168 H, A. Newton— Origin of Comets, 
11. But if AS is not large the above stated conclusion (10) 
would not hold true. hus if the comets came from the 
region between Mars and Jupiter, being, for example, asteroids 
somehow thrown out of the usual region of the asteroid orbits, 
the total area of the impacts in the target plane would not 
large relative to a circle whose radius is equal to the diameter 
of the orbit of Mars. The distribution of the inclinations of 
the orbits would in that case naturally exhibit some evidence 
of the law of distribution of the original motions. 
12. Suppose, however, that the cometic masses are made 
from the more distant matter of the solar nebula, matter that 
should perhaps have gone to form a planet outside of the orbits 
of known planets. The masses must be supposed to come from 
points in or near the plane of the solar system, which for present 
purposes may be regarded as the ecliptic. Referring their 
inclinations to that plane, those inclinations, for reasons like 
those given above (10), should have been originally uniformly 
distributed through the two right angles from 0° to 180°. The 
aphelia of the orbits should all have been near the ecliptic. 
13. But suppose, on the other hand, that the cometic masses 
are made from the matter in the stellar spaces. The points 
from which they approach the sun are no longer, as under the 
other supposition, points in or near the ecliptic. These points 
are scattered over the heavens uniformly. For, only those 
masses whose motions through space are very nearly equal to 
sun’s motion can come within sight of the earth. The 
14. If now we consider a very large number of orbits and 
draw lines through the sun at right angles to the plane of each 
orbit, the points where these lines meet the celestial sphere will 
the poles of the planes of the orbits, and their distribution 
over the heavens must be uniform. For the directions from 
ich comets enter the solar system are uniformly distributed 
(13), and the poles for any direction of the line AS are unt- 
formly distributed (10) about that line. Hence there is n0 
n why there should be more poles in one part of the 
heavens than in another. : 
15. If we refer these orbits (14) to the ecliptic, the inclina- 
tion of any orbit to the ecliptic will be equal to the distance of 
the two poles from each other, the pole of the orbit from the 
pole of the ecliptic. If we divide the surface of the celestial 
* Prof. Schiaparelli by introducing (improper! e will concede) 
the motion of dus tesdbabe ie decide ‘lias cane comets. 
See Analyst, I, p. 80. 
