John Frederick William Herschel (1792-1871)

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JOHN FREDERICK WILLIAM HERSCHEL (1792-1871)

LIFE SKETCH OF JOHN HERSCHEL
Biographical information in the following section on John Herschel was mainly obtained from the 1970 book by Gunther Buttmann, The Shadow of the Telescope: A Biography of John Herschel.

WILLIAM HERSCHEL, JOHN’S FATHER
Eleven years before John’s birth, Frederick William Herschel (1738 – 1822) discovered the planet Uranus near M1 on March 13, 1781 while surveying the sky with a homemade 6-inch diameter reflector from his garden in Bath, England. William had become interested in astronomy while he was director of the Bath orchestra, and this discovery brought him great fame as an astronomer.

Five years later, in April 1786, King George III appointed William as the Royal Astronomer. John’s father and his aunt, Caroline Herschel (1750-1848), moved to Slough, where William was paid £200 per year and Caroline £50 per year to assist her brother. William made thousands of telescopes at Slough and sold them all over Europe. He also made two telescopes for himself; 20-inch aperture and 48-inch aperture reflecting telescopes. With Caroline’s help he used these to make catalogues of double stars, star clusters and nebulae.

William (aged 49) married Mary Pitt (aged 38), nee Baldwin on May 8, 1788 and John Frederick William Herschel was born in their home, Observatory House, at Slough, on March 7, 1792. As a child, John had little contact with other children. During the day, he had to maintain silence while his father slept, as William made his astronomical observations at night. Under Caroline’s guidance, John developed an interest in chemical experiments, which they carried out at her house.
(The Herschel monument at Slough. https://maps.app.goo.gl/cP3SNQ9YWRLEyype7)

JOHN’S EDUCATION
In May 1800 at the very young age of 8, John was a boarding pupil at Eton (one mile south of Slough) for a short period. “One day his mother, no doubt overanxious about his somewhat delicate health, saw her son inveigled into a boxing match by an older and stronger boy and knocked to the ground.” He was withdrawn from Eton and sent to a private school at Hitcham, where a private tutor was also provided. John was not proficient at mathematics at this stage of his life, but at age 21 became a Fellow of the Royal Society after a “brilliant mathematical investigation.”

John, aged 17, enrolled in the University of Cambridge in October 1809 and studied mathematics and physics in St John’s College. He was an exceptional student, the best candidate doing Mathematical Tripos (becoming Senior Wrangler) within the Bachelor of Arts degree. He developed close friendships with George Peacock (1791-1858) and Charles Babbage (1792-1871). They started the Analytical Society, in 1812. “The object of this society was to make known in England the modern methods of infinitesimal calculus developed chiefly in France and Germany and to replace the rather cumbersome notation of Newton’s ‘calculus of fluxions’ by the more elegant usages practised on the Continent. This ambitious project by the three undergraduates was to achieve remarkable success within five years.” Herschel and Peacock translated a book on calculus by the French mathematician Lacroix in 1816. They supplemented this in 1820, with two volumes containing examples of the French methods, and Newton’s notation was soon displaced.

During his vacations John did experiments in his own small laboratory at Slough. Chemistry at the time was undergoing major changes due to the work of Humphry Davy and Joseph Louis Gay-Lussac. He showed great enthusiasm for new ideas. In January 1814, against his father’s wishes, John decided to become a lawyer and moved to London to study at Lincoln’s Inn. William wanted John to become a clergyman, because “clerical duties would provide more leisure for the pursuit of private hobbies and scientific interest than any other profession could offer.” Much of John’s time in London was spent pursuing chemistry and mineralogy under the influence of William Hyde Wollaston and Edward Daniel Clarke. By the summer of 1815, John decided to quit law because of poor health and a lack of interest. He returned to St John’s at Cambridge as a sub-tutor and examiner in mathematics where he spent eight to twelve hours a day “examining 60 or 70 blockheads.” He took the degree of Master of Arts in July 1816, but his life was about to take a new turn.

JOHN TAKES UP ASTRONOMY
In the summer of 1816 John accompanied his father on a 275 km trip to Dawlish, a popular resort on the SW coast. William Herschel, who was then in his seventy- eighth year, had for some time suffered from various ailments brought on by advancing age and had been compelled to restrict his astronomical observations more and more.

In October 1816, soon after the holiday together, John decided to become his father’s astronomical assistant. He wrote, “I am going, under my father’s directions, to take up the series of his observations where he has left them and continuing his scrutiny of the heavens with powerful telescopes.”

John thus began the work for which he is best remembered, revising and continuing his father’s life work. William, who had made or attempted to make 2160 telescope mirrors, taught John to grind and polish mirrors. He also taught John to sweep the sky. “These (north-south) ‘sweeps’ or surveys were carried out by systematically observing all noteworthy objects – star clusters, nebulae, double stars, and so forth – in successive zones of the sky; the results were recorded in a catalogue. From personal experience the son came to appreciate the incredible physical exertions that the father’s years of night watches had entailed.”

However John never devoted himself exclusive to astronomy. His other interests included physics, chemistry, geology and mathematics as well as travel, but the study of light was his first love. He became interested in polarisation and birefringence (double refraction); he studied the interference of light and sound waves; and he investigated “spherical and chromatic aberrations of compound lenses.” In 1819 he discovered that “sodium thiosulphate has the property of dissolving silver salts rapidly and completely.” Twenty years later this contributed to the invention of photography. John also did mathematical research and contributed an article on the history of mathematics to the Edinburgh Encyclopedia. Another interest was the study of the solar spectrum. John, like his father, believed “that the Sun was a dark body surrounded by a luminous envelope.” Later in South Africa John carried out a major study of the Sun.

On January 12, 1820 John Herschel, with his friends Babbage, South, Colebrooke, Pearson and Baily established the Astronomical Society, (which became the Royal Astronomical Society in 1831). Sir Joseph Banks, then president of the Royal Society opposed the establishment of the Astronomical Society and persuaded its first president Edward Seymour to resign. William Herschel was eventually persuaded to be president and when Banks died in June 1820, the opposition ceased.

William catalogued 800 double stars and was particularly interested in binary stars. He found fifty binary stars by 1804. In 1816, soon after he decided to carry on his father’s work, John resolved to extend and improve this catalogue. He began working with James South in 1821, and together they made a catalogue of double stars using two refractors, one 5-foot and the other 7-foot in focal length with 3.75-inch and 5-inch apertures respectively. South’s refractors were made by Edward Troughton and were ideal for measuring double stars as they could measure position angles to one arc-minute. Together they searched for any movement in the double stars since William first measured them. By the end of 1823, Herschel and South had catalogued 380 double stars. South went to France with his 7-foot refractor in 1825 and catalogued a further 458 double stars. In 1828 the French astronomer Felix Savary used William Herschel’s measurements to calculate the first orbit of a binary star, Xi Ursae Majoris, “followed in 1829 by a solution from [John] Herschel (1832).”

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EUROPEAN TRAVELS, 1821 - 1826
During the summer of 1821 John, aged 29, made the first of several trips to the continent, accompanied
by Babbage. There they met with other scientists doing similar experiments on physical
optics in France, Switzerland and Italy. During his travels John measured the temperature, the
altitude (with a barometer) and made drawings with his camera lucida. This pocket sized
instrument, invented by Herschel’s friend Wollaston in 1807, consisted of two inclined sheets
of plain glass arranged so that “the image of an object produced by it is seen by the eye as if
lying on a sheet of paper placed beneath and the image can be traced out on the paper.”

In the summer of 1822 he made a second trip to Europe, touring Holland and Belgium. His
father died on August 25, 1822 while John was in Europe and his Aunt Caroline later
returned to Hanover, Germany. That same year John described a new method for calculating occultations of the stars by the moon and provided tables to determine the places of fundamental stars.

John’s third continental trip to France, Italy and Sicily began in April 1824. Within eight
hours of his arrival in Paris, he met with 7 famous people, Arago, Laplace, Humboldt, Thénard, Gay-Lussac, Poisson and Fourier. He also visited Guiseppi Piazzi who was famous for making a catalogue
of 7500 stars from Sicily and discovering the first asteroid, Ceres (now a dwarf planet). In Munich,
Joseph von Fraunhofer presented him with a large prism of flint glass, which he later used to
study photochemistry. The six and a half month journey concluded with a visit to Aunt
Caroline at Hanover, before his return to England in October 1824. He also made a short
journey to France in the autumn of 1826 where he used the actinometer he had invented to
measure radiation from the sun.

Between 1825 and 1833 John Herschel produced two great catalogues. The first contained
2306 nebulae and clusters including 525 newly discovered objects, and also included 100
drawings of remarkable objects. The second was a six-part catalogue of double stars,
containing 5075 pairs. This was an amazing feat considering that clear, moonless nights are
rare in England. Some nights he was very discouraged as the following quote from his notes
shows. “Two stars last night, and sat up till two waiting for them… Ditto the night before.
Sick of star-gazing – mean to break the telescope and melt the mirrors.”

John now concentrated on measuring position angles between double stars. He wanted to
measure the parallax shift and hence the distance to the stars. In 1826 Herschel published a
paper entitled “On the parallax of the fixed stars” which contained a table giving the approximate annual parallaxes for some 70 double stars. Two astronomers measured stellar parallaxes by the late 1830s. Thomas Henderson, in Cape Town, measured the first stellar distance by the parallax method (to Alpha Centauri), but he did not publish it timeously. Friedrich Bessel accurately measured the distance to 61 Cygni, publishing first in 1838.

In July 1825, John helped supervise a whole detachment of artillery, deployed to measure the
difference in longitude between Paris and Greenwich, using rockets. The measurement for
Paris was calculated to be 2 deg 20’ 24”, out by only 10.5” according to modern measurements.

However John tried to avoid paid employment like this and he was fortunate to be able to do
so, because “his father had left him a very considerable fortune, which enabled him not only
to fill all material needs but to finance his sometimes quite expensive scientific enterprises
without requiring a professional salary.”

Herschel was elected president of the Astronomical Society in February 1827, but found this
seriously interfered with his research. “He wanted above all to keep his personal freedom and
scientific independence, and not to have the scope of his private researches restricted by any
official and public engagements.” He was offered academic positions at Cambridge and
the University of London, but refused both. “It was partly out of vanity that he would prefer
his contribution to knowledge to be regarded as that of an amateur rather than a professional
scientist,” preferring he said to “loiter on the shores of the ocean of sciences and pick up
such shells and pebbles as take my fancy for the pleasure of arranging them and seeing them
look pretty.”

John did much for the adoption, in England, of the wave theory of light. This was at odds
with Newton’s particle theory. (Light turned out to be a wavelike particle). His 1827 treatise on light, written for an encyclopedia, was translated into French in 1830 and into German in 1831. He also wrote a book called Preliminary Discourse on the Study of Natural Philosophy, which gave a general introduction to the nature and method of science and short surveys of astronomy, physics, chemistry, geology and mineralogy. The book also included much of Herschel’s philosophy of life.

MARRIAGE AND CHILDREN
Herschel’s friends, Whewell, Grahame, Peacock and Babbage were all involved in scientific
pursuits and apart from them he had few social contacts outside of science. He was becoming
a “crotchety and eccentric old scholar” and Grahame, urging him to marry, introduced him
to a widow by the name of Mrs Alexander Stewart. On March 3, 1829, when John was about to turn 37, he married 18 year old Margaret, one of Mrs Stewart’s two daughters. She was almost twenty years younger than him.

In the late 1820s, after James Dunlop had catalogued the southern sky, John decided to travel to the southern hemisphere to make a catalogue of the southern skies. However the expedition was delayed because his mother, Mary, was dying. She died on January 4, 1832 and was buried at St Laurence’s Church, Upton with her husband.

John’s first child, Emilia Mary was born on March 31, 1830 and his second daughter, Isabella was born in 1831, both before his mother’s death. His first son, William James was born in 1833, six months before they left for Cape Town. Altogether John and Margaret had twelve children. John and Margaret’s other children were Margaret Louise (1834), Alexander Stewart (1836), Colonel John (1837) (3 born at the Cape), Maria Sophie (1839), Amelia (1841), Julia Mary (1842), Matilda Rose (1844), Francisca (1846) and Constance Ann (1855). (6 were born after their stay at the Cape)

After the death of his mother, John and his family moved from London back to the old family home at Slough. In June 1832 he paid a farewell visit to Aunt Caroline in Germany.

CAPE TOWN, 1834 - 1838
Herschel planned to collect all his father’s published papers, written over 40 years, into a
single volume, but this was not done until 1912 when J L E Dreyer published them in two
volumes called The Scientific Papers of Sir William Herschel. Instead Herschel decided to
explore the southern sky with his father’s 18.5” aperture, 20-foot reflector. He considered traveling to Parramatta but decided to go to Cape Town instead for a number of reasons, including the fact that
Margaret’s brother was there. The Royal Society and the British Admiralty offered to help
with this expedition but Herschel refused because he did not want to compromise his independence.

On November 13, 1833 John Herschel, his wife and 3 children sailed from Portsmouth on the ship
Mountstuart Elphinstone, bound for Cape Town. The journey took nine weeks. They arrived
on January 16, 1834 and spent several days unloading their apparatus and baggage and
moving into a large property called Feldhausen, ten kilometers southeast of Cape Town on
the eastern side of Table Mountain. Orchards and a grove of trees surrounded it. The weather there was much better than in England.

Herschel’s assistant, John Stone, helped him set up two telescopes; the 18.5-inch aperture 20-
foot long reflector and the 5-inch aperture 7-foot refractor. On February 22, Herschel looked
at the triple star Alpha Crucis and the nebula Eta Argus (Carinae) for the first time using the
20-foot, but the 7-foot was not used until May 2. Thus John became the first person to explore the southern sky using a large telescope. James Dunlop had explored it in 1826 with a 9” aperture reflector.
(John’s 20’ telescope was set up here. https://maps.app.goo.gl/nBkTGkWHS4Q7u8rr9)

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THE TWENTY FOOT REFLECTOR
The 20-foot (6.1 m), 18.5-inch aperture telescope with its standard 39 mm eyepiece had a power of
157 times and a field of view of 15.1 arc-minutes.
(The 20’ https://www.sciencephoto.com/media/1309187/view)

“Like most of the Herschel telescopes, the 20-foot reflector was constructed on the
Newtonian principle, but without a secondary… It was suspended by a system of ropes from
a framework mounted on movable rollers. A movable platform gave the observer access to
the eyepiece in any position. There was no secondary mirror; the Herschel’s looked straight
down the tube. Of the three interchangeable mirrors constructed for this telescope, William
Herschel had made one, another had been ground and polished by father and son together,
and John Herschel had produced the third on his own. All three mirrors had the same aperture
of 18.5-inches and the same focal length of 20 feet, so that they were identical in their optical
performance.”

Salt spray sometimes spoiled the mirror within a week and it had to be repolished. John estimated that the 20-foot telescope could see 5.3 million stars in both hemispheres using a power of 180 times.
William Herschel calculated that a new speculum mirror absorbed 33% of the light and hence reflected 67% while modern aluminium mirrors reflect 89% of the visible light. This means John’s 18.5-inch had the same magnitude limit as a 16.8-inch aluminium mirror since there was no secondary in Herschel’s telescope.

On March 5, Herschel began regular sweeps. He searched for star clusters, nebulae and
double stars in a series of zones 3 degrees long (north-south) in Declination. In four years he catalogued 1708 clusters and nebulae and 2102 double stars in the southern sky. He also studied the structure
of the Milky Way by counting a total of 68,948 stars in 3000 areas of the sky. His father
William believed that there were a vast number of cosmic gaseous masses “a shining fluid, of
a nature totally unknown to us,” but John thought all nebulae were made up of stars. As a
result John sometimes catalogued several parts of one nebula with different numbers instead
of seeing the nebula as a single object. The invention of the spectroscope proved William
correct.

John made an astrometer to measure the magnitudes of 191 bright stars by comparing them
with the light of the moon. He also arranged the naked eye stars by magnitude using his step
method. To do this, he divided the star charts made by the German astronomer Johann Bode
into triangular fields and “all stars visible to the naked eye were arranged in sequences. This
was done by writing down a list of stars having very marked differences in brightness
between them, leaving enough space between successive entries so that more stars could be
interpolated.”

William Herschel correctly thought the Milky Way was a lens-shaped system, but John
thought it was ring-like. He noted some dark patches in the Milky Way, such as the Coal
Sack, and he discovered a large number of nebulae outside the Milky Way, but did not know
that these were distant galaxies. He also made detailed catalogues of the Magellanic Clouds,
which he called the Cape Clouds. John listed 244 objects in the small cloud and 919 objects
in the large cloud. All the catalogues he made were arranged by Right Ascension and he
used north polar distance (NPD) not Declination.

A map made of the area around the Orion nebulae contained 150 stars and a map of the area
around Eta Argus included 1216 stars. The star Eta Argus (eta Carinae) was fourth magnitude according to Halley and second magnitude according to others but it suddenly brightened at the end of
1837 to be equal to Alpha Centauri (magnitude –0.1). By January 20, 1838 it had faded to the
magnitude of Rigel (magnitude 0.1) and by April 14, it was similar to Aldebaran (magnitude
0.8). Thomas Maclear, who was the director of the Cape Observatory at Cape Town, thought
it was only slightly fainter than Sirius (magnitude –1.5) at its maximum in early 1843.
Herschel observed this very unusual occurrence between 1834 and 1838.

Maclear and Herschel worked jointly on a number of projects, including measuring the
61” difference in longitude between Feldhausen and the Cape Observatory (5.55 km apart).
Maclear provided Herschel with the exact positions of a number of fundamental stars and
Herschel helped Maclear with financial support for tidal and meteorological observations,
especially at the solstices and equinoxes.

John observed Halley’s Comet between October 28, 1835 and May 5, 1836. It was magnitude
2.4 when he first saw it in the evening near M14, and magnitude 12.7 at the end. He moved the 7-foot telescope to the sand hills on the Cape Town flats, south-east of the city, and cut down some oak trees near the 20-foot telescope in order to study the comet. It was visible in the evening sky until November 10 (elongation 33 deg from the sun) and in the morning sky after January 26 (elongation 66 deg from the sun). Herschel speculated on the cause of the comet’s tail, and made the radical (and correct) proposal that it was due to positive and negative charges. He also tracked the positions of Saturn’s satellites including two faint moons that were discovered by William in 1789, and subsequently lost.

Herschel made drawings to record the positions of sunspots by projecting the sun with a power of 105 or 179, and he speculated on the cause of them, believing sunspots were holes in the solar atmosphere, which allowed a view of the dark solid core. He inherited his belief in the dark core from his father.

As already mentioned three children were born in Cape Town, Margaret Louisa on
September 10, 1834, Alexander Stewart on February 5, 1836 and John on October 29, 1837.
On Sundays the family attended church at the nearby village of Rondebosch. Herschel
developed an interest in botany and collected tuberous and bulbous plants to take back to
England. Using his camera lucida he drew the plants and his wife coloured the drawings.
Herschel’s other interests included poetry and music and he played the flute and violin. On
June 15, 1836 he was visited by Charles Darwin who described him as “a very modest man,
rather shy and even gauche (socially awkward), despite his lively intellect.”

While Herschel was at Cape Town, the New York Sun published a series of false articles
about his “discoveries” on the moon. These included paradise-like woods and meadows, hills
and valleys and moon men and women. It was some time before Herschel found out about
these articles and denied them.

On March 11, 1838 the Herschel family left Cape Town for England on the Windsor. The voyage, including a stop over at St Helena, took nine weeks. A stone obelisk commemorating their stay was later erected at Feldhausen, in the grounds of the current Grove Primary School, 10 km SE of Cape Town (latitude 33.983 deg S, longitude 18.460 deg E). John believed his time at the Cape was the happiest time of his life.

BACK IN ENGLAND, 1838 - 1840
Back at England Herschel visited Lord Glenelg, Secretary of State for the Colonies regarding
education in South Africa. While in Cape Town, Herschel had campaigned for public education, demanding “fundamental improvement in the social and economic position of teachers and the creation of a secure professional status.”

On June 28, 1838, Herschel was made a Baronet, at the time of the coronation of Queen Victoria. Soon after this John paid another visit to his aunt Caroline Herschel in Hanover and also met with other scientists on the Continent. In London he discussed constellation reform with the Astronomer Royal, George Biddell Airy. John proposed a “complete rearrangement of the constellations in the southern sky.” “Herschel’s plan was not accepted by astronomers on the Continent, and he withdrew it,” but in 1928, the IAU (International Astronomical Union) used a similar method to draw constellation boundaries for the whole sky.

In October 1838 Herschel dined with the Queen and Lord Melbourne at Windsor Castle and
they discussed a planned trip to the south magnetic pole. Herschel was a member of a
committee convened to study geomagnetism and meteorology, using geomagnetic stations
established at St Helena, Van Diemen’s Land (Tasmania), Cape Town and Madras (India) in 1840 and 1841. Another forty-seven stations were set up in other countries. These found a correlation “between disturbances of the compass needle and events in the solar atmosphere, after the discovery of the eleven-year periodicity of sunspot numbers.” As part of this project voyages were made to the north and south magnetic poles.

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Herschel reluctantly became involved in many official duties and willingly became president of the Royal Astronomical Society. While president he wrote a preface for A catalogue of 9766 stars in the southern hemisphere, for the beginning of the year 1750, from the observations of Lacaille, made at the Cape of Good Hope in the years 1751 and 1752. The catalogue was published after the data from Lacaille’s observations were finally reduced under the superintendence of Thomas Henderson.

The University of Oxford gave John an honorary doctorate in June 1839, and he was a member of the Board of Management of the British Museum and the Board of Visitors of the Royal Observatory at Greenwich. Between 1839 and 1844 Herschel investigated photography and photochemistry using his understanding of physics and chemistry. He was the first to use the words ‘positive’ and ‘negative’ for the images. He also used glass plates, coated in silver nitrate and later silver bromide. These had a greater sensitivity to light and could be exposed in a few seconds. He realised that susceptible paper, a good lens and a chemical fixer were needed to produce pictures. His discovery that sodium thiosulphate dissolves silver salts and fixes the image was included in subsequent patents made by others. On January 30, 1839 Herschel took a picture of the 40-foot telescope at Slough using paper coated with silver carbonate solution. On July 9, 1839 he made a picture of the solar spectrum.

January 1, 1840, found the Herschel family (they had 7 children then) assembled inside the tube of the dismantled 40- foot telescope while John read a poem written by him for the occasion. Leaving some
grinding and polishing tools inside, the tube was closed, sealed and left in the grounds of
Observatory House. John’s 20-foot reflector lay in the cellar at Slough and was never used
again. It was eventually displayed at the Royal Observatory at Greenwich and in Washington DC.

HAWKHURST, 1840 – 1871
Herschel decided to move from Slough in 1840 because of the increasing urbanisation and
because he wanted a refuge where he could reduce his Cape Observations. Also Observatory
House had become too small for his family of seven children (Maria Sophia was born after
their return from South Africa). In April 1840, he purchased a house called Collingwood at
Hawkhurst, 90 km southeast of London, an “isolated country house in Kent where he spent
the remainder of his life.” (Hawkhurst. https://maps.app.goo.gl/Jci1YQXefqzsNmGK9)

Here he set up the 5-inch aperture 7-foot refracting telescope on a small observing platform on the roof.
John observed a solar eclipse on July 8, 1842. He must have travelled to see this, the path of totality passed near Lisbon and Vienna. He thought the three large prominences were enormous cloud formations. This supported his father’s model of the sun. He proposed a permanent watch over sunspot activity and Warren de la Rue began photographing the sun systematically in 1858 from England. John used “a cylindrical vessel of sheet-zinc 3.75 inches in diameter and 2.4 inches deep, filled with dark-coloured water” to measure the heat output from the sun.

While at Collingwood, John discovered that Betelgeuse in Orion was a variable star. He observed the great magnitude zero comet of March 1843 and magnitude 5.7 Biela’s Comet early in 1846. Herschel also spent many hours analysing the results of four hundred nights observing at the Cape. By 1844, with his health failing from continued trouble with rheumatism and bronchitis, he wrote, “I feel my health rapidly breaking and I have many and distinct warnings that what I have to do I must do quickly, that time is the stuff of which life is made.”

His Results of Astronomical Observations Made during the Years 1834, 5, 6, 7, 8 at the Cape
of Good Hope; Being a Completion of a Telescopic Survey of the Whole Surface of the
Visible Heavens, Commenced in 1825, was finally completed on March 7, 1847, on his 55th birthday and published in London that year. The book contained seven chapters as outlined below:

1. 1708 nebulae and star clusters, 919 objects in the LMC and 244 in the SMC
2. 2102 double stars seen with the 20’ telescope and 1081 double stars seen with the 7’ telescope
3. Brightness estimates for 2341 stars
4. Star counts done with the 20-foot telescope
5. A description of Halley’s Comet from October 1835 to May 1836
6. A summary of observations of seven satellites of Saturn and
7. Observations of sunspots.
The book earned Herschel another Copley Medal in 1847. A copy of the book was sent to
Aunt Caroline in Hanover, a year before she died aged 98.

Visitors to Collingwood included Encke in 1840, Bessel in 1842, and Airy, Babbage, Whewell, Peacock and Pritchard. He also hosted a meeting on July 10, 1847 between rivals Urbain Jean Joseph Leverrier (1811-1877) and John Couch Adams (1819-1892) after both allegedly made independent predictions for the position of Neptune. On September 23, 1846 Johann Gottfried Galle (1812-1910) at Berlin Observatory found Neptune at the position predicted by Leverrier while John Challis at Cambridge Observatory and George Airy at Greenwich Observatory failed to search for it at the position given by Adams.

Herschel was now devoting most of his time to writing and he authored a 700 page book,
Outlines of Astronomy, which was printed in at least thirteen editions between 1849 and
1902. He also wrote an article on meteorology, which was printed in the eighth edition of the
Encyclopedia Britannica and in 1845 published two papers on fluorescence.

The year 1847 saw him elected president of the Royal Astronomical Society (RAS) for the
third time but his role was largely as a figurehead because his name gave the RAS prestige.
His daughter Constance wrote The Herschel Chronicle in 1938, a collection of documents about William and Caroline Herschel. John turned 63 in 1855, the year Constance was born.

In December 1850, probably because of financial need, Herschel decided to take up public
office, and he was appointed Master of the Mint, a post that was once held by Sir Isaac
Newton. He attempted to introduce decimal currency but did not succeed. During this time he
lived in London while his family remained 90 km away at Collingwood. He no longer had
time for his scientific pursuits and, suffering from bronchitis, rheumatism and gout, he took
opium to relieve the pain. Late in 1854 he suffered a nervous breakdown and resigned from
the mint in April 1856.

Back at Collingwood he continued his solar observations and attended a meeting in Aberdeen
on terrestrial magnetism in 1859. This was “his last major public appearance.” He also
produced the General Catalogue which contained almost all the nebulae and star clusters
discovered before 1863, a total of 5079 objects. To do this he had to reduce fifty thousand
separate objects.

This was printed in the Philosophical Transactions in 1864 and enlarged in 1888 by Dreyer to become the New General Catalogue of Nebulae and Clusters (NGC), which is still used today. John found 1518 new NGC objects; 1147 galaxies, 303 open clusters, 38 nebulae, 18 planetary nebulae and 12 globular clusters between 1823 and 1838.

He also produced a catalogue of 10,300 double stars, which was published after his death and a more detailed catalogue of double stars, which was never published.

John Herschel died May 11, 1871 at Collingwood, aged 79 and was buried in Westminster
Abbey. A contemporary wrote in an obituary, “He touched nothing that he did not adorn.”
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[AstralTraveller (David)]

Thanks for another interesting read, you are a font of knowledge. And a belated congratulations on 20 years on IIS.

[glenc (Glen)]

Thanks David

[EpickCrom (Joe)]

Hi Glen.

Thank you for compiling all the great information for us, I'm thoughly enjoying reading all this historical information

[Saturnine (Jeff)]

Hi Glen. Thoroughly enjoyed reading your posts about John Herschel, and all your other articles that you have posted. Thanks for your efforts.

[glenc (Glen)]

Thanks Joe and Jeff

[Crater101 (Warren)]

Really enjoying these astronomer histories, many thanks once more.

[glenc (Glen)]

If you include all the objects found by others, John Herschel catalogued 1337 southern objects between 1826 and 1838.
749 Galaxies
358 Open Clusters
116 Nebulae
74 Globular Clusters
20 Planetary Nebulae
11 Asterisms
9 MW star clouds