he is overpowered by a thief who takes the key and makes the rounds, the central office will be advised of the fact by having a signal from the box that is not generally rung. These same boxes can be used for fire alarms. Where this service is not available, there are other means of controlling the watchman's round. All of these depend upon a box containing a clock and mechanism for registering the time at which a key is inserted in them. Sometimes there are different keys in the various rooms and the watchman carries the clock. In other cases the clock is in the room and the watchman carries the key.
In Europe, police dogs often accompany the watchman and are a great protection to him as well as good company and faithful servants. See Museums Journal, vol. VII, 411, Canine Custodians.
For the safeguarding of works of art either by day or night, a system of electric contact has been installed in many European museums which is efficient and absolutely invisible if desired. It consists in a little spring similar to that in the ordinary push button which rests against the object to be protected. The releasing of pressure immediately rings a bell which calls an attendant. The wires for these attachments are usually hidden, but where visible can be so arranged that the
