Nicholson's hydrometer
Date: circa 1850
Inventory Number: 1998-1-0160
Classification: Hydrometer
Subject:
Maker: American ?
Cultural Region:
Dimensions:
23.5 x 4.8 x 4.8 cm, 0.2 lb. (9 1/4 x 1 7/8 x 1 7/8 in., 0.1 kg)
Material:
Description:
A metallic cyllinder with conical ends. One of its ends has a small hook, while the other is connected to a flat disk by a long thin metallic rod.
Signedunsigned
FunctionThis is a hydrometer (measures the specific gravity of a liquid) that is almost completely submerged during its use. The hook would be tied to a weight forcing the cylinder to be underwater with only the metallic disk and part of the rod remaining above the surface. Weights would be placed on the disk until the water surface coincided with a mark on rod. One would then be able to determine the specific gravity of unknown liquids by immersing the hydrometer in them and noting the difference between the weight necessary to bring the mark to the unknown liquid's surface and the weight that was used to do the same with water.