Hartsoeker (or Hartsoecker), Nicolaas

(b. Gouda, Netherlands, 26 March 1656; d. Utrecht, Netherlands, 10 December 1725)

physics, technology.

Hartsoeker was the son of Christiaan Hartsoeker, an evangelical minister, and Anna van der Mey. Although his father wished him to study theology, Hartsoeker preferred science; he secretly learned mathematics and lens grinding. Most sources suggest that he may have studied anatomy and philosophy at the University of Leiden in 1674; a letter from Constantijn Huygens to his brother Christiaan, however, refers to him as having had no higher education, so it is possible that he was largely self-educated in his chosen fields. It is known that by 1672 he had visited Leeuwenhoek and that in 1678 he accompanied Christiaan Huygens to Paris, where he met some of the French scientists and worked for a time at the Paris observatory. In his correspondence with Christiaan Huygens from about this period, Hartsoeker claimed to have invented the technique of making small globules of glass for use as lenses for microscopes, but it is more probable that priority in this belongs to Johann Hudde.

In 1679 Hartsoeker returned to Holland, where he settled in Rotterdam and married Elisabeth Vettekeuken. He established himself as an instrument maker and wine merchant, but went bankrupt after a few years and returned to France. From 1684 until 1696 he lived in Passy, near Paris; here, with the assistance of his wife, he made lenses, microscopes, and telescopes, including some for the Paris observatory. He continued to study physics, and in 1694 published Essai de dioptrique.

In 1696 Hartsoeker was again in Holland, first in Rotterdam and then, the next year, in Amsterdam, where he gave instruction in physics to Peter the Great upon the visit of the Grand Embassy. He refused the czar’s offer of a professorship of mathematics at St. Petersburg, however.

The town council of Amsterdam had erected a small observatory for Peter’s use, and after his departure Hartsoeker was allowed to work there. It was there that Hartsoeker was visited by the count of Hesse-Kassel, to whom also he taught physics (Hartsoeker’s books Conjectures physiques and Suite des conjectures physiques contain these lessons). The count of Hesse-Kassel then used his influence to secure for Hartsoeker, in 1704, a professorship of mathematics and philosophy at the University of Dusseldorf. Hartsoeker was also accorded the title Hofmathematicus des Kurfürsten von der Pfalz und Honorar-Professor von Heidelberg. He remained in Dusseldorf until 1716, and then returned to Utrecht.

Hartsoeker’s career was further marked by his controversies with other scientists; as early as 1712 he had engaged in a dispute concerning the work of Leibniz, while as late as his years in Utrecht he debated the conclusions of Newton and Jakob I Bernoulli. His criticisms of Leeuwenhoek (contained in the posthumously published Cours de physique of 1730) are in large part ill-founded.

Of Hartsoeker’s lenses, two known to be by his hand are preserved, one signed “Nicolaas Hartsoeker, pro Academia Ludg. Batav: Parisiorum 1688” in the museum of natural history in Leiden, and the other in the museum of the University of Utrecht. It is known, however, that he had made three telescopes for the Utrecht observatory at the time of Pieter van Musschenbroek’s arrival in 1723.

In addition to his instrument work, Hartsoeker did research in embryology. In 1674 he recognized small “particles” in the sperm, which he at first thought to be signs of disease. Three years later he again saw these particles and showed them to Christiaan Huygens. As a result of his investigations, Hartsoeker believed that the fetus was preformed in the spermatozoon and published illustrations of the homunculus crouched there.

Hartsoeker was elected a foreign member of the Académic des Sciences in 1699 and was later also a member of the Berlin Royal Society. His work may be said to have been more honored in France than in his native Holland.

BIBLIOGRAPHY

I. Original Works. Hartsoeker’s books include Essai de dioptrique (Paris, 1694), trans. into Dutch by A. Block as Proeve der Deursicht-Kunde (Amsterdam, 1699); Principes de physiques (Paris, 1696), trans. into Dutch by A. Block as Beginselen der Natuurkunde (Amsterdam, 1700); Conjectures physiques (Amsterdam, 1706); Suite des conjectures physiques (Amsterdam, 1708); Éclaircissements sur les conjectures physiques (Amsterdam, 1710); Nova methodus utendi maximis objectivis (Berlin, 1710); Description de deux niveaux d’une nouvelle invention (Amsterdam, 1711); Suite des conjectures physiques et des éclaircissements... (Amsterdam, 1712); Seconde partie de la suite des conjectures physiques (Amsterdam, 1712); Recueil de plusieurs pièces de physique où l’on fait principalement voir l’invalidité du système de Mr. Newton... (Utrecht, 1722); and Cours de physique accompagné de plusieurs pièces concernant la physique qui ont déjà paru... (The Hague, 1730), which also contains “Extrait critique des lettres de feu M. Leeuwenhoek.”

For his work in embryology, see Proeve der Deursicht- Kunde, pp. 223-229; and N. Andry, De la génération des vers dans le corps de l’homme (Amsterdam, 1701), with two letters by Hartsoeker.

Poggendorff gives a list of Hartsoeker’s articles in various journals; many editions of the Oeuvres complètes of Christiaan Huygens contain Hartsoeker’s correspondence with him.

II. Secondary Literature. Christiaan Huygens’ collected works, above, include many references to Hartsoeker and his work. See also M. Daumas, Les instruments scientifiques (Paris, 1953); M. Rooseboom, Bijdrage tot de geschiedenis der instrumenmakerskunst in de noordelijke Nederlanden tot omstreeks 1840 (Leiden, 1950); and Levensbeschrijving van eenige voorname meest Nederlandsche mannen en vrouwen, II (Haarlem, 1794), 167-186.

J. G. van Cittert-Eymers