170 LIGHT SCIENCE FOR LEISURE HOURS. 



in the direction towards or from the sun round which 

 the body traversing that orbit is travelling, which is 

 of course impossible. 



I cannot, then, believe with Mr. Russell that the 

 earth can ever come exactly opposite a streamer or 

 projection of meteoric matter extending radially from 

 the sun, simply because the position is demonstrably 

 impossible. But this does not at all invalidate 

 the meteoric explanation of the cold days in February r 

 April, and May. It would doubtless be easier to believe 

 in the effective shadows of meteors, if they could fall 

 lengthwise along the space between the earth and the 

 sun. But if two or three meteor streams should chance 

 to lie between the earth and sun, not lengthwise but 

 athwart, their effect in shading the earth might be 

 quite sufficient to produce the fall of two or three 

 degrees in temperature observed during the cold spells. 



For it must be observed that the fall of temperature, 

 if caused by meteoric interposition, would be due, not 

 to the diminution of the sun's outpour of heat at any 

 particular moment, but to the entire loss of heat 

 during his passage past the interposed meteor stream, 

 and that might last two or three days, affecting the 

 entire earth, not only those places where day was in 

 progress. The actual supply of heat at any moment 

 would of course only be diminished where the sun was 

 shining ; but even where the sun was not shining the 

 effects of the diminution in the total terrestrial supply 

 would presently be felt. 



Let ns make a rough calculation, however, to see 



