Herschel'sA preliminary discourse on the study of natural philosophy, published early in 1831 as part ofDionysius 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 ofnatural philosophy was understanding these laws throughinductive reasoning, finding a single unifying explanation for a phenomenon. This became an authoritative statement with wide influence on science, particularly at theUniversity of Cambridge where it inspired the studentCharles Darwin with "a burning zeal" to contribute to this work.[12][13][14]
Herschel published a catalogue of his astronomical observations in 1864, as theGeneral Catalogue of Nebulae and Clusters, a compilation of his own work and that of his father's, expanding on the senior Herschel'sCatalogue of Nebulae. A further complementary volume was published posthumously, as theGeneral Catalogue of 10,300 Multiple and Double Stars.
Herschel correctly consideredastigmatism 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 theEncyclopædia Metropolitana in 1845.[16]
Dumbbell Nebula illustrations in "Observations of Nebulae and Clusters of Stars, Made at Slough, with a Twenty-Feet Reflector, between the Years 1825 and 1833" inPhilosophical Transactions of the Royal Society, London, 1833Orion Nebula from the results of astronomical observations made during the years 1834–1838 at the Cape of Good Hope; being the completion of a telescopic survey of the whole surface of the visible heavens, commenced in 1825
The Herschel Memorial Obelisk marking the location of Herschel's telescope in Cape Town.
He declined an offer from theDuke of Sussex that they travel toSouth Africa on aNavy ship.[17]Herschel had his own inherited money and he paid £500 for passage on the S.S.Mountstuart Elphinstone. He, his wife, their three children and his 20 inch telescope departed fromPortsmouth on 13 November 1833.[1]
The voyage to South Africa was made to catalogue the stars,nebulae, and other objects of the southern skies.[6] This was to be a completion as well as extension of the survey of the northern heavens undertaken initially by his fatherWilliam Herschel. He arrived inCape Town on 15 January 1834 and set up a private 21 ft (6.4 m) telescope at Feldhausen (site of present dayGrove Primary School) atClaremont, a suburb ofCape Town. Amongst his other observations during this time was that of the return ofComet Halley. Herschel collaborated withThomas Maclear, the Astronomer Royal at the Cape of Good Hope and the members of the two families became close friends. During this time, he also witnessed the Great Eruption ofEta Carinae (December 1837).
In addition to his astronomical work, however, this voyage to a far corner of theBritish empire also gave Herschel an escape from the pressures under which he found himself in London, where he was one of the most sought-after of all British men of science. While insouthern Africa, he engaged in a broad variety of scientific pursuits free from a sense of strong obligations to a larger scientific community. It was, he later recalled, probably the happiest time in his life.[18] Avillage in the contemporary province ofEastern Cape is named after him.
Herschel combined his talents with those of his wife, Margaret, and between 1834 and 1838 they produced 131 botanical illustrations of fine quality, showing the Cape flora. Herschel used acamera 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 asFlora Herscheliana in 1996. The book also included work byCharles Davidson Bell andThomas Bowler.[19]
As their home during their stay in the Cape, the Herschels had selected 'Feldhausen' ("Field Houses"),[19] an old estate on the south-eastern side ofTable Mountain. Here John set up his reflector to begin his survey of the southern skies.
Herschel, at the same time, read widely. Intrigued by the ideas of gradual formation of landscapes set out inCharles Lyell'sPrinciples of Geology, he wrote to Lyell on 20 February 1836 praising the book as a work that would bring "a complete revolution in [its] subject, by altering entirely the point of view in which it must thenceforward be contemplated" and opening a way for bold speculation on "that mystery of mysteries, the replacement of extinct species by others." Herschel himself thoughtcatastrophic extinction and renewal "an inadequate conception of the Creator" and by analogy with otherintermediate causes, "the origination of fresh species, could it ever come under our cognizance, would be found to be a natural in contradistinction to a miraculous process".[20][21] He prefaced 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 and referring to evolutionary descent from aproto-language, Herschel commented:
Words are to the Anthropologist what rolled pebbles are to the Geologist – battered relics of past ages often containing within them indelible records capable of intelligent interpretation – and when we see what amount of change 2000 years has been able to produce in the languages of Greece & Italy or 1000 in those of Germany France & Spain we naturally begin to ask how long a period must have lapsed since the Chinese, the Hebrew, the Delaware & the Malesass [Malagasy] had a point in common with the German & Italian & each other – Time! Time! Time! – we must not impugn the Scripture Chronology, but wemust interpret it in accordance withwhatever shall appear on fair enquiry to be thetruth 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.[22][23]
The document was circulated, andCharles Babbage incorporated extracts in his ninth and unofficialBridgewater Treatise, which postulated laws set up by a divine programmer.[20] WhenHMSBeagle called atCape Town, CaptainRobert FitzRoy and the young naturalistCharles Darwin visited Herschel on 3 June 1836. Later on, Darwin would be influenced by Herschel's writings in developing his theory advanced inThe Origin of Species. In the opening lines of that work, Darwin writes that his intent is "to throw some light on the origin of species – that mystery of mysteries, as it has been called by one of our greatest philosophers," referring to Herschel. However, Herschel ultimately rejected the theory of natural selection.[24]
Herschel returned to England in 1838, was created abaronet, of Slough in the County of Buckingham,[6] and publishedResults 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 ofSaturn:Mimas,Enceladus,Tethys,Dione,Rhea,Titan, andIapetus.[25] 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 ofUranus:Ariel,Umbriel,Titania, andOberon. A stone obelisk, erected in 1842 and now in the grounds ofThe Grove Primary School, marks the site where his 20-ft reflector once stood.[26]
Herschel's first glass-plate photograph, dated 9 September 1839, showing the mount of his father's40-foot telescope[27]John Herschel, Portrait byJulia Margaret Cameron, April 1867
Herschel made numerous important contributions to photography. He made improvements inphotographic processes, particularly in inventing thecyanotype[28] process, which became known asblueprints,[3][4][5] and variations, such as thechrysotype. In 1839, he made a photograph on glass, which still exists, and experimented with some colour reproduction, noting that rays of different parts of the spectrum tended to impart their own colour to aphotographic paper. Herschel made experiments usingphotosensitive emulsions of vegetable juices, called phytotypes, also known asanthotypes, and published his discoveries in the Philosophical Transactions of theRoyal Society of London in 1842.[29] He collaborated in the early 1840s withHenry Collen, portrait painter toQueen Victoria. Herschel originally discovered the platinum process on the basis of the light sensitivity of platinum salts, later developed byWilliam Willis.[30]
Herschel coined the termphotography in 1839.[31][32] Herschel was also the first to apply the termsnegative andpositive to photography.[6]
Herschel discoveredsodium thiosulfate to be a solvent of silverhalides in 1819,[33] and informedTalbot andDaguerre of his discovery that this "hyposulphite of soda" ("hypo") could be used as aphotographic fixer, to "fix" pictures and make them permanent, after experimentally applying it thus in early 1839.
Herschel's ground-breaking research on the subject was read at the Royal Society in London in March 1839 and January 1840.
Herschel wrote many papers and articles, including entries on meteorology, physical geography and the telescope for the eighth edition of theEncyclopædia Britannica.[6] He also translated theIliad of Homer.
In 1823, Herschel published his findings on the optical spectra of metal salts.[34]
Herschel invented theactinometer in 1825 to measure the direct heating power of the Sun's rays,[35] and his work with the instrument is of great importance in the early history ofphotochemistry.
ACalotype of a model of the lunar crater Copernicus, 1842. Photographs of the Moon's surface were not yet possible at the time
Herschel proposed a correction to the Gregorian calendar, making years that are multiples of 4000common years rather thanleap years, thus reducing the average length of thecalendar year from 365.2425 days to 365.24225.[36][failed verification] Although this is closer to themean tropical year of 365.24219 days, his proposal has never been adopted because theGregorian calendar is based on the mean time between vernalequinoxes (currently365.242374 days).[37]
In 1835, theNew York Sun newspaper wrote a series of satiric articles that came to be known as theGreat Moon Hoax, with statements falsely attributed to Herschel about his supposed discoveries of animals living on the Moon, including batlike winged humanoids.
While it is commonly accepted that Herschel Island, in the Arctic Ocean, part of theYukon Territory, was named after him, the entries in the expedition journal of SirJohn Franklin state that the latter wished to honour the Herschel family, of which John Herschel's father, SirWilliam Herschel, and his aunt,Caroline Herschel, are as notable as John.[39]
Herschel marriedMargaret Brodie Stewart (1810–1884) on 3 March 1829[1] at St. Marlyebone Church in London, and was father of the following children:[40]
Caroline Emilia Mary Herschel (31 March 1830 – 29 January 1909), who married the soldier and politicianAlexander Hamilton-Gordon
Herschel died on 11 May 1871 at age 79 at Collingwood, his home nearHawkhurst in Kent. On his death, he was given a national funeral and buried inWestminster Abbey.[43]
A demi-terrestrial sphere Proper thereon an eagle wings elevated Or.
Escutcheon
Argent on a mount Vert a representation of the forty feet reflecting telescope with its apparatus Proper a chief Azure thereon the astronomical symbol of Uranus or the Georgium Sidus irradiated Or.
On the Aberration of Compound Lenses and Object-Glasses. London: W. Bulmer and W. Nicol. 1821.,Herschel, J. F. W. (1831). "On the Aberrations of Compound Lenses and Object-Glasses. [Abstract]".Abstracts of the Papers Printed in the Philosophical Transactions of the Royal Society of London.2:146–147.JSTOR109979.
"On the Chemical Action of the Rays of the Solar Spectrum on Preparations of Silver and Other Substances, Both Metallic and Non-Metallic, and on Some Photographic Processes",Philosophical Transactions of the Royal Society of London,130:1–59, 20 February 1840,Bibcode:1840RSPT..130....1H,doi:10.1098/rstl.1840.0002,ISSN0261-0523,JSTOR108209,S2CID98119765.
^abGo, F. E. (1970). "Blueprint".Encyclopædia Britannica. Vol. 3 (Expo'70 ed.). Chicago: William Benton. p. 816.
^abBridgwater, William; Sherwood, Elizabeth J., eds. (1950). "blueprint".The Columbia Encyclopedia in One Volume (2nd ed.). New York City: Columbia University Press. p. 214.
^abRosenthal, Richard T. (2000)."The Cyanotype".Vernacular Photography. Archived fromthe original on 30 March 2013. Retrieved19 June 2018.
Field, Henry W. (1871). "Obituary Notice of Sir John Frederick William Herschel, Bart".Proceedings of the American Philosophical Society.12 (86):217–223.JSTOR981703.
Kossoy, Boris (2004).Hercule Florence : el descubrimiento de la fotografía en Brasil. Instituto Nacional de Antropología e História.ISBN968-03-0020-X.OCLC59139803.
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