from the matter being dense, it is on the whole no heavier than water. This, however, is on the supposition that we see the solid surface of the planet. What we see, however, may be only an envelope far above the surface of the nucleus, which may have a much greater density. Though the sun has dwindled down to one-thousandth its size, its light is by no means so dim as might be supposed. We have a proof of this in the case of eclipses. If the most slender crescent be left uncovered by the moon, the diminution of light is by no means startling. It is only at the moment of totality that the dread effects of an eclipse are produced. We can conceive of the Neptunians thriving very well, notwithstanding their stinted supply of light; and we can suppose that all unpleasant effects might be completely obviated, by having the pupil of the eye enlarged, and the sensibility of the retina increased. The diminution of heat would be more difficult to endure, but, with a properly constituted atmosphere, and with the central heat of the planet itself, we can have no difficulty in conceiving of its being inhabited. The human frame proves how low a temperature is compatible with the functions of life. In this climate, the sinking of the temperature ten degrees below the freezing-point, is more keenly felt than a sinking of twenty degrees below zero during a Canadian winter. The reaction of the vital powers seems to come more into play at
