The Flight of a Meteor 



STORY OF THE FLIGHT OF STONE AND IRON METEORS THROUGH 

 THE AIR. THEIR DIRECTION AND IMPACT WITH THE EARTH.— 

 EXPLANATION OF THE TRAIL OF FIRE OF A -SHOOTING STAR" 



By E L I H U THOMSON 



At this time, when the application of science to national defense and to internal industrial 

 development has been forced into an importance that centers the world 's attention on its 

 scientific men, any word from an American like Elihu Thomson is of especial note. While 

 the following article concerns pure science rather than applied science, Elihu Thomson stands 

 to Americans chiefly as an exponent of applied science. His contributions to electrical en- 

 gineering have yielded him some five hundred patents, among them the very great discovery 

 of electrical welding. He is in fact one of the few men of today whose personal achievement 

 is having a large effect upon industrial progress. In addition he has given his cooperation 

 to others working in applied science to such an extent that President Maclaurin, of the 

 Massachusetts Institute of Technology, recently bestowing upon Dr. Thomson the Fritz 

 medal of that institution, pronounced him one of the greatest teachers of his generation. 

 With this in mind it is an unusual pleasure to read the following clear explanation of an 

 astronomical matter which for most of us has heretofore been enveloped in vagueness. 



The collections of meteorites in the American Museum of Natural History are unusually 

 large and important, and also are unusually well arranged for study by the visitor. In a 

 brief paper following the present article Dr. Chester A. Reeds, assistant curator of geology 

 and invertebrate paleeontology in the American Museum, has suggested a few of the collec- 

 tions and specimens which particularly illustrate the points made by Dr. Thomson. — The 

 Editor. 



THE following may assist to a 

 proper understanding of the 

 physical and chemical actions 

 which occur during the passage of a 

 meteor into our atmosphere. Outside 

 of our air a mass of matter such as con- 

 stitutes a meteor or shooting star would 

 necessarily be very cold. Its velocity on 

 entering our air will be its velocity in 

 space compounded with the earth's mo- 

 tion or velocity around the sun, accord- 

 ing to the direction of its motion in 

 relation to that of the earth. When the 

 velocity relatively to the earth is high, 

 the earth's gravitational force can mod- 

 ify the motion but slightly. In such 

 cases, the earth's atmosphere acts so 

 effectively as a protective sheath, that 

 only a few of the very numerous bodies 

 variously known as shooting stars, 

 meteors, aerolites, and siderites ever 

 reach the earth's surface. If the 

 velocity is as high as thirty or forty 



miles per second in entering our air the 

 crushing strains brought upon it by air 

 resistance in its path may be great 

 enough to break it into fragments, 

 while the high temperature of the 

 compressed air in front of it and op- 

 posing its motion melts or vaporizes the 

 materials of which it is composed. 

 Stony meteors resembling pieces of 

 rock would naturally yield to fracture 

 and dissemination more readily than 

 masses of solid iron. This may account 

 for so large a proportion of the bodies 

 which reach the ground being composed 

 of iron, known as meteoric iron. 



Rock masses are, however, occasion- 

 ally found and have perhaps survived 

 because they were moving, in a general 

 sense, along with the earth in its orbit, 

 and would thus have a lower velocity in 

 entering our air. But the iron meteors 

 are so strong as to resist enormous 

 crushiner strains and remain intact, or 



