366 ANNUAL OF SCIENTIFIC DISCOVERY. 



into our system, furnishes materials for calling a new comet into 

 existence. 



As to the cosmical masses revolving round the sun in ellipses whose 

 transverse axes are in different positions, it seems impossible that a 

 number of them could be drawn together by their mutual attraction, 

 either to form a single mass or to revolve round a new centre. The 

 attractive power even of the asteroids, could not control the enor- 

 mous velocity with which bodies sweep by one another on meeting in 

 the planetary spaces, when they move in different planes, or in ellipses 

 differently situated. A mass of matter one mile in diameter would 

 be prevented by an eccentricity equal to 1-10,000 part of its trans- 

 verse axis from collecting by its attraction smaller bodies equidistant 

 from the sun. An eccentricity 1,000 times smaller should present an 

 ^insurmountable obstacle to the union of the largest meteoric stones 

 which visit the earth. Should collisions occur between them, they 

 will only be broken into smaller fragments ; or they will at least 

 rebound into space, in spite of their feeble attraction, or the resist- 

 ance from the exceedingly rare atmosphere they are able to confine 

 around them. 



Bodies revolving round the sun in the same direction, in planes 

 nearly coincident, and in orbits almost circular, and differing little in 

 dimensions, should be likely to come together, and unite at their first 

 conjunction or soon afterward ; for in this case, their relative motion is 

 slow enough to be controlled, and they remain long enough in prox- 

 imity to render their attraction adequate to this object. These con- 

 ditions, which chance could never supply, together with another still 

 more favorable, will be found to arise from a peculiar state of the 

 disturbing forces, which come into play in the remote parts of the 

 solar system. 



Although no kind of action calculated to correct the eccentricities 

 of the planetary orbits, has been hitherto discovered, I shall shew that 

 every body which comes within the sphere of the sun's attraction, and 

 happens to describe an elongated ellipse round him, will have its 

 orbit gradually changed into one nearly circular. The principle on 

 which this is effected, will be understood from the action of the sun 

 on a satellite about 800,000 miles from the earth ; for the very great 

 disturbance in this case, will change a very eccentric orbit to a more 

 circular form. The first step to this alteration, is a curious arrange- 

 ment in the position of the transverse axis, so that the higher apsis 

 will be always in conjunction with the sun. It has been long known 

 that if the planets were elipsoids, their longest diameters should be 

 always directed to the sun, if not prevented by too rapid a rotation. 

 A similar tendency is manifested by the orbits of their satellites : and 

 the line of apsides would be continually directed to the sun when- 

 ever the disturbing force exceeds a certain amount, at least, when it 

 is adequate to cause a motion of the apsides differing little from the 

 sun's increase of longitude during the satellite's revolution. The 

 smallest distance at which this phenomenon could occur cannot be 

 stated with much precision, as it depends on the eccentricity ; but 



