Maclear T.

MACLEAR,  Thomas [Rev; Sir; Dr][Knt; F.R.S.; F.R.A.S.]

Professional Astronomer

Born: 17 March 1794, Newton Steward, County Tyrone, Ireland
Died:14 July 1879, Cape Town, South Africa


In brief :
Famous for:
Director of the
Cape Observatory (1834 – 1870)
Land Survey: Maclear re-measured
La Caille‘s Arc  of the Meridian in order to find out where La Caille went wrong, and so Maclear proved that the earth is round.
Maclear’s  geodetic work led to the setting up of the Government Trigonometrical Survey Office of South Africa.
Originated the Meteorological Commission. (for South Africa?)
Originated the Commission of Standards for Weights and Measurements (for South Africa?)
Assisted in the establishment of lighthouses.
Thomas Maclear was a medical doctor by profession, who became an Astronomer and Land Surveyor.  He did sterling  work in the field of Astronomy & he made so many observations  that it kept two successive directors busy reducing the data.   Maclear’s greatest contribution is as Land Surveyor.   Apparently he was also a good doctor.

Historical background :

Historical Index:
Childhood / Cape Observatory / Arc of the Meridian / Latter Years / Social life and other aspects
Career / Personal

The Early Life of Thomas Maclear.
Thomas Maclear was born at Newton Steward, County Tyrone, in Ireland on 17 March 1794. He has been described as having a good Irish face. An early proficiency in Latin led to a young Thomas to be groomed to enter the Anglican Church. His objections to a life in the church led to a permanent breach between him and his father. At an early stage he decided that this would not give him enough scope for his scientific interests, and he gladly agreed to the suggestion of two distinguished medical uncles, Sir George and Dr T McGrath, that he should become a doctor. He was apprenticed to Dr. T McGrath in 1808. After qualifying, at Guy s and at Thomas’s, he was appointed house surgeon at Bedford Infirmary in 1814, where he was a distinct success. Indeed, he appears to have been as good a doctor as he was later to become an astronomer and surveyor. [Moore, p. 48; Warner-Astronomers, p.37.]
In 1825 he made a happy marriage to Mary Pearse, daughter of Theed Pearse, Clerk of the Peace for the county of Bedford. (In 1820’s he became interested in astronomy and met Mary, who was also interested in astronomy, at a lecture.) By now he was in partnership with one of his uncles at Biggleswade, and the practice prospered. Yet a complete change in his life lay close. [Moore, p. 48; Warner-Astronomers, p.37.]
Influence of the Smythe family.
One of the Astronomers, who worked with Maclear at the Cape, was Charles Piazzi Smythe. (Sometimes spelled Smyth) Maclear had a close acquaintance with the Smythe family.  “While living at Bedford, Maclear had made the acquaintance of the Smyth family, whose head, Admiral William Henry Smyth, had served in the Royal Navy during the Napoleonic Wars. Later he was also acted as a hydrographer to chart the Mediterranean. The old Admiral, was very much of a character – to put it kindly, he was an eccentric.
Smyth married the daughter of a British merchant who lived in Naples and naturally made various Italian friends. One of them was the astronomer Giuseppe Piazzi, who had acted as director of the Palermo Observatory in Sicily and had achieved fame in 1801 when he had discovered (and named) the first asteroid or minor planet, Ceres.
It was from his meeting with Piazzi that the Admiral’s interest in astronomy dated. On his retirement to Bedford he armed himself with the best instruments he could find and they were very good indeed – and became a Fellow of the Royal Astronomical Society.  He also published some astronomical books, one of which, the Cycle of Celestial Objects is still regarded as something of a classic. To quote a contemporary reviewer: “The descriptions of the various objects are enlivened with a vast amount of general classic and antiquarian lore, introduced in the most genial spirit.”
When the Admiral’s second son arrived, the name chosen was
Charles Piazzi Smyth. This was predictable; but less predictable was the fact that for a long period this same son would become a staunch assistant to Maclear at the Cape – and that eventually he would become the second Astronomer Royal for Scotland.” [Moore, pp. 48 – 49; Warner – Astronomers, p.37.]
Maclear and the Admiral struck up a friendship, and while Maclear was at Bedford he was given free, unrestricted use of the Admiral’s astronomical equipment. He began observing, and his results were so good that the professionals soon took notice of him. He became a Fellow of the Royal Astronomical Society and frequently attended London meetings, so that his circle of scientific friends increased. Through the Admiral he met Sir Francis Beaufort, (Hydrographer, and inventor of the well known scale of wind forces), and
John Herschel, who was destined to play a major role in astronomy at the Cape. Maclear and Herschel became life long friends.
Appointment to the Cape of Good Hope.
Meanwhile the British Admiralty established the
Royal Observatory at the Cape of Good Hope. (John Herschel had a hand in the establishment) The first astronomer at Cape was Fearon Fallows (an acquaintance of Maclear), who died prematurely of scarlet fever. His replacement was a Thomas Henderson, a friend of Maclear. Henderson hated the assignment at the Cape and resigned after thirteen months. Maclear was appointed as the next astronomer. (He was considered after the death of Fallows) He accepted the appointment with caution after hearing bad reports from Henderson who described it as a “Dismal Swamp”. He wrote to Fallows widow who assured him it was not that bad. He had opposition from his partner in the medical practice, his uncle, thought him mad to accept it. When Maclear asked for a relatively small loan so that he could pay his fare to South Africa, his uncle flatly refused to help in what he thought would be the ruin of his nephew’s life. However, Maclear passion for astronomy has become so great that he decided to leave behind a profitable practice in medicine and accept a reduction in income.  [Moore, p. 48; Warner – Astronomers, p.39.]

Life at the Cape Observatory.
  Maclear was send to the Cape with a specific mission. He must prepare a catalogue of Southern Stars. As we will see he never quite got around to it, as there were other very important projects that required his attention.
One of the reasons that Maclear decided to move to the Cape was because his good friend, John Herschel, decided to move to Cape Town and set up his own private observatory. Due to financial considerations Maclear could not travel to Cape Town on the same vessel as the Herschel’s. Maclear came out to the Cape on the Tam O’Shanter with his wife, five daughters, a governess, a nursemaid and a manservant. The manservant was
Thomas Bowler, who went on to become a famous artist, and a lot of the detail we know today about how the observatory looked at the time is due to his painting and sketches. On the voyage Maclear had to act as medical doctor, and as navigator as the Captain was “too fond of the brandy bottle.” He also examined the phosphorescence in the wake of the ship under his microscope and determined that it “proved to be animalculae”. Maclear arrived at the Cape on 7 January 1834, and Herschel on January 16th.  [Warner – Astronomers, pp. 40 – 41.]
After landing at Cape Town “… my youngest child was suddenly taken ill on Tuesday and died on Thursday. A sad blow to our spirits on landing at the Cape.” No more encouraging was the greeting of his Assistant Director,
Lieutenant Meadows, an eternal pessimist, “So Sir, you have determined to accept this wretched appointment”. [Warner – Astronomers, p.41.]
However, Maclear loved the observatory and would stay the rest of his life, going back to Europe on holiday only once. His first impressions are recorded a letter to Dr. Lee: “The observatory – is a beautiful building, substantial and well situated. A clear view except at one point to the S. W. where Table Mountain and the Lions Rump cut of a few degrees. The panoramic views Bowler took, stationed a few feet in front of the observatory will at once convey an idea of the surrounding scenery – The Transit room is well contrived. The shutters open by Pulleys in small lengths of three feet at a time. This is a great advantage where high winds prevail. The circle room is provided for in the same way. On the whole the Transit and Circle rooms are better arranged and constructed, than any I have seen or read of. The domes are badly placed and at the present useless, because the shutters cannot be opened … Sir J. and Lady Herschel were much pleased with the observatory and agree with me in opinion that the spot is well chosen for the purpose. It is certainly not convenient for us who reside in it, and merely from this cause, that no steps whatsoever have been taken to make a road to it, the consequence is, that about 50 or 100 pound per annum additional expense is entailed upon me, in keeping a servant and a cart more than I otherwise would require, and there is in reality no stabling or offices of any sort, or Enclosure to the building.” [Warner – Astronomers, p.41.]
An important factor for the success of the Cape Observatory during Maclear’s time was his friendship to
John Herschel. As already mentioned he met Herschel through another mutual friend, Admiral Smythe. John Herschel, son of the famous William Herschel, decided to move to Cape Town (1834 – 38) in order to extent work his father began to the Southern Skies. His move to Cape Town was one of the reasons Maclear decided to accept the appointment at the Cape. Herschel’s help, opinions and advice were invaluable to Maclear during the relative short time of four years that Herschel spends at the Cape. However, once Herschel returned to England, he was a respected scientist near to the seat of power (Queen Victoria conferred a Baronetcy on him), and influential with the British Admiralty and important scientific institutions. He used his influence to help Maclear and the Cape Observatory whenever he could.
Maclear made great improvements to the comforts and general functionality of the Observatory. His whole attitude was different to his predecessor Henderson and Maclear build up a better working relationship with the Admiralty. He also had the help of his very influential friend, John Herschel. Great was the improvement when water closets were installed. A boundary fence brought greater control and kept cattle from messing the terrain and cause damage to the buildings. (Cattle came into the shade of the building and pocked their horns through the windows and damaged the shutters. Before the fence went up Maclear had sixty cattle impounded.) [Warner – Astronomers, p.46.]
From their first meeting, the personality of his assistant,
Lieutenant Meadows, had irked Maclear. (It was Meadows who greeted Maclear with, “So Sir, you have determined to accept this wretched appointment”.) Things between them came to a head when a woman in Meadows service was reprimanded for “insolent conduct”. Maclear insisted on her removal from the observatory grounds. Meadows refused to remove the woman and threaten to resign. The outcome of which was that Meadows took three months leave with the intention never to return.  [Warner – Astronomers, p.34, p.49.]
Maclear asked the admiralty for a new assistant. The assistant sent out to him was a very capable astronomer,
Charles Piazzi Smyth. He was the son of one of Maclear’s best friends, Admiral Smythe (referred to earlier). Charles was only sixteen years old. (He went on to become Astronomer Royal for Scotland)
Maclear expanded the time service by firing a cannon from Signal Hill at 9 p.m. In 1836 a time ball was erected at the observatory. [Warner – Astronomers, p.47.]

Arc of the Meridian:
  In 1751-3
Abbe De La Caille was send by the Paris Academie of Science to Cape Town in order to measure the curvature of the Earth. Something went wrong and the measurement showed the Earth to be pear shaped, not round like an orange. This put the scientific community in a conundrum and now, 80 years later, the Admiralty wanted a conclusive answer and the mystery solved. Maclear was tasked to re-measured La Caille’s Arc of the Meridian. It was probably the most important project Maclear ever did.  This was the start of Land Surveying in South Africa as Maclear set the standard length measure. With a bit of poetic licence it can be said he proved that the earth is round. For the complete story, click here.

Latter Years Improvements at the Cape Observatory.
In 1839 important instruments arrived at the Cape, due to the influence of Herschel. These included replacing the
Jones- with the Greenwich Mural Circle.  The Bradley Zenith Sector was used to by Maclear to re-measure the Arc of the Meridian.
Maclear was a “bossy” director. For example, in 1843 Smyth took the
Herschel 14 ft telescope outside the building onto solid ground in order to observe a comet. This was a logical move as the telescope was mounted on a wooden floor in the observatory, which made it unstable. Maclear, who was in the field to re-measure the Arc of the Meridian, heard about this and ordered “that all enquiries of a physical description with regard to the Comet are to b thrown overboard; that the 14 feet reflector is to be replaced in the Telescope room; and that nothing is to be done but the determining of the place of the Comet.” Smyth and Mann started thereafter to refer to Maclear as “The Emperor”. [Warner – Astronomers, p.58.]
In 1841 a new addition was made to the Cape Observatory, a Magnetic and Meteorological Observatory. It was run and administered quite separately to the Astronomical Observatory. Maclear was deeply dissatisfied with this intrusion to his kingdom but there was nothing he could do about it. [Warner – Astronomers, p.59.]
In 1844 Maclear started using his auxiliary telescopes, a
Dollond 3-inch and Jones 3 – inch telescopes, and new domes separate from the main building was constructed.  Meanwhile Herschel’s influence with the Admiralty culminated in an excellent telescope, the Mertz 7-inch, being sent to the Cape. A permanent dome for this instrument was built in 1849. [Warner – Astronomers, p.58.]
By 1853 Cape Town has expanded so much that the ships in the harbour could not see the time ball on the Observatory grounds anymore. Two new time balls were added to the time service, one at Signal Hill and the other at Simon’s Town. By 1861 telegraph lines were installed in the Cape Colony and the drop of the balls were now done automatically with electrically from the Observatory. In 1865 another time ball was added to the system, in Port Elizabeth, 500 miles (+/- 750 km) distant. [Warner – Astronomers, pp.63 – 65.]
In 1859 Maclear took extended leave and this was to be his only time that he returned to England. He also visited Ireland, Paris and Brussels. He received the Knighthood during the visit, and was now Sir Thomas Maclear, Knt. [Warner – Astronomers, p.70.]
His wife Mary died on 27 July 1861. He received permission to bury her on the grounds of the Cape Observatory. [Warner – Astronomers, p.70.]
In 1866 Maclear published the “Verification and extension of La Caille’s Arc of Meridian at the Cape of Good Hope. (Two volumes, edited by Sir George Airy, Astronomer Royal).” He received international acclaim for solving the riddle caused by Abbe de la Caille. In 1867 he received the Lalande Medal from the French Academie of Science, and in 1869 the Gold Medal of the Royal Society. [Warner – Astronomers, p.70.]
All the above mentioned accolades aside, Maclear was send to the Cape for a specific purpose. It was required of him to prepare a catalogue of Southern Hemisphere Stars. He was a prolific observer and made an incredible amount of observations, but with all his other activities he never got around to reducing the data. Nearly four decades after Maclear was send to the Cape to fulfill this specific instruction he still could not show results. [Warner – Astronomers, p.73.]
By 1868 Airy suggested that Maclear should retire. He declined but said he would do so if William Mann, his son-in-law, were appointed as his replacement. Reports reached London that Maclear was very frail. In 1870 the Admiralty wrote him a letter saying: “Most of the Civil Departments of the Government have lately been undergoing reorganization, and the Heads and other officers belonging to them who have reached a certain age have been advised to, and among other Institutions the Cape Observatory has not been overlooked.” The letter continues with what sterling work he has done. Maclear retired at the age of 76, having been Her Majesties Astronomer at the Cape of Good Hope for 36 years. [Warner – Astronomers, pp.70 – 71.]
In his last years Maclear retired to his house in Mowbray, Cape Town. He was a well-liked and respected citizen of Cape Town, who played not only a mayor role as Scientist and Astronomer, but also played a central part in the social life of Cape Town. Sir Thomas Maclear died on 14 July 1879 and was buried next to Mary on the grounds of the Observatory. On 17 July the House of Assembly in Cape Town resolved “That this house desires to express its deep sense of the signal services rendered by the late Sir Thomas Maclear, Knt, F.R.S., F.R.A.S., to the general cause of astronomical and geographical science while in charge of the Royal Observatory, Cape Town, and also to the material interest of the colony in the appreciation of his researches; and, furthermore, its high appreciation of his devotion for so long a period of years to the cause of South African Exploration and civilisation, and that this resolution be recorded in the journals of the House.”  [Warner – Astronomers, pp.71 – 72.]

Social life and other aspects at Cape Town:
-Maclear became a Trustee of the South African Library and Museum. [Laing, p. 11; Warner – Astronomers, p.69.]
-Active member of the South African Literary and Scientific Institution (the old S.A. Institution, the name change occurred in 1832) [Warner – Astronomers, p.69.]
-He instructed David Livingstone in the use of sextant.  [Laing, p. 11]
-Maclear gave valuable help in the establishment of lighthouses in South African coastal waters. [Warner – Astronomers, p.69.]
-Served on the examining body of the South African College (later to become the University of Cape Town) [Warner – Astronomers, p.69.]
-Active on the Commission of Standards for Weights and Measurements. [Warner – Astronomers, p.69.]
-Committee of the Association for Exploring Central Africa. [Warner – Astronomers, p.70.] Herschel was also on the Committee.
-Ordained Minister in the Anglican Church
-Freemason at the English Lodge and rose to Deputy Principal Grand Master. [Warner – Astronomers, p.69.]

1834 (January 5) Maclear arrived at Cape Town as director of the Royal Observatory.
1838 to 1847: Re-measured La Caille’s Arc of the Meridian. (Moore state 1838, Smits give date as 1840)
1860:  Knighted
1867:  Lalande Medal of the French Institute (for re-measurement of the Arc of Meridian)
1869: Gold Medal of the Royal Society (for re-measurement of the Arc of Meridian)
1870:  Retire. (Age 76)


  • 1794: Born in County Tyrone, Ireland.
  • 1825:  Married Mary Pearse.
  • Maclear brought a valet with him to South Africa. The valet became a famous painter in South Africa, Thomas Bowler.
  • 1850: Instructed David Livingstone in the use of a sextant. They became close friends. [Warner – Astronomers, p.70.]
  • 1861:  (July 27) Mary Maclear die. Buried in the grounds of the Cape Observatory.
  • 1870:  Retired to Mowbray, Cape Town [Laing, p. 11]
  • 1876 Maclear became blind.
  • 1879 July 14: Died at his house in Mowbray, Cape Town. Buried besides Mary in the grounds of the Cape Observatory. [Warner – Astronomers, p.70.]
  • – Maclear tended to be dictatorial as director and was referred to as “The Emperor”.
    – He was a bee keeper. He imported “swarms of English bees”, which in time moved in under the floorboards at the observatory and caused problems for Gill, one of the successor directors. [Warner – Astronomers, p.86.]
    – He was a very social person, as well as serving on several committees.
  • Family:
    – One of his sons,
    George William Herschel Maclear, followed in his father’s footsteps and became an astronomer at the Cape Observatory. George made valuable observations of the 1882 Transit of Venus. [Koorts – British, p.52]
    – Another son, John Fiot Lee Pearse Maclear (called Jack), joined the Royal Navy and rose to the rank of Admiral. Jack married Julia, the sixth daughter of
    John Herschel, on 4 June 1878. In 1874 Jack arrived at the Cape as the second-in-command of the H.M.S. Challenger. The vessel was on an epic thousands day voyage around the world – the first major oceanographic expedition. Jack was granted permission to use the magnetic observatory at the Cape Observatory (then under the directorship of Stone) [Warner – Astronomers, pp.76 – 77.]
    William Mann married Maclear’s daughter.


Link to the Telescope Manufacturers.

Telescope (Museum Africa MA 772)
Dollond Transit Circle
Jones Mural Circle
Greenwich Mural Circle
Bradley Zenith Sector
Herschel 14-ft Telescope
Dollond 3-inch Telescope
Jones 3 ½ inch Telescope
Mertz 7-inch Telescope
Airy Transit Circle.


Link to the Main Bibliography Section and more information about Sources.

Remaining Artifacts:
Maclear’s  Base line for land survey measurement (to standardise distance  as a unit of measurement), is to be found at the Grand Parade in Cape Town.  Two old cannons erected in an upright position  mark it. [Smits]
Maclear’s  Beacon (Table Mountain)
Grave:   Maclear and his wife are buried in a single grave on the grounds  of the Cape Observatory in Cape Town.   (Grave about  50m from Fallows grave.)
Spyglass (Museum Africa acq. no MA 775)
Drawing  Instruments (Museum Africa acq. no MA 773)
Sextant  (Museum Africa acq. no MA 769)
Rhinoceros hide walking stick given to him by Livingstone. It is still in the possession of the Observatory. [Warner – Astronomers, p.70.]
Portrait Maclear (South African Library) [Laing; Moore p. 48.]
Portrait Lady Maclear (Museum Africa acq. no MA 75/1128a)
Survey:  Measurement by Maclear of the base line on the Grand Parade in  Cape Town, December 1837. (South African Archives) [Moore p. 58.]
Sketches of Maclear’s tent by Piazzi Smyth (Africana Museum) [Moore p.  62.]
Drawing  by Maclear during a sea voyage. (South African Library) [Moore  p. 67.]
Honorary: (Non tangible) Places named after him.
Town and District of Maclear in the Eastern Cape Province (South Africa).
Cape Maclear near Cape Point. [Smits]
Cape Maclear on Lake Malawi. [Smits]
Maclear Crater on the Moon
Amod A, et. al., A History of Geodetic Surveying in South Africa –  Part 1, The Cape Odyssey, Historical Media cc, Cape Town, Aug./Sept. 2002 – Vol. 2 Issue 7, pp. 1 – 9.
Koorts, W.: The 1882 transit of Venus: The British expeditions to South Africa; MNASSA April 2004, Vol. 63 nos. 3 & 4, pp. 34 – 57.
Laing, J.D. (ed.), The Royal Observatory at the Cape of Good Hope 1820  – 1970 Sesquicentennial Offerings, pp 11 – 12.
Moore, P. & Collins, P., Astronomy in Southern Africa, pp.47 -52; pp.55 – 60; pp.64 – 70.  (General Source)
MNASSA,  Vol. 48, Nos. 5 & 6, 1989 June, p. 59.
Smits, P., A Brief History of Astronomy in Southern Africa. (Unpublished)
Warner, B., Astronomers at the Royal Observatory Cape of Good Hope.
By Maclear:
Maclear, T., Verification and extension of La Caille’s Arc of Meridian  at the Cape of Good Hope. London, 1866 (Two volumes, edited by Sir George Airy, Astronomer Royal)
“Published his Transit and Mural Observations made during his early years at the Cape in 1840”
-Maclear Family papers 1843-90. 5 items (Ref. A253f) (contains MS  account of early life of Maclear, letter book 1878-79 of Capt. Harry  Maclear, meteorological notes).
-Draft of obituary of Maclear (Ref. A616f).
-Letter from Maclear to J. Herschel 1851 November 28, recommending  Bain (Ref. Bain Papers A6).
-Letter 1837 August 9 from Sir J. Barrow (Secretary to the Admiralty) to Maclear on instructions for setting up Bradley’s Zenith  Sector (which was used by Maclear for his determination of an arc  of meridian) (Ref. Macartney Papers A88/473).AFRICANA MUSEUM, JOHANNESBURG [JHA8, p. 218.]
Miscellaneous letters: Sir G. Airy to Maclear (Ref. 1998)  containing instructions for observations; Maclear to Sir Harry Smith  concerning proposed Memorial to J. Herschel (Ref. 828); Stone to Maclear, 1872 (Ref. 82).LIBRARY OF THE SOUTH AFRICAN TRIGONOMETRICAL SURVEY, MOWBRAY, CAPE TOWN [JHA8, p. 220.]
-Maclear: Folio volume of sketches computations, diagrams and descriptions of Maclear’s survey expeditions.  Also including Journey of 1837 May with Capt. Williams in search of Lacaille’s trigonometric station and Base Line site; triangulation to connect Cape Observatory with Feldhausen (J. Herschel’s residence) and Lacaille’s site in Cape Town; local triangulations around Lacaille’s other sites.
-Maclear: Correspondence and financial accounts of Maclear and W.  M. Mann (Maclear’s assistant) 1843-45 concerning the measured arc of meridian (N.B.: the writer is recommending to the Trigonometrical Survey that these items be transferred to the extensive collection contained in the South African Archives).SOUTH AFRICAN ARCHIVES, ROELAND STREET, CAPE TOWN [JHA8, pp. 220 – 221.]
-Maclear-Mann Papers (Accession No. 515): this extensive accumulation  of manuscripts and correspondence is contained in 139 files. They  derive from presentations made by members of the Maclear family and from donations from the Trigonometric Survey and from the Royal Observatory, Cape. Although mostly concerning Sir Thomas Maclear and William Mann, a considerable amount of material relates to Sir  John Herschel and to the early history of the Cape Observatory. Excluding miscellaneous files of accounts, testimonials, newspaper  cuttings, etc., the most significant references are:
Files 1-15Letters received by Maclear, 1811, 1813-14, 1816-26, 1828-79,  arranged in alphabetical order. File 2 contains correspondence from  Sir Francis Beaufort. File 5 contains letters from John Herschel  to Maclear.
20 David Livingstone-Maclear correspondence.
54-72 Maclear diaries, 1840-75.
73-77Letters received by Mrs Maclear.
78-79 Mrs Maclear’s diaries 1832-59.
80-83Correspondence of other members of Maclear family.
85-91 Diaries of Miss Mary Maclear (Maclear’s daughter) 1859-1900.
97 Letters to Maclear concerning Surveys.
100Miscellaneous Arc of Meridian and Observatory accounts.
101-103 Miscellaneous Observatory (Maclear) papers.
108-111 Miscellaneous observatory accounts (Maclear).
135-139 Papers connected with Surveys (Maclear).THE SOUTH AFRICAN ASTRONOMICAL OBSERVATORY (S.A.A.O.) (FORMERLY  THE ROYAL OBSERVATORY, CAPE TOWN) [JHA8, pp. 221 – 222]
-Almost all documents relating to the business of the Royal Observatory  prior to Gill’s arrival in 1879 have been sent to the Archives at the Royal Greenwich Observatory. Exceptions are a bound volume of  official letters received by Maclear (1834-53), copies of letters  sent 1856-57 (water damaged, partly illegible) and several volumes  of copies of magnetic and meteorological observations made in the  mid-1800s. The writer proposes to request the transfer of the first of these items to the Maclear papers in the South African Archives.
-A boxed collection of observations of comets, mostly positional determinations, is available. These are mostly Maclear’s observations of such comets as Halley (1835), Gambart (1845), Wilmot (1845),  Klinkerfues (1853), Encke (1855, 1861), Donati (1859), D’Arrest (1857-58) and comets in 1843, 1861, 1862, etc.SOUTH AFRICAN MUSEUM, GOVERNMENT AVENUE, CAPE TOWN [JHA8, p. 222.]
– The Archives of this Museum contain extensive correspondence on  Museum matters by Sir Thomas Maclear and Sir David Gill, both of  whom were Trustees.

– David Livingstone: Astronomical Observations (1853-72) with computations and summaries therefrom made by Maclear (Ref. LI, 1/3).
These consist of miscellaneous papers and diaries and field  notes kept by Livingstone, with Maclear’s calculations of positions deduced from Livingstone’s observations. Includes lunar occultations and observations of phenomena of Jupiter’s satellites. Maclear gives  a short account of Livingstone’s trips.

-Thomas Maclear (1833-70). Meridian observations, corrections and  reductions (1834-54), 12 vols. Comet and occultation observations (1834-65), 7 vols. Observing notes 1834-37 (including extensive  notes and sketches of Halley’s comet).
– Official correspondence: Simon’s Town (1850-69), Admiralty (1853-70),  Colonial Government (1861-72), General (1844-69), II vols. Weekly registers (reports of work done), 1849-60.
Chronometer books (1836-38, 1849). Magnetic observations (1842-57).  Meteorological records (1834-42,1865-73).
-Maclear’s personal diaries (April 1834-May 1835) and memoranda.
-Personal correspondence: extensive collections with C. P. Smyth (on Arc of Meridian in the Cape), Airy and Jacob (Madras).
-Arc of Meridian (1839-48): Original observations (II vols.), general  correspondence (mainly with Airy) 1849-70 (3 vols.).

Related Internal Links:
Royal Observatory at the Cape of Good Hope.
Arc of the Meridian.
Related External Links:
Historical Astronomical Posts in Britain and Ireland




Sir Thomas Maclear.
Published in “The Graphic”
Mrs. Mary Maclear.
Source: Warner, Maclear
Source: Laing; Evans
Maclear was knighted for his work in order to re-measure Lacaille’s Arc of the Meridian. In this carricature drawn by Smyth it shows Maclear just to the left of the centre, at his microscope measuring the distance between two measuring rods.
“Modus Operandi” Courtesy Royal Greenwich Observatory. Source: Warner, Smyth