by John & Henri Boggs.

The Jarvis Water Indicator.

This device is interesting as it uses a float mechanism to indicate the level of fluid in the car's cooling system.  The meter has a long tube which extends into the radiator and measures the water level in the radiator top tank.  The device, along with the cap it is mounted on, are nickel plated.  It was manufactured by the W.B. Jarvis Company of Grand Rapids, Michigan.

In the bottom two photographs I have shown how the device works.  This demonstration uses a coloured liquid to represent the engine coolant in the radiator, and shows how the indicator displays the level in its dial.