[The Horological Journal. Vol. XXI (?), No. ?? (January, 1879): 58-59.]
(Continued from Vol. XX.)
[In the original, all of the figures were collected on, and comprised, page 59. Here they are reproduced first at a reduced size and inserted into the text, for ease of reference, and later again at full size.]
Fig. 1 - Lebon's Train Remontoire [reduced size]
LEBON'S (I.) train remontoire is a specimen of the very old style in which the striking train supplies the going part with motive power by re-winding a weight in connexion therewith every time the clock strikes. In fig. 1, B is that weight, E the wheel of the going part which it drives through the medium of C, and D the wheel of the striking part. The lever from which B hangs carries the wheel C on a stud, and is movable about A. The dotted lines show the arc which the lever describes.
In this arrangement there is no check against D being moved too often. THIOUT therefore gives the following (fig. 2) to avoid that danger: the maintainer B, instead of being re-wound directly by D, as in fig. 1, is actuated by the lever catch I K L, movable about L, and hinged at K. The disc M N represents D in the former arrangement, and one of its pins will act on I K L, and pull E round by the ratchet F; E, which is fixed to F, thus arms B by winding up C, and will continue to do so until arm O on the lever pushes the catch at I out of connexion with the ratchet F; whenever, and as long as that is the case, M N can turn without any effect on the maintainer.1
Fig. 2 - Thiout's Improvement [to Lebon's train remontoire] [reduced size]
[Note: Figures 3, 4, and 5 are covered by a single caption, "Figs. 3, 4, and 5. - Wagner's Constant Force Escapement" as show in the fragment below. However, Fig. 5 is actually of an escapement by Detouche and Houdin. The "Fig. 5" referred to in the text is actually the lower portion of Fig. 4. This is noted in the February 1979 installment, where this figure is again shown.]
[Caption for Figs. 3, 4, and 5] [reduced size]
Fig. 3 shows a constant force escapement exhibited by WAGNER in 1855, and figs. 4 and 5 details of the same escapement enlarged;2 [Note: Fig. 5 is not of Wagner's escapement, but instead is of an escapement by Detouche and Houdin, as noted by Frodsham in the February 1879 installment. The "Fig. 5" of the text is actually the lower portion of Fig. 4 here.] B top of pendulum with two arms b and b'; P chops to make the pendulum swing from the same centre as the maintainers j K n (and j' K' n'), and the arms m p and m' p' all having their centre of motion at j; the train locking is by a pin-wheel (of which only four pins f e i a are shown) on jewelled pallets h q. The piece D' D is part and parcel of Z, and carries at each extremity an adjusting screw g' g, the maintainer falling upon one of these at the end of each impulse, allows a pin to slip off the opposite pallet of Z, the train moves forward a space, and the next pin lifts the other pallet, thereby arming the maintainer by lifting it up and locking it on catch v u b, which m p carries at its end: v u b also serves to hold m p suspended free of the pendulum between impulse and unlocking by the arm b catching on a pin on X (X is a fixture to the plate) because v is banked by pin y.
The train being locked by pin i on h, and the right-hand maintainer armed, the pendulum having completed its excursion to the right, begins to descend, impulsed by the weight of K, until b comes in contact with the pin on X; v is thus withdrawn from n, and the next moment m p is locked up immovabl,e, and the connexion of the mechanism with the pendulum completely cut off; K, free to fall, actuates g; i, released from its detent, lets escape wheel lift q by pin i, and e arms the left-hand maintainer and locks on detent of q.
[Fig. 3.] - Wagner's Constant Force Escapement [reduced size]
[Fig. 4.] - Wagner's Constant Force Escapement [reduced size]
[Fig. 5. - escapement by Detouche and Houdin mislabelled as Wagner's] [reduced size]
[Here are the full-sized versions of the figures.]
Fig. 1 - Lebon's Train Remontoire
Fig. 2 - Thiout's Improvement [to Lebon's train remontoire]
[Fig. 3.] - Wagner's Constant Force Escapement
[Fig. 4.] - Wagner's Constant Force Escapement
[Fig. 5. - escapement by Detouche and Houdin mislabelled as Wagner's]
[Caption for Figs. 3, 4, and 5]
[Footnotes to the January, 1879 installment. In the original these footnotes were, unlike many previous installments, numbered.]
1 Thiout's "Traité de l'Horologerie," vol. ii. p. 206. Paris 1741.
2 "Revue Chronométrique," vol. i. p. 209. Figs. 4 and 5 are photo-zincographed from figs. 12 and 13, plate ii., same vol.
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