124 ROUGH WAYS MADE SMOOTH. 



For the earth passes during the next three days across the 

 orbit of Biela's comet, about as far in front of the head as 

 she passed behind the head in 1872. Now, there is no 

 known reason for supposing (on d priori grounds) that 

 meteors get strewn behind a comet's nucleus more readily 

 than in front of it. The disturbing forces which would tend 

 to delay some meteoric attendants would be balanced by 

 forces which would tend to hasten others. As a matter of 

 fact it would seem that the meteor flights which follow a 

 comet's nucleus are commonly denser than those which pre- 

 cede the nucleus. Yet in 1865 many thousands of Leonides 

 were seen which were in advance of the main body forming 

 the comet of 1866. In 1859, 1860, and 1861, many Per- 

 seids were seen, which were in advance of the comet of 1862. 

 So that we might fairly expect to see a great number of An- 

 dromeds to-night (or on the following nights) even if we 

 had none but the probabilities thus suggested to guide us. 

 But since many were seen on November 27 last, when the 

 head of the comet, now some four months' journey from us, 

 was a whole year's journey further away, it seems probable 

 that on the present occasion a display well worth observ- 

 ing will be seen should fine weather prevail. It will be 

 specially interesting to astronomers, as showing how 

 meteors are strewn in front of a comet. How meteors are 

 strewn behind a comet we already know tolerably well from 

 observations made on the Perseids since 1862 and on the 

 Leonides since 1865. 



