114 ANNUAL OF SCIENTIFIC DISCOVERY. 



application of force to the secondary tumblers, and unless the former 

 can be blown or drilled away, which many years' test has proved im- 

 possible, the lock stands impervious to any instrument except the 

 proper key. 



Another lock is so constructed that when the key-hole is open no 

 access can be had to the tumblers. When the key, which is merely 

 a series of bits without a pipe, is introduced, a knob is turned, which 

 revolves a disk inside the lock which covers the key-hole, and as it 

 revolves further, the key-hole remaining shut, uncovers the passage to 

 the tumbler. A cam on the spindle of the disk then lifts the bits and 

 carries them in contact with, and finally lifts the tumblers. The bolt 

 may now be withdrawn, and a further turning of the knob repeats 

 these operations in reverse direction and order, finally leaving the bits 

 under the now open key-hole in such a situation that they may be 

 withdrawn. It appears to me that this lock cannot be picked, and 

 that its construction is such as to bring into play the doctrine of 

 chances, which Bramah and Chubb have both claimed, fallaciously, 

 as being the true exponent of the difficulties of opening their locks 

 by other means than the true key. 



An improvement in the tumblers, or rather the manner of support- 

 ing the tumblers of the locks, has been patented. In ordinary tum- 

 bler locks, each tumbler moves in a certain determined plane and no 

 other, and must be moved by a pick or key to a fixed and certain 

 point, neither beyond it, nor short of it, before the bolt can be 

 moved. 



In the present lock each tumbler is free to swing, and can be 

 moved in many planes, but must be moved precisely to the right spot, 

 and in a certain plane, before the bolt can be operated. A lock-pick- 

 er must therefore, by repeated trials, find the proper plane of motion 

 of each tumbler, and, by some instrument, hold each in that plane, 

 before he can proceed to pick the lock in the ordinary manner. 

 It is evident that longer time and increased skill will be re- 

 quired to pick this lock, when contrasted with the ordinary tumbler 

 lock. 



A very curious, novel, and it appears, unpickable lock has also been 

 patented. The key-bit of this lock is composed of a series of closely 

 packed cylindrical disks of different sizes. The key-hole is a small 

 cylindrical cavity, closed at the bottom, and when open has no con- 

 nexion with the tumblers or any part of the interior of the lock. 

 The key-bit is attached to the handle by a spring connexion, and 

 when the operator introduces them and commences to turn the key, 

 the first operation of the lock is to separate the bit from the handle ; 

 as he turns, the former is carried in the cylindrical opening away from 

 the handle ; a solid metal block occupies the place of the cylinder ; 

 the key-hole is entirely closed ; the bit moves on and lifts the turn- 



V *> 



biers, and, by a continuation of the turning motion, the bolt is finally 

 retracted. A reverse motion of the handle shoots the bolt, drops the 

 tumblers, carries the key-bit beneath the handle, reattaches it thereto, 

 and, when the latter is withdrawn, the key aperture is again in its 

 place and exposed. 



