only from the equatorial side, but also from the polar sides, by the gradual back rush of photosphere. This would prevent the formation of spots in those parts. Moreover, as the equatorial parts of the photosphere become gradually forced into a latitude having a slower motion of rotation, a certain gyratory commotion must ensue tending to break its continuity. These breaks would also, from this reason, be more likely to occur at the beginning of the cycle in the higher latitudes, where there would be greater difference in the comparative speed of the parallels. The third difficulty, namely, the acceleration of their rotation in proportion to their vicinity to the equator, may be explained under the assumption of the flattened nebulous mass before alluded to, when we consider that all the parts of the sun's atmosphere, which rotate with him, must tend to travel at greater velocities the higher they are above the sun's surface. When, therefore, the higher parts, directly over the sun's equator, are caused to descend to the sun's surface, by either a general or local oscillation, they must travel faster than the sun's equator, and act like a constant wind blowing in the direction of the sun's motion. The same result will happen, though in a gradually reduced degree, as we depart from the equator; the solar spots will therefore travel at greater speed the nearer they are to the equatorial regions. After the downward oscillation is terminated, the upward one commences; but by this time the solar spots have mostly disappeared for the photosphere resumes its ordinary thickness. This variation in the speed of different parallels of the photosphere, arising from the downward oscillation, must, I think, produce those agitations in the photosphere so apparent just before the appearance of spots, and most likely conspires to their formation. The general drift of the spots in lines of parallel, to the with the common arrangement of a number of spots in lines parallel to the equator, appear hereby explained. The very fact of the solar spots being proved, by observation, to travel faster in the equatorial parts, appears to prove the existence of a lenticular-shaped mass surrounding the sun; for a merely spherical atmosphere could not, by its downward oscillation, effect a change in their rotation. Regarding the fourth difficulty, of the greater prevalence and size of sunspots in northern latitudes, it is pretty certain that, owing to the intense heat of the sun's mass, a certain amount of adjustment must be already attained in its photosphere. If then gravity, at the sun's surface, is balanced by the expansive force of heat, any slight alteration in the pressure of his atmosphere must modify the equilibrium of all other forces there exerted. Can it be that the sun's own proper motion in space, in impinging on the interstellar medium, gives an additional pressure upon the sun's