The star Beta, of the constellation Lyra, has a full period of twelve days and twenty-two hours, divided into two periods of six days and eleven hours, in each of which the star has a maximum brightness of about the three and one-half magnitude, but in one period the minimum is about the four and one-third magnitude, while in the other it is about the four and one-half magnitude. This peculiarity points, it is said, to an opaque orb with a satellite, the satellite being occulted by the primary in the alternative transits, and therefore the loss of light is less. The star Delta of Cepheus is quite different, however, for, while it takes only one, day and fourteen hours in passing from its minimum to maximum of brightness, it occupies three days and nineteen hours, or somewhat more than double this time, in passing from maximum to minimum. Two or three hundred of these variable stars are already known. The above examples are cited in detail because they furnish the strongest possible proof of the truth of the hypothesis which we are endeavoring to present. While the movements of the stars Algol and Beta Lyræ may find an adequate interpretation in the one case in a large occulting planet, and in the other in an occulting planet with a satellite, it is obvious that Mira and Delta Cephei cannot be explained except by the presence of planetary bodies or satellites which do not mechanically occult the light of their suns. In these regularly variable stars it is the light which varies, but of course the solar heat must vary also,--that is to say, the solar energy varies regularly, but with unequal periods of growth and decline and with larger periods of cyclical variation in addition. Such variations can only be produced by the action of permanently connected and orbitally rotating planetary bodies, acting dynamically through space, to regularly increase and diminish the solar energy, and such bodies can only do this by their orbital positions with reference to each other and to the central sun itself. In this case, since the activity of solar energy is most unquestionably varied by the planetary energies, by their position and movements, at least a portion of solar energy must be due to planetary action, and if this be so, it may be affirmed with certainty that substantially all solar energy may be produced in the same way; for, otherwise, we seek for two diverse causes to produce a single effect, which may be produced by one. We have no knowledge, however, of any planetary energy which could operate to increase or diminish the energy of the central sun in its emission of light, except that which we have already presented, and no theory of our own sun's energy hitherto advanced has ever taken cognizance of the planetary energies of our system as an effective cause for those of the sun. But while the sun's energy is--as it must be in this case--the outcome of that of the planets, it is equally obvious that the planets themselves