428 FRAGMENTS OF SCIENCE. 



seasons of the year they shower down upon us in great 

 numbers. In Boston 240,000 of them were observed 

 in nine hours. There is no reason to suppose that the 

 planetary system is limited to ' vast masses of enormous 

 weight ; ' there is, on the contrary, reason to believe 

 that space is stocked with smaller masses, which obey 

 the same laws as the larger ones. That lenticular 

 envelope which surrounds the sun, and which is known 

 to astronomers as the Zodiacal light, is probably a crowd 

 of meteors ; and moving as they do in a resisting 

 medium, they must continually approach the sun. 

 Falling into it, they would produce enormous heat, and 

 this would constitute a source from which the annual 

 loss of heat might be made good. The sun, according 

 to this hypothesis, would continually grow larger ; but 

 how much larger ? Were our moon to fall into the 

 sun, it would develope an amount of heat sufficient to 

 cover one or two years' loss ; and were our earth to fall 

 into the sun a century's loss would be made good. Still, 

 our moon and our earth, if distributed over the surface 

 of the sun, would utterly vanish from perception. In- 

 deed, the quantity of matter competent to produce the 

 required effect would, during the range of history, cause 

 no appreciable augmentation in the sun's magnitude. 

 The augmentation of the sun's attractive force would 

 be more sensible. However this hypothesis may fare 

 as a representant of what is going on in nature, it cer- 

 tainly shows how a sun might be formed and main- 

 tained on known thermo-dynamie principles. 



Our earth moves in its orbit with a velocity of 

 68,040 miles an hour. Were this motion stopped, an 

 amount of heat would be developed sufficient to raise 

 the temperature of a globe of lead of the same size as 

 the earth 384,000 degrees of the centigrade thermo- 



