Duplex Dead Escapement

Various contrivances have been proposed for diminishing the amount of dead friction, such as having separate pallets for the dead part of the action, which are to be left behind by the pendulum as it advances beyond the angle of escape(c'), and carries the impulse pallets with it. It will be seen, when we come to remontoire escapements, why this plan is objectionable, besides the difficulty of constructing it. Perhaps it might answer to put a large and a small scape-wheel on the same arbor, and short and long pallets on the same pallet arbor, the small wheel to give the impulse on the long pallets, and the teeth of the large wheel to be stopped by the short pallets containing only the dead part, which however is to have a small recoil in it. In that case the impulse might be given through a small angle near the middle of the vibration; and the pressure which causes the dead friction would be less from a large wheel than a small one, and the space to be travelled over on the dead part of the short pallets would also be less than on long pallets; so that in every way there would be an advantage as regards friction. This may be called a duplex escapement, as it agrees with the escapement of that name in watches. It would require considerable accuracy in its construction, but not more than another, which I shall mention presently, as having been constructed, and at work. -A Rudimentary Treatise on Clock and Watch Making：With a Chapter on Church Clocks; and an Account of the Proceedings Respecting the Great Westminster Clock by Edmund Beckett Denison 1850