Sir John Frederick William Herschel, 1st Baronet, (March 7, 1792 – May 11, 1871) was an English polymath, mathematician, astronomer, chemist, inventor, and experimental photographer, who in some years also did valuable botanical work.
He was the son of Mary Baldwin and astronomer William Herschel and the father of twelve children.
Herschel originated the use of the Julian day system in astronomy. He named seven moons of Saturn and four moons of Uranus. He made many contributions to the science of photography, and investigated color blindness and the chemical power of ultraviolet rays.
Early life and astronomy: Herschel was born in Slough, Berkshire, the son of Mary Baldwin and William Herschel. He studied shortly at Eton College and St John’s College, Cambridge, graduating as Senior Wrangler in 1813. It was during his time as an undergraduate that he became friends with Charles Babbage and George Peacock. He took up astronomy in 1816, building a reflecting telescope with a mirror 18 inches (460 mm) in diameter and with a 20-foot (6.1 m) focal length. Between 1821 and 1823 he re-examined, with James South, the double stars catalogued by his father. For this work, in 1826 he was presented with the Gold Medal of the Royal Astronomical Society (which he won again in 1836), and with the Lalande Medal of the French Academy of Sciences in 1825, while in 1821 the Royal Society bestowed upon him the Copley Medal for his mathematical contributions to their Transactions. Herschel was made a Knight of the Royal Guelphic Order in 1831.
He served as President of the Royal Astronomical Society three times: 1827–1829, 1839–1841 and 1847–1849.
His A preliminary discourse on the study of natural philosophy published early in 1831 as part of Dionysius Lardner’s Cabinet cyclopædia set out methods of scientific investigation with an orderly relationship between observation and theorising. He described nature as being governed by laws which were difficult to discern or to state mathematically, and the highest aim of natural philosophy was understanding these laws through inductive reasoning, finding a single unifying explanation for a phenomenon. This became an authoritative statement with wide influence on science, particularly at the University of Cambridge where it inspired the student Charles Darwin with “a burning zeal” to contribute to this work.
He published a catalogue of his astronomical observations in 1864, as the General Catalogue of Nebulae and Clusters, a compilation of his own work and that of his father’s, expanding on the senior Hershel’s Catalogue of Nebulae. A further complementary volume was published posthumously, as the General Catalogue of 10,300 Multiple and Double Stars.
He also conceptualizes a practical contact lens design in 1823.
Photography: Herschel made numerous important contributions to photography. He made improvements in photographic processes, particularly in inventing the cyanotype process and variations (such as the chrysotype), the precursors of the modern blueprint process. In 1839, he made a photograph on glass, which still exists, and experimented with color reproduction, noting that rays of different parts of the spectrum tended to impart their own color to a photographic paper. Herschel made experiments using photosensitive emulsions of vegetable juices, called phytotypes and published his discoveries in the Philosophical Transactions of the Royal Society of London in 1842. He collaborated in the early 1840s with Henry Collen, portrait painter to Queen Victoria. Herschel originally discovered the platinum process on the basis of the light sensitivity of platinum salts, later developed by William Willis.
Herschel coined the term photography in 1839. He may, however, have been preceded by Brazilian Hércules Florence, who used the French equivalent, photographie, in private notes which one historian dates to 1834. Herschel was also the first to apply the terms negative and positive to photography.
He discovered sodium thiosulfate to be a solvent of silver halides in 1819, and informed Talbot and Daguerre of his discovery that this “hyposulphite of soda” (“hypo”) could be used as a photographic fixer, to “fix” pictures and make them permanent, after experimentally applying it thus in early 1839. His ground-breaking research on the subject was read at the Royal Society in London in March 1839 and January 1840.
General: Herschel wrote many papers and articles, including entries on meteorology, physical geography and the telescope for the eighth edition of the Encyclopædia Britannica. He also translated the Iliad of Homer.
He invented the actinometer in 1825 to measure the direct heating power of the sun’s rays, and his work with the instrument is of great importance in the early history of photochemistry.
He proposed a correction to the Gregorian calendar, making years that are multiples of 4000 not leap years, thus reducing the average length of the calendar year from 365.2425 days to 365.24225. Although this is closer to the mean tropical year of 365.24219 days, his proposal has never been adopted because the Gregorian calendar is based on the mean time between vernal equinoxes (currently 365.2424 days).
In 1836, he was elected a foreign member of the Royal Swedish Academy of Sciences.
In 1835, the New York Sun newspaper wrote a series of satiric articles that came to be known as the Great Moon Hoax, with statements falsely attributed to Herschel about his supposed discoveries of animals living on the Moon, including batlike winged humanoids.
The village of Herschel in western Saskatchewan (Canada), Mount Herschel (Antarctica), the crater J. Herschel on the Moon, and the Herschel Girls’ School in Cape Town (South Africa), are all named after him. While it is commonly accepted that Herschel Island (in the Arctic Ocean, part of the Yukon Territory) was named after him, the entries in the expedition journal of Sir John Franklin state that the latter wished to honour the Herschel name, about which John Herschel’s father (Sir William Herschel) and his aunt (Caroline Herschel) are two other notable members of this family.