What is this????

[Guest designer2301]

I bought this item at a yard sale and have no idea of what it was used for and the age of this tool. It is a totally closed glass tube with a ball at the top that is filled with many tiny balls. The balls look like they are made of metal. The other end is shaped like a thermometer with a piece of paper inside that reads,'' FOR GASOLINE Tp. 60 DEGREES F''. The other side of the paper has 60 to 80 degrees marked off every two degrees. The center of this glass tube flares out and is empty. It came in a glass test tube like cylinder that was all placed inside a 6 1/2'' l x 1 1/4'' w x 1 1/4'' d wooden dovetailed box with a slide lid. I thought that perhaps a club member could give me some information on this unique tool. Please respond to roses_2@me.com

Thanks for your expert help.

[DLynskey]

It's a gasoline hydrometer, used for measuring the specific gravity of gasoline. The tube floats in the fuel with the weighted side down (obviously). In lighter weight fuel the hydrometer sinks further, in heavier fuel it floats further up. You read the point on the scale corresponding to the surface of the fuel.

Specific gravity is related to the additives in the fuel. I'm not familiar with it, but it is used in racing fuels.

Don