But the King of Serendib must die, nor will the relentless scythe of Time spare our Etherians, with all their exalted attributes. They will die repeatedly; and after having through sundry periods of probation attained spiritual perfection, they will all pour into the sun. Since it is the sun which originates life and feeling and thought upon the surface of our earth, "why may we not declare that the rays transmitted by the sun to the earth and the other planets are nothing more nor less than the emanations of these souls?" And now we may begin to form an adequate conception, of the rigorously scientific character of our author's method. There have been many hypotheses by which to account for the supply of solar radiance. One of the most ingenious and probable of these hypotheses is that of Helmholtz, according to which the solar radiance is due to the arrested motion of the sun's constituent particles toward their common centre of gravity. But this is too fanciful to satisfy M. Figuier. The speculations of Helmholtz "have the disadvantage of resting on the idea of the sun's nebulosity,--an hypothesis which would need to be more closely examined before serving as a basis for so important a deduction." Accordingly, M. Figuier propounds an explanation which possesses the signal advantage that there is nothing hypothetical in it. "In our opinion, the solar radiation is sustained by the continual influx of souls into the sun." This, as the reader will perceive, is the well-known theory of Mayer, that the solar heat is due to a perennial bombardment of the sun by meteors, save that, in place of gross materialistic meteors, M. Figuier puts ethereal souls. The ether-folk are daily raining into the solar orb in untold millions, and to the unceasing concussion is due the radiation which maintains life in the planets, and thus the circle is complete. In spite of their exalted position, the ether-folk do not disdain to mingle with the affairs of terrestrial mortals. They give us counsel in dreams, and it is from this source, we presume, that our author has derived his rigid notions as to scientific method. In evidence of this dream-theory we have the usual array of cases, "a celebrated journalist, M. R----," "M. L----, a lawyer," etc., etc., as in most books of this kind.