$80 DESCRIPTION OF A SECRET tOCK. 



Conftruftion of number of methods. That which I have defcribed is the Uft 



ceffible t onl k to C " re ^ u ^ t °^ m ? erK *eavours dn tms objeft; it feems to me to be 



the proprietor, the fyftem that beft anfwers all the conditions of the problem. 



I think, however, that it will not be ufelefs to make known 



fome more, if it were only to prevent others from making un- 



ncceffary attempts on the fame fubject. 



lft, The front part of the lock prefents 25 fmall rectangles, 

 10 wide by 15", difpofed in a right line, and forming in all 250. 

 The 24 letters, of the alphabet are marked on thefe re&angles : 

 they are included between the two partitions of the horizontal 

 channel or groove, and they all touch one another, They may 

 be pulled outwards to the diflance of 4 millemetres, like the 

 flops of an organ. Each of thefe Hops has a little fpring at 

 top, which gives it an eafy and fmooth motion, and prevents 

 it from dragging with it any of its neighbours. Each flop, in 

 the iniide of the lock, has a projection in the form of a tooth. 



The bolt has, on its fuperior and horizontal face, 24 dove- 

 tailed grooves with dovetails, each of. which receives a regifler 

 or flop of the fame form, having a tooth at top. Thefe flops 

 of the bolt may be put into their grooves with the extremity 

 ■ having the tooth, or the other end, jufl at pleafure. The bolt 

 is enclofed in a box, the viiible and interior face of which 

 moves in a groove, in order to take out and replace the bolt at 

 pleafure. 



The lock is thus ufed. If it is to be opened, the exterior 

 flops forming the fecret are brought forward, then the 25th flop 

 is drawn, and this renders the reft of the flops immoveable. 

 After having returned it, it is turned by means of a knob or 

 handle which it carries, and the bolt is thus made to move. 



When the fecret is to be changed, the interior regi tiers are 

 to be placed in the grooves cut in the bolt, by the extremity 

 which has no tooth. They are then inverted with refpect. to 

 the others, and their teeth become in a line with thofe of the 

 exterior flops. 



The number of combinations in this lock is equal to the 

 eightieth power of 2, nearly 17 million : It is convenient for a 

 bureau, but the workmanfhip muft be exquifite: Befides, it 

 is not convenient for a door, becaufe flops which project feveral 

 millimetres may be eafily damaged. I cannot here enlarge 

 Upon the other imperfections which it prefents. -In this fyflem 



the 



