[The Horological Journal. Vol. ??, No. ?? (June, 1878): 130-131.]
[Note: Figs. 10 (Harrison) and 1 (Ulrich) originally were all contained on, and constituted, page 130.]
HARRISON'S TRAIN, FIG. 10.
[Note: In the August installment a correction is made, noting that "the fusee thread should have sloped the other way."]
ULRICH'S - FIG. 1.
(Continued from page 122.)
JOHN HARRISON'S Chronometer (continued), The wheel S S, see figs. 5 and 7, page 121 [May 1878], gears into a wheel of the same size on the second's arbor, which is in the centre in this watch.
Fig. 10 shows as much of the calliper as is necessary to explain the re-winding. T H, i.e., the third wheel, which is contrate with internal teeth, arms the maintainer by its action on pinion B, by winding up the drum to which is connected the eye of the maintainer spiral. The train locking, as will be seen, is at P; that of the maintainer is of course the escapement.
ULRICH'S1 (fig. 1) is of the entirely detached class, differing characteristically from previous examples in the arming of the maintainer, which is here effected by the double action of a pair of pallets (l, o, [Note: In the August installment a correction is made, noting that these two pallets "are to be read in the reverse order."] on the disc m, m, shown separately, fig. 2). Supposing the maintainer d to have given its impulse to the balance g, g, and unlock the train by releasing detent b, b, the scape-wheel a revolving, will first lift pallet o, and push the maintainer by means of the limb n under the detent e, f, pallet l then being lefted by the wheel, will take limb n out of the way and tense the spring; the arming thus effected, the scape-wheel a locks again on detent b b.
ULRICH'S - FIG. 2. [smaller version]
Fig. 3 is another arrangement of Ulrich's, elaborately described in his Specification, No. 5,639, A.D. 1825, to which, for want of space here, the reader desirous of details must be referred.
ULRICH'S - FIG. 3. [smaller version]
1 J. G. Ulrich's Specification, No. 5,136, A.D. 1825.
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