Nov 152013
 

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Today is the birthday (1738) of Sir Frederick William Herschel, KH, FRS (German: Friedrich Wilhelm Herschel), German-born British astronomer, technical expert, and minor composer. He was born in Hanover and followed his father into the Military Band of Hanover, before emigrating to Britain at age 19. He became famous for his discovery of the planet Uranus, along with two of its major moons (Titania and Oberon), and also discovered two moons of Saturn. In addition, he was the first person to discover the existence of infrared radiation.  He was also a musician and composed a number of symphonies, organ pieces, and other works.  Being rather derivative and lackluster, these works have largely been forgotten except by enthusiasts.

Herschel was born in Hanover, Electorate of Hanover, one of ten children of Anna Ilse (née Moritzen) and Isaac Herschel. His family were Protestant Christians, probably descended on his father’s side from converted Moravian Jews. His father was an oboist in the Hanover Military Band. In 1755 the Hanoverian Guards regiment, in whose band Wilhelm and his brother Jakob were engaged as oboists, was ordered to England. At the time the crowns of Great Britain and Hanover were united under George II. As the threat of war with France loomed, the Hanoverian Guard was recalled from England to defend Hanover. After the Hanoverian guard was defeated at the Battle of Hastenbeck, Herschel’s father Isaak sent his two sons to seek refuge in England in late 1757. Although his older brother Jakob had received his dismissal from the Hanoverian Guard, Wilhelm was accused of desertion (for which he was pardoned by George III in 1782). Wilhelm, nineteen years old at this time, was a quick student of the English language. In England he went by the English rendition of his name, Frederick William Herschel.

Herschel moved to Sunderland in 1761 when Charles Avison immediately engaged him as first violin and soloist for his Newcastle orchestra, where he played for one season and wrote his symphony no. 8 in C minor. He was head of the Durham Militia band 1760–61 and visited the home of Sir Ralph Milbanke at Halnaby Hall in 1760, where he wrote two symphonies, as well as giving performances himself.

After Newcastle he moved to Leeds and Halifax where he was the first organist at St John the Baptist church (now Halifax Minster). He became organist of the Octagon Chapel, Bath, a fashionable chapel in the well-known spa, and also became Director of Public Concerts. He was appointed as the organist in 1766 and gave his introductory concert on 1 January 1767. When he arrived the organ was still being built so he wrote pieces including a violin concerto, an oboe concerto, and a harpsichord sonata to fill the gap until the organ was ready.

His sister Caroline went to England in 1772 and lived with him there in New King Street. His brothers Dietrich, Alexander and Jakob also appeared as musicians in Bath. In 1780, Herschel was appointed director of the Bath orchestra, with his sister often appearing as soprano soloist.

Herschel’s music led him to an interest in mathematics, not an uncommon connexion in the Enlightenment era, and then he became interested in optics and lenses. His interest in astronomy developed after he made the acquaintance of the English Astronomer Royal, Nevil Maskelyne. He started building his own reflecting telescopes and would spend up to 16 hours a day grinding and polishing the speculum metal primary mirrors.  He “began to look at the planets and the stars” in May 1773 and on 1 March 1774 began an astronomical journal by noting his observations of Saturn’s rings and the Great Orion Nebula (M 42).

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Herschel’s early observational work soon focused on the search for pairs of stars that were very close together visually. Astronomers of the era expected that changes over time in the apparent separation and relative location of these stars would provide evidence for both the proper motion of stars and, by means of parallax shifts in their separation, for the distance of stars from the Earth (a method first suggested by Galileo). From the back garden of his house in New King Street, Bath, and using a 6.2-inch aperture (160 mm), 7-foot focal length (2.1 m) (f/13) Newtonian telescope “with a most capital speculum” of his own manufacture, in October 1779, Herschel began a systematic search for such stars among “every star in the Heavens,” with new discoveries listed through 1792. He soon discovered many more binary and multiple stars than expected, and compiled them with careful measurements of their relative positions in two catalogues presented to the Royal Society in London in 1782 (269 double or multiple systems) and 1784 (434 systems). A third catalogue of discoveries made after 1783 was published in 1821 (145 systems).

In 1797 Herschel measured many of the systems again, and discovered changes in their relative positions that could not be attributed to the parallax caused by the Earth’s orbit. He waited until 1802 (in Catalogue of 500 new Nebulae, nebulous Stars, planetary Nebulae, and Clusters of Stars; with Remarks on the Construction of the Heavens) to announce the hypothesis that the two stars might be “binary sidereal systems” orbiting under mutual gravitational attraction, a hypothesis he confirmed in 1803 in his Account of the Changes that have happened, during the last Twenty-five Years, in the relative Situation of Double-stars; with an Investigation of the Cause to which they are owing. In all, Herschel discovered over 800 confirmed double or multiple star systems, almost all of them physical rather than virtual pairs. His theoretical and observational work provided the foundation for modern binary star astronomy; new catalogues adding to his work were not published until after 1820 by Friedrich Wilhelm Struve, James South and John Herschel.

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In March 1781, during his search for double stars, Herschel noticed an object appearing as a nonstellar disk. Herschel originally thought it was a comet or a star. He made many more observations of it, and afterwards Russian Academician Anders Lexell computed the orbit and found it to be probably planetary. Herschel determined in agreement that it must be a planet beyond the orbit of Saturn. He called the new planet the ‘Georgian star’ (Georgium sidus) after King George III, which also brought him favor; the name did not stick. In France, where reference to the British king was to be avoided if possible, the planet was known as ‘Herschel’ until the name ‘Uranus’ was universally adopted. The same year, Herschel was awarded the Copley Medal and elected a Fellow of the Royal Society. In 1782, he was appointed “The King’s Astronomer” (not to be confused with the Astronomer Royal). He and his sister subsequently moved to Datchet (then in Buckinghamshire but now in Berkshire) on 1 August 1782. He continued his work as a telescope maker and achieved an international reputation for their manufacture, profitably selling over 60 completed reflectors to British and Continental astronomers.

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From 1782 to 1802, and most intensively from 1783 to 1790, Herschel conducted systematic surveys in search of “deep sky” or nonstellar objects with two 20-foot focal length (610 cm), 12-inch aperture (30 cm) and 18.7-inch aperture (47 cm) telescopes (in combination with his favoured 6-inch aperture instrument). Excluding duplicated and “lost” entries, Herschel ultimately discovered over 2400 objects defined by him as nebulae. (At that time, nebula was the generic term for any visually extended or diffuse astronomical object, including galaxies beyond the Milky Way, until galaxies were confirmed as extragalactic systems by Edwin Hubble in 1924.)

Herschel published his discoveries as three catalogues: Catalogue of One Thousand New Nebulae and Clusters of Stars (1786), Catalogue of a Second Thousand New Nebulae and Clusters of Stars (1789) and the previously cited Catalogue of 500 New Nebulae … (1802). He arranged his discoveries under eight “classes”: (I) bright nebulae, (II) faint nebulae, (III) very faint nebulae, (IV) planetary nebulae, (V) very large nebulae, (VI) very compressed and rich clusters of stars, (VII) compressed clusters of small and large [faint and bright] stars, and (VIII) coarsely scattered clusters of stars. Herschel’s discoveries were supplemented by those of Caroline Herschel (11 objects) and his son John Herschel (1754 objects) and published by him as General Catalogue of Nebulae and Clusters in 1864. This catalogue was later edited by John Dreyer, supplemented with discoveries by many other 19th century astronomers, and published in 1888 as the New General Catalogue (abbreviated NGC) of 7840 deep sky objects. The NGC numbering is still the most commonly used identifying label for these celestial landmarks.

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In 1783 he gave Caroline a telescope, and she began to make astronomical discoveries in her own right, particularly comets. She discovered or observed eight comets, eleven nebulae and, at her brother’s suggestion, updated and corrected Flamsteed’s work detailing the position of stars. This was published as the British Catalogue of Stars. She was honored by the Royal Astronomical Society for this work. Caroline also continued to serve as his assistant, often taking notes while he observed at the telescope.

In June 1785, owing to damp conditions, he and Caroline moved to Clay Hall in Old Windsor. In 1786, the Herschels moved to a new residence on Windsor Road in Slough. He lived the rest of his life in this residence, which came to be known as Observatory House. It is no longer standing. On 7 May 1788, he married the widow Mary Pitt (née Baldwin) at St Laurence’s Church, Upton in Slough. His sister Caroline then moved to separate lodgings, but continued to work as his assistant.

During the course of his career, he constructed more than four hundred telescopes. The largest and most famous of these was a reflecting telescope with a 49 1?2-inch-diameter (1.26 m) primary mirror and a 40-foot (12 m) focal length. Because of the poor reflectivity of the speculum mirrors of that day, Herschel eliminated the small diagonal mirror of a standard newtonian reflector from his design and tilted his primary mirror so he could view the formed image directly. This design has come to be called the Herschelian telescope. On 28 August 1789, his first night of observation using this instrument, he discovered a new moon of Saturn. A second moon followed within the first month of observation. The “40-foot telescope” proved very cumbersome, and most of his observations were done with a smaller 18.5-inch (47 cm) 20-foot-focal-length (6.1 m) reflector. Herschel discovered that unfilled telescope apertures can be used to obtain high angular resolution, something which became the essential basis for interferometric imaging in astronomy (in particular Aperture Masking Interferometry and hypertelescopes).

In his later career, Herschel discovered two moons of Saturn, Mimas and Enceladus; as well as two moons of Uranus, Titania and Oberon. He did not give these moons their names; they were named by his son John in 1847 and 1852, respectively, after his death.

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In 2007 evidence was cited by Dr. Stuart Eves that Herschel might have discovered rings around Uranus. Herschel measured the axial tilt of Mars and discovered that the martian ice caps, first observed by Giovanni Domenico Cassini (1666) and Christiaan Huygens (1672), changed size with the planet’s seasons.

From studying the proper motion of stars, he was the first to realize that the solar system is moving through space, and he determined the approximate direction of that movement. He also studied the structure of the Milky Way and concluded that it was in the shape of a disk.

He also coined the word “asteroid,” meaning star-like (from the Greek asteroeides, aster “star” + -eidos “form, shape”), in 1802 (shortly after Olbers discovered the second minor planet, 2 Pallas, in late March), to describe the star-like appearance of the small moons of the giant planets and of the minor planets; the planets all show discs, by comparison. By the 1850s ‘asteroid’ became a standard term for describing certain minor planets.

On 11 February 1800, Herschel was testing filters for the sun so he could observe sun spots. When using a red filter he found there was a lot of heat produced. Herschel discovered infrared radiation in sunlight by passing it through a prism and holding a thermometer just beyond the red end of the visible spectrum. This thermometer was meant to be a control to measure the ambient air temperature in the room. He was shocked when it showed a higher temperature than the visible spectrum. Further experimentation led to Herschel’s conclusion that there must be an invisible form of light beyond the visible spectrum.

On 25 August 1822, Herschel died at Observatory House, Windsor Road, Slough, and is buried at nearby St Laurence’s Church, Upton (now in Slough).  Slough is the butt of many derisive jokes because in the post-war era it became known for its industrial estate that was, at the time, distinctly not idyllic, rural England.  But Herschel is very much respected in the town and there are several memorials to him and his discoveries. In 2011 a new bus station was built in the town center, the design of which was inspired by Herschel’s infrared experiment.  My father was a member of the Slough freemason’s lodge, named Herschel lodge.

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Written in 1747, Hannah Glasse’s (1708–1770) The Art of Cookery made Plain and Easy represents one of the most important references for culinary practice in England during the latter half of the 18th century and the beginning of the 19th. In the introduction she writes:

A Frenchman in his own country will dress a fine dinner of twenty dishes, and all genteel and pretty, for the expence he will put an English lord to for dressing one dish. But then there is the little petty profit.  I have heard of a cook that used six pounds of butter to fry twelve eggs; when every body knows (that understands cooking) that half a pound is full enough, or more than need be used: but then it would not be French. So much is the blind folly of this age that they would rather be imposed on by a French booby, than give encouragement to a good English cook!

Here is a delightful recipe from the book:

A ragoo of eggs

BOIL twelve eggs hard, take off the shells, and with a little knife very carefully cut the white a cross long-ways, so that the white may be in two halves, and the yolk whole. Be very careful neither to break the whites, nor yolks, take a quarter of a pint of pickled mushrooms chopped very fine, half an ounce of truffles and morels, boiled in three or four spoonfuls of water, save the water, and chop the truffles and morels very small, boil a little parsley, chop it fine, mix them together with the truffle-water you saved, grate a little nutmeg in, a little beaten mace, put it into a sauce-pan with three spoonfuls of water, a gill of red wine, one spoonful of catchup, a piece of butter, as big as a large walnut, rolled in flour, stir all together and let it boil. In the mean time get ready your eggs, lay the yolks and whites in order in your dish, the hollow parts of the whites uppermost, that they may be filled; take some crumbs of bread, and fry them brown and crisp, as you do for larks, with which fill up the whites of the eggs as high as they will lye, then pour in your sauce all over, and garnish with fry’d crumbs of bread. This is a very genteel pretty dish, if it be well done.

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I took a shot at this recipe using what I had on hand, and the photo shows the result. Truffles and morels are in short supply in my pantry right now, so I made do with some rich brown fresh mushrooms.  By “catchup” Glasse means a rich and spicy mushroom sauce in vinegar which you can still find in gourmet stores or online (or make yourself). I used a Chinese mushroom sauce.  I am not sure how to fry breadcrumbs “as you do for larks” so I just browned them in a dry skillet.  Cutting the eggs was a challenge in that I could not keep the yolks whole – they fell in half even though I was careful cutting the whites.  A sauce of mushrooms and nutmeg does go well with eggs, and the breadcrumbs add a toasted note and a slight crunch. I ate them cold and hot – delicious both ways.

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