tia IN STARRY REALMS. 



would never have become conscious that such a shoal of 

 meteors existed, had it not been for a certain circum- 

 stance, which, for want of a better expression, I must 

 speak of as accidental. 



Our globe pursues a certain definite track around the 

 sun. Year after year, with undeviating regularity, the 

 earth performs the stages of its journey. If it reaches 

 certain points on the 1st of January and the 12th of Octo- 

 ber in one year, then it reaches the same points on the 

 1st of January and the 12th of October respectively on 

 next year, or any other year. The same may be asserted 

 with regard to any other dates, so that when a date is 

 given the station at which the earth will then have arrived 

 is at once indicated. 



The Leonids and the earth have each a certain track. 

 It might of course have happened that one of these tracks 

 lay quite outside or quite inside the other. It might also 

 have been the case that one of these tracks passed through 

 the other, so that the two orbits were related in the 

 manner of a pair of consecutive links of a chain. Had 

 any of these conditions prevailed, the two tracks would 

 have been quite independent, and the meteors could never 

 have become known to us. It might, however, have 

 happened that the two tracks did actually intersect, and 

 had therefore the point of crossing common to both orbits. 

 This would, generally speaking, be an unlikely circum- 

 stance, but it is an indispensable condition if the meteors 

 are to be visible from the earth. In the case of the 

 Leonids, it has chanced that their orbit does intersect 

 the orbit of the earth, and to this circumstance we are 

 indebted for the glorious displays every thirty-three years. 



