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The PREFACE.
THERE have been many Planiſpheres invented and published, at different periods, within a century or two past, for different uses; some for Geography, some for Astronomy and Chronology, and some applicable to a few detached articles of all the three; but all that I have seen are very unsatisfactory, and some very erroneous: yet there are some Planiſpheres now extant, which are perfect in their kind, but not very useful, they being projected upon the Plane of the Meridian, are not capable of a Rotatory Motion, and, consequently rendered very limited: others have been projected on the Planes of the Horizon, or the Ecliptic, but none of them are adapted for, or capable of showing the Diurnal Motions; and, consequently, of very little utility, in comparison of what is wanted: my seeing these wants and defects, set me to consider, that, as the Earth's Diurnal Rotation was made upon the Poles of the Equator, so a Planiſphere, projected upon the Plane of the Equinoctial, would answer my utmost wishes, and would be capable, not only to solve the daily apparent Motions of the Heavens, but also far more other Astronomical Problems than any of the abovementioned can do: this Planiſphere is a true representation of the Celestial Sphere, in the parallel of London,
