(b. Amsterdam, Netherlands, 10 June 1808; d. Leiden, Netherlands, 28 July 1872)
Known chiefly for his reorganization of the Leiden observatory and his work on the fundamental coordinated of stars, Kaiser was the son of Johann Wilhelm Kaiser, a teacher of German, and Anna Sibella Liernur. His father died when he was eight years old and his uncle, who educated him, died when he was fourteen. By than Kaiser had already published a computation of the occultation of the Pleiades by the moon. In 1831 he married Aletta Rebecca Maria Barkey, who bore him one daughter and three sons. Although Kaiser was given the name Friedrich at birth, he preferred the Dutch form, Frederik.
In 1826 Kaiser became observer at the Leiden observatory, but the instruments were inferior and his relationship with the director Uylenbroek was tense. Kaiser left the observatory in 1831 and in the same year graduated from the university. In 1835 he gained some prominence by calculating the orbit of Halley’s comet and predicting its return more accurately then any of his contemporaries. In the same year he was awarded a doctoral degree honoris causa by the University of Leiden. He became a lecturer in astronomy and director of the observatory in 1837, and three years later a professor. After years of strenuous observational work and a year–long campaign for a new observatory building, for which appreciable funds had been raised through a national subscription, he succeeded in inaugurating the new Leiden observatory (1861-1862), where the meridian circle was the main instrument. In planning this building he had been considerably inspired by the Pulkovo observatory; although he himself had never visited Russia, he acquired a detailed description of the Pulkovo observatory in 1854. (A history of the Leiden observatory and of the new building is found in Annalen der Sternwarte in Leiden, 1 , intro.) Kaiser’s staff was extremely small and he was overburdened by his administrative and teaching duties. Nervous and sensitive, he struggled throughout his life with bad health; he nevertheless continued to be productive and thorough in his work.
Kaiser is noted primarily for his observations and measurements of fundamental stellar positions; certainly the most precise made at that time, they became the basis for the international reputation of the Leiden observatory. Applying Bessel’s classical precepts, Kaiser carefully determined any errors in his instruments or observations. In volume 1 of the Annalen (1868) he fully explained his methods and recorded about 16,000 meridian observations of 190 stars, which were not fully reduced. The reduced declinations for those stars, used in European triangulation, and the results for the polar height at Leiden appeared in volume 2 (1869).
Kaiser also devoted special attention to the theory of the equatorially mounted telescope, to time determination, and to a critical investigation of Airy’s double-image micrometer. He advised the government on nautical instruments, becoming inspector of instruments for the navy, and on methods for position determination in the Dutch East Indies. For such purposes he invented the fluid compass and improved Steinheil’s prismatic circle, which was more precise than the sextant. Kaiser represented the Netherlands on the Commission for the Triangulation of Europe and played and important role in this enterprise (1864–1871). He made numerous drawings of Mars (1862, 1864) and of the comets 1861 (II) and 1864 (II) which were posthumously published in the Annalen volume 3 (1872).
Kaiser contributed in and important way to the diffusion of astronomical knowledge in the Netherlands by his popular book De Sterrenhemel, which had several editions; by his popular account of planet discoveries (1851); and by his Populair Sterrekundig Jaarboek.
I. Original Works. See Annalen der Sternwarte in Leiden, 1 (1868), 2 (1870), and 3 (1872). See also De inrigting der Sterrewachten, beschreven naar de Sterrewacht op den heuevel Pulkowa en het ontwerp eener Sterrewachtvoor de Hoogeschool te Leiden (Leiden, 1854); De Sterrenhemel (Amsterdam, 1843–1844), which had several eds.; De geschiednis der ontdekkingen van planeten (Amsterdam, 1859); and Populair Sterrekunding Jaarboek (Amsterdam, 1845–1863).
II. Secondary Literature. A biography and bibliography covering Kaiser’s career up to 1868 is found in Annalen der Sternwarte in Leiden, 1 (1868), intro. For a general biography and complete bibliography see J. A. C. Oudemans, Jaarboek van de K. akademie van wetenschappen gevestigd te Amsterdam (1875), pp. 39–104. Shorter biographies appear in Vierteljahrsschrift der astronomischen Gesellschaft, 7 (1872), 266–273, and Monthly Notices of the Royal Astronomical Society, 33 (1873), 209–211.
M. G. J. Minnaert