Check the listing for details. Antique Simplex Opisometer/Curvimeter/Wheel Map Measure, c1910. Condition: Used. Listed at 25.92 USD. Antique Simplex Opisometer/Curvimeter/Wheel Map Measure, c1910 Here we have a antique opisometer/curvimeter/wheel map measure, dating to the c1910. This tool is an opsiometer, but is sometimes called a curvimeter or map measuring wheel. An opisometer is used for measuring the lengths of curving roads, boundaries or rivers on maps. This is a simple effective and well-made tool. The body is made of a white metal. There are no makers marks, but The instructions tell us the brand name is SIMPLEX. To use the instrument, the milled-edged wheel on the screw axis is first turned clockwise all the way to the pointer on the frame. It is then placed with the pointer placed at one end of the line that is to be measured. By gently, but firmly press the wheel onto the map, pushing on the handle to follow the required line. Once the end point has been reached, you lift the wheel up and place on the straight scale marker on the map and measure the distance, it might be necessary to lift the wheel and run it several times along the scale to give the distance seeked from the map. This rare little item is offered in excellent condition, it measures about than 4cm long. The box and instructions are in great condition. The box has the owners name, above it has the uniquely Cornish phrase ‘THE PROPER JOB’. A great example of a rare opsiometer. Please see my pictures for the details of the condition. Thanks for looking and Happy Bidding! Please ask if you would like me to look at cheaper delivery services. I am always happy to combine postage, all I ask if you let me know if you are bidding on more than one item within a few days of each other. I will pack and weigh the items together and get the best possible price that I can, sometimes weight or value might dictate that I send multiple parcels to get a better value for you