Use this small quadrant to measure the altitude of celestial objects. The small star-disc is used as a plumb bob at the end of a short length of string. Run the string between the hole in the upper left of the device to the small hole passing through the bob. Arrange the length so that the bob just reaches the angle scale. It goes without saying that you should never use this quadrant to directly look at the Sun. But use can hold the device properly so that the Sun's light travels down the sight tube to cast a shadow, therefor making Sun angle measurements possible.

For more, visit my astronomy class website at carpecaelum.com

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