John Herschel

Sir John Herschel

John Herschel 1846 (cropped).png
Drawing of John Herschel, published in 1846
Born(1792-03-07)7 March 1792
Died11 May 1871(1871-05-11) (aged 79)
Collingwood, near Hawkhurst, Kent, England
Resting placeWestminster Abbey
Residence
NationalityBritish
EducationEton College
Alma materSt John's College, Cambridge
Known forThe invention of photography
Spouse(s)Margaret Brodie Stewart
Awards
Scientific career
InfluencesWilliam Herschel (father), Caroline Herschel (aunt)

Sir John Frederick William Herschel, 1st Baronet KH FRS (ɛər-/;[1] 7 March 1792 – 11 May 1871)[2] was an English polymath, mathematician, astronomer, chemist, inventor, experimental photographer who invented the blueprint,[3][4][5] and did botanical work.[2]

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 colour blindness and the chemical power of ultraviolet rays; his Preliminary Discourse (1831), which advocated an inductive approach to scientific experiment and theory building, was an important contribution to the philosophy of science.[6]

Early life and work on astronomy

A Calotype of a model of the lunar crater Copernicus, 1842

Herschel was born in Slough, Buckinghamshire, the son of Mary Baldwin and William Herschel. He was the nephew of astronomer Caroline Herschel. He studied shortly at Eton College and St John's College, Cambridge, graduating as Senior Wrangler in 1813.[7] It was during his time as an undergraduate that he became friends with the mathematicians Charles Babbage and George Peacock.[2] 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.[8] He was one of the founders of the Royal Astronomical Society in 1820. 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.[2]

Herschel served as President of the Royal Astronomical Society three times: 1827–29, 1839–41 and 1847–49.[9][10]

Herschel's 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.[11][12][13]

Herschel 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 Herschel'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.[14]

Discoveries of Herschel include the galaxies NGC 7, NGC 10, NGC 25, and NGC 28

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