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DE LA CAILLE, Nicolas Louis

Visiting Professional  Astronomer
(Later known as Abbe De La Caille, today as Lacaille)

Born:1713, Rumingy, France.
Died: 1762

New authoritative book by I.S. Glass:

Photo Gallery: Lacaille


Summary; History; Instruments; Source; Links

In brief :

Famous For:

  • His astronomical work (star chart & constellations)
  • His mathematical precision.
  • Land Survey (He did a land survey of the Arc of Meridian at Cape Town.  The survey showed the earth to be pear shaped instead  of round.)
  • Laid the foundations for Southern Hemisphere astronomy.

Whilst at the Cape, he charted positions of almost 10 000 stars,  grading them according to brightness.
Added  new constellations & instead of naming them after mythology,  he used scientific instruments. Some names for constellations in shortened form are still used today.

Historical background :

Historical Index:
Introduction; Early Career; Duties at Cape; Achievements; After Cape Town; Career; Personal.

"The Abbe de la Caille," as he was later to become, laid the foundations of Southern Hemisphere astronomy. He was the predecessor of all the later pioneers such as
Maclear, Herschel and Gill. It has sometimes been suggested that La Caille's achievements were largely vitiated by the lack of adequate instrumentation for his basic work, but a scientist of the stature of Sir Thomas Maclear did not think so and neither did Sir John Herschel, whose  survey of the southern sky is now generally held by astronomers  to have been the true starting-point of modern scientific work  in this field. Had La Caille been able to use modern-type instruments  as well, his work would have advanced our knowledge of southern-hemisphere  astronomy by almost a hundred years. As it was, he showed later generations how to set about an intensive observing programme  and his diligence in pursuing it, has become legendary. It is not from pure sentiment that a piece of charcoal from one of  his signal fires is preserved at the Cape Observatory to this  day. With several excellent works on mathematics and astronomy  to his credit, La Caille was singled out. It was because of his proven competence and wide knowledge that when he later made an error in one of his major geodetic measurements (Arc of the Meridian), men of the calibre of Maclear and Herschel went to enormous lengths  to discover how the calculations of such an expert could possibly  have gone wrong. Establish the cause of La Caille's mistake, they reasoned and an important scientific principle could be unearthed. They were right. [Copied Moore, pp. 29 - 31.]
 Sir George Everest, Surveyor General of India (after whom the  highest mountain in the world was named and who had many experiences  with the effect of mountains on surveys), came to South Africa  and inspected La Caille's work. He realised the mistake that La  Caille made, but it was left to Maclear to prove it. [Amod, p.  3]

Early Career:
 Lacaille  received formal classical education & the religious title of Abbe was conferred upon him when he completed his studies. He did not pursue a career in religion.
 Jacques Cassini of University of Bologna's Observatory employed Lacaille to survey the French coast from Nantes to Bayonne. He did  an impressive job!
 In  1739 Jacques Cassini employed Lacaille to re-measure the French arc of Meridian. (This was important to determine the size & shape of the earth). He did an impressive job.
 The excellent work that that he did on the survey of the coastline & arc of meridian got Lacaille admitted to the French Academy  of Sciences. He was appointed the chair of Mathematics at Mazarin College (now Institute of France). Here a small  observatory was established for him.
 The French Academy of Science decided to send an expedition to the Southern Hemisphere. Lacaille was chosen in 1750.

Duties at Cape Town:
Measured the Earth-Mars distance: and Lacaille arrived at value equal to 131 500 000 km (81 710 310 mile). [Koorts; MNASSA, April 2004, p.36]
-Measure an arc of Meridian to prove the earth's shape  is oblate (flattened at the Poles)
-To establish exact longitude at the Cape
-Provide a reliable catalogue of the Southern stars to  aid navigation
-Magnetic variation studies
-Measure distances to moon & closer planets.
Lacaille arrived at Cape Town on the 19th of April 1751 [Forbes]

Lacaille's achievements while in Cape Town:
 Chartered positions of almost 10 000 stars (9 766), grading them  according to brightness. (Stoy, p.412.)
Catalogue  of Nebulae. In 1755 he dispatched to French Army a catalogue  of 42 nebulaes.
 Daily record of weather & tides.
 Regular magnetic observations.
 Fixed longitude of Cape by using observations of the satellites of Jupiter.
Measured height of Table Mountain. (Stoy, p.414.)
 He  drew up a number of constellations & named them. Some  of the constellations are still in use today. Titles are in a shortened form. "
Instead of the classical nomenclature of mythology, he used scientific instruments as the inspiration for his new titles.
Thus we have:
-Apparatus Sculptoris (the Sculptor's Tools)
-Fornax Chemica (the Chemical Furnace)
-Horologium (the Clock)
-Reticulus Rhomboidalis (the Rhomboidal Net)
-Caela Sculptoris (the Sculptor's Chisel)
-Equuleus Pictoris (the Painter's Easel)
-Pyxis Nautica (the Mariner's Compass)
-Antlia Pneumatica (the Air-Pump)
-Octans (the Octant)
-Circinus (the Compasses)
-Norma, alias Quadrans Euclidus' (Euclid's Square)
-Telescopium (the Telescope)
-Microscopium (the Microscope)
-Mons Mensae (Table Mountain)" [Copied from Moore, p. .37.]

 Measured  the
Arc of Meridian at Cape Town. He did painstakingly exact work and the results proved the earth to be pear shaped, i.e. round at the top and bulge out in the bottom half.
* (The arc of Meridian is important to determine the size &  shape of the earth. Scientists knew from measurements & Newton's  theory of gravity that the earth is round and a bit flattened  at the Poles). It took a scientist of equal repute i.e. Herschell & Maclear to discover the mistake Lacaille made. [The story  concerning the Arc of Meridian is to be found under the section Projects ]
"A subsequent check also showed that the tape he had used, was in error by nearly 10 cm." [Copied from Smits]

After Cape Town:
 Lacaille  left the Cape on 8th of March 1753 for Mauritius & later returned to France where he went back to the Mazarin College.
 Lacaille  deduced a number of important results from his trip to the Southern Hemisphere.  His contributions to science were against the  most valuable of 18th Century.

Formal education
Religious  title Abbe conferred onto Lacaille.
Measured coastline of France.
1739:  Measured Arc of Meridian in France.
Lecturer in Mathematics at Mazarin College in France
1751:  Sent to Cape Town to measure the Arc  of the Meridian in the Southern Hemisphere.
1753 (08 March): He left Cape Town for Mauritius
Lecturer at Mazarin College.

Born 1713 in Rumingy, Ardennes, not far from the Cathedral City of Rheims.
Died 1762 (Age 48)


Link to the Telescope Manufacturers.

Telescope 28 inches long. Half inch aperture.


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

Remaining artifacts:
Address:   Erected an observatory in the courtyard of the residence of Jan Laurens Bestbier, 7 Strand Street, Cape Town.
Several other prominent visitors also stayed here.
Photo of House [Moore p. 35, p. 40; Smits]
Plaque:  Designed by Sir Herbert Baker. Located in Cape Town Station?
Tape for measurement (Whereabouts?)
"A subsequent check also showed that the tape he had used, was in error by nearly 10 cm." [Copied from Smits
Piece of coal from a fire made by Lacaille kept at the Cape Observatory [Warner – Astronomers, p.50.]

Painting of Abbe De La Caille. (South African Library) [Moore p. 28.]
Two  sketches by C. Piazzi Smyth of La Caille's northern point. (South African Library) [Moore pp. 60 - 61.]


  • Amod A,, 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.
  • Forbes,  S., Some Scientific Matters in Early Writings on the Cape, A History  of Scientific Endeavour in South Africa, Royal Society of South Africa, 1977.
  • Glass, I.S.: “Nicolas-Louis de la Caille, Astronomer and Geodesist”, Oxford University Press, 2012. ISBN 978-0-19-966840-3
  • Koorts, W.: The 1882 transit of Venus: The British expeditions to South Africa; MNASSA April 2004, Vol. 63 nos. 3 & 4, pp. 34 - 57.
  • Moore, P. & Collins, P., Astronomy in Southern Africa, pp.28 - 43.  (General Source)
  • Smits  P.  A Brief History of Astronomy in Southern Africa. (Unpublished).
  • Stoy, R.H. Astronomy in South Africa, pp.409 - 426.
  • Warner, B., Astronomers at the Royal Observatory Cape of Good Hope.

By De La Caille:
Notebook:  University of Witwatersrand have a notebook.
Astronomae Fundamenta (Africana Museum)
Journal  Historique: 1763 (SA Library)
Coelum australe stelliferum (Paris, 1763).
Book based on his work published by British Astronomers after his death:  A catalogue of 9766 stars in the Southern Hemisphere: from the observations of the Abbe de la Caille: 1847.


-Lacaille's working notebook 1746-54 (Ref. A892) contains observations made at the Cape from 1751 April 19 to 1753 March 8. Also observations made elsewhere and a list of expenses in connection with his observatory at St Martin (Paris) in 1748. The results of his Cape observations  were published in Coelum australe stelliferum (Paris, 1763).

-Lacaille: Letter 1754 August 20 to M. de la Condamine, reporting  on his astronomical observations at the Cape (see Quarterly bulletin of the South African Library, vii (1952), 3-7).
-Lacaille: Historical journal of the voyage made to the Cape of  Good Hope (1750-53): typescript translation by Mrs E. Melck. Accompanied  by Notes and reflections upon Kolbe's work, by Lacaille.

 This is the principal depository for all the early Government records and thus contains official correspondence concerning the visits of Kolbe and Lacaille.

Maclear - Mann Papers (Accession No. 515): This extensive accumulation of manuscripts and correspondence are 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 relate 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 129 Fallows's observing books 1822-23. Copies of observations  1823- 24, 1828, 1829-31.


Related Internal Links:
Arc of the Meridian.

An authoritative book on a titled “Nicolas-Louis de la Caille, Astronomer and Geodesist” written by I.S. Glass will be published on 13 December 2012.


Interesting Links:
Link to Objects
Lost and / or Found.
Link to a short
History of Astronomy in Southern Africa.
Link to a
Time Line to see how Events on this page relates to the bigger time dimension.
Link to view the
Achievements and other Interesting Aspects of Southern African Astronomers.
Link to the
Telescope Manufacturers.
Link to the Main Bibliography Section and more information about Sources and the Archive.

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