WILL you, or one of your spectroscopical contributors, kindly inform me in what respects (if at all) the spectrum of the electric light differs from that of the sun? At a time apparently not far distant from the almost universal application of the electric light, the question I ask is not unimportant, as it, I believe, affects the tolerance of the human eye for other than solar light. It is already well known that much work done by gas-light is by many found prejudicial to their vision, and this may, I presume, be caused by the inherent qualities of the light. It will be interesting to me therefore to learn in what respects electric light and gas-light differ from solar, as shown by spectrum analysis.