232 Canadian Record of Science. 



meteorites. Thus it is reasonable to suppose that the shoot- 

 ing stars are made of such matter and such varieties of 

 matter as are found in meteorites. On the other hand, since 

 star-showers are surely related to comets, it is reasonable to 

 look for some relation of the meteorites to the astronomical 

 bodies and systems of which the comets form a part. 



This common nature of the stone-meteor and the shooting 

 stars enables us to get some idea, indefinite, but yet of great 

 value, about the masses of the shooting stars. Few meteoric 

 stones weigh more than one hundred pounds. The most 

 productive stone-falls have furnished only a few hundred 

 pounds each, though the irons are larger. Allowing for 

 fragments not found, and for portions scattered in the air, 

 such meteors may be regarded as weighing a ton, or it may 

 be several tons, on entering the air. The explosion of such 

 a meteor is heard a hundred miles around, shaking the air 

 and the houses over the whole region like an earthquake. 

 The size and brilliancy of the flame of the ordinary shoot- 

 ing star are so much less than that of the stone-meteor that 

 it is reasonable to regard the ordinary meteoroid as weighing 

 pounds or even ounces, rather than tons. 



Determinations of mass have been made by measuring the 

 light and computing the energy needed to produce the light. 

 These are to be regarded as lower limits of size, because a 

 large part of the energy of the meteor is changed into heat 

 and motion of the air. The smaller meteors visible to the 

 naked eye may be thought of without serious error as being 

 of the size of gravel stones, allowing, however, not a little 

 latitude to the meaning of the indefinite word gravel. 



These facts about the masses of shooting stars have 

 important consequences. 



The meteors, in the first place, are not the fuel of the 

 sun. We can measure and compute within certain limits of 

 error, the energy emitted by the sun. The meteoroides, 

 large enough to give shooting stars visible to the naked 

 eye, are scattered very irregularly through the space which 

 the earth traverses, but in the mean, each is distant two or 

 three hundred miles from its near neighbors. If these 

 meteoroides supply the sun's radiant energy, a simple com- 



