THIRD BOOK

The Uſe of the Lines of Numbers, Sinesand Tangents, for the drawing of Hour · lines onall ſorts of Planes. 8

on from thoſe Great Circles to which chey are Parallels, andmay ſufficiently for our uſe be repreſented in chis one Funda-mental Diagram, and be known by their Horizontal and Perpendicular1155 of ſuch as know the Latitude of the Place, and the Circles of cheSphere. 2. 1. An Horizontal Plane parallel to the Horizon, here repreſentedl by theoutward Circle ES W N. 3

2. A Vertical Plane, parallel to the prime Vertical Circle, which paſ-ſeth through the Zenith, and the Points of Eaſt and Weſt in the Hori-zon, and is right to the Horizon and the Meridian; that is, maketh rightAngles with them both. This is repreſented by EZ W.

3. A Polar Plane parallel to the Circle of the Hour of 6, which paſſeththrough the Pole, and che Points of Eaſt and Weſt, being right to theEquinoctial and the Meridian, but inclining to the Horizon, with an Angleequal to the Latitude. This is here repreſented by EP W.

4. An Equinoctial Plane parallel to the Equinoctial, which paſſethhrough the Points of Eaſt and Weſt, being right to the Meridian, but in-clining to the Horizon, with an Angle equal to the Complement of theLatitude. This is here repreſented by EA W..

5. AVertical Plane inclining to che Horizon, parallel to any GreatCircle, which paſſeth rhrough the Points of Eaſt and Weſt, being right

to the Meridlian, but inclining to the Horizon, and yet not paſſing throughche pole, nor parallel to the Equinoctial. This is here repreſented either by

EI, or EV W, or ELW. 55 Aa a— 6. QA

1 are ten ſeveral ſorts of Planes, Which take their denominati-