James How, made and sold a variety of optical instruments and supplies, including microscopes and slides from his shop in Foster lane London between 1863 to his death in 1872. Prior to that the shop was owned by George Knight, James how is believed to have worked for Knight since around 1843.

Although microscope slides sold by How have not been identified, photographs in magic lantern slides are known. James How produced a large series of photomicrographs (small objects enlarged by photography through a microscope) taken by Richard Maddox. The 1867 Catalogue of the Educational Division of the South Kensington Museum described a “Series of Enlarged Photographs of Microscopic Objects; the Negatives by Dr. Maddox, printed by J. How.

How displayed his products at the 1867 Paris Universal Exhibition. According to the catalogue, these included “photographs”, a “photography tent” (portable dark room) and a “field box” (probably a portable, light-tight box that one could reach inside to manipulate photographic plates, protected from daylight).