Page:Description and Use of a New Celestial Planisphere.pdf/16

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which is the Equinoctial Colure and Hour Circle of ſix, theſe two Circles do interſect each other in the Pole of the world, and you will find the ſituation and names of all theſe Circles in the Planisphere; the next is the Circle of Months; and if you look on the horizon of any new Globe, or in any Almanac, you will there ſee the Sun's place to every day of the year; then lay an index from the center of the Plane through every point of the Ecliptic into the Circle of Months, and mark the days accordingly, and it is done: the index conſiſts of an Hour Circle, next to the Circle of Months; and, as you hold the South point from you, the left hand hours are the morning and forenoon hours, and the right hand are the afternoon hours, to twelve at night, which is at the bottom next to you, due North; then the Meridian reaches from 12 to 12 through the Pole, and on the ſouthern part is a ſcale of meridional Altitude from the Horizon up to the Zenith of London; and, on the northern part, is a ſcale of Declination, North and South; the Circle of the Horizon hath the points of the Compaſs, the Azimuth, and the Amplitude; and note, that the inward edge of the Circle is the ſenſible and apparent Horizon; next is the Prime Vertical, or Azimuth of Eaſt and Weſt, and on it is a ſcale of Altitude when due Eaſt or Weſt, up to the Zenith; the next is the Equinoctial Colure and Hour Circle of ſix; and above this is a ſmall index, or director, to be used, as will be taught among the Problems. This may ſuffice for a deſcription of the principle and conſtruction of the Planisphere. I muſt now proceed to it's uſes, as it relates to Aſtronomy: and