SCHUMACHER, HEINRICH CHRISTIAN

(b. Bad Bramstedt, Holstein, Germany, 3 September 1780: d. Altona, Germany, 28 December 1850),

astronomy, geodesy.

Schumacher was the son of Andreas Schumacher, a magistrate, who died when the boy was nine. Schumacher was then placed under the care of a minister named Dörfer at the Lutheran church of Altona. He attended the Gymnasium at Altona, where he was introduced to mathematics, astronomy, and the use of astronomical instruments: studied jurisprudence at the universities of Kiel and Göttingen: and was awarded the LL.D. at Göttingen in 1806. In 1805 – 1806 he was a Dozent at the Faculty of Law of Dorpat and wrote two legal treatises. It was at Dorpat that Schumacher’s interest in astronomy was revived by J. Pfaff.

In 1807 Schumacher obtained a salaried position at the University of Göttingen and studied astronomy under the direction of Gauss. His firm friendship with Gauss, begun at this time, was lifelong. From 1808 to 1810 Schumacher studied mathematics in Hamburg and translated Lazare Carnot’s La gémétrie de position. J. G. Repsold gave Schumacher access to the observatory at Hamburg, where he made a series of observations that served as the basis of a new star catalog.

In 1810 Schumacher was named extraordinary professor of astronomy at the University of Copenhagen; but he did not assume the duties connected with this post until after Thomas Bugge’s death in 1815, serving in the meantime as director of the observatory at Mannheim (1813 – 1815). In 1817 the Danish government released Schumacher from his duties so that he could take part in the geodetic survey of Schleswig and Holstein.

During the years 1800– 1825, the mapping of territory was in progress in many European states including Holland, Prussia, Hesse, and Bavaria. The work simultaneously in progress in many centers had to be coordinated. Schumacher was involved in the measurement of a degree between Skagen and Lauenburg, and also in the determination of the longitude along the arc between Copenhagen and the west coast of Jutland.

In 1821 Schumacher was appointed to direct the survey by the Royal Danish Academy of Copenhagen. In the same year the king, Frederick VI, arranged for the building and equipping of the observatory at Altona, where Schumacher worked for many years. His determination of the base line for the measurement of a degree between Skagen and Lauenburg was a masterpiece of accuracy and was in almost perfect agreement with the Hannoverian measurement by Gauss and the Hessian and Bavarian triangulations. Bessel used Schumacher’s results in his calculations of the figure of the earth.

Schumacher rendered considerable service to astronomers of his day by the institution of various publications. Between 1820 and 1829 he published astronomical ephemerides and auxiliary tables in a form that did not necessitate reduction calculations. From 1829 the Berliner astronomisches Jahrbuch, edited by Bessel, continued to publish similar tables. In 1823 Schumacher edited the first volume of Astronomische Nachrichten, a journal to which astronomers of all nations could contribute. The founding of this journal, which is still published, is perhaps his greatest contribution to astronomy. He was at the center of a lively correspondence with the leading astronomers of his day, including Gauss, Olbers, and Bessel.

In conjunction with the English Board of Longitude, Schumacher in 1824 determined the difference in longitude between the observatories of Greenwich and Altona, using English and Danish chronometers. In 1830 he determined the length of a seconds pendulum at the castle of Güldenstein in Holstein, and between 1837 and 1839 he carried out experimental work for the Danish government on a comparison of the most important legal units of weight. Schumacher continued his topographical work until 1837, when the preparation of maps was taken over by the army.

Schumacher was elected to the Royal Society of London in 1821, and his portrait by H. Wolf was presented to the Society by the artist in 1847. Schumacher was honored by the Danish kings Frederick VI and Christian VIII.

BIBLIOGRAPHY

I. Original Works. Sixty-four titles of papers and scientific writings by Schumacher are listed in the Royal Society Catalogue of Scientific Papers, V. 576–577. See also Poggendorff, II , cols. 866 – 867.

II. Secondary Literature. A biographical account of Schumacher is given in a lengthy obituary by C. F. R. Olufsen in Astronomische Nachrichten, 36 , supp. 864 (1853), cols. 393–404. Further biographical information appears in English Cyclopaedia, Biography Div., V (London, 1867). 343; Allgemeine deutsche Biographie, XXXIII, 32–33; and Dansk biografisk Leksikon, XXI, 429–432.

Sister Maureen Farrell, F.C.J.