Sangamo Type H Wattmeter, 1911-1914

In the late 1800s, companies that supplied electricity to consumers needed a way to measure how much customers used--and then charge them accordingly. Induction-type wattmeters proved reliable and would become the industry standard, but until 1910 Westinghouse held the patent rights. Sangamo Electric Company introduced this induction-type meter -- the smallest model on the market at the time -- in 1911 after the Westinghouse patents had expired.