Among the most gracious and beautiful offices performed by the atmosphere is the reflection and refraction of light. The blue dome of the sky, the magnificent coloring of the clouds, and all the delicate and ever varying tints of the morning and evening twilight are due to its influence. Without the air we should be in complete darkness until the sun rose, a fiery ball, above the horizon. All day long the only light we should receive would come directly from the sun, or be reflected from objects on the earth. At sunset, darkness would instantly be spread over us like a pall. No gentle gradations of light and deepening shade would usher in and close the day. All must have observed during the past year the remarkable appearance of the western sky after the sun had set. Cities were more than once supposed to be burning, reflecting their lurid blaze upon the clouds. The cause of this is still a matter of dispute, but is generally attributed to the presence of star dust, or some minute mineral matter suspended in the higher atmosphere. It will be remembered that color is not an inherent property of a substance, but depends upon what portion of the light rays it absorbs. Snow is white, as it absorbs none of the prismatic colors, but reflects them all to the eye. Whatever, then, varies the absorbing or reflecting power of an object varies its tints. Thus, objects seen on the horizon are red, because the dense atmosphere has turned aside the violet, indigo, blue, green, yellow and orange, and only the red color reaches the eye. Observe that the initial letter of the prismatic colors taken in their order make the word “vibgyor.” Again, were there no atmosphere, there could be no CLOUDS NOR RAIN. The moon is destitute of these, or at least that half of it which is always turned toward us. The most powerful telescopes can detect there the presence of neither atmosphere nor cloud. A most remarkable proof of divine wisdom can be seen in the nice adjustment by which the pressure of the air prevents undue evaporation from the lakes and seas, and at the same time furnishes the medium by which moisture is conveyed to the remotest parts of the earth. The fact that water, in the form of mist or clouds, should float, and not fall in a substance many times lighter than itself, is one of the most wonderful of nature’s phenomena. When shot are dropped into water, we expect that they will sink; yet lead is but eleven times heavier than water, while water is eight hundred times heavier than air.