John Herschel

John Frederick William Herschel (7 March, 1792 – 11 May, 1871) was an English mathematician and astronomer. He was the son of astronomer William Herschel.

John Herschel originated the use of the Julian day system in astronomy and made several important contributions to the improvement of photographic processes (Cyanotype). He coined the terms "photography", "negative", and "positive", and discovered sodium thiosulphite as a fixer of silver halides.

Early life and work on astronomy

Herschel was born at Slough, Buckinghamshire, and studied at Eton College and St John's College, Cambridge. He graduated 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 in diameter and with a 20 foot focal length. Between 1821 and 1823 he re-examined, with James South, the double stars catalogued by his father. For this work he was presented in 1826 with the Gold Medal of the Royal Astronomical Society (which he would win again in 1836); and with the Lalande Medal of the French Institute in 1825; while the Royal Society had in 1821 bestowed upon him the Copley Medal for his mathematical contributions to their Transactions. He was knighted in 1831.

Visit to South Africa

In 1833 Herschel travelled to South Africa in order to catalogue the stars of the southern skies. Amongst his other observations during this time was that of the return of Comet Halley. Intrigued by the ideas of gradual formation of landscapes set out in Charles Lyell's Principles of Geology, he wrote to Lyell commenting and urging a search for natural laws underlying the "mystery of mysteries" of how species formed, prefacing his words with the couplet:

He that on such quest would go must know not fear or failing

To coward soul or faithless heart the search were unavailing.

Taking a gradualist view of development, he commented

"Time! Time! Time! — we must not impugn the Scripture Chronology, but we must interpret it in accordance with whatever shall appear on fair enquiry to be the truth for there cannot be two truths. And really there is scope enough: for the lives of the Patriarchs may as reasonably be extended to 5000 or 50000 years apiece as the days of Creation to as many thousand millions of years."

The document was circulated, and Charles Babbage incorporated extracts in his Ninth 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 the eminent Herschel on 3 June 1836. Later on, Darwin would be influenced by Herschel's writings in developing his theory on The Origin of Species.

He returned to England in 1838 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.[1] (http://adsabs.harvard.edu//full/seri/MNRAS/0008//0000042.000.html) In the same year 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's other works included Outlines of Astronomy (1849); General Catalogue of 10,300 Multiple and Double Stars, (published posthumously); Familiar Lectures on Scientific Subjects; and General Catalogue of Nebulae and Clusters. At his death he was given a national funeral and buried in Westminster Abbey.

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 John Herschel about his supposed discoveries of animals living on the Moon, including batlike winged humanoids.

He had three sons: one of whom, Alexander Stewart Herschel, was also an astronomer. He also had nine daughters.

External links

• http://www-groups.dcs.st-and.ac.uk/~history/Mathematicians/Herschel.html
• Biography: JRASC 74 (1980) 203 (http://adsabs.harvard.edu//full/seri/JRASC/0074//0000203.000.html)de:John Herschel

fr:John Herschel it:John Herschel ja:ジョン・ハーシェル pl:John Herschel sl:John Frederick William Herschel sv:John Herschel