Specific gravity beads

Specific gravity beads are used to measure the density of a liquid at a given temperature and thus its alcohol content. These beads (pictured here in their mahogany case) were made around 1810, probably in Edinburgh by Isabella Lovi, the widow of Angelo Lovi, a scientific instrument maker who emigrated to Scotland from Milan, in 1772. The beads could be used for precise measurements in various industries, including testing the richness of milk. They represent perhaps the largest set of beads developed in Edinburgh.

The set features 363 beads, together with two slide rules, one thermometer, six glass rods and an instruction book. The beads are of different buoyancy, and are dropped into the liquid successively until one just sinks. It will be marked, so that the specific gravity of a particular liquid can be measured. These 'philosophical beads' were invented by Alexander Wilson of Glasgow in the 1750s, and were particularly popular in Scotland.

From the late 18th century, immigrant Italians arrived in Britain in some numbers. The particular trades they brought with them were glass-blowing and carving and gilding, which extended naturally into looking-glass and barometer manufacture.

Record details

To search on related items, click any linked text below.