278 PISCRIPTION O? A SECRET LOCK. 



Conftru£tfon of fame time from the teeth and the wedges. No external exa- 

 ! *££* lo ^ k J ac ' mination can therefore (hew the difference in fituation of the 



ceflible only to I 



the proprietor, four ferrils. It is obvious that in order to infure this effett, the 

 wedges ought to fit the cuts between the teeth in the ferrils ex- 

 actly ; which is very eafily obtained in the conftru&ion. An- 

 other advantage refulting from the wedge is, that if any of the 

 deep notches or openings be not exactly in a line with the reft, 

 the wedge eafily adjufts it, and the bolt is not in the leaft im- 

 peded on that account j this advantage renders it unneceflary 

 that the workmanfhip of the lock fliould be exquifite, a condi- 

 tion which, in a work of a moderate price like the prefent, 

 would render it ufelefs. 



2d, My lock is eafily opened, it having only four fcrew- 

 heads : it has neverthelefs 331,776 * combinations, a number 

 fully fufficient to fet the moft fufpicious mifer at eafe. 



We may add, that it is much eafier to recoiled one word than 

 a number, which mull: be the cafe in Reignier's lock. 



3d, When characters are engraven externally on the fcrew- 

 heads, they are either difficult to be perceived, or may be eafily 

 damaged. A key with characters engraved on it, is I think a 

 great improvement : a faving is likewife afforded, which is a 

 consideration of fome confequence in a machine of common 

 ufe. 



Uh, The method by which I vary the pofition of each ferril 

 with refpect to its fcrew-head, is at once fimple and folid. 



Bth, The mechanifm by which the bolt is attached to the 

 lock, is concealed, and cannot be damaged. As nothing is 

 feen of the lock but a fmooth plate on either fide, it would be 

 very proper for a bureau or 'fcrutoire. 



Another Singular property refulting from this mechanifm is, 

 that it can only be taken to pieces by the proprietor, whether 

 the door be open or fhut : it could not even be done by a per- 

 fon ihut in the apartment. 



6th, The lock may eafily be fet: as the interior fcrevv- 

 heads do not turn on wood, there is no danger that their mo- 

 tion fhould become lefs regular or eafy on account of wear. 

 The fame may be obferved of the bolt, which Aides in a 

 groove of iron. 



* This is the fourth power of 24. 



1th, 



