SPECULATIONS ABOUT COMETS. . 395 



consider the spheres of different densities that intervene in our solar system be- 

 tween the eye and comet beyond the confines of that system. 



We have not the space here to elaborate this hypothesis, and can only sug- 

 gest it by the statement that a body like that of a comet, when approaching the 

 boundary of its own system, and subject to the attractive force of the solar sys- 

 tem, would invariably be an elongated body — the length of its tail being in ratio 

 with its size and the forces operating upon it. Comets must obey and be con- 

 trolled by the central forces of the system to which they belong, and when they 

 approach near or come in contact with our system, they must from the law refer- 

 red to, have tails. 



The effect of the earth sphere and other spheres of the solar system upon the 

 appearance of a comet must differ with the position of the comet itself. Suppose 

 the sphere of the attractive force of the solar system to be convex. The light 

 projected on this convex surface would be to expand it. But when we view it 

 from the earth, with nothing but the earth sphere between, th.e effect is that of a 

 convex lens, and the comet will appear smaller and present a more natural ap- 

 pearance than under the other conditions. If dense strata or the sphere of an- 

 other planet He between the eye and the comet the appearance will greatly differ, 

 as the comet would then project itself upon the convex surface of that interven- 

 ing sphere. 



The intervention of this sphere as related to the eye of the observer is both 

 concave and convex, and of necessity affects the image seen through it. But 

 even this fact is not all, for we know that the planetary spheres are more dense 

 than the sphere of the system, and light from the comet projected upon such 

 sphere is not so freely transmitted, and will be reflected back upon the outer or par- 

 ent sphere, which from one point of view is convex — thus presenting to the eye 

 a distorted image of the comet. 



Taking these well known facts in optics into consideration, and noting the 

 other fact that in the position of the present comet we see it not only through the 

 sphere of the solar system, but through that of other planetary spheres, the ob- 

 server may readily be misled to the conclusion that the comet and Sun have been 

 in actual contact, the former appearing by its reflected light to have been so near 

 the latter. But it will be noted that no one observed the comet in conjunction, 

 either inferior or superior, which would have been the case had it been within 

 the solar system, for it was first observed so near to the Sun as to preclude the 

 possibility of its escaping the close search of the astronomers when it was on the 

 other limb of that orb, as it must have been to pass around and come in contact 

 with it. And particularly if it has been broken into so many pieces by the col- 

 lision it must have been much larger when intact, and more readily observable. 

 And as the tail is in proportion to the size of the nucleus it would have been a 

 much more conspicuous object before than after the catastrophe. These facts 

 can only be explainable upon the hypothesis suggested above. And this can be 

 more readily admitted when we know that the direction of the tail often changes, 



