Elements of astronomy ..with explanatory notes, and questions for examination . r elapses between the pas-sage of the vernal equinox, and that of the star acrossthe meridian of the place of the observer. 72. The subject is illustrated by Figure 20, where Prepresents the north of the heavens, F°f a celestialmeridian passing through the vernal equinox, QAQ, thecelestial equator, S, the place of a star, PSA, a part of acelestial meridian passing through the star, and C thecentre of the celestial sphere; or what is the same ineffect the place of the spectator. Now the declination of the star is th
Elements of astronomy ..with explanatory notes, and questions for examination . r elapses between the pas-sage of the vernal equinox, and that of the star acrossthe meridian of the place of the observer. 72. The subject is illustrated by Figure 20, where Prepresents the north of the heavens, F°f a celestialmeridian passing through the vernal equinox, QAQ, thecelestial equator, S, the place of a star, PSA, a part of acelestial meridian passing through the star, and C thecentre of the celestial sphere; or what is the same ineffect the place of the spectator. Now the declination of the star is the arc SA, sincethis arc measures the angular distance of the star fromthe equator QAQ1. PSA, is one quarter of a meridian with his eye at P, then views a star in the direction, PCLS, the angle meas-ured on the arc, DO, from D, viz., DCL, or HCS, will be the altitude of thestar, S, above the horizon, H. In the figure it is fifteen degrees. If thebrass arc is held horizontally, and the edge, CD, is in a line with the me-ridian, the angle, SCH, will be the azimuth of the 1. The character °f is called Aries and is that point in the celestialequator which is termed the vernal equinox. P3)0 is read thus, P,Aries. Show from figure what is the declination and right ascension of the star at S LATITUDE AND LONGITUDE. 53 passing through S, and contains ninety degrees, and ifAS contain forty degrees, the declination of the star isforty degrees north. The right ascension of the star is TA,
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