TIME-KEEPING IN LONDON. 



157 



shown in Fig. 1,* representing a back view of the clock-train. The 

 crutch-axis, supported by the arm (c) and the back plate {V) 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 ^is 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 jew- 

 eled 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 im- 



* Figs. 1, 3, 4, 5, and 6, have been taken from Lockyer's "Stargazing," through the 

 courtesy of JIacmillan & Co., London, publishers, by permission of the author. 



