Willson, Robert Wheeler, 1853-1922 · Boston, New York Ginn & company · leaf 17
rough thispoint, and a series of numbered points showing the position of theshadow of the pin-head at different times; the height of the pin isknown and also the fact that its head was in the same vertical linewith its point. In the discussion of these results, it will be convenient to proceedas… … Fig. 5 it makes with the magnetic meridian is called the magnetic bearingof the line. This angle, which may be directly measured on thediagram by a protractor, fixes the position of the vertical plane whichcontains the observed point and passes also through the center ofthe pin-head and the sun. If…
Astronomy
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