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

A Strait.

18. A Strait is a narrow passage lying between two shores, whereby two seas are joined together; as, the Straits of Dover, between the British Channel and the German Sea; the Straits of Gibralter, between the Atlantic and the Mediterranean Sea. The Mediterranean itself is also sometimes called the Straits.

These are all the necessary terms commonly used in Geography. The names of the several countries and seas, and all the principal divisions of the Earth, the reader will find expressed upon the Terrestrial Globes. To give a tolerable account of the produce of each country, the genius of the people, their political institutions, &c. is properly a particular subject of itself, and quite foreign to our design. We shall next proceed to the use of the Globes; but first it may not be amiss to take a short review of their appurtenances.

Those circles of the sphere that are fixed, are (as has been already said) drawn upon the Globes themselves; those that are moveable, are supplied by the Brass Meridian, the Wooden Horizon, and the Quadrant of Altitude.

Brass Meridian.

1. That side of the Brazen Meridian, which is divided into degrees, represents the true Meridian; this side is commonly turned towards the East, and ’tis usual to place the globe so before you, that the North be to the right hand, and the South to the left. The meridian is divided into 4 quadrants, each being 90 degrees, two of which are numbered from that part of the equinoctial, which is above the horizon, towards each of the Poles; the other two quadrants are numbered from the Poles towards the equator. The reason why two quadrants of the meridian are numbered from the equator, and the other two from the Poles, is because the former of these two serve to shew the distance of any point on the globe from the equator, and the other to elevate the globe to the latitude of the place.

Wooden Horizon.

2. The upper side of the wooden frame called the Wooden Horizon; represents the true horizon; the circles drawn upon this plane have been already described; we may observe, that the first point of ♈ is the East, and the opposite being the first point of ♎ is the West, the meridian passing through the North and South points.

Quadrant of Altitude.

3. The Quadrant of Altitude is a flexible plate of thin brass, having a nut and screw at one end, to be fastened to the meridian of either globe, as occasion requires. The edge of this quadrant which has the graduations upon it, called the fiducial edge, is that which is always meant whenever we make mention of the quadrant of altitude.