Wolferdus Senguerdius

Wolferdus Senguerdius (also Wolfgang Senkward or Wolferd Senguerd, 1664–1724) was a Dutch natural philosopher (physicist), jurist, author and librarian. At Leiden University he taught philosophy as a professor since 1675 and later was also librarian of Leiden University Libraries (1701 - 1724). Although he was appointed professor to defend the philosophy of Aristotle against the rising Cartesianism, he took an eclectic stance promoting the combination of experimentation and rational argument in natural science. He improved the design of the vacuum pump resulting in the Van Musschenbroek vacuum pump and with Burchardus de Volder pioneered public demonstrations of experimental physics.

Biography Born the only son of Arnoldus Senguerdius, a theology and philosophy professor at Utrecht and later at Amsterdam, Wolferdus Senguerdius studied law and philosophy at Leiden University starting in 1667.

He obtained a PhD doctorate thrice: firstly in 1666 at the Athenaeum Illustre of Amsterdam with the thesis Compendium physicae and as advisor his father Arnold Senguerdius, secondly in 1667 at Leiden University with Disputatio philosophica inauguralis de tarantula on tarantism related to the wolf spider Lycosa tarantula, with an unknown advisor. His third doctorate was in law at the University of Harderwijk in 1681. In 1669 Senguerdius obtained the right to teach and hold disputations at Leiden University. There he was appointed professor of natural philosophy in 1675.

He agreed with the atomists and Descartes that natural phenomena are caused by particles in motion, including gravity up to the Moon. But superlunary gravity was deemed impossible to investigate. He also denied the infinity of the universe and rejected the relativity of motion, but affirmed the existence of empty space. According to him, weight of air could not explain the effect of Otto von Guericke's Magdeburg hemispheres. Senguerdius was a staunch promotor of experimental natural science: according to him human reason by itself cannot understand nature, input from the senses is crucial. An experiment can imitate nature, also living bodies such as the breathing lung.

Although Senguerdius kept objecting to the Copernican system, he nevertheless as the librarian installed a Sphaera automatica in the university library in 1711. This was a heliocentric planetarium built in 1672 by Steven Tracey in Rotterdam, and Senguerdius encouraged its use in demonstrations. The planetarium was publicised in a special pamphlet, included in Senguerdius' 1716 university library catalogue, to promote Leiden University.

Improvement of the air pump Van Musschenbroek 1698 vacuum pump, designed by Wolferdus Senguerdius. Senguerdius' efficient new design of the air pump caused this instrument to become widespread in Europe with production ongoing into the 1770s. Senguerd improved on the air pump designs of Von Guericke, Huygens, Hooke/Boyle and Papin, resulting in a simple single barrel pump, which was initially produced by both Samuel and Johannes Joosten van Musschenbroek at Leiden, and later imitated in Britain, France and Germany. Jacob Leupold started a workshop in Leipzig and described his Senguerd air pump in his book Antlia pneumatica illustrata (1707).

Students Senguerdius' doctoral students, all at Leiden University, include:

CandidateThesisYearNumber of descendants 1690 53340 Johannes Colonius Disputatio philosophica inauguralis De fulmine 1681 John Gale Inquisitio philosophica inauguralis De lapide solis 1699 Pieter van Musschenbroek De aëris praesentia in humoribus animalibus (About the presence of air in animal bodily fluids), with co-advisor Herman Boerhaave 1715 2914

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Publications Senguerdius' publications include:

Natural philosophy Full text scan at Utrecht University Library. Full text scan at Bayerische Staatsbibliothek München. 432 pages.

58 pages. 328 pages. Includes Disquisitio de tarantula. Also

Library science Planetarium "Sphaera automatica" on p. 499,

Secondary literature

. On page 82. . Unpublished notes of Senguerdius' lectures by a student. Manuscript at Koninklijke Bibliotheek, The Hague. 105 pages.

460 pages. Pages 23–24, 28, 47, 119, 134, 162, 165.