Valtoestel, Jan van Musschenbroek, 1722

V09630

Valtoestel

Gravesande, Willem Jacob 's (Ontwerper)‎, Musschenbroek, Jan van (Maker)‎, Poleni, Giovanni (Ontwerper)‎

1722 - 1722

Houten stellage met kleibak onderin Liniaal met houten schroef erdoorheenVoor doelstelling (vis viva- controverse) en verdere gegevens over dit instrument, zie Leids Fysisch Kabinet. De relatie Poleni/'s Gravesande wordt uitgewerkt in Maffioli (zie boven). Een vergelijkbaar valtoestel in Utrechts Universiteitsmuseum van de hand van Antoni Rinssen. Volgens de oude kaart zijn een verbindingslatje bovenaan (?!) en de losse liniaal met schroef (liniaal was gebroken, schroef ontbrak) bijgemaakt in 1955. Volgens Arch. 17, p. 20 ontbrak de liniaal al in ca. 1880.

Hoogte: 111 cm
Breedte: 37.5 cm
Diepte: 44 cm

One issue about which natural philosophers were very much divided in the early 18th century was the 'Force' (what we now would call Energy) of moving bodies. This issue is known as the vis viva (living force) controversy. The Englishman Isaac Newton was convinced that the 'Force' was proportional to the velocity (v) of the body. Quite another suggestion was made by the German mathematician and philosopher Gottfried Leibniz. He stated that the 'Force' was proportional to the square of the velocity (v2).

Professor 's Gravesande of the Leiden University was an adept of Newton and so he supported Newton's theory. A publication of his Italian colleague Giovanni Poleni inspired 's Gravesande to test the theory though. Therefore he designed this fall apparatus. 's Gravesande dropped several equally sized, but different weighted balls from four different heights. The balls fell into a layer of potter's clay. By measuring the depth of the impression, 's Gravesande could derive the 'Force'. After he had performed this experiment and realized its consequences, 's Gravesande exclaimed: 'So it was I who made a mistake'. For he derived the fact that the 'Force' was indeed proportional to the square of the velocity as Leibniz had suggested.

The fact that 's Gravesande revised a view he had reached rationally on the basis of experiments impressed the world of 18th-century science. In his inaugural lecture at Utrecht, Petrus van Musschenbroek called it an example of the importance of the experimental method in arriving at the truth.

Literature
W.J. 's Gravesande, Physices Elementa Mathematica (Leiden 1742), §833 and further, Tab. XXXII
Peter de Clercq, The Leiden Cabinet of Physics (Leiden 1989), pp. 28,29
Peter de Clercq, The Leiden Cabinet of Physics (Leiden 1997), p. 42

W.J. 's Gravesande, Physices Elementa Mathematica (Leiden 17423), par. 833 e.v. en Tab. XXXII, fig. 2-4
Peter de Clercq, Het Leids Fysisch Kabinet (Leiden 1989), p. 28-29
C.S. Maffioli, 'Italian hydraulics and experimental physics in 18th century Holland. From Poleni to Volta', in C.S. Maffioli and L.C. Palm, Italian scientists in the Low Countries in the 17th and 18th centuries p. 263 e.v.
H.J.M. Bos, Descriptive catalogue. Mechanical instruments in the Utrecht University Museum (Utrecht 1968), 46-48
Peter de Clercq, The Leiden Cabinet of Physics, a descriptive catalogue (1997), p. 42

03.01 Mechanica (onderwerp)
03.01.1 Dynamica (onderwerp)
Leiden; the Netherlands (geografie)

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