Patent GB-190921843-A (GB)
Title: Improvements in Compensating Balances and Pendulums for Timepieces.
Inventor: ECAUBERT FREDERIC
IPC: G04B17/10
Filed: 1909-09-24
Granted: 1910-05-12
Abstract: 21,843. Ecaubert, F. Sept. 24. Balances; pendulums. -Relates to devices for compensating balances and pendulums for changes in temperature. All the arrangements described are provided with one or more members made of non-magnetic material having a very low coefficient of expansion, such as fused quartz or glass, which members are constantly subjected to a compressive force. Fig. 1 shows a balance in which weighted arms A are integral with spokes H of brass or other non-magnetic metal having a relatively high coefficient of expansion. Each arm tends to bend inwardly about the junction a so that it exerts an end-pressure on a rod L of quartz &c. held between the hub C and a point b near the spoke. When the spokes H expand or contract each arm A turns about a fulcrum, which is approximately the point b, so that the weights W approach or recede from the centre of the wheel, and the rate of oscillations is kept constant. The spokes may lie along the same diameter, in which case each spoke H may carry two weighted arms A, four corresponding rods L being provided; or, with only two arms A, the rods L may be nearly equal in length to the diameter of the wheel, Fig. 5. In another form, the wheel may have three spokes, a single member L, in the form of a triangular plate, being supported by the arms A at points b. Adjustable shoes may be provided in all cases at the points b, as supports for the members L. Fig. 4 shows a further modification, in which the expansible members H are formed as a triangular frame, to the corners of which the weight-bearing arms A are hinged. Each rod L of quartz &c. is interposed between an abutment 1 on the frame and a socket 9 on the hinged arm. Springs 7 exert an inward pull on the arms A by means of projections 8. For the purpose of adjusting the mass of the balance without disturbing the compensating action, a radially adjustable weight 10 may be provided at the " true fulcrum," as shown in Fig. 4; or auxiliary weights w, Fig. 5, may be provided on each weight W. In an application of the invention to a torsion-pendulum, the compensating action may be obtained by producing changes in the effective length of the suspending ribbon, Fig. 7. In this case, a forked lever A, which embraces the ribbon 13, is pivoted on a metal bar H and exerts a pressure on a rod L of glass &c. held between suitable sockets. Fig. 8 illustrates a pendulum in which weights W are carried by levers A hinged to a metal block B, which is attached to the torsion-ribbon 13. Each lever is supported by a rod L of glass &c., of which the lower end rests in a stirrup suspended from the block B by a differential-screw device. With this construction, any change in the length of the ribbon 13 is accompanied by a compensating movement of the weights W towards or away from the axis of oscillation. The same principle is applied in another arrangement in which two weights are supported by metal sleeves closed at one end, the sleeves being in alinement, with the torsion-ribbon centrally between them. The sleeves enclose a system of concentric tubes of glass or the like and metal, and are drawn together by a spring. A pendulum which vibrates in the ordinary manner, Fig. 13, comprises two steel rods 30 passing through glass tubes 35, the top ends of which rest in sockets 34 extending upwardly from a suspended yoke-piece X. A lower yoke Y, supporting the bob W by means of a screwed rod 39, is pressed against the lower ends of the tubes 35 by the action of springs 7 abutting against nuts 37 on the steel rods. With this arrangement, the distance of the yoke Y from the point of suspension is not affected by the expansion of the steel rods. In a simpler form of pendulum, a single steel rod is employed, in which case the rod, suspended by any suitable means, is surrounded by a tube of glass or quartz, and has a nut screwed on its lower end. A spring abuts against this nut, and presses the closed lower end of a sleeve, preferably of brass, upwardly against the end of the glass tube, the bob-weight being attached to this sleeve. The member made of glass &c., instead of consisting of a tube, may be a rod enclosed in a metal tube or having one or more metal rods alongside of it.