Physical description
Planimeter consisting of brass disc and measuring instrument made of white disc and attached bar. To measure area up to about the size of one A4 page. The instrument is stored in a black hinged box with purple velvet lining and small metal catches. Instruments instructions are attached to a label on the inside of the case. A small key is attached to the case lid by string. (23.1 = box, 23.2 = brass disc, 23.3 = planimeter)
Inscriptions & markings
On planimeter (23.3): “G.Coradi Zurich Switzerland No. 3509” On box (23.1): “Nat. Phil. Lab. No. 1199, Gebr Wichmann Berlin”