Rainbow

Aiton's Encyclopedia (1910)

a beautiful arch of colors seen in the heavens during a shower. The center of the bow, the observer, and the sun are in a straight line. The bow is seen only when the sun is shining. The nearer the sun is to the horizon, the higher the arch of the bow. At whatever time of the day, it appears, of course, in that part of the horizon which is directly opposite the sun. This being the case, the observer must stand with his back to the sun. The cause of the rainbow is very simple, yet it is not easily understood. A part of the white sunlight, entering each drop of falling water, is turned back by the farther side of the drop as though from a mirror, and returns toward the sun in a stream of different colored lights, violet, indigo, blue, green, yellow, orange, and red, the scientific name of which is a spectrum. The initials of the colors form the word vibgyor. Each drop sends back all these colors, but, in reality, the observer sees the violet rays from drops in a certain layer, the indigo from those in another, and so on. Two people a mile apart see a rainbow in apparently the same position; as a matter of fact, they see two entirely different bows. The truth is, the observer changes his rainbow every time he moves his head. There is an old tradition that a pot of gold lies buried under the end of every rainbow, that the first to reach the spot may secure the treasure. Seeing that the rainbow flits with the observer, it is, of course, impossible to reach the end of it. The pot of gold is therefore perfectly safe. Rainbow chasing is a good deal like trying to step on the shadow of one's head. No matter how quickly a boy darts, his shadow has moved ahead before he can put his foot upon it. The rainbow is without comparison the most beautiful natural phenomenon known. It attracted the attention of the earliest writers. No more beautiful interpretation has been given it, however, than that of the oriental nations who saw in the rainbow a promise that the shower should not turn into a flood. I do set my bow in the cloud, and it shall be for a token of a covenant between me and the earth . . . and the waters shall no more become a flood to destroy all flesh.--Gen. ix. A miniature rainbow may be seen by looking at the flame of a candle through a piece of glass dusted with lycopodium--the spore dust of a fern-like plant. See Light ; Spectrum ; Mirage