ESCAPEMENT LEVER—Invented by Thomas Mudge about 1765. It is the preferred escapement for watches because of the certainty of its performance. Possibly inferior to the chronometer escapement as a timekeeper. Its most noticeable defect is the necessity of applying oil to the pallets, the thickening of which affects the action. There are many other kinds of lever escapements. The Mudge escapement was essentially like the modern Double Roller. The connection between the balance and the escape wheel is made by a lever to which the pallets are fastened, and into the forked end of which plays the ruby pin which is carried on a roller on the same staff as the balance. Each pallet has an impulse face and a locking face. The impulse is given by the escape wheel tooth striking the impulse face of a pallet and is communicated to the balance by the lever, raised by the pallet's movement striking the ruby pin in the roller. This ruby pin also serves to unlock the pallets by causing the lever to lift them in turn. This escapement is of the detached type. The action of the lever is kept within the desired limits by banking pins. ESCAPEMENT, LEVER—CLUB TOOTH—An escapement like the Table Roller in the action of the lever and roller, but differs in the pallet action. The impulse planes are partly on the teeth and partly on the pallet. This is the standard watch escapement of today. ESCAPEMENT, CRANK LEVER—An escapement with a small roller having a tooth like a pinion leaf projecting from its circumference. This tooth acts in a square notch cut in the end of the lever. The lever is formed like a fork the two points of which act as safety pins against the edge of the roller to prevent the lever from getting out of action with the roller. It necessitated very careful construction and was not so good as the Double Roller or Table Roller. [Illustration] ESCAPEMENT, LEVER—DOUBLE ROLLER—This escapement has two rollers on the balance staff, the large one carrying the balance staff and the small one used for a safety roller only. The best form of lever escapement but more delicate, expensive, and difficult to make than the Table Roller; hence not so much used as the latter. ESCAPEMENT, PATENT DETACHED LEVER—Introduced in 1766 by Thomas Mudge, but neglected for years thereafter even by Mudge himself. It was in some of its parts the model of the best form of lever escapement—the Double Roller. The first pallets had no "draw" on the locking faces which rendered the escapement peculiarly sensitive to jolt and jar. This may have suggested to Mudge the addition of the small roller, whose worth has been since unquestionably demonstrated. ESCAPEMENT, LEVER—PIN-PALLET—A lever escapement with round pins for pallets, and the inclines on the escape teeth. Used in alarm clocks.