The description and use of the globes and the orrery / To which is prefix'd, by way of introduction, a brief account of the solar system

by Joseph Harris

This circle is divided by astronomers into four quadrants, and each of the quadrants into 90 degrees, &c. The four points quartering this circle are called the Cardinal Points, and are termed the East, West, North, and South. The East is that point of the Horizon where the Sun rises when he is in the equinoctial, or on that day when he ascends above the Horizon exactly at six o’clock; and the West is that point of the Horizon which is directly opposite to the East, or where the Sun Sets when he is in the Equinoctial. The South is 90 degrees distant from the East and West, and is toward that part of the Heavens wherein the Sun always appears to us in Great-Britain at Noon; and the North is that part of the Heavens which is directly opposite to the South: Or, the North and South points of the Heavens may be found by turning yourself either directly towards the East or the West: If you look towards the (East/West) the (South/North) will be to the right Hand, and the (North/South) to the left.

Points of the Compass.

Besides the aforementioned divisions of the Horizon into degrees. Mariners divide it into 32 equal parts, which they call the Points of the Compass; to each of which points they give a particular name, compounded of the four Cardinals, according to what quarter of the Compass is intended.

Zenith.

Nadir.

The center of the Horizon is the place of observation, and the Poles of it are one exactly over our heads, called the Zenith; and the other exactly under our feet, called the Nadir.

Vertical Circles.

Meridian.

Azimuth.

13. All circles conceived to pass thro’ the Zenith and Nadir, are called Vertical Circles, or Azimuths. Of these circles, that which passeth thro’ the North and South points of the Horizon, is called the Meridian; so that when any object is upon the Meridian, it then bears either due South, or due North from us; and the Azimuth of any object is an arch of the Horizon intercepted between the vertical circle passing through it, and either the North or South part of the Meridian; which part is commonly specified.