Westinghouse Ammeter, Used in the North Union Station Power House, Boston, Mass., circa 1893

When Boston's North Union Station opened in 1893 it required a central power station to supply electricity to light the massive train shed and terminal and to operate turntables and machinery. At the station's Minot street powerhouse, electrical engineers monitored power usage. This ammeter--used to measure the current in a circuit--was one of many switches, circuits, and meters found in the power plant.