No. 151.] 203 



They have remarkf tl in the lock a number of important advantages, 

 and in particular very great improvements upon the permutation lock 

 formerly submitteil by him to the American Institute. Thus, while it 

 retains all the advantages of the permutation priiiciple,combine(l with 

 the property that the act of locking sets the slides to the particular 

 arrangement of the bits in the skeleton key, the parts thus set are 

 completely screened from observation, from being reached by false in- 

 struments, or from being injured by any violence not sufficient to 

 break the lock to pieces. 



Having, in the course of their inquiries, examined the different ex- 

 isting modes in •vhich locks may be picked, forced, or opened by false 

 keys, the coiumittee have come to the conclusion, that the parautoptic 

 lock cannot be opened by any ot the methods now practiced, unless 

 by a person in possession of the key by which it was locked, in the 

 exact form of combination in which it was used for the purpose, or 

 in the almost impossible case of the bits being adjusted to the ske- 

 leton key by accident in that very form. As the chances of such 

 accidental combination range, according to the number of moveable 

 bits, from several thousands to several millions, to one, the commit- 

 tee do not consider that so small a chance of success would ever lead 

 to an attempt to profit by it. 



In conclusion, the committee feel warranted in expressing the 

 opmion that, unless methods hitherto unknown or imagined, should 

 be contrived for the specific object, the lock in question may be con- 

 sidered as affording entire and absolute security. 



THOS. W HARVEY, 

 J AS. REN WICK. 

 American Institute, July llh, lSi6. 



