220 Outlines of Meteoric Astronomy. 



matter in a state of extremely fine division encompassing the 

 sun, it seems hardly possible to doubt. Aerolites, on the con- 

 trary, are fragments of solid stone, and of these the source and 

 origin must at least be on a larger scale, and composed of the 

 same materials. The conclusion appears inevitable that parent 

 planets in the immediate vicinity of the earth, too small and 

 powerless to reclaim their fragments, have scattered the lapide- 

 ous morsels broadcast into space. These circulating round, the 

 sun with their initial projectile- velocities, should the orbits of 

 both intersect each other, must sooner or later encounter the 

 earth. 



(16.) It maybe presumed that the suspected planets are 

 situated within the orbit of the earth, because by far the 

 greatest number of aerolites are experienced by day, while 

 the sun is still above the horizon, and the largest detonating 

 fire-balls occur about the time of sunset. In this way the pas- 

 sage of dark bodies across the disc of the sun, and more 

 rarely across the disc of the moon, may be explained. For it 

 can be calculated that a planet twelve miles in diameter, at ten 

 times the moon's distance from the earth, subtending 1" of arc 

 at its passage across the sun, would appear as a morning and 

 evening eighth magnitude star. But as at the time of its 

 greatest brightness it would also be stationary, or nearly so, 

 and almost lost in the ra} T s of twilight, it is not impossible 

 that such planets, if accidentally observed, should have 

 been mistaken for fixed stars. Should the suspected planets, 

 however, be situated outside the orbit of the earth, it is dif- 

 cult to perceive how they could so long have eluded the gaze 

 of our sharp-eyed astronomers, as their lustre in this case would 

 be vastly superior. But in the meantime the bombardment 

 of aerolites continues ; and whatever may be their origin, some 

 new light must before long be obtained from these " pocket- 

 planets" themselves, as they have been termed by Humboldt, 

 to settle the perplexiDg question, and to open out new fields 

 for speculation. 



