Herschel, John F. W. (John Frederick William), Sir, 1792-1871 · London : Longman, Brown, Green, Longmans, and Roberts · leaf 237
201 NONAGESIMAL. ANGLE OF SITUATION. referable to the same data and quaesita, are resolved by the spherical triangle ZPE, formed by the zenith Z (considered as the pole of the horizon), the pole of the equinoctial P, and the pole of the ecliptic E. The … from which we may find, 1st, the side Z E, which is easily seen to be equal to the altitude of the nonagesimal point sought ; and 2dly, the angle P Z E, which is the azimuth of the pole of the ecliptic, and which, therefore, being added to and subtracted from 90°, gives the azimuth of the eastern…
Astronomy
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