Patent for a new and improved lock. This design "is to produce a lock and key in which the lock-case has no exterior opening communicating with its wards or works, but is provided with a recess only for supporting the shank or axis of the key, while the only opening for the admission of the key to the interior of the lock, whereby its wards or bolt may be operated or controlled, is upon the interior of the lock-case, so that there is no possibility of introducing . . . picking devices therein, or of introducing any explosive agents" (lines 15-27).