right to entertain in respect to those Titanic circles with which we have to deal, at least in fancy, when we suppose our system, with its fellows, revolving about a point in the center of the galaxy. Let the most vigorous of human imaginations but attempt to take a single step toward the comprehension of a circuit so unutterable! It would scarcely be paradoxical to say that a flash of lightning itself, traveling _forever_ upon the circumference of this inconceivable circle, would still _forever_ be traveling in a straight line. That the path of our sun along such a circumference--that the direction of our system in such an orbit--would, to any human perception, deviate in the slightest degree from a straight line even in a million of years, is a proposition not to be entertained; and yet these ancient astronomers were absolutely cajoled, it appears, into believing that a decisive curvature had become apparent during the brief period of their astronomical history--during the mere point--during the utter nothingness of two or three thousand years! How incomprehensible, that considerations such as this did not at once indicate to them the true state of affairs--that of the binary revolution of our sun and Alpha Lyrae around a common center of gravity! _April 7th._--Continued last night our astronomical amusements. Had a fine view of the five Neptunian asteroids, and watched with much interest the putting of a huge impost on a couple of lintels in the new temple at Daphnis in the moon. It was amusing to think that creatures so diminutive as the lunarians, and bearing so little resemblance to humanity, yet evinced a mechanical ingenuity so much superior to our own. One finds it difficult, too, to conceive the vast masses which these people handle so easily, to be as light as our own reason tell us they actually are.