The predecessor of the modern photograph was the daguerreotype. It was named for its inventor, Louis Daguerre, a French scene-painter, who was born in 1789. In 1829 he formed a partnership with Niepce, and together they labored to advance the art of photography. The discovery of the daguerreotyping process was announced in January, 1839. The process of Daguerre consisted in "exposing a metal plate covered with iodide of silver for a suitable time in a photographic camera, the plate being afterwards transferred to a dark room, and exposed to the vapor of mercury, which develops the latent image, it being afterwards fixed. Although this process has become almost obsolete, it was really the first which was of any practical value, and experts all agree that no other known process reproduces some subjects--for example, the human face--with such fidelity and beauty." A little while before the daguerreotyping process was announced, Fox Talbot, a British investigator, discovered a method of making pictures by means of the action of light on chemically prepared paper instead of metal, as in the case of Daguerre. Talbot originated the terms _negative_ and _positive_ which are still used in photography. Daguerre in France and Talbot in Great Britain had independently achieved success in producing pictures, but neither had discovered a way to make photographs permanent. In the course of time the pictures faded. In 1839 Sir John Herschel of England found a chemical process for making photographs permanent, by removing the cause for their fading. The first sunlight photograph of a human face was that of Miss Dorothy Catherine Draper, made by her brother, Prof. John William Draper, of the University of the City of New York, early in 1840. Various chemical discoveries for improving photographs have been made by different persons from time to time, until the art of photography has now reached a high state of development. An important improvement is in the lessening of the time of exposure to light necessary for producing a photograph. Formerly hours were required, but under improved conditions only the shortest instant of time is requisite. In 1906 a photographic paper for producing prints in color from an ordinary negative was placed on the market. This paper is coated with three layers of pigmented gelatin, colored respectively red, yellow, and blue. After being exposed to the daylight in the usual way, the paper is placed in hot water, where the image is developed. The grays and blacks of the negative are translated into the colors they represent in the object. The brothers Lumière of Paris have found a method of producing a photograph on a sensitive plate which, viewed as a transparency, shows the object in its original colors. No prints can be taken from this plate, and the picture cannot be viewed by reflected light, but the colors are true and brilliant.