此款極座標式求積儀是由美國Keuffel & Esser公司在德國製造，型號為4236。固定桿與追蹤桿可拆開收納，固定桿的一端配有加重塊其底下含有細針以確保移動中不會位移，另一端有定位銷可放置在追蹤桿上的定位孔中，用於連接固定桿與追蹤桿。使用方式為，將固定桿的細針端固定於圖形外，利用追蹤點沿著圖形邊緣繞一圈，讀取刻度數值並乘上儀器盒內提供的單位係數，即可獲得該區域的面積。

This polar planimeter was manufactured in Germany by the American company Keuffel & Esser, model No. 4236. The fixed arm and tracing arm are detachable for storage. One end of the fixed arm is equipped with a weighted block and a needle underneath to ensure it stays in place during use. The other end has a positioning pin that can be placed into a locating hole on the tracing arm, connecting the fixed arm and tracing arm. To use it, the needle of the fixed arm is anchored outside the chart. The tracing point is then moved along the edge of the chart, and the scale reading is multiplied by the coefficient provided in the instrument case to calculate the area on the chart.