Auburn Motometer, circa 1925

Automobiles often came without temperature gauges before the early 1930s, so enterprising manufacturers sold aftermarket motometers. Mounted on a car's radiator, these devices measured and displayed coolant water vapor temperature, notifying drivers if their automobiles were in danger of overheating. Moto-Meter Co. Inc. dominated the American market, producing the popular Boyce motometer and others featuring an automotive manufacturer's name or logo.