LOCKS 



141 



plate, and the barrel can be then turned.' Tomlinson on the Construction of Locks. 

 In this work the details of construction are given with great clearness. 



The American bank locks, especially that of Messrs. Day and Newall, have ex- 

 cited much attention. Their English patent describes it thus : 



' The object of the present improvements is the constructing of locks in such 

 manner that the interior arrangements, or the combination of the internal moveable 

 parts, may be changed at pleasure according to the form given to, or change made in, 

 the key, without the necessity of arranging the moveable parts of the lock by hand, 

 or removing the lock or any part thereof from the door. In locks constructed on 

 this plan the key may be altered at pleasure ; and the act of locking, or throwing out 

 the bolt of the lock, produces the particular arrangements of the internal parts, 

 which correspond to that of the key for the time being. While the same is locked, 

 this form is retained until the lock is unlocked or the bolt withdrawn, upon which 

 the internal moveable parts return to their original position, with reference to each 

 other ; but these parts cannot bo made to assume or bo brought back to their original 

 position, except by a key of the precise form and dimensions as the key by which they 

 were made to assume such arrangement in the act of locking. The key is change- 

 able at pleasure, and the lock receives a special form in the act of locking according 

 to the key employed, and retains that form until in the act of unlocking by the same 

 key it resumes its original or unlocked state, Thp lock is again changeable at plea- 

 sure, simply by altering the arrangement of the moveablo bits of the key ; and the 

 key may be changed to any one of the forms within the number of permutations of 

 which the parts are susceptible.' April 15, 1851. 



Mr. Hobbs who has been carrying out the manufacture of American locks in this 

 country has introduced an inexpensive- lock, which he calls a protector lock. The 

 following description is borrowed from Mr. Charles Tomlinson's ' Treatise on the 

 Construction of Locks ' : 



'When the American locks became known in England, Mr. Hobbe undertook 

 the superintendence of their manufacture, and their introduction into the commercial 

 world. Such a lock as that just described must necessarily be a complex piece of 

 mechanism ; it is intended for use in the doors of receptacles containing property of 

 great value ; and the aim has been to baffle all the methods at present known of 

 picking locks, by a combination of mechanism necessarily elaborate. Such a lock 

 must of necessity be costly ; but in order to supply the demand for a small lock at 

 moderate price, Mr. Hobbs has introduced what he calls a protector lock. This is a 

 modification of the ordinary six-tumbler lock. It bears an affinity to the lock of 

 Messrs. Day and Newall, inasmuch as it is an attempt to introduce the same prin- 

 ciple of security against picking, while avoiding the complexity of the changeable 

 lock. The distinction which Mr. Hobbs has made between secure and insecure locks 

 will be understood from the following proposition : viz. ' that whenever the parts of 

 a lock which come in contact with the key are so affected by any pressure applied to 

 the bolt, or to that portion of the lock by which the bolt is withdrawn, as to indicate 

 the points of resistance to the withdrawal of the bolt, such a lock can be picked.' 

 Fig. 1401 exhibits the internal mechanism of this new patent lock. It contains the 

 usual contrivances of tumblers and springs, with a key cut into steps to suit the dif- 

 ferent heights to which the tumblers must be raised. The key is shown separately 

 in Jig. 1402. But there is a small additional piece of mechanism, in which the 



1402 



1401 



1400 



tumbler stump shown at s infys. 1400 and 1401 is attached; which piece is intended 

 to work under or behind the bolt of the lock. In Jig. 1401, b is the bolt; t t is the 



