Radiator-cap mounted engine temperature gauges bridge a time period between plain utilitarian radiator caps, and cap-mounted mascots. In the early years there was no way to tell the engine temperature unless the driver saw steam coming from the radiator cap! There was a need to know the temperature of the engine cooling system. The systems were very crude by today's standards and very susceptible to overheating.
The first cooling systems were not pressurized, and the coolant had a low boiling point. To monitor the temperature, a simple device was invented which would display the engine temperature to the driver. It was very important to maintain the most efficient operating temperature, preventing engine destruction should it overheat. These devices took different approaches, from complicated gear type indicators using a bi-metallic device manufactured by Wilmot-Breeden in England, to the simple thermometer commonly referred to as the motormeter. Probably the best-known manufacturer was Boyce in the United States. Their factory was located in Long Island City, New York, and their device was known as the Boyce Motometer. Some companies copied the device, which resulted in patent infringement battles being fought over their manufacture.
The photographs and information in this section were kindly supplied by John Boggs Jr. and his wife Henrietta. Visit the contributors section to read John and Henri's biography, and also their essay on motometers - which includes tips on collecting and restoring them. The contributors section also contains photographs and information donated by other generous people. You can also find out how to add your own contributions to Mascot Mania.