Canvasback ducks are considered the finest of the water-fowls for the table. The canvasback duck is so called from the appearance of the feathers on the back. They arrive in the United States from the north about the middle of October, sometimes assembling in immense numbers. The waters of Chesapeake Bay are a favorite locality for them. Here the wild celery, their favorite food, is abundant, and they escape the unpleasant fishy flavor of the fish-eating ducks. Why doesn’t the Sky ever Fall Down? The sky never falls down because there is nothing to fall. What we see and call the sky is the reflection of the sun’s rays on the belt of air that surrounds the earth. That beautiful blue dome that we sometimes hear spoken of as the roof of the earth is just the reflected light of the sun on the air. The atmosphere of the earth consists of a mass of gas extending to a height which has been variously estimated at from forty-five to several hundred miles, possibly five hundred, and bearing on every part of the earth’s surface with a pressure of about fifteen pounds per square inch. How are Sand-Dunes Formed? Sand-dunes are composed of drift sand thrown up by the waves of the sea, and blown, when dry, to some distance inland, until it is stopped by large stones, tree roots or other obstacles. It gradually accumulates around these, until the heaps become very large, often forming dunes or sand-hills. What do We Mean by an “Eclipse”? Any good dictionary will tell us that an eclipse is an interception or obscuration of the light of the sun, moon or other heavenly body by the intervention of another and non-luminous heavenly body. Stars and planets may suffer eclipse, but the principal eclipses are those of the sun and the moon. An eclipse of the moon is an obscuration of the light of the moon occasioned by the interposition of the earth between the sun and the moon; consequently all eclipses of the moon happen at full moon; for it is only when the moon is on that side of the earth which is turned away from the sun, and directly opposite, that it can come within the earth’s shadow. Further, the moon must at that time be in the same plane as the earth’s shadow; that is, the plane of the ecliptic in which the latter always moves. But as the moon’s orbit makes an angle of more than five degrees with the plane of the ecliptic, it frequently happens that though the moon is in opposition it does not come within the shadow of the earth. [Illustration: DIAGRAMS ILLUSTRATING THE THEORY OF ECLIPSES.]