Читать книгу The Modern Clock. A Study of Time Keeping Mechanism; Its Construction, Regulation and Repair онлайн

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This soldering makes the lower section and the zinc practically one piece and without loose joint, and the next joint is that made by the pin pinning the outside bar and the zinc together. This is necessarily formed this way, as in this stage of the operation we do not know just what length the zinc bar will be to exactly compensate for the expansion and contraction of the balance of the pendulum. By the changing of the pin into the different holes, 5, 6, 7, 8, 9, 10, ssss1, the zinc is made relatively longer or shorter, and so a compensation is arrived at in time after the clock has been running. After it is definitely settled where the pin will remain to secure the compensation of the rod, then that hole can have a screw put in to match the three upper ones. This screw must be tapped into the front bar and the zinc, and be very free in the back bar to allow of its expansion. It is supposed that in this example given of a zinc and steel compensation seconds pendulum that there has been due allowance made in the lengths of the several bars to allow for adjustment to temperature by the movements of the pin along the course of the several holes described, but the zinc is a very uncertain element, and its ultimate action is largely influenced by its treatment after being cast. Differences of working cast zinc under the hammer or rolls produce wide differences practically, and therefore materially change the results in its combination with iron in their relative expansive action. Wrought zinc can be obtained of any of the brass plate factories, of any dimensions required, and will be found to be satisfactory for the purpose in hand.