& Sons Diamond Detector Lock Invented prior to 1856 7 Lever
4 1/2 x 4" Body Case.
Diamond Detector lock. The detector is fixed to the main bolt
and works upon a stiff joint If the levers are overlifted it
blocks the main bolt against a stump fixed in the lock-plate
preventing the bolt from being withdrawn. Mr.Duce(jnr.) is one
of a very few master locksmiths who worked at the vice and he
is considered to be a first class workman.