Anna Winlock

Quick Info

15 September 1857
Cambridge, Massachusetts, USA
4 January 1904
Boston, Massachusetts, USA

Anna Winlock was the daughter of the mathematician and astronomer Joseph Winlock and, following his death, was employed as an assistant at the Harvard College Observatory. She did outstanding work as a computer and gained fame computing the orbit of an asteroid discovered in 1901.


Anna Winlock was the daughter of Joseph Winlock (1826-1875) and Mary Isabella Lane (1832-1912). Joseph Winlock was a mathematician and astronomer who had been appointed Superintendent of the American Nautical Almanac and had begun working at the American Nautical Almanac Office in Cambridge, Massachusetts two weeks before his marriage to Isabella Lane on 9 December 1856. Isabella Lane had been born on 6 May 1832 at Palmyra, Marion, Missouri, USA, to parents George Washington Lane Sr (1790-1841) and Frances Tolson Adams (1792-1844). Joseph and Isabella Winlock had six children: Anna Winlock, the subject of this biography; William Crawford Winlock (1859-1896); Louisa Winlock (1860-1916); George Lane Winlock Sr (1862-1948); Isabella L Winlock (1865-1926); and Mary Peyton Winlock (1867-1942). Let us give a few details of Anna's siblings before continuing with her biography.

William Crawford Winlock made observations of the force of gravity for the United States Coast Survey, then graduated from Harvard University in 1880. He was then employed at the United States Naval Observatory in Washington. He spent the years from 1889 working for the Smithsonian Institute becoming assistant secretary. Louisa Winlock worked at Harvard College Observatory for 29 years from 1886 to 1915. She assisted her sister Anna Winlock and Mina Fleming with numerical computations. Mary Peyton Winlock was educated at the School of the Museum of Fine Arts, Boston in the 1890s. She became a master silversmith specialising in creating jewellery and serving pieces embellished with exquisite enamel work.

Joseph Winlock served in the role of Superintendent of the American Nautical Almanac from 23 November 1856 to 10 August 1859 and from 18 September 1861 to 1 May 1866. In fact in 1857 he had been appointed as Professor of Mathematics in the United States Navy and was an assistant at the Naval Observatory in Washington for several months. In 1859 he resigned as Superintendent of the American Nautical Almanac when he became head of the Mathematics Department at the Naval Academy at Annapolis, Maryland. The Academy moved to Newport, Rhode Island when the Civil War broke out in 1861 and at this point Joseph Winlock resigned and returned to the American Nautical Almanac Office in Cambridge, Massachusetts where again he became Superintendent.

Anna Winlock was three days past her fourth birthday when her father took up the role of Superintendent at the American Nautical Almanac Office in Cambridge, Massachusetts for the second time. In 1866, when Anna was ten years old her father became Phillips Professor of Astronomy at Harvard College and Director of the Harvard College Observatory. The next years went well for Anna. She attended schools in Cambridge, Massachusetts where she soon showed a talent for mathematics. Her father encouraged her education, being particularly keen to teach her some of the mathematical techniques in which he was expert. There was a total eclipse of the sun on 7 August 1869 and Joseph Winlock led a party to Kentucky to observe the total eclipse. Anna went with the observing party which set up their equipment in Shelby College in Shelbyville, Kentucky, where Joseph Winlock had studied and taught. While in Shelbyville, Kentucky, Anna was able to meet many of her father's cousins, sisters and aunts. This expedition was important for the excitement of seeing the eclipse while the hard work of the astronomers in observing it, gave Anna an understanding of what it meant to be an astronomer.

The 1870 census gives a picture of the family on 4 August of that year. They are living in a house in the grounds of the Observatory in Cambridge Ward 5, Middlesex, Massachusetts. Joseph Winlock, "astronomer," is the head of the family with Isabella, his wife, "keeping house." Their children, Anna Winlock (aged 12), William C Winlock (aged 11), Louisa Winlock (aged 9), and George L Winlock (aged 7) are all "at school." Their youngest two children, Isabella L Winlock (aged 4) and Mary P Winlock (aged 2) are both "at home." Also living in the house are three domestic servants, all born in Ireland, Bridget Henry, Ellen O'Brien and Ann McCormick. Joseph McCormick, Ann McCormick's sixteen year old son who is "at school," is living with them. The final person listed as living in the house is Arthur Searle (1837-1920), an astronomer born in London, England, appointed to the Harvard College Observatory by Joseph Winlock in 1868 and promoted to Assistant in the following year.

Anna Winlock continued her schooling in Cambridge, Massachusetts, at the High School showing her mathematical talents and also an exceptional ability in Greek [7]:-
It was not a common thing in those days for young girls to study Greek and at the time of graduation she received a letter from the principal expressing in the warmest terms his appreciation of her Greek and of her character.
Anna graduated in April 1875 but tragedy struck the family two months later when her father Joseph Winlock died. The Winlock family now had Isabella as its head with six children, the oldest being Anna aged seventeen. They were living in a house owned by the Harvard College Observatory which would clearly be required for the new director when he was appointed. Arthur Searle, who had married in 1873 and was no longer living with the Winlock family, was appointed as temporary director. The Observatory treated the Winlock family kindly, gave them plenty of time to find a new home and provided help for them to find the right house. Once this was achieved, the Observatory could no longer support them financially and so Anna decided to ask if the Observatory would give her a job as a computer.

William Augustus Rogers (1832-98) had been appointed to the Observatory in 1870. He had married Rebecca Jane Titsworth in 1857 and in 1875, before Anna Winlock approached the Observatory, Rebecca Rogers had been appointed by Arthur Searle, the temporary director, as the first female computer to assist her husband. The Observatory had vast amounts of data which needed to be reduced but had little in the way of funds to employ people to do the work. Employing women at a very low wage was a way to solve this problem. Anna Winlock was known to have considerable mathematical skills and she had been helping her father and had learned from him. When Anna asked if the Observatory could employ her, she was offered work at 25 cents an hour. This would be roughly equivalent to $7 an hour by 2023 values. She accepted and began working at the Observatory as a computer. Two computers were insufficient to handle Rogers' data and he asked the President of Harvard College, Charles W Eliot, if he could employ Rhoda G Saunders. Eliot agreed to the offer being made and on 23 November 1875 Rogers received Saunders' reply. He wrote to Arthur Searle four days later [26]:-
Will you have the kindness to engage Miss Saunders as a computer at the Observatory for one year at a salary of $600 a year.
By the end of 1875, therefore, Anna Winlock was one of three female computers at Harvard Observatory [46]:-
The first women who joined the Harvard Observatory staff in 1875 ... spent their days conducting mathematical calculations for the male astronomers who worked at the telescopes overnight. The women computers took the astronomers' observation notebooks and "reduced" the data recorded inside - averaging numbers, and correcting them for refraction, parallax, and error inherent in different instruments in order to record an object's absolute position in the sky.
Anna worked in the Computing Room at the Observatory which [21]:-
... was a specialised library, with rows of books that contained the tables and formulas [the computers] needed to perform their calculations.
By the time of the 1880 census the family are living in Langdon Street, Cambridge, Massachusetts, a road off Massachusetts Avenue. Isabella, now head of the family, is "keeping house" while Anna is an "assistant at the Observatory." William C has "no occupation," Louisa "lives at home", while Isabella L and Mary P are both "at school." Two of the three servants who were with the family ten years earlier, Ellen O'Brien and Ann McCormick, are both listed as "house servant." Also living in the same house were Price Lane and Ralph Lane, both nephews of Anna's mother, who aged 18 and 16 respectively; they were both "at school." The boys were from the Missouri family of Francis Adams Lane and his wife Emma Horner Price. Since Anna was the only wage earner in the household, we conjecture that the brothers Price Lane and Ralph Lane had gone to Cambridge for their schooling and their parents were contributing to the finances of the household. We note that the Massachusetts census was taken in June 1880 but by the time of the Missouri census in November 1880 both boys were back living with their parents in St Louis, Missouri.

Anna Winlock worked with the huge amount of data that Rogers had produced observing with a meridian circle which had been installed by her father Joseph Winlock. She [11]:-
... was often involved in meridian circle computations, which were for many years astronomy's most reliable source of positional information about stars. Meridian circles were telescopes which were locked into a position that could scan along the meridian (the great circle that runs through the celestial north and south poles, and the local zenith). Rather than chasing after stars, these telescopes waited for stars to pass over them, and took down information about the timing of that procession and the angles to the observed star. Taking that information and changing it into stellar positions was an intense process that Winlock mastered and employed over the course of nearly three decades of work, while simultaneously overseeing the thirty-eight-volume 'Observatory Annals', which collected tables of variable star positions and observations within star clusters.
Rogers and Winlock presented the joint paper A Catalogue of 130 Polar Stars for the Epoch of 1875.0 to the American Academy of Arts and Sciences on 16 June 1886. Although it was a joint paper, Rogers put the following note at the beginning [35]:-
Note by William A Rogers. - My connection with this work is limited to the methods of discussion adopted, and to an examination of the numerical results obtained. Beyond this, all the work in the preparation of this paper has been done by my assistant, Miss Winlock, and she is entitled to all the credit therefor.
Here are some extracts from the 63-page paper to give an indication of its content [35]:-
It is the purpose of the present paper to discuss the modern observations of such polar stars north of +7º declination as are found in the Harvard College Catalogue of 1213 Stars. Of the 130 stars in this list, 68 are found in the Fundamental Catalogue of Dr Auwers.

There will be no attempt to determine the proper motions of these stars, but the places determined for the epoch 1875.0 will serve a useful purpose in future discussions of this element. ... .

All the observations employed in this discussion will be reduced to the System of Publication XIV, of the 'Astronomische Gesellschaft', either directly through the medium of the fundamental stars common to the observed and the fundamental systems, or indirectly through the medium of the Harvard College Catalogue.

For many reasons, it was found advisable to construct a yearly ephemeris of each of the stars in the proposed list, extending from 1860 to 1885. For the fundamental stars of the list, the places for 1880 and for subsequent years were taken directly either from the catalogues of the 'Astronomische Gesellschaft' or from the 'Berliner Jahrbuch'. For the years 1871 to 1879 inclusive, they were obtained by applying to the yearly ephemerides of the Gesellschaft the corresponding corrections by which the provisional system is reduced to the system of Publication XIV.

For the places of the fundamental stars between 1860 and 1870, and for the places of all non-fundamental stars for the entire period between 1860 and 1885, the reduction-elements given in the Harvard College Catalogue were employed.

For stars below 85° north declination the development of α\alpha and δ\delta in terms of the first, second, and third powers of the time will be sufficiently accurate for the limit of fifteen years. For the reduction of stars near the pole, the problem becomes more difficult. Since the method of development by differential coefficients in terms of the ascending powers of the time has necessary limitations in its application, it has been thought advisable to give an illustration of the various methods by which the coordinates for any time t0t_{0} are reduced to those for any time tt'. The star Groombridge 1119 is selected for this purpose. The reductions for precession and for proper motion will be considered independently.
The second part of this paper will be comprised under the following subdivisions:-

(a) Treatment of the proper motion for close polar stars.

(b) Yearly ephemerides of all stars within 3° of the pole, between the limits 1860 and 1885.

(c) Tabular values of the terms UI,UII,UIII,UIV,UVU^{I}, U^{II}, U^{III}, U^{IV}, U^{V}, &c., carried as far as will be necessary to give the exact reduction for 40 years.

(d) Tabular values of the proper motions at intervals of 8 years for close polar stars, and at intervals of 20 years for all other stars.

(e) Data for the reduction of the different catalogues employed to the system of Publication XIV.

(f) Tabular values of the systematic relations between the catalogue of Publication XIV and the different catalogues compared.

(g) Final catalogues of 130 stars resulting from this discussion.

(h) Comparison of the final catalogue with the various catalogues from which it has been derived.

The review of the paper in the Sidereal Messenger ends as follows [1]:-

To show how the work was done, the necessary formulae are stated in order fully, and the tables of constants given, and then a single star Groombridge 1119, for epoch 1875.0, is taken as an example and its reduction shown in detail. The method of the paper seems excellent and complete, and is a credit to its authors. We shall look with interest for succeeding papers, in which will appear the discussion of other kindred topics named at the close of the one before us.
A number of observatories around the world had agreed to collaborate on producing a star catalogue, the 'Astronomische Gesellschaft Katalog', for the northern sky from the first to ninth magnitude. Harvard College Observatory was one of the observatories allocated a specific zone [10]:-
The results were published in phases between 1891-1896, and Winlock's dedication to the project allowed Harvard to be one of the first of the collaborating observatories to publish its portion of the project.
It was Winlock's calculations of the orbit of a recently discovered asteroid in 1901 which brought her to wide public attention; this asteroid is now named Ocllo. Pickering reported in the Harvard College Observatory Circular in 1901 [32]:-
From an examination of a plate taken on August 14, 1901, with the Bruce Telescope, Dr Stewart found an asteroid having the great southern declination, -62°. As no known asteroid was so far south at that time, a series of photographs was taken, from which, and from one previous photograph, the approximate positions ... have been derived. A circular orbit was first computed by Miss Anna Winlock. This gave the surprising result that the heliocentric diurnal motion exceeded 2200", corresponding to a distance from the Sun less than that of any known asteroid. As Professor Newcomb was spending a few days in Boston, he courteously undertook, with the assistance of Miss Winlock, to determine elliptical elements for this object. ... From these elements it appears that the great peculiarity of this orbit is the ellipticity, which exceeds that of any known asteroid. ... At the time of discovery the asteroid was near perihelion, and therefore was moving very rapidly around the Sun, at a distance of about 1.6. An approximate ephemeris for Greenwich Midnight ... shows that the asteroid is moving rapidly north, and is now within reach of the telescopes in Europe and the United States.
A consequence of this was a number of newspaper articles which made it widely known how Winlock and other women astronomers were doing important work. For example, see [8], [12], [18], [39], [44] and [45].

It is quite difficult to comprehend how Winlock managed to undertake such a vast quantity of work. Mary Byrd, in her obituary of Winlock in [7], does a good job of explaining what was involved; you can read the obituary at THIS LINK.

We should note that Mary Emma Byrd had studied astronomy at Harvard College Observatory in the 1880s and knew Winlock well. She was appointed Director of the Smith College Observatory and professor of astronomy in 1887.

Winlock worked at the Observatory up to 17 December 1903 although by that time she was feeling a little unwell but made light of it. Spending Christmas at home did not mean that she stopped work and she continued to make calculations and notes up to New Year 1904. Her death three days later at the age of 46 at her home, 59 Langdon Street, was totally unexpected. Her death certificate gives the cause of her death as "exophthalmic goitre," an autoimmune disease related to the thyroid gland. The certificate also gives "myocarditis with marasmus." Myocarditis is inflammation of the heart muscle and marasmus is a form of malnutrition.

Mary Byrd writes the following about Anna Winlock [7]:-
To friends and kindred she leaves a rich legacy simply by having lived. Her delicate sense of humour gave a very human touch to a nature too spiritual and too intellectual to be understood by all. Her gentle loving kindness veiled in part the power of her intellect. Doubtless many knew her without realising how far beyond the average were her powers of mind. She seemed not to realise it herself. For a little thing that others did she was prodigal with hearty praise while she quietly, but persistently ignored real achievements of her own.
Edward Pickering, the Director of the Harvard College Observatory, wrote [31]:-
Miss Winlock was the eldest daughter of Professor Winlock, the former director of the Observatory, and began her astronomical work soon after the death of her father in 1875. She assisted the late Professor W A Rogers in the reduction of his meridian circle observations, including those of the zone 49º 50' and 55º 10' north declinations, and after his death she took charge of the reduction of those still remaining unpublished. In addition to this work, she undertook many other contributions of importance, some of them belonging to the department of theoretical astronomy. Her care, efficiency, and good judgement were of great value to the Observatory.

References (show)

  1. A catalogue of polar stars, The Sidereal Messenger 6 (Carleton College Observatory, 1887), 157.
  2. Anna Winlock, Grupo de Estudios Peirceanos, Universidad de Navarra.
  3. Anna Winlock, Find a Grave.
  4. Anna Winlock, Cambridge Chronical (9 January 1904).
  5. Anna Winlock, in Biography Index. A cumulative index to biographical material in books and magazines. Volume 15: September, 1986-August, 1988 (H W Wilson Co., New York, 1988).
  6. Anna Winlock, in Women in World History. A biographical encyclopedia (Yorkin Publications, Waterford, CT, 1999-2002).
  7. M E Byrd, Anna Winlock, Popular Astronomy 12 (1904), 254-258.
  8. Camera Reveals New Asteroid: Phenomena of Solar Satellite Recently Photographed at Arequipa, The Washington Post (16 November 1901).
  9. A Commire, Anna Winlock, in Dictionary of Women Worldwide. 25,000 women through the ages (Yorkin Publications, Waterford, CT, 2007).
  10. E Coquillette, Anna Winlock, Wolbach Library. Supporting research about the Universe, Harvard University Library (2022).
  11. D DeBakcsy, Anna Winlock, in A History of Women in Astronomy and Space Exploration: Exploring the Trailblazers of STEM (Pen and Sword History, 2023), 72-73.
  12. Disciples of Hypatia: Women Engage in Astronomical Pursuits: America Has Many Who Observe, Classify, and Compute, New York Tribune (24 November 1901).
  13. C Elliott, Anna Winlock, in Biographical Index to American Science. The seventeenth century to 1920 (Greenwood Press, New York, 1990).
  14. T L Flood (ed.), Women as Astronomers, The Chautauquan. A monthly magazine, October 1891 to March 1892 Vol 14 (T L Flood Publishing House, Meadville Pa, 1892), 341.
  15. J Gibbons, Underpaid women "computers" mapped the universe in the 19th century, Smithsonian Insider (27 March 2018).
  16. D A Grier, When Computers Were Human (Princeton University Press, 2013).
  17. P A Haley, Williamina Fleming and the Harvard College Observatory, Antiquarian Astronomer 11 (2017), 2-32.
  18. Her Camera Caught Asteroid: Woman Astronomer Offers a Surprise to Scientists Which Interests Them, Brooklyn Daily Eagle (15 November 1901).
  19. E Holland, Edwardian Women In STEM: The Harvard Computers, Edwardian Promenade (12 September 2016).
  20. W J L, William A Rogers, A.M., Ph.D., President of the American Society of Microscopists, The Microscope. An Illustrated Monthly Designed to Popularize the Subject of Microscopy 7 (D O Haynes & Company, Detroit, 1887), 45-50.
  21. M Mazzotti and M G Ames (eds.), Anna Winlock, in Algorithmic Modernity. Mechanizing Thought and Action, 1500-2000 (Oxford University Press, 2023), 131.
  22. Miss Anna Winlock, Boston Transcript (Monday, 11 January 1904).
  23. Miss Anna Winlock, in The Register of the Kentucky Historical Society 2 (Kentucky Historical Society, 1904), 71.
  24. Miss Anna Winlock, in Annual Report of the Director of the Astronomical Observatory of Harvard College 1892 (Harvard College Observatory, 1892).
  25. P Murdin, Rock Legends. The Asteroids and Their Discoverers (Springer International Publishing, 2016), 84.
  26. D Nash, G Kass-Simon and P Farnes (eds.), Anna Winlock, in Women of Science. Righting the Record (Indiana University Press, 1993), 86-87.
  27. M B Ogilvie, Anna Winlock, in Women in Science : Antiquity Through the Nineteenth Century : A Biographical Dictionary With Annotated Bibliography (MIT Press, Cambridge, Massachusetts, 1986), 177-178.
  28. M B Ogilvie, Winlock, Anna (1857-1904),
  29. M Ogilvie and J Harvey, Anna Winlock, The Biographical Dictionary of Women in Science. Pioneering Lives From Ancient Times to the Mid-20th Century (Taylor & Francis, 2003).
  30. M Ogilvie and J Harvey, Anna Winlock, The Biographical Dictionary of Women in Science: L-Z (Routledge, 2000), 1388-1389.
  31. E C Pickering, Fifty-ninth Annual Report of the Director of the Astronomical Observatory of Harvard College for the year ending September 1904 (Harvard University, Cambridge, Mass., 1904).
  32. E C Pickering, An asteroid orbit of great eccentricity, Harvard College Observatory Circular No 63 (1901), 1-2.
  33. H L Reed, Women's Work at the Harvard Observatory, New England Magazine (April 1892).
  34. A Reser and L McNeill, Forces of Nature. The Women who Changed Science (Frances Lincoln , 2021), 128-129.
  35. W A Rogers and A Winlock, A Catalogue of 130 Polar Stars for the Epoch of 1875.0, Resulting from All the Available Observations Made between 1860 and 1885, and Reduced to the System of the Catalogue of Publication XIV of the Astronomische Gesellschaft, Memoirs of the American Academy of Arts and Sciences 1886, New Series 11 (4) (V) (1886), 227-299.
  36. W A Rogers and A Winlock, A Catalogue of 130 Polar Stars for the Epoch of 1875.0, Resulting from All the Available Observations Made between 1860 and 1885, and Reduced to the System of the Catalogue of Publication XIV of the Astronomische Gesellschaft, Memoirs of the American Academy of Arts and Sciences Centennial Volume 40 (John Wilson and Son, Cambridge, 1888), 227-299.
  37. W A Rogers and A Winlock, On the limitations in the use of Taylor's theorem for the computation of the precessions of close polar stars, The American Journal of Science 132 (1886).
  38. W A Rogers and A Winlock, Miscellaneous Observations, Preserving Harvard's Early Data and Research in Astronomy, Harvard College Observatory.
  39. The New Asteroid: Elliptical Elements Computed From Photograph Taken in Peru Last Summer, New York Times (16 November 1901).
  40. H H Turner and A A Common (eds.), Harvard College, The Observatory. A monthly review of astronomy 13 (Taylor and Francis, London, 1890), 251.
  41. Winlock, Anna,
  42. A Winlock, Absolute work. Meridian Circle observations 1879-1881, Preserving Harvard's Early Data and Research in Astronomy, Harvard College Observatory.
  43. Women and Stars: Many of the Fair Sex Skilled in Observations, The Topeka Daily Herald (8 January 1902).
  44. Women As Astronomers, The Nashville American (22 December 1901).
  45. Women Engaged in Astronomy: Good Work Done By Them Home and Abroad: Progress in the Science, The Washington Times (1 December 1901).
  46. L S Zrull, Women in Glass: Women at the Harvard Observatory during the Era of Astronomical Glass Plate Photography, 1875-1975, Journal for the History of Astronomy 52 (2) (2021), 115-146.

Additional Resources (show)

Other pages about Anna Winlock:

  1. Obituary by Mary E Byrd

Other websites about Anna Winlock:

  1. zbMATH entry

Written by J J O'Connor and E F Robertson
Last Update June 2023