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This sector or proportional compass (also known as a "military compass") was designed and built by Galileo Galilei (1546-1642) around 1597. It combined two separate instruments: one for making observations (by adding a quadrant to its arms); the other was a calculator for solving problems in proportion, trigonometry, multiplication and division, and for various functions, such as squares and cube roots. Its several scales permitted easy and direct solutions of problems in gunnery, surveying and navigation. |
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