. Astronomy without a telescope:. POSITION ABOVE THE HOEIZON. 61 ness, by estimating for the intermediate positionof the center, and striking the circle exactly throughthe points of intersection of all the circles in thediagram. Or, the circle of the horizon may bedrawn independently, for any latitude, by findingin the table of differences (page 56) the differencefor 30° or 60° of declination in the given latitude, setting off the semi-diurnal arcs from any meridianon Map No. XIV., on the Circles of Declination(parallels), and finding a point in the meridian fromwhich, as a center, the horizon
. Astronomy without a telescope:. POSITION ABOVE THE HOEIZON. 61 ness, by estimating for the intermediate positionof the center, and striking the circle exactly throughthe points of intersection of all the circles in thediagram. Or, the circle of the horizon may bedrawn independently, for any latitude, by findingin the table of differences (page 56) the differencefor 30° or 60° of declination in the given latitude, setting off the semi-diurnal arcs from any meridianon Map No. XIV., on the Circles of Declination(parallels), and finding a point in the meridian fromwhich, as a center, the horizon circle may bestruck, passing through the given points on theDeclination Parallels, and also crossing the Equi-noctial in two exactly opposite Define and explain (the figures refer to the sections): 147. Map No. XIV.; concentric projection. 148. Stars on the meridian at any given time. 149. Position of Starswith reference to the horizon. 150. Prime Vertical. 151. Circle of the horizon. THE SOLAR SYSTEM. 152. Several star-like bodies are often seen inthe heavens, among the fixed stars already de-scribed, but changing their places with varyingdegrees of rapidity ; always, however, within a fewdegrees of the Ecliptic line (Sec. 27). They some-times appear to move forward with steady pace,increasing their longitudes nightly; then are sta-tionary, keeping the same place among the fixedstars for several nights in succession ; then seem tomove backward among the stars, which is calledRetrograding ; and after another stationary period,again move forward. The comparative prominence and brilliancy ofeach of these bodies varies with its rate of move-ment, the greater number being most brilliant whenretrograding; but they all shine with
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