Which function did the "umbra recta" and "umbra versa" scales serve on a medieval astrolabe?

💡 Explanation

The 'umbra recta' and 'umbra versa' scales allowed altitudes to be measured using shadows because they related the height of an object to the length of its shadow formed by a stylus. Therefore altitude measurement was possible, rather than trigonometric calculation, planetary positioning or calendar conversion which used different parts and mechanisms on the instrument.

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