- Subject
- Thermometers
- Item type
- Object
- Provenance
- Purchased from R. Hammond Esq in 1970.
- Primary inscriptions
- Unsigned and undated
- Object type
- Thermometer
- Dimensions
- Diameter: 216mm Height: 429mm Weight: 1194g
- Inventory No
- 90224
- Accession Number
- 1970-23
Description
Glass cylinder with copper alloy fittings, on heavy cast iron tripod. Two copper alloy electrodes ending in balls; upper adjustable. Manometer at side of main tube; its glass tube is missing. A small quantity of water is poured into the main glass cylinder and its level in the manometer noted. The "explosive force" of the spark jumping the spark gap between the two electrodes is measured by the rise of the level in the manometer caused by the expanding air heated in the main tube. This crude determination of the quantity of charge was developed in 1761 by the American E. Kinnersley, who was a friend of Franklin.
