remarkable lightness. The outer planets may Le compared to wood,while those within the zone of asteroids are more allied to metals in density.
But our fiery chariot is now, on account of its proximity to the sun, experiencing strange internal commotions. The globular mass is now elongated towards the sun, the nucleus being situated near the foremost end, and as we approach still nearer, the nucleus is thrown into a state of wild excitement. A jet of bright luminous matter rises from it, similar in shape to a bat-wing gas-burner; and, in other respects, this fan of light is not unlike a jet of gas. It is sometimes seen to dance like a gas-burner when there is water in the pipe. The whole comet seems for a moment or two to be extinguished, and then suddenly flashes out with its former brilliancy. This excited action increases in intensity, till the comet reaches its nearest point to the sun, and it is only after the comet has emerged from the rays of the sun, that it has attained its maximum brilliancy. The motion of the comet, and the increase of brilliancy, is sometimes so rapid, that it appears to burst all at once, as in the case of the recent comet (1861), upon an astonished world.
As our vehicle now advances with such rapidity, and as the stations are now very close to one another, we shall take but a cursory glance at each body as we advance. The first of the heavy planets is Mars, and on his surface we can readily descry the circle of
