Just as electricity has always been therapeutically abused by those who have taken advantage of the suggestive influence of its marvelous energy, so each new discovery in light has been the source of pseudo-scientific applications to medicine. When the explanation of photography was first made, shortly after the middle of the nineteenth century, and it was demonstrated that it was the blue light, or at least that end of the spectrum, and even some of the rays beyond the visible violet, which were the most active in this regard, applications of this fact to popular medicine became the order of the day. We had a wave of "blue light therapy" that wandered over this country and sold tons of blue glass. People simply sat beneath the blue glass as the sun shone through it and were supposed to absorb the actinic rays and acquire new life. According to many who had tried them, the ultra-violet rays were quite equal in their power to heal and restore new vigor to old frames to the fabled elixir of life of the olden time. "Rheumatism (that universal ill of the unthinking) in all its hydra-headed forms disappeared," as one enthusiast declared, "before the blue light, like the mists of the morning before the sun." All this, though it is said that the movement had no more serious foundation than the desire of a manager of a glass factory, who found himself stocked up with blue glass through a mistake, to dispose of his surplus stock. He not only did so, but many other manufacturers turned special attention to the new product because of the demand for it. The newspaper advertising was through the reading columns. The results were heard of on every side.