A superb mechanical engine indicator - the predecessor to modern engine diagnostics - as manufactured by Dobbie McInnes of Glasgow. Such instruments were used to accurately analyse pressure versus piston displacement through the cylinder stroke of an engine, with the output being recorded onto a roll of paper. Dobbie McInnes specialised in these instruments, patenting a number of variations for both steam and early diesel engines. The company ran from Glasgow's Bothwell Street from 1841 and operated under the name of Dobbie McInnes Ltd from 1902 onwards. Most likely this particular instrument dates to the early 1920s.

Case measures 24cm x 20cm x 16cm.

Condition: In excellent used/ex-service condition with only minor age-related wear. Untested. Case with original protective layer of French Polish with minor scuffs, scratches and accumulated grease.

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