Vintage Planimeter Complete With Everything And Leather Case

Description

Vintage Planimeter Complete with Leather Case. Outside leather of case is starting to fray and rip. It’s small now, but if not tested right it will gradually get worse.
Amsler type 6 planimeter, serial number 81352 dating from c1939. This planimeter is adjustable to a range of metric and imperial scales. It was retailed by Dobbie McInnes, whose name is printed on the case, and it is of the special type for measuring engine indicator diagrams. By setting the adjustment such that the distance apart of the two points on the top of the instrument equals the base length of the indicator diagram, the mean effective pressure can be read directly. Dobbie McInnes are perhaps best known as manufacturers of engine indicators for steam, and low speed oil & gas engines.