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118 absorption in the red that only the blue and green in anything like their entirety get through; which accounts for the well-known sea-green look of the planet. Furthermore, the spectroscope shows that this atmosphere, or the great bulk of it, must lie above what we see as the contour of the disk. For the spectroscope is as incapable of seeing through opacity as the eye, though it distances the eye in seeing the invisible. It is not what is condensed into cloud, but what is not, of which it reveals the presence. We are thus made aware of a great shell of air enveloping the planet.

In Uranus, then, we see a body in an early amorphous state, before the solid, the liquid, and the gaseous conditions of matter have become differentiate and settled each into distinctive place. Without even an embryo core its substance passes from viscosity to cloud.

Neptune has proved a planet of surprises. Though its orbital revolution is performed direct, its rotation apparently takes place backward, in a plane tilted about 35° to its orbital course. Its satellite certainly travels in this retrograde manner. Then its appearance is unexpectedly bright, while its spectrum shows bands which as yet, for the most part, defy explanation, though they state positively the vast amount of its atmosphere and its very peculiar constitution. But first and not least of its surprises was its discovery,—a set of surprises, in fact. For after owing recognition to one of