Specific gravity beads

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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

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• Online ID: 000-100-104-227-C
• Image Rights Holder: National Museums Scotland
• Project: National Museums Scotland
  Project description   View all records in project
• Ref: National Museums Scotland  T.1962.115
• Date: Around 1810
  c. 1810
  
• Material: Box wood slide-rule / bone slide-rule / glass rods / mahogany box
  Bead, gravity / bubble, philosophical / sliderule / thermometer
  
• Dimensions: Box 13.13" x 12.38" x 5.38" H
  
• What: Bead, gravity / bubble, philosophical / sliderule / thermometer
  
• Subject: 22. PHYSICS, Hydrostatics (Departmental Classification)
  
• Who: Mrs J. Lovi, High Street, Edinburgh (Maker)
  
• Where: Scotland, Midlothian, Edinburgh
  
• Event:
• Description: Three hundred and sixty three aerometrical beads, two slide-rules, one thermometer, six glass rods and an instruction book, all in a drawer of a mahogany box, and made by J. Lovi of Edinburgh, c. 1810
  
• References:
  • For Mrs Lovi, see A.D. Morrison-Low, Women in the Nineteenth-Century Scientific Instrument Trade, in Marina Benjamin (ed.), Science & Sensibility: Gender and Scientific Enquiry 1780-1945, Oxford, 1991, p 103 
  • I. Lovi and J.R. Irving, British Patent 2826, 9 March 1805, 'Apparatus for determining the specific gravity of fluid bodies'.I. Lovi, Directions for Using the Patent Aerometric Beads, Edinburgh, 1813. 
  • T.C. Hope, 'Report of a Committee of the Highland Society appointed to examine the Beads for Ascertaining the Specific Gravity of Liquids Invented by Mrs Lovi and the application of them to discover the richness of milk, Transactions of the Highland Socie 
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