Page:Popular Science Monthly Volume 22.djvu/169

Rh shown in Fig. 1, representing a back view of the clock-train. The crutch-axis, supported by the arm (c) and the back plate (b) of the clock-train, carries an arm (e), attached at f to the left-hand pallet arm. The pallets are carried by the crutch-rod (d). At gis attached a detent projecting toward the left and ending in a light curved



spring. Near the top of the escape-wheel this detent carries a jeweled pin which locks the wheel. The action is as follows: When the pendulum swings toward the left, the arm (e) lifts the delicate spring at the end of the detent, the wheel is released and drops forward so that a tooth presses against the face of the pallet and gives an