Antique fire detector

Believe it or not, this relic once worked as fire alarms. The mechanism, known as the "Indicator Geymvella" dates from the late 19th century. Boston became the first city in the U.S., which launched on its territory a central fire alarm system, setting in most parts of the street manual call points. John Geymvell also acquired a patent for "light" and set them in the buildings. Devices to send a fire alarm on the telegraph lines to the central office fire alarm telegraph to the receiver unit. The figures on the drums "programmed" in advance and identify the exact location of the detector.