192 The November Shooting Stars. 



a fixed point among the stars, we know for certain that the 

 direction of their motion is independent of the earth's rota- 

 tion, and therefore — there being no possibility of an artificial 

 arrangement corresponding to that of the equatorial — that the 

 shooting stars come from external space. The notion of a 

 lunar origin, and the satellite theory of meteors are similarly 

 overthrown, though indeed, at the present day, no competent 

 person entertains either of these views, which are for other 

 reasons, wholly untenable. When the occurrence of a ec radiant 

 point - " is coupled with " annual periodicity and independence 

 of geographical position, referring us at once to the place 

 occupied by the earth in its annual orbit/'' the most sceptical 

 (or, in this case, we must say those least able to appreciate 

 the mathematical demonstration of the meaning of a radiant 

 point), must be led " directly to the conclusion that the earth 

 is liable to encounters or concurrences with meteor streams in 

 their progress of circulation round the sun/' 



It must be mentioned that the earth's motions have their 

 effects upon the apparent motion of bodies moving in space. 

 The motion of rotation, however, may be neglected in com- 

 parison with the motion of revolution and the proper motion 

 of meteoric bodies. Travelling in space, under the sun's 

 attraction, they cannot, at the moment of encountering the 

 earth, be moving with a less velocity than that due to a body 

 moving circularly round the sun at the earth's distance (a rate 

 very slightly less than the earth's) and they may have a velocity 

 nearly half as great again as this. Between these values then- 

 velocity necessarily lies. Further, their velocity, relatively to 

 the earth, must lie somewhere in value between the sum and 

 difference of their actual velocity and the earth's, or between 

 zero and about forty-five miles per hour ; the first value giving 

 the extreme case of meteors travelling in the same direction, 

 and at the same rate as the earth ; the second giving the case 

 of meteors travelling in a parabolic orbit, and encountering the 

 earth directly, just when they are in 'perihelion. 



I have mentioned these limits and considered the nature of 

 meteors' motion relatively to our earth, because it is on this 

 relative motion that the position of the " radiant point " 

 depends. If we suppose the earth reduced to rest, and her 

 motion, reversed, added to the motion of the meteoric stream, 

 we get the same relative motion, and the same radiant point as 

 under the actual circumstances of the case. For clearness of 

 explanation let us suppose this to happen, and that on the 

 night of November 13 — 14 the earth's motion of revolution is 

 non-existent (her motion of rotation continuing, however), and 

 that the meteors arc sweeping towards her from their radiant 

 point (i.e. at a rate and in a direction resulting from the 



