250

ON LOCKS AND KEYS.

in one of the three notches of the principal bolt n s(fig. 106); but there is also a second set of notchese e in the gdchette g o (fig. 103) and a pin attachedto one of the plates of the lock fits into one of

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Sfet

Fig. 105.—Another view of the same.

these notches, thereby preventing the bolt frombeing moved until the gdchette is lowered by therevolution of the key ; so that in attempting to pick

Fig. 100—The two holts detached.

this lock, not only must the spring h be raised soas to release the stud from the notches of the greatbolt, but the gdchette must be lowered to disengagethe fixed pin from the notches. There is yet athird source of security. Attached to the largebolt are short projecting pins f (fig. 103) against