Willson, Robert Wheeler, 1853-1922 · Boston, New York Ginn & company · leaf 38
Fig. 2G 26 LABORATOEY ASTRONOMY. that end of the staff at which the eye is placed. The figure, whichis taken from an old book on navigation, illustrates the use of thisinstrument for measuring the suns altitude above the sea horizon;the rod in the position shown indicates that the suns altitude…
Astronomy
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