Sir William de Wiveleslie Abney KCB FRS FRSE (24 July 1843 – 3 December 1920) was an English astronomer, chemist, and photographer. Abney was born in Derby, England, the son of Edward Abney (1811–1892) vicar of St Alkmund's Derby, and owner of the Firs Estate. He attended Rossall School, the Royal Military Academy, Woolwich and joined the Royal Engineers in 1861, with whom he served in India for several years. Thereafter, and to further his knowledge in photography, he became a chemical assistant at the Chatham School of Military Engineering. Abney was a pioneer of several technical aspects of photography. His father had been an early photographic experimenter and friend of Richard Keene, an early Derby photographer. Keene became a close friend of William and his brother Charles Edward Abney (1850–1914). Both Abney sons subsequently became founder members of the Derby Photographic Society in June 1884.[1] His endeavors in the chemistry of photography produced useful photographic products and also developments in astronomy. He wrote many books on photography that were considered standard texts at the time, although he was doubtful that his improvements would have a great impact on the subject. Abney investigated the blackening of a negative to incidental light. In 1874, Abney developed a dry photographic emulsion, which replaced "wet" emulsions. He used this emulsion in an Egyptian expedition to photograph the transit of Venus across the sun. In 1880, he introduced hydroquinone. Abney also introduced new and useful types of photographic paper, including in 1882 a formula for gelatin silver chloride paper. He was elected a Fellow of the Royal Society in 1876. Abney conducted early research into the field of spectroscopy, developing a red-sensitive emulsion which was used for the infrared spectra of organic molecules. He was also a pioneer in photographing the infrared solar spectrum (1887), as well as researching sunlight in the medium of the atmosphere. He became assistant secretary to the Board of Education in 1899 and advisor to that body in 1903.[2] In 1900 he was Director of the Science and Art Department. He sold his father's estate, most of which went for housing in the St Luke's Parish of Derby, but retained 11 acres until 1913 when they were purchased by the Council to become the site of Rykneld Secondary Modern School and Rykneld recreation ground.[2] Abney invented the "Abney level", a combined clinometer and spirit level, used by surveyors to measure slopes and angles. He was responsible for the "Abney mounting" of a concave grating spectrograph in which the photographic plate was fixed and the entry slit moved to accommodate different regions of the spectrum. He died in Folkestone, England. He had married twice: firstly Agnes Matilda Smith (died 1888), and secondly Mary Louisa Mead.[3] Publications Chemistry for Engineers, 1870. W. de W. Abney, Instruction in Photography, London, published by S. Low, Marston & company, 1900. A New Developer, Photographic News, 1880, 24:345. W. de W. Abney and E. R. Festing, Intensity of Radiation through Turbid Media, Proceedings of the Royal Society of London, Volume 40, pages 378–380, 1886. Published by The Royal Society. W. de W. Abney and E. R. Festing, Colour Photometry. Part III.Proceedings of the Royal Society of London, Volume 50, pages 369–372, 1891–1892. Published by The Royal Society. Less