The Chronotherm thermostat as it might have appeared on the living room walls of those that could afford it in the late 1930s.

Chronotherm thermostat

As a fuel saving device, the Chronotherm was among the first “green machines.” Using electricity, it saved energy automatically, by turning the heat down at night and up in the morning.

G. Leslie Oliver, Mark Dorlandt Photography.
Ron Shuker, Nigel Heseltine
c. 1935
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