EXPECTED METEORIC DISPLAY. 255 



actual path pursued by a meteor may be on one side of the heavenly 

 sphere, while the radiant is on the other ; precisely as any particular 

 yard of a set of parallel railway lines and telegraph wii-es may be to 

 the right or the left, or above or below, or may be behind an observer, 

 while the point from which all these lines converge is in front of him. 

 Yet two meteor-tracks, carefully observed, will suffice, unless abso- 

 lutely coincident, to show the radiant point belonging to them, assum- 

 ing of course that they belong to the same system. And when on any 

 night many meteors of the same system are seen, the radiant point of 

 the system, w^hich indicates the direction from which with respect to 

 the earth they all seem to travel, can be most accurately determined. 

 In this way each meteor system is perfectly distinguishable from all 

 others ; and also, from the position of the radiant point of a system, 

 the question whether the meteors are or are not bodies following in the 

 track of any known comet, can be at once set at rest. The path of 

 such bodies can be calculated with perfect exactness. The apparent 

 path resulting from the combination of their motions with the motions 

 of the earth can equally well be determined. This gives the radiant 

 point of such bodies, if such bodies there are, as they appear in 

 shooting-star displays in our skies. No scattered meteors, still less 

 any meteor-shower, can be mistaken for attendants on such a comet — 

 at least, if we set aside the bare possibility (for such it is) that bodies 

 really traveling in a different course may appear to travel on the same 

 course. This can happen ; but it is so exceedingly unlikely, that if 

 a meteor-flight appears at the time, and from the radiant point, cor- 

 responding to the attendants of a particular comet, it may be confi- 

 dently assumed that they really are such attendants. 



But, as I have said, on former occasions when displays of meteors 

 occurred during the last week in November or the first week of De- 

 cember, which might therefore have indicated the earth's passage 

 through the train of Biela's comet, no special observation was made of 

 the tracks of individual meteors, so that it was not possible to ascertain 

 afterward whether such showers might or might not be thus explained. 

 Nor were any observations made for Biela meteors when the earth 

 passed through the track of the comet in 1836, when, from what we 

 now know, a display of such bodies might have been expected. 



It was otherwise in 1872. Biela's comet itself having been searched 

 for fruitlessly, several astronomers called attention to the circumstance 

 that in the last week of November the earth might be expected to pass 

 through a train of meteors following in the track of the now disin- 

 tegrated comet. They showed also how Biela meteors, if such existed, 

 could be distinguished from other shooting stars ; the radiant point 

 corresponding to attendants on Biela's comet lying in the region where 

 the constellation Andromeda borders on Cassiopeia, near the feet of 

 the former of these celestial bodies. I myself wrote in the following 

 terms, in a paper written in October, and which appeared in the " St. 



