Elementary astronomy; a beginner's text-book (1899)
Holden, Edward Singleton, 1846-1914 · New York, H. Holt and company · leaf 145
shadow point due north? Say how you could makea sun-dial with a pole and a common watch. Water-clocks. Tellwhat they were. Pendulums. How can you make a pendulum thatswings in a second of time? Divided circles. Say how you could makeone. Describe how to use it in measuring the angle between two… … Fig. 69. This figure shows the way in which the rays of light move in a reflectingtelescope. They come from a star as a beam of light and cover the wholeof the curved mirror at the bottom of the tube (A). This mirror reflectsthem towards a focus (like F in the preceding figure). Before the…
Astronomy
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