John Van Zandt’s “combined cane and burglar alarm,” patented in 1884, is low-tech but effective: The head contains a percussion cap, and the ferrule contains a spring clamp.

“The operation is as follows: The occupant of the room simply takes the cane and suspends the same over the top of the door, as hereinbefore explained. On the door being slightly opened the support for the cane is released, whereupon the cane drops and, striking the floor, explodes the cap, thus frightening away the thief and arousing the occupant of the room.”