THE EARTH IN METEORIC SHADOW. 175 



(however dark its substance may be) reflect a measur- 

 able or recognisable quantity of sunlight, when favour- 

 ably placed for observation. Is there any evidence to 

 show that this has happened in the case of the meteoric 

 streams we have been considering above ? 



When should they be looked for? Manifestly, 

 during eclipses occurring at the time when the earth is 

 opposite, or nearly opposite, the part of her orbit on 

 which such meteor streams cast their shadows. For 

 instance, if the fall of temperature on or about 

 February 7 is caused by the interposition of one or 

 more meteor systems, then, during an eclipse occurring 

 near August 11, say within two or three weeks on 

 either side of that date, we should see meteoric 

 streamers extending apparently diametrally from the 

 sun (that is, forming opposite radiations really due to 

 their lying behind the sun). 



Now in the eclipse of July 28, 1851, Airy, the 

 Astronomer Koyal, noticed that the corona looked like 

 a radiated cloud behind the moon. In the eclipse of 

 July 29, 1878 (more favourably seen than any other 

 has ever been), a bar of light was seen forming two 

 radiations along the ecliptic, while athwart was another 

 stream of light (both probably being meteoric streams). 

 In the eclipse of August 7, 1869, four long radial 

 streams were traced by General Myer to a distance of 

 two or three diameters of the lunar disc. (He calls 

 them straight, massive, silvery rays, seeming distinct 

 and separate from each other, the whole spectacle 

 showing as upon a background of diffused rose-coloured 



