Contribution of Swiss scientists in Watch Making Industry


The latter device is, to this day, the only one employed in all marine trigger chronometers manufactured in England as well as in Switzerland, Germany and the United States. Fig. 3 reproduces the layout after "Horology", the excellent work of MJ Eric HaswellI, published in 1928.

Arnold and Earnshaw both had to make, at the expense of the Admiralty, an enlarged model of their exhausts, during the investigations which the commissioners of the Board of Longitude were charged to judge their claims. We are happy to reproduce Earnshaw's model, thanks to the kindness of LieutCommander Gould, who was fortunate enough to find it at Greenwich Observatory.
This model, in very poor condition, could be identified among other ignored parts, in accordance with its description, published in 1806. The reconditioned escapement has since been used for demonstration purposes by the School of Porstmouth navigation.

It is also to Earnshaw that the method of manufacturing the bimetallic strips of the balancing balances, still universally employed, is due. While John Arnold separately executed the bimetallic blades, then welded the steel and the brass together, then arched them to the desired shape to screw them onto a diametrical arm, Earnshaw imagined forming the entire bimetallic balance by a process fusion.

He united the constituent parts of the bimetallic strip in the most intimate way, by first shaping a steel disc pierced in its center and making a circular cylindrical groove in it. The disc, loaded with shot-blasted brass and borax, was heated until the molten brass completely filled the groove, so as to form intimately one with the steel walls.
After cooling, Earnshaw put the disc back on the lathe, formed the ring of the bimetallic strip to the desired dimensions, after having hardened the brass coating; then he proceeded to cut out the diametral arm, and finally to drill the holes intended to receive the adjusting screws. He then cut his ring into two diametrically opposed regions, to obtain, after suitable annealing, two bimetallic blades each having a free end, the fixed ends being integral with the diameter bar itself.

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