28G l f RA OMENTS OF SCIENCE. 



of coal. How much greater must be the heat developed by 

 a body falling against the sun! The maximum velocity 

 with which a body can strike the earth is about seven miles 

 in a second; the maximum velocity with which it can 

 strike the sun is 390 miles in a second. And as the heat 

 developed by the collision is proportional to the square of 

 the velocity destroyed, an asteroid falling into the sun 

 with the above velocity would generate about 10,000 times 

 the quantity of heat produced by the combustion of an 

 asteroid of coal of the same weight. 



Have we any reason to believe that such bodies exist in 

 space, and that they maybe raining down upon the sun? 

 The meteorites flashing through the air are small planet- 

 ary bodies, drawn by the earth's attraction. They enter 

 our atmosphere with planetary velocity, and by friction 

 against the air they are raised to incandescence and caused 

 to emit light and heat. At certain 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 con- 

 trary, 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 develop 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 sur- 

 face of the sun, would utterly vanish from perception. 

 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 repre- 

 sentant of what is going on in nature, it certainly shows 



