376 FEAGMENTS OF SCIENCE. 



tain seasons of the year they shower down upon us in 

 great numbers. In Boston 240,000 of them were ob- 

 served 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 percep- 

 tion. Indeed, 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 na- 

 ture, it certainly shows how a sun might be formed and 

 maintained on known thermo-dynamic 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 ther- 

 mometer. It has been prophesied that ' the elements 



