Astronomy, a handy manual for students and others (1918)
Dyson, Frank Watson, Sir, 1868-1939 · New York, E.P. Dutton & Co. · leaf 72
flect the plumb-line towards it. Theamount of this deflection is measured astronomic-ally by observing the angle which the direction ofa star makes with the plumb-line at two stations onopposite sides of the mountain. If there were nomountain, the angle between the plumb-lines atthe two places… … which pulls the plumb-line in different directions at A and B, the actual measured angle is found to be greater than the angle AOB. The amount of the excess is due to the pull of the mountain, which is thus compared with the pull of the Earth. In this way Maskelyne found the attraction of the Earth…
Astronomy
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