138. Wynne's Watch-pattern Actinometer, c. 1895
Signed: 'Wynne's Infallible Hunter Meter'
Tintmeter in which exposure is calculated by measuring the time it takes for a fresh piece of sensitized paper to darken to a standard tint. The calculation is done on the simple circular slide rule in the lid. This method was used as soon as photography began and continued until the 1930s.
Diameter 50 mm, depth 5 mm.
Inventory no. 77,511.