John Herschel

English Polymath, Mathematician, astronomer, chemist, inventor and experimental photographer Sir John Frederick William Herschel, 1st Baronet KH FRS was born 7 March 1792 in Slough Buckinghamshire. He was the son of Mary Baldwin and astronomer William Herschel, nephew of astronomer Caroline Herschel and the father of twelve children. 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 left Cambridge in 1816 and started working with his father. 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. He was one of the founders of the Royal Astronomical Society in 1820.[5] For his work with his father, he was presented with the Gold Medal of the Royal Astronomical Society in 1826 (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: 1827–29, 1839–41 and 1847–49.

He wrote a discourse on the study of natural philosophy, published early in 1831 as part of Dionysius Lardner’s Cabinet cyclopædia, using methods of scientific investigation to create 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. Herschel also 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.

Herschel correctly considered astigmatism to be due to irregularity of the cornea and theorised that vision could be improved by the application of some animal jelly contained in a capsule of glass against the cornea. His views were published in an article entitled Light in 1828 and the Encyclopædia Metropolitana in 1845.

Declining an offer from the Duke of Sussex to travel to South Africa on a Navy ship, Herschel and his wife paid £500 for passage on the S.S. Mountstuart Elphinstone, which departed from Portsmouth on 13 November 1833 in order to catalogue the stars, nebulae, and other objects of the southern skies and complete the survey of the northern heavens started by his father William Herschel. He arrived in Cape Town on 15 January 1834 and set up a private 21 ft (6.4 m) telescope at Feldhausen at Claremont, a suburb of Cape Town. Amongst his other observations during this time was that of the return of Comet Halley. Herschel also collaborated with Thomas Maclear, the Astronomer Royal at the Cape of Good Hope and also witnessed the Great Eruption of Eta Carinae (December, 1837). While in southern Africa, he engaged in a broad variety of scientific pursuits free from a sense of strong obligations to a larger scientific community.

Herschel also collaborated with his wife, Margaret, and between 1834 and 1838 they produced 131 accurate botanical illustrations showing the Cape flora. Herschel used a camera lucida to obtain accurate outlines of the specimens and left the details to his wife. Even though their portfolio had been intended as a personal record, and despite the lack of floral dissections in the paintings, their accurate rendition makes them more valuable than many contemporary collections. Some 112 of the 132 known flower studies were collected and published as Flora Herscheliana in 1996. As their home during their stay in the Cape, the Herschels had selected ‘Feldhausen’ (“Field Houses”), an old estate on the south-eastern side of Table Mountain. Here John set up his reflector to begin his survey of the southern skies. Herschel, meanwhile, read widely. Intrigued by the ideas of gradual formation of landscapes set out in Charles Lyell’s Principles of Geology, he speculated about evolution and the replacement of extinct species by others. Herschel himself thought catastrophic extinction and renewal inadequate and by analogy with other intermediate causes, considered the origination of fresh species, through extinction and evolution. The document was circulated, and Charles Babbage incorporated extracts in his ninth and unofficial Bridgewater Treatise, which postulated laws set up by a divine programmer. When HMS Beagle called at Cape Town, Captain Robert FitzRoy and the young naturalist Charles Darwin visited Herschel on 3 June 1836. Later on, Darwin would be influenced by Herschel’s writings in developing his theory advanced in The Origin of Species.

Herschel returned to England and published Results of Astronomical Observations made at the Cape of Good Hope in 1847. In this publication he proposed the names still used today for the seven then-known satellites of Saturn: Mimas, Enceladus, Tethys, Dione, Rhea, Titan, and Iapetus and 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. In 1847, Herschel received his second Copley Medal from the Royal Society for this work. A few years later, in 1852, he proposed the names still used today for the four then-known satellites of Uranus: Ariel, Umbriel, Titania, and Oberon.

Herschel also 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 some 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 and coined the term photography in 1839. He may however have been preceded by Brazilian Hércules Florence, who used the French equivalent, photographie, to describe his own experiments in private notes in 1834, although as Florence was not in communication with the European scientific community, Herschel has historically been credited with coining and popularising the term. 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.

Herschel also 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 and invented the actinometer in 1825 to measure the direct heating power of the sun’s rays, 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 365.242374 days).

Sadly Herschel died 11 May 1871, however he received many honours during his lifetime. He was created a baronet, of Slough in the County of Buckingham, in 1838 and Foreign Honorary Member of the American Academy of Arts and Sciences in 1832, and in 1836, he was made a foreign member of the Royal Swedish Academy of Sciences. 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.

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