“There is just one other thing to which I must ask your attention, and then we shall return to the moon herself and the phenomena of the eclipse now in progress. You will notice in the diagram, that two arrows show the direction in which the earth is continually rotating on its axis, and that a dotted curve, terminating with an arrow point, indicates the course of the moon in her orbit surrounding the earth. The rotation of the earth is so much more rapid than the motion of the moon that the points A and B are carried out of the line drawn from the center of the moon to the center of the earth, in the direction of the arrows. From this it follows that the tides are never directly under the moon, or exactly opposite to her, but sweep in great waves round the globe. The tides produced by the attraction of the sun are only about two fifths as high as those caused by the moon. As I have already explained they are sometimes superposed upon the lunar tides—at New and at Full Moon—and sometimes they are situated at right angles to the lunar tides—at First and Last Quarters.” “But the eclipse!” interrupted my friend, whose attention had evidently begun to wander. “I think the totality of which you spoke must be at hand, for notice how dark the park has become, and the fireflies are so brilliant under the trees.” The total phase of the eclipse was, indeed, beginning, and we stepped out on the lawn before the door to watch it. The moon had now passed entirely within the earth’s shadow, but although her light was almost completely obscured as far as its power to illuminate the landscape was concerned, still the face of the moon was dimly visible, as if concealed behind a thick veil. Certain parts of it had a coppery color, producing a very weird effect. “Dear me!” exclaimed my companion, “I did not think it would look like that! I naïvely supposed that one could not see the eclipsed moon at all, but that she either disappeared or was turned into a kind of black circle in the heavens. And what a strange color she has! Positively it fills me with awe.” “It is very rare,” I said, “for the moon to become invisible during an eclipse. That can only occur when the earth is enveloped in clouds.” “Indeed, and what have the clouds to do with it? If the solid body of the earth cannot cast a shadow dense enough to hide the moon, I should not expect things so evanescent as clouds to be more effective.”