72 x 35.5 x 14
Carved wood and stell
Index 1788 : E. V. 204
Elasterium simile capsula lignea inclusum, quae stylobate insistit: hic duabus columnis sustinetur basi lignea suffultus.
Similar spring included in a wooden box which is supported on a stylobate; the stylobate is held up by two columns maintained on a wooden base.
The essential and unique part of this machine, for experimental purposes, is an elastic spring. The rest is a wooden frame in which it is contained and which both beautifies it and makes it more convenient to use.
The copy in the Gabinete de Física in Coimbra consists of a wooden base over which sits a prismatic box with a rectangular section, inside of which the spring is suspended. To bottom end of the spring is attached to a cord, which extends along the interior of the box. A hook, intended to suspend the weights that will cause the deformation of the spring, is attached to the end of the cord.
The experiment would suggest that the deformations of the spring are proportional to the intensity of the force which causes them. This is ´s Gravesande's conclusion: a weight, weighing half a pound, stretches the spring half an inch; a second weight of half a pound provokes another stretch of another half-inch.
From Colégio dos Nobres, catalogue n.º 194.
Carvalho, Rómulo de, História do Gabinete de Física da Universidade de Coimbra, Universidade de Coimbra, Biblioteca Geral, Coimbra, 1978, pp. 369.
's Gravesande, Willem Jacob, Physices Elementa, Leiden, 1742, § 1337, tab. XLIV, Fig. 8.