it may be still farther west. It crossed at a height of 

 between sixty and thirty miles the states of Kansas, Mis- 

 souri, Illinois, Indiana, and Ohio and passed on over 

 Lake Erie and the state of New York. No sound was 

 heard, so far as I know, in the state of Kansas ; but in 

 Missouri, and still more, in Illinois, the explosions >vere 



