218 DESCRIPTION OF A SECRET LOCX. 



fcribedas the moft perfect, in the art of lock-making (Serrurie) ' 

 in the Encyclopedic Methodique. I fliall fhew that the lock 

 of Reguier, as well as many others, contains an imperfection, 

 or rather a radical defect, which efcaped the inventor, and 

 renders its other properties of little value *. It will be ken 

 how I have avoided this defect in mine And, laftly, I fliall 

 concifely defcribe (bine other fyftems of locks which feem to 

 offer particular advantages, but which, neverthelefs, do not 

 poflefs the fame degree of perfection as that to which I have 

 given the preference. 



Description of tlie new Lock. 



Particular dc- The front of this lock confifts of a plate 230 millimetres f in 



1 ™k- ** len S tn * 67 in width > and 4 or 5 thick ' AIon g the middle line 

 are difpofed five nuts or fcrew heads, of 18 in diameter. In 

 the centre of thefe nuts is a fquare ftem of 5 in the fide, which 

 ends in a fcrew. 



This fquare ftem carries immediately on the other fide of the 

 plate, a round plate of 38 in diameter and 3 thick, having a 

 fquare hole in the center, and having 24 teeth in its circum- 

 ference, with fpars between them equal to the teeth. 



Upon this round plate is placed a cylindrical cup or ferril, 

 having its bottom in contact; with that wheel, and connected 

 with it by the item, . which partes through a round hole in its 

 center, and binds it down by the fcrew nut. This ferril, of 

 which the thicknefsis 2 and the height about 29, has a promi- 

 nent ftud at its flat face, which entering between any two 

 teeth of the wheel, ferves to vary at pleafure the relative peti- 

 tions of the wheel and ferril at the time of fcrewing them to- 

 gether. Laftly, The ferril has 24- teeth cut in its edge, having 

 a fpace of about 4 between each. Thefe teeth are about 3 in 

 depth, excepting one of the intervals which is cut to the depth, 

 of 6. We (hall hereafter explain the ufe of this depth. 



* Citr Reguier has, neverthelefs, £he honour of being the firft 

 who nearly refolved this problem. 



f To avoid fractions, I have not reduced thefe meafures. As 

 the metre is 39.371 inches (Phi lof. Joum. II. 250), it will be fuffi- 

 ciently near if the reader multiplies the numbers in the text by 4, 

 and then cuts off two figures : Thus 230x4=9.20 inches, or $ £ 

 inches.— N. 



The 



