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. Later, Senguerdius was rector magnificus of Leiden University in the years 1685–1686, 1691–1692, 1701–1702, and 1715–1716. In 1701 Senguerdius was appointed university librarian as the successor of Friedrich Spanheim the Younger, and remained in function up to his decease in 1724.
Science and education Senguerdius rejected Copernicus' heliocentrism, instead opting for the solar system according to Tycho Brahe (Tychonic system) with still a stationary earth at the centre. The absence of a measurable stellar parallax was a crucial argument to reject a moving earth. Like Newton, Senguerdius also rejected the Cartesian solar vortex pushing the planets, because it was contradicted by the actual behavior of swirling liquids. However, Senguerdius preserved the immobility of the earth in a Cartesian celestial fluid. 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
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:
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Publications Senguerdius' publications include:
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