An enlarger is a specialized transparency projector used to produce photographic prints from film or glass negatives, or from transparencies. Construction All enlargers consist of a light source, normally an incandescent light bulb shining though a condenser or translucent screen to provide even illumination, a holder for the negative or transparency, and a specialized lens for projection. The light passes through a film holder, which holds the exposed and developed photographic negative or transparency. Prints made with an enlarger are called enlargements. Typically, enlargers are used in a darkroom, an enclosed space from which extraneous light may be excluded; some commercial enlargers have an integral dark box so that they can be used in a light-filled room. History Josef Maria Eder, in his History of Photography attributes the invention of photographic enlargement to Humphry Davy who realised the idea of using a solar microscope to project images onto sensitised paper. In June 1802 Davy published in the first issue of the Journals of the Royal Institution of Great Britain his An Account of a Method of Copying Paintings upon Glass, and of Making Profiles, by the Agency of Light upon Nitrate of Silver. Invented by T. Wedgwood, Esq. With Observations by H. Davy in which he described their experiments with the photosensitivity of silver nitrate. Eder credits the first mention of enlargements after the announcement of the daguerreotype (unique images on metal plates) to John William Draper who in 1840, during, wrote prophetically in the American Repository of Arts; "Exposures are made with a very small camera on very small plates. These are subsequently enlarged to the required size in a larger camera on a rigid stand. This method will probably contribute very much to the practice of the art" In March 1843 Americans Wolcott and Johnson patented a means of copying and enlarging daguerreotypes. In June 1843 Henry Fox Talbot in his patent for an enlarger for his calotype process which produced a paper negative, mentions that using lenses it is possible to produce a large negative from a smaller, so having made such enlargements has a priority claim to be the inventor of a system for making an enlarged print from a negative, though it did not go into production and was not practical given the lengthy exposures required. In 1848 Talbot recommended to fellow photographer Thomas Malon the enlarging camera made by Thomas Ross of lens manufacturers