n
of the fork standing at the bank. The ruby pin
o
touches it, but has not as yet acted on it;
s s
illustrates a single roller, while
S2
illustrates the safety roller for a double roller escapement. In order to find the dimensions of the crescent in the single roller we must proceed as follows:
WA
is in the center of the fork when it rests against the bank, and is, therefore, one of the sides of the fork angle, and is drawn from the pallet center;