[Illustration: Fig. 160]
[Illustration: Fig. 161]
It was not until 1695 that the first dead-beat escapement appeared upon the scene; during the interval of over twenty years all thought had been directed toward the one goal, viz.: the perfecting of the verge escapement; but practice demonstrated that no other arrangement of the parts was superior to the original idea. For the benefit of our readers we shall give a few of these attempts at betterment, and you may see for yourselves wherein the trials failed.
Fig. 157 represents a verge escapement with a ratchet wheel, the pallets P P’ being carried upon separate axes. The two axes are rigidly connected, the one to the other, by means of the arms o o’. One of the axes carries besides the fork F, which transmits the impulse to the pendulum B. In the front view, at the right of the plate, for the sake of clearness the fork and the pendulum are not shown, but one may easily see the jointure of the arms o o’ and their mode of operation.
Another very peculiar arrangement of the verge escapement we show at Fig. 158. In this there are two wheels, one, R’, a small one in the form of a ratchet; the other, R, somewhat larger, called the balance wheel, but being supplied with straight and slender teeth. The verge V carrying the two pallets is pivoted in the vertical diameter of the larger wheel. The front view shows the modus operandi of this combination, which is practically the same as the others. The tooth a of the large wheel exerts its force upon the pallet P, and the tooth b of the ratchet will encounter the pallet P’. This pallet, after suffering its recoil, will receive the impulse communicated by the tooth b. This escapement surely could not have given much satisfaction, for it offers no advantage over the others, besides it is of very difficult construction.
[Illustration: Fig. 162]
[Illustration: Fig. 163]
Much ingenuity to a worthy end, but of little practical value, is displayed in these various attempts at the solution of a very difficult problem. In Fig. 159 we have a mechanism combining two escape wheels engaging each other in gear; of the two wheels, R R’, one alone is driven directly by the train, the other being turned in the opposite direction by its comrade. Both are furnished with pins c c’, which act alternately upon the pallets P P’ disposed in the same plane upon the verge V and pivoted between the wheels. Our drawing represents the escapement at the moment when the pin C’ delivers its impulse, and this having been accomplished, the locking takes place upon the pin C of the other wheel upon the pallet P’. Another system of two escape wheels is shown in Fig. 160, but in this case the two wheels R R are driven in a like direction by the last wheel A of the train. The operation of the escapement is the same as in Fig. 159.