Willem Jacob \'S Gravesande

Willem Jacob “S Gravesande (born with Wood-the-Duke in 1688, died with Leyde in 1742) was a lawyer and diplomat of the United Provinces, impassioned by sciences and the experimentation. Large initiator of the experimental method on the continent, it studied the effects of gravity and the fall of the bodies and built a column to measure the effect machines (pulleys, winches, tilted plan).

He is 19 years old when he publishes a first work: Test on the prospect , which will be approved by Jean Bernoulli, and engages soon a collaboration with the Journal of the Republic of the Letters in which it is charged with the scientific chronicle.

When to the beginning of the year a 1700 controversy opposed Newtoniens and Leibnitziens on the causes of the movement of the stars, the Literary journal of $the Hague was one of the rare reviews to be made the echo in continental Europe of it. In a series of articles, “S Gravesande recalled to it in which terms the mathematical Principes of natural philosophy of Newton criticize the theory of the swirls of ether of Descartes. Then it exposed the refutation of Leibnitz ( Tentamen of motuum coelestium causis , 1689) of the Newtonian gravitation, and which rests on a correction of the theory of the swirls of Descartes.

In 1713, Newton publishes second version of its Principles mathematical of philosophy natural, where it answers those which criticize its theory of Gravitation, which rests in particular on the possibility of a remote action and, which more is, of an instantaneous action. The reception favorable of this new edition to the university of Leyde is the work of Hermann Boerhaave, large vice-chancellor. In 1715, 'S Gravesande accompanies in London, in the capacity as embassy secretary, the deputies of the General states of Holland charged to compliment king Georges 1st for its advent with the throne, and meets on this occasion several collaborators of Newton. Two years later, Boerhaave names it mathematics professor and of astronomy at the university of Leyde. At this station, it stresses the experimental character which the study of sciences of nature must take on. In this spirit, 'S Gravesande writes an adaptation of the Principes of Newton: mathematical Elements of natural philosophy drawn from the experiment . Newtonian and member of the Royal Society of London, it as well exposed to his students the doctrines of Descartes, Leibniz and Locke (prévalentes on the continent and particularly in France), that experiments of Galileo and Newton.

Its research on the shock of the solids suggests an experiment to him consisting in releasing copper balls since various heights (in order to vary the impact speed) on soft clay. According to Newton, the depth of the print left in clay is supposed being proportional to the impulse, i.e. with the bulk product of the ball by its speed; while according to Leibnitz, this print is proportional to the potentia motrix or “lifeblood”, i.e. with the bulk product of the ball by the square speed. However the experiment sliced in favor of this second assumption.

Among the many apparatuses which 'S Gravesande developed, it is necessary to distinguish:

the dilatometric ring, to measure the volumetric dilation of the solids,
the first heliostat (1720),
various pneumatic machines.

References

François Duchesneau, article Leibniz in traditional science (1998), ouvr. coll ED. by Mr. Blay and R. Halleux, Flammarion. ISBN 2-08-211566-6
K. Van Berkel, Newton in the Netherlands , Re-examined North - 1987, n°4, pp. 21-25

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