Page:Description and Use of a New Celestial Planisphere.pdf/11

vi extending to the Southern Horizon, or fifteen degrees below the Tropic of Capricorn; it is fitted with a circular and movable Index, consisting of an Horizon, an Hour Circle, the prime Vertical, the Meridian, and Equinoctial Colure, with a straight director above it, and moving on the center of the projection, or Pole of the Equinoctial; it generally solves each Problem at one remove, and in less time than can possibly be done by the Globe, or by any Planiphere hitherto extant, they being applicable to the use of Scales and Compasses, or of some troublesome and tedious Index: in short, a sight only, of the construction of this Planiphere, will sufficiently convince every discerning person of its superior utility and readiness in all the purposes of Astronomy to which it is intended; also, the World will readily be aware, that the Diurnal and Horary Motions of the Spheres is the most useful, the most general, and practical part of Astronomy; it is that which attracts the attention of every thinking being; all can discern the apparent Diurnal Motions of the Heavens, and would wish the phenomena solved to their capacities; indeed, most men are, more or less, deeply concerned in this part of Astronomy, either for profit or pleasure, or both. Who does not make some use or other of the rising, culminating, (or, passing the Meridian) and setting of the Sun, Moon, and Stars?—The merchant, the mariner, the traveller, and every public and private student, down to the peasant, who knows and regulates his times and seasons, his labour and rest, by the Sun, Moon and Stars, all have their interests in this part of Astronomy, the Diurnal and Horary Motion of the