| Description | A diagram of Main's 'testing machine', constructed by Herr Ingenieur Usteri-Reinacher of Zurich. Parts of the diagram are labelled A-N. Main describes the machine in the accompanying paper: 'It was on the compound lever principle, the ratio of the arms of the equivalent simple lever being 1:20. All parts where friction could be prejudicial were provided with knife-edges. The design of the machine is obvious from the figure, in which A represents the specimen of ice to be tested, held by the collars at B and C. D is an equipoise, to balance the weights of the levers and of the vessel E, through which the power is applied by means of shot. E is a hand-wheel fixed to the screw G, by means of which, as the specimen extends, the under collar C may be lowered, so that the position of the upper collar B and of the two levers may remain the same. An index at H shows when the parts of the instrument are in the relative position required, and by its motion enables a rough estimate to be formed of the extension of the specimen. The temperature was rendered more equable by enclosing the apparatus in two wooden boxes, KL and MN. A delicate thermometer, graduated to tenths of a degree centigrade, and reading from —6° C to -+-6° C, was attached to the central wooden pillar, which, supports the upper lever.'
Subject: Physics / Scientific apparatus and instruments
A print of this diagram was published in volume 42 of the Proceedings of the Royal Society alongside the paper 'Note on some experiments on the viscosity of ice'. |