The International Exhibition: Messrs. Hobbs and Co.s lock-indicator, 1862. One of Hobbss locks illustrates a new principle of security specially adapted for iron safes and prison cells. The chief feature is, that a dial-plate indicates whether the door is opened or locked...When the door stands merely closed, the indicator, or handle, rests on "open." Turn the handle, or indicator, and the door is fastened by the first movement, when the indicator, or handle, will point to "shut." A second motion of the handle, and the bolt shoots out beyond its reach, the indicator, or handle, at the same moment resting on "locked." The lock can only be opened by the key, because, at the second turn, the handle loses its control of the bolt; the action of the bolt returning into the lock, on unlocking with the key back to "open," resetting it. The advantages of this index must be of the highest importance, as the person, would be able to see in an instant what condition the bolts of the locks were in without "trying" his keys. Again, if the door of a safe or strong room was closed tight there would be no danger of leaving it unlocked by neglect, as a glance at the index would show whether it had been locked or not. From "Illustrated London News", 1862.