Wargentin, Pehr Wilhelm
WARGENTIN, PEHR WILHELM
(b. Sunne Jämtland, Sweden, 11 September 1717: d. Stockholm, Sweden, 13 December 1783), astronomy, demography.
Wargentin seems to have been destined for science from his early years. His father, Wilhelm Wargentin, had devoted much time to scientific studies and had tried to obtain an appointment as professor of physics at the University of Dorpat before he had been called to a parish in northern Sweden. He taught his eager son the wonders of the skies at an early age, and in 1729 they observed a lunar eclipse. Wargentin continued his astronomical observations as a student at the Gymnasium in Härnösand; and after he entered the University of Uppsala in 1735, astronomy soon became his main interest. Initially, the competent observer Olof Hiorter was his teacher; but in 1737 Anders Celsius, professor of astronomy, returned from his travels and took Wargentin’s scientific development in hand. At Celsius’ suggestion Wargentin began to concentrate upon calculating the orbits of the moons of Jupiter; in 1741 he completed a work on this subject (De satellitibus Jovis), but the important tables were not published until 1746. Wargentin obtained his master’s degree in 1743 and remained at the University of Uppsala, where he was appointed assistant professor on the Philosophical Faculty in 1748. In the fall of 1749 he was offered the position of secretary of the Royal Swedish Academy of Sciences and moved to Stockholm to assume his new duties.
Wargentin was active in three fields: astronomy where Jupiter’s moons remained his specialty; population statistics, of which he is considered one of the modern founders; and the Academy of Sciences, which he served until his death.
Founded in 1739, the Academy of Sciences in Stockholm had already acquired stability and respect; but it remained for Wargentin, as its secretary and moving force for a generation, to extend its activities and to bring it into close contact with the international scientific community. Through it Wargentin became a central figure in the scientific flowering of Sweden in the mid-eighteenth century. He edited the Academy’s Transactions, published the Swedish almanac, for which the Academy had the license, and actively supported Sweden’s introduction of the Gregorian calendar in 1753. As the Academy’s astronomer he supervised the construction of its astronomical observatory in Stockholm, which was completed in 1753; the necessary instruments were obtained in London. During the international astronomical years, especially at the times of the transits of Venus of 1761 and 1769, Wargentin organized the Swedish effort and saw to it that the results obtained were immediately communicated to foreign astronomers for publication. His immense correspondence with foreign academicians and scholars—over 4,000 letters that he received have been preserved—constitutes an invaluable source for Swedish as well as European history of science.
Wargentin kept a careful journal of his observations from 1749 on. His main interest remained the moons of Jupiter, which he had begun studying in his youth. The first ephemerides of the satellites of Jupiter had been published by Gian Domenico Cassini in 1666. Although better ones were produced by James Pound and James Bradley in England and by Jacques Cassini in France in 1740, the irregularities of the satellites’ movements caused great problems and more exact calculations of the orbits were needed. Here Wargentin made a basic contribution. Working in a purely empirical and statistical manner, he collected a great number of trustworthy observations that he interpreted with intuitive certainty. They were first published as “Tabulae pro calculandis eclipsibus satellitum Jovis” in Acta Regiae societatis scientiarum Upsaliensis pro 1741 (1746).
Wargentin’s values were far more accurate than those of his predecessors, but he nevertheless continued his observations and calculations, which he communicated to Lalande, with whom he corresponded regularly. Wargentin’s revised tables of the satellites of Jupiter were published by Lalande in his enlarged edition of Tables astronomiques de M. Halley (1759); through new equations he had obtained improved calculations for the movements of the third and the fourth satellites. Wargentin continued to publish new contributions to this subject in Swedish and foreign scientific journals and until his last years he was engaged in improving the theory for the third satellite.
Among his contemporaries Wargentin was considered the outstanding expert in his field, and his tables of Jupiter’s moons remained authoritative until the improvement of mathematical analysis made possible exact theoretical solutions of the problems. And his empiricism, even when compared with modern theory, must be considered surprisingly reliable.
Outward circumstances led Wargentin to his other lifelong scientific occupation, population statistics. In 1736 it was decreed that the pastors of Sweden should collect yearly reports on births and deaths, and within the Academy of Sciences the idea grew that the collected material should be submitted to statistical analysis. In 1754 the authorities ordered Wargentin to assume this task. The Royal Table Commission, established two years later with Wargentin as the guiding power, was officially assigned to work with the deposited population tables.
In 1754 Wargentin began publishing his results in a series of demographic articles in the Transactions of the Academy. He used both the older and the contemporary pioneers in the field of population statistics (Graunt, Petty, J. P. Süssmilch, Deparcieux); but in his later works he surpassed them and showed a sure, methodical touch. In his most important article, “Mortaliteten i Sverige” (1766), he calculated the mortality rate for different groups in the community: men, women, all inhabitants of Stockholm. He also dealt with birth and mortality rates in different months, the population increase of Stockholm, and the total population increase of Stockholm, and the total population of the country. Wargentin may well have been the first to compile mortality tables based on exact figures. His results were of practical importance, especially for life insurance. Richard Price contacted Wargentin and then published the latter’s mortality tables in his Observations on Reversionary Payments (1783).
Wargentin received many scientific distinctions and in 1783, shortly before his death, became one of the eight foreign members of the Paris Academy. Although not noted for brilliance or innovation, he had a clear and penetrating mind, even when dealing with mundane matters, almost unlimited energy, and a strong moral integrity.
I. Original Works. Wargentin’s extensive writings in astronomy, population statistics, and other fields are scattered in many short articles, most of them published in Kungliga Svenska vetenskapsakademiens handlingar. His works on the moons of Jupiter are listed by Nordenmark (see below), 224–231. The Royal Swedish Academy of Sciences in Stockholm has his papers, including letters that he received (catalogued by Nordenmark, 425–449).
II. Secondary Literature. The basic biography is N. V. E. Nordenmark, Pehr Wilhelm Wargentin (Uppsala, 1939), in Swedish. See also Sten Lindroth, in Kungliga Svenska vetenskapsakademiens historia 1739-1818, 1 ; pt. 1 (Stockholm, 1967), 48–59, 411–416; and his “Pehr Wilhelm Wargentin,” in Swedish Men of Science (Stockholm, 1952), 105–112. On the moons of Jupiter, see Bertil Lindblad, “P. W. Wargentins arbeten över Jupitermånarna och modern teori,” in Populär astronomisk tidskrift15 (1934), 9–19. Wargentin as a population statistician has been treated (apart from Nordenmark) by A. R. Cederberg, Pehr Wargentin als Statistiker (Helsinki, 1919); and O. Grönlund, Pehr Wargentin och den svenska befolkningsstatistiken under 1700-talet (Stockholm, 1946).