42 Mr. H. A. Newton on certain recent 



solar system from the beginning, or whether they be supposed 

 to have come from space, being attracted hither by the sun. 



There are two arguments which show that the meteoroids 

 should be classed with the comets as originally strangers to our 

 system, rather than with the planets. The first is that their or- 

 bits seem to be inclined at all angles to the ecliptic*; the second 

 that their velocity requires a long if not a parabolic orbit. 



Admit, then, that the shooting-stars come from stellar space, 

 and we have no longer closed rings of short period, but streams 

 of a parabolic form, for which the period of revolution, if there 

 is one, is very great. Now this parabolic current, which at first 

 seems so strange a form, is not only possible, but it is the only 

 form in which a cosmical cloud drawn from stellar space by solar 

 attraction can approach the sun and become visible to us. 



To prove this, he supposes a cosmic cloud of the size of the 

 sun to be at first at a distance equal to 20,000 (the mean dis- 

 tance from the earth to the sun being unity). The rarity of the 

 matter in this cloud is regarded as such that the mutual attraction 

 of the particles may be disregarded. This cloud of particles is 

 then supposed to have a velocity (relative to the sun) perpendi- 

 cular to a line drawn to the sun, 775^00 °^ ^he mean velocity of 

 the earth, or about 100 yards a minute. 



The several particles will move in elliptic orbits about the sun, 

 but these ellipses will not be exactly equal. M. Schiaparelli 

 shows that a cloud, of spherical form at first, would be deformed 

 little by little, and ultimately drawn out so as to have a very 

 small transverse section. It will now lie along a parabolic arc, 

 of which the sun is the focus. When the particle originally at 

 the centre of the globe reaches its perihelion, at a distance from 

 the sun equal to J, the anterior portion of the group will have 

 passed its perihelion 193'5 days, and have already crossed in its 

 outward course the orbits of the minor planets. The end of the 



* That the inclinations of the orbits of the meteoroids are of all mag- 

 nitudes, M. Schiaparelli infers, principally, from the positions of the 

 radiants given by Messrs. Greg, Herschel, and Heis. Although these 

 radiants are open to criticism, yet the above conclusion is undoubtedly true. 

 It is readily seen that if the orbits of the meteoroids are but little inclined 

 to the earth's orbit, the apparent paths of the meteors should themselves 

 rarely be seen to cut the ecliptic, and that the paths produced forward 

 should rarely cut the ecliptic above the horizon. In other words, the paths 

 as seen in the sky should, with rare exceptions, appear to lead away from 

 that circle. So far as my own observation is concerned, I find no such 

 regularity. The meteors go toward the ecliptic as often as from it. Ap- 

 parent radiation from points of such considerable latitude as those given in 

 the Table on pp. 35, 36, shows also that many of the orbits of the meteo- 

 roids, at least, are inclined at large angles to the earth's orbit, 



