SEC^jET I,,OCK. ^§g 



with wax, like the impreffion of a feal, or more fpeedily by 

 indentation upon a piece of moiflened paper, or by various 

 other means ; and it muft be admitted, that very little Ikill is 

 required to enlarge the openings of a common key, fo as to 

 make it pafs the wards of a fuperior lock. 



fhefe neceflfary and unavoidable iraperfe6iions of common Secret locks; 

 locks, have long ago led to the introdudion of fecret locks, ^^"^j'. ^'■"^"'« 

 which are fo conftrudted as to require fome particular mani- tion. 

 pulation in opening them ; (iich as that the key ftioijl^ be 

 turned twice round, or that it fliouid be turned through a cer- 

 tain (pace in one dire<5lion, and then back again ; or that it 

 fliouId zB. upon fome delicately refilling piece, very likely to 

 be dirregarded by an uninfirufted poflefibr of the key j or that 

 a number of viable parts fliould be placed in fome determined 

 order, before the common procefs of opening, either with or 

 without a key, can take place. Upon all tliefe contrivances 

 one general remark may be made, namely, that the pofl"eflbr 

 muft always in perfon open his own lock ; for if this be toiae 

 done by the mere pradice of a fecret without a key, his cabi- 

 net becomes forever open to him who, by communication or 

 otherwife, thai! poflefs that fecret; and if a key be ufed, his 

 lock, as to that perfon, becomes as fubje^t to violation as a 

 common lock. 



In the mechanical confideration of ^ fecret lock, we may Methods of »!«• 

 fuppofe the conftrudiion to be entirely unknown to him who ^^''"S them, 

 is defirous of opening it. In this, according to the experience 

 and fagacity of the operator, the difficulties will be greater 

 or lefs, and a very fliallow contrivance may occafionally pre- 

 fent a greater obftacle than a much more elaborate ftructure. 

 But if we fuppofe the fyfiem of the lock to be known, but 

 the particular conditions of opening it to be fecret, the ex- 

 aminer will then take for his guide the probable circumftance 

 that the re-adtion of the parts may feel conliderably different, 

 when they are duly placed for opening, than when their litu- 

 ation is fuch as to prevent that effect. By this clue, and by 

 careful examination, moft of thefe locks may be opened ; and 

 it is remarkable, that the belter the workmanfliip the more 

 eafy it is in general to make the intended difcovery. 



The following are the conditions which appear to me to be Conditions of ?. 

 ncceffarv in a lock of the moft perfeft kind : P^rfeft lock 



• ~ ■ ■ '^ enumerated. 



^2 l.That 



