MAYER, CHRISTIAN

(b. Meseritsch, Moravia [now Mederizenhi, Czechoslovakia], 20 August 1719; d. Heidelberg, Germany, 17 April 1783)

astronomy.

Claims that Mayer studied Greek, Latin, philosophy, theotogy, and mathematics at Brno, Vienna, Turnau, Rome, and Würzburg have not been confirmed. The first authenticated fact about his life is his entering the Jesuit novitiate at Mannheim on 13 September 1745, after he had left home because his father did not approve of his decision. He subsequently taught languages and then also mathematics in a Jesuit school at Aschaffenburg, spending his evenings making astronomical observations. In 1752 he was appointed professor of mathematics and physics at Heidelberg University, and in 1753 his first physical work was printed there. He also published a series of mathematical and physical works at Heidelberg, but his main interest soon turned to astronomy.

In 1762 the elector palatine, Karl Theodor, who was very interested in the arts and sciences, constructed an astronomical observatory for Mayer at Schwetzingenu, his summer residence. In 1772–1774 a second and larger observatory was erected at Mannheim, then the capital of the electoral Palatinate, This observatory was well equipped for the time, with instruments from the best British workshops, A great quadrant by Bird was installed in 1775 and other instruments were made by Doltond, Troughton, and Ramsden; but Mayer did not live to see the observatory acquire all the instruments he had requested. Appointed court astronomer, Mayer was relieved of his duties as a theotogian (the Jesuit order was dissolved by Pope Clement XIV in 1773, which made such a step easier).

In the 1760’s Mayer participated in the measurement of a degree of the meridian, inaugurated by Cassini de Thury, visiting Paris and also executing the measurement of a geodetic base in the plain of the Rhenish Palatinate, He observed the transits of Venus across the sun in 1761 and 1769, invited to Russia for the latter by Catherine II. He also drew up a map of the Russian empire for her.

In 1776 Mayer turned to a branch of astronomy not previously investigated; the observation of double stars of all classes. Mayer could not distinguish between truly binary stars and those that are nearly on a line of sight from the earth but distantly separated in space. He made uncritical observations of all such apparent pairs and compiled a catalog of those that were near enough to be doubles in his sense of the word. The work was superseded in 1782 by W. Herschel’s catalog of double stars, but his pioneer work should not be forgotten.

Mayer became involved in a polemic with his colleagues, typical of the time and caused by his name for the double stars. In his lecture at the Mannheim Academy and in his first note published in a Mannheim newspaper in 1777, Mayer said he had discovered more than 100 satellites of fixed stars. This term was misunderstood and Mayer’s colleagues inferred that he was claiming to have discovered planets of other fixed stars. Today we speak of a companion of a fixed star, such as the companion of Sirius. But the contemporary astronomers, especially Hell, argued against Mayer’s observations—which marked the beginning of systematic observation and an important impetus to this new branch of astronomy.

Mayer’s reputation was unharmed by the quarrels. He was widely known and published his observations in various foreign journals—including the United States, an uncommon practice among European astronomers. He was a member of scientific academies and societies in London, Philadelphia, Mannheim, Munich, Bologna, and other cities.

BIBLIOGRAPHY

Mayer’s writings include Selecta physices experimentalis elementa mathematico-physica (Heidelberg, 1753); Disquisitio de momenta virium mechanicarum (Heidelberg, 1756); Basis Palatina anno 1762 ad normam Academiae Regiae Parisinae scientiarum exactam bis dimensa… (Mannheim, 1763); Solis et lunae eclipseos observatio astronomica, facta Schwetzinage in specula nova electoralia (Mannheim, 1764); “Obsersaiiones astronomicae,” in Phitosophical Transactions of the Royal Society (1764 and 1768); Ad Augustissimam Russiarum omnium Imperatricem Catarinam II. Aliexiewnam expositio de transitu Veneris ante discum solis d. 23 Maji anno 1769 (St. Petersburg, 1769); Nouvelle méthode pour lever… une carte generate exacte de toute la Russie… (St, Petersburg, 1770); Directio meridiani Palatini per speculam electorialem arcis aestivae Schwetzingenis ducti, observutionibus ef calculis definita (Heidelberg, 1771); Gründiche Vertheidigung neuer Beobachtungen von Fixstern Trabanten, welche zu Mannheim an der Sternwarte entdeckt worden sind (Mannheim, 1778); De novis in coeto sidereo phaenomenis, in miris stellarum fixarum comitibus Mannhemii detectis (Mannheim, 1779); and “Observationes astronomicae,” in Transactions of the American Phitosophical Society, 2 (1786), 34–41.

On Mayer and his work, see J. L. Kluber, Die Sternworte zu Mannheim (Mannheim, 1811 K 58–59; and W. Meyer, “Geschichte der Doppelsterne,” in Vierteljahrsschrift d. naturforschenden Gesellschaft in Zurich (1876), 695 ff.

H.-Christ. Freiesleben