l^ 



SECRET tOCk^ 



"ti'Thif Certain parts of the lock flioutd be variable in por- 

 tion thVoagh a great number of combinations, one only of 

 which fliall allow the lock to be opened or (hut. 



2. That this iaft mentioned combination (hould be variable 

 at the pleafure of the pofleflbr. 



3. That it fliall not be poflible, after the lock ?s clofed and 

 the combination difturbed, for any one, not even the maker 

 of the lock, to difcover by any examination what may be the 

 proper fituations of the parts required to open the lock. 



4. That trials of this nature fliall not be capable of injuring 

 the work, 



" 3. Tliat it fliall require no key ; 

 ** t5. And be as eafiiy opened in the dark as in the light. 



Thefe conditions are in fome refpefls liable to the inconve- 

 niences already mentioned. I would therefore add the foU 

 lowing conditions : 



7. That the opening and fliutting fliould be done by a pro- 

 cefs as (imple as that of a common lock. 



8. That it fliould open without a key, of with one, at 

 pleafure. 



9. That the key-hole be concealed, defended, or inac- 

 ceflible. 



10. That the key tnay be ufed by a ftranger without his 

 knowing or being able to difcpver the adopted combination. 



1 1. That the key be capable of adjuftment to all the varia- 

 tions of the lock, afid yet be limple. " 



12. That the lock fliould not be liable to be taken off and 

 examined, whether the receptacle be open or fliut, except by 

 one who knows the adopted combination. 



pefcription of a ^^ meditating upon this mechanical problem, I have thought 

 new lock of of various conftruclions, but have not yet matured one in 

 which all the above conditions are complied with. The lock 

 delineated in Plate HI. pofleifes the firlt fix requifites. Fig. 1, 

 reprefents the plate of the lock, of which the other fide is feen 

 at Fig. 4. In this laft figure the middle piece Is a handle or 

 knob, reprefcnted Fig, 6, which, when turned, ferves to 

 Ihoot the double bolt ik, Fig. 1, by any common connexion. 

 In the aclual lock this bolt is carried backward and forward by 

 a pin ftanding out of Fig. 2, foon to be Jefcribed. The other 

 lot.T circles in Fig. 4, are handles, reprefenled in Fig. 5, whieh 

 ' •»»*'*-s*- '"^^■' ^-"^^- ' (erve 



combination. 



