Fichet lock. - Lot 49

Fichet lock. Miniature model lock with anti-pick stripper and four acid-proof tumblers. The key measures only 2.73 cm, the shank has a diameter of only 2.5 mm and the lock is only 5.78 x 5.82 cm. France, circa 1829 The snitch is triggered by an attempt to pick the lock by raising one of the tumblers a little too high. It then blocks the bolt and the right key can no longer open it. This is how the attempt is signaled. To open, the right key has to "over-close" the bolt a little further, thus rearming the dislodger and allowing it to open. The tumblers are alternately made of steel and brass to resist tumbler-destroying acid attack. A simple hook was then all that was needed to open the door. It was assumed that a single acid could not eat away both steel and brass. Although unsigned, this lock and its key are the work of Alexandre Fichet in support of his patent n°3883 dated March 28, 1829, whose drawings show the key with the same ring and, above all, the same combination of sizes. It seems that this invention is a shameless copy of Jeremiah Chubb's patent registered eleven years earlier on February 3, 1818 under the name "detector lock", which won him the competition launched by the English crown for an un-pickable lock.