There is a prejudice against gaslight as being the most injurious form of artificial illumination. As against the proper and well regulated use of gas, this prejudice is entirely groundless, but there can be little doubt that from its abuse and bad management it is really doing more mischief than any other kind of light; its vcry excellencies are turned to bad account; its extreme cheapness, compared with other sources of illumination, naturally leads to its use in excessive quantities ; floods of light are poured forth, so that persons may read and sew for hours together in the remotest corners of the room. The air is heated by the excessive combustion, and poisoned by large quantities of carbonic acid, which there are no means of removing. The eye is unprotected from the glare by screen or shade; extraneous light is freely admitted, which obscures the impression, and strains the nerve of vision, and in proportion as the sensibility of the eye is impaired, stronger light is used, which gives temporary relief, but with danger of ultimate and permanent injury to the sight. On the other hand, good, well purified gas, judiciously controlled in accordance with the hints we have given, is perfectly harmless.