Details and Image
|Date||Scale Length||Area of Use
|Polar||K&E Model 4230||Keuffel & Esser||USA||German silver and brass||ca. 1920||N/A||General area measurement
Notes: "An impressive polar planimeter from K&E. The full length of the tracing arm is graduated to allow it to be set to any scale map or drawing. The bottom of the pole weight (the large brass ‘hockey puck’), is smooth so that it can be moved around to zero the planimeter. Its weight guarantees that it won’t move on its own. The testing disc (the thin brass disc) has three pins that stick in the drawing board, and a groove around its perimeter for testing the accuracy of the planimeter. Serial number 7."