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

The distribution of the Stars into 6 classes.

Of Telescopical Stars.

The astronomers distribute the Stars into several orders or classes; those that are nearest to us, and appear brightest to the eye, are called Stars of the first magnitude; those that are nearest to them in brightness and lustre, are called Stars of the second magnitude; those of the third class, are stiled Stars of the third magnitude; and so on, until we come to the Stars of the sixth magnitude, which are the smallest that can be discerned by the naked eye. There are infinite numbers of smaller Stars, that can be seen through telescopes; but these are not reduced to any of the six orders, and are only called Telescopical Stars. It may be here observed, that tho’ the astronomers have reduced all the Stars that are visible to the naked eye, into some one or other of these classes, yet we are not to conclude from thence that all the Stars answer exactly to some or other of these orders; but there may be in reality as many orders of the Stars, as they are in number, few of them appearing exactly of the same bigness and lustre.

The Stars digested into constellations

The ancient astronomers, that they might distinguish the Stars, in regard to their situation and position to each other, divided the whole starry firmament into Several Asterisms, or systems of Stars, consisting of those that are near to one another. These Asterisms are called Constellations, and are digested into the forms of some animals; as Men, Lyons, Bears, Serpents, &c. or to the images of some known things; as, of a Crown, a Harp, a Triangle, &c.

Zodiac.

The starry firmament was divided by the ancients into 48 images, or constellations; twelve of which they placed in that part of the Heavens wherein are the planes of the Planetary orbits; which part is called the Zodiac, because most of the constellations placed therein resemble some living creature. The two regions of the Heavens that are on each side of the Zodiac, are called the North and South parts of the Heavens.

Constellations within the Zodiac.