objects by placing in the focus of a camera-obscura a metallic plate covered with a film of asphalt dissolved in oil of lavender. Mr. Fox Talbot, without any knowledge of M. Niepcé’s experiments, had been engaged in the same pursuit, and must be regarded as an independent inventor of photography, one of the most beautiful arts of modern times: he was the first who succeeded in using paper chemically prepared for receiving impressions from natural objects; and he also discovered a method of fixing permanently the impressions—that is, of rendering the paper insensible to any further action of light. In the calotype, one of Mr. Talbot’s applications of the art, the photographic surface is prepared by washing smooth writing-paper, first with a solution of nitrate of silver, then with bromide of potassium, and again with nitrate of silver, drying it at a fire after each washing; the paper is thus rendered so sensitive to light that even the passage of a thin cloud is perceptible on it, consequently it must be prepared by candle-light. Portraits, buildings, insects, leaves of plants—in short, every object is accurately delineated in a few seconds; and in the focus of a camera-obscura the most minute objects are so exactly depicted that the microscope reveals new beauties. Since the effect of the chemical agency of light is to destroy the affinity between the salt and the silver, Mr. Talbot found that, in order to render these impressions permanent on paper, it was only necessary to wash it with salt and water, or with a solution of iodide of potassium. For these liquids the liquid hyposulphites have been advantageously substituted, which are the most efficacious in dissolving and removing the unchanged salt, leaving the reduced silver on the paper. The calotype picture is negative, that is, the lights and shadows are the reverse of what they are in nature, and the right-hand side in nature is the left in the picture; but if it be placed with its face pressed against photographic paper, between a board and a plate of glass, and exposed to the sun a short time, a positive and direct picture, as it is in nature, is formed: engravings may be exactly copied by this simple process, and a direct picture may be produced at once by using photographic paper already made brown by exposure to light.