This is a book review of Een Passie voor Precisie by Rob van den Berg.
Een passie voor precisie: Frederik Kaiser (1808--1872) Vader van de Leidse Sterrewacht, by Rob van den Berg (Prometheus), 2022. Pp. 383, 23 × 15 cm. Price ¤30.00 (paperback, ISBN 978 90 446 5147 8).
This is a book written by a historian of science from Leiden. At the same time, the text is well written and not at all in a dry, scholarly tone — the best of both worlds. While German astronomers such as Bessel and Gauß are perhaps better known, Kaiser played a similar role in the Netherlands, where he was clearly the leading astronomer of his generation. Astronomy at the time was concerned mainly with stellar surveys, astrometry, Solar System bodies, and binary stars; quantitative astronomical spectroscopy was just getting underway towards the end of Kaiser's life, as was astrophotography (of which Frederik Kaiser's son Pieter Jan Kaiser was a pioneer.) The book covers Kaiser's science, his personal life, and the astronomy of the time. After a sketch of the family history, van den Berg gives us some background on pre-Kaiser astronomy in the Netherlands.
Kaiser got off to a good start, managing to qualify for university studies by passing exams in Latin and Ancient Greek in 1830, enrolling in the faculty of mathematics and natural science on 15 February 1831, and getting married less than three weeks later to Aletta Rebecca Maria Barkey (1805--1872). They had a daughter in 1832 and a son in 1834, just after Kaiser had graduated magna cum laude. Another son was born in 1836 and twin sons, including Pieter Jan, in 1838. Scientifically, Kaiser attained significant fame due to his calculation of the orbit of Halley's comet, which had returned in 1835, making the necessary observations from his own house with a borrowed telescope. He then set about improving the observatory and its reputation by obtaining better instruments, corresponding with and visiting (during a "grand tour") German astronomers, and settling down on various observational programs: apart from the typical mid-nineteenth-century areas mentioned above, observations of planets and Saturn's rings (which at the time some believed to show short-term changes in structure) were important. Kaiser often had better results even though others had better instruments; his value for the period of rotation of Mars differs from the currently accepted value by only a tenth of a second, a feat which requires both precise observations and precise time-keeping. Kaiser was active in learned societies and as a popular-science writer, both of which led to astronomy being more highly regarded in the Netherlands. Astronomy was of course important for navigation, and Kaiser was involved in constructing better maps of Indonesia and, within the framework of a large European project, with measuring the precise shape of the Earth. Even more so than with respect to the bread-and-butter astronomy which Kaiser did so exactingly (while expecting similar precision from those who worked for him, which gave him a reputation for being difficult), van den Berg addresses the scientific, political, and personal aspects of Kaiser's involvement with those projects. A monument to Kaiser's effort is the then-new Leiden Observatory, finished in 1860 (the old one being in the Academiegebouw). Kaiser was also admired as a teacher, from popular-science talks to post-graduate students, his influence extending beyond astronomy as well. Among his students were van der Waals and Lorentz (who are so famous that first names are not needed to identify them); Lorentz's wife was also Kaiser's niece.
Kaiser's professional and personal life and the astronomical community in the Netherlands in particular and in Europe in general are covered well, and also documented well: the endnotes comprise sixty-three and the bibliography twenty-two small-print pages. The main text, containing occasional quotations from documents of the time, reads almost like a novel (that's a compliment) and is self-contained (but with more information available via the endnotes and references). The book represents a huge amount of work which is very well presented and should be valuable for all with an interest in mid-nineteenth-century European astronomy (and who can read Dutch).