THE EARTH IN METEORIC SHADOW. 157 



do know are necessarily the richest, is to suppose what, 

 according to the laws of probability, is exceedingly 

 unlikely. 



But we also know that the earth can pass through, 

 centrally or skirtingly, but a .very minute proportion 

 of the meteor systems which really exist in the solar 

 domain. Picture the earth's path around the sun as 

 what it really is, a mere thread-like ring of space 

 around the sun, having a circular cross-section with a 

 diameter of less than 8,000 miles (a mere nothing), 

 while the diameter of the ring itself is no less than 

 185,000,000 miles, and we say how exceedingly minute 

 is the space swept each year by the earth, in compari- 

 son with the sun's domain even to the earth's distance, 

 and still less with the entire spherical region enclosed 

 within the orbit of Neptune. If we lived on another 

 planet Venus, for example we should become aware, 

 there also, of multitudes of meteor systems, not one 

 of which the earth passes through. Another set of 

 entirely new meteor systems would come within our 

 ken if we transferred our abode to Mercury or to Mars, 

 or to any of the giant planets which travel outside the 

 zone of asteroids. But even all the planets together 

 do not actually traverse (in the way essential to 

 meteoric encounter), do not, as it were, sweep through 

 more than a very minute portion of the solar domain. 

 Assuming within the orbit of the earth the same degree 

 of meteoric wealth that the earth encounters in each of 

 her annual circlings, we should have to believe in 

 millions nay, in millions of millions of meteoric 



