Notes: "In 1925 the K&E Model 4211 first appeared on a price list for the 1921 K&E catalog. In the 1927 catalog, the 4210 was gone and replaced by the 4211, which used a completely different style of construction and added a multiplier wheel. K&E described the 4211 as ""the polar planimeter in its simplest form,"" probably because of the fixed-length pole and tracing arms. This one is serial number 1050. "
