How to Make a Simple Theodolite

First referenced in the 1500s in a surveying textbook by Leonard Digges, a theodolite is a precision instrument commonly used in surveying, to measure the height of objects that can't easily be measured, such as buildings. Theodolites can be expensive, however, you can make your own simple device for the price of a protractor, a fishing weight and a few bits and pieces that you probably have at home. You need a tangent table to help you do the simple calculation for determining the height of the building you're measuring.

Things You'll Need

• Drill with fine drill bit
• Protractor
• Cardboard
• Scissors
• Push pin
• Eraser
• Fishing weight
• Thin string, 12-inches

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Instructions

1. • 1

     Cut a piece of cardboard approximately three times the size of your protractor.

   • 2

     Drill a small hole in your protractor, 1/2 inch in from the center point of its longest edge.

   • 3

     Align the center point with the center of one of the longest edges of the piece of cardboard and attach it with a push pin. Attach a small eraser to the pointed end of the push pin to hold it secure.

   • 4

     Attach the fishing weight to one end of a piece of string and tie the other end to the push pin.