Dancer, John Benjamin (1812–1887)

British optician and instrumentmaker. He pioneered microphotography and by 1840 he had developed a method of taking photographs of microscopic objects using silver plates. The photographic image was capable of magnification up to 20 times before clarity was lost. By 1859 he was showing microscope slides which carried portraits or whole pages of books.

Dancer improved many of the standard laboratory practices of the period. He introduced unglazed porous jars in voltaic cells to separate the electrodes. Dancer improved on the Daniell cell by crimping or corrugating its copper plates to increase the electrode surface area. He also constructed the apparatus with which James Joule determined the mechanical equivalent of heat.

Dancer was born in London but grew up in Liverpool. He trained in the family business of manufacturing optical and other scientific instruments and giving public lectures at the Liverpool Mechanical Institution.

In 1839 he began a series of experiments based on Daguerre's and Fox Talbot's photography techniques, and adopted the collodion method in the 1850s. By 1856 Dancer had prepared hundreds of microphotographs and his work was exhibited throughout Europe. They included photographs of distinguished scientists of the era and portraits of the British royal family.