ARE THERE PLANETS AMONG THE STARS? 175 



against such beings as the inhabitants of the earth. Beyond the 

 sun's domain only whirling stars, coupled in eccentric orbits; dark 

 stars, some of them, but no planets; a wilderness, full of all energies 

 except those of sentient life ! This is not a pleasing picture, and I do 

 not think we are driven to contemplate it. Beyond doubt, Dr. See 

 is right in concluding that the double and multiple star systems, with 

 their components all of magnitudes comparable among themselves, 

 revolving in exceedingly eccentric orbits under the stress of their 

 mutual gravitation, bear no resemblance to the orderly system of our 

 sun with its attendant worlds. And it is not easy to imagine that 

 the respective members of such systems could themselves be the 

 centers of minor systems of planets, on account of the perturbing 

 influences to which the orbits of such minor systems would be sub- 

 jected. 



But the double and multiple stars, numerous though they be, 

 are outnumbered a hundred to one by the single stars which shine 

 alone as our sun does. What reason can we have, then, for ex- 

 cluding these single stars, constituting as they do the vast majority 

 of the celestial host, from a similarity to the sun in respect to the 

 manner of their evolution from the original nebulous condition? 

 These stars exhibit no companions, such planetary attendants as they 

 may have lying, on account of their minuteness, far beyond the reach 

 of our most powerful instruments. But since they vastly outnumber 

 the binary and multiple systems, and since they resemble the sun 

 in having no large attendants, should we be justified, after all, in 

 regarding our system as " unique "? It is true we do not know, by 

 visual evidence, that the single stars have planets, but we find 

 planets attending the only representative of that class of stars that 

 we are able to approach closely — the sun — and we know that the 

 existence of those planets is no mere accident, but the result of the 

 operation of physical laws which must hold good in every instance 

 of nebular condensation. 



Two different methods are presented in which a rotating and 

 contracting nebula may shape itself into a stellar or planetary system. 

 The first is that described by Laplace, and generally accepted as the 

 probable manner of origin of the solar system — viz., the separation of 

 rings from the condensing mass, and the subsequent transformation 

 of the rings into planets. The planet Saturn is frequently referred 

 to as an instance of the operation of this law, in which the evolution 

 has been arrested after the separation of the rings, the latter having 

 retained the ring form instead of breaking and collecting into globes, 

 forming in this case rings of meteorites, and reminding us of the 

 comparatively scattered ring of asteroids surrounding the sun be- 

 tween the orbits of Mars and Jupiter. This Laplacean process Dr. 



