ditions, visible to an observer in the corresponding crystal in the other world; and vice versa. At present, indeed, we do not know of any way in which two crystals could so come en rapport, but nowadays we know enough to understand that the thing is not altogether impossible. This view of the crystals as en rapport was the supposition that occurred to Mr. Wace, and to me at least it seems extremely plausible. . . . .
And where was this other world? On this, also, the alert intelligence of Mr. Wace speedily threw light. After sunset, the sky darkened rapidly—there was a very brief twilight interval indeed—and the stars shone out. They were recognisably the same as those we see, arranged in the same constellations. Mr. Cave recognised the Bear, the Pleiades, Aldebaran, and Sirius: so that the other world must be somewhere in the solar system, and, at the utmost, only a few hundreds of millions of miles from our own. Following up this clue, Mr. Wace learned that the midnight sky was a darker blue even than our midwinter sky, and that the sun seemed a little smaller. And there were two small moons! "like our moon but smaller, and quite differently marked" one of which moved so rapidly that its motion was
