To which is prefix’d, By Way of Introduction , A brief Account of the Solar System . By JOSEPH HARRIS, Teacher of the Mathematics . The Eleventh Edition. LONDON : Printed for B. Cole , at the Orrery , near the Globe Tavern , in Fleet street , late the Shop of Mr. Thomas Wright , Instrument-maker to his late Majesty ; and E. Cushee , near St. Dunstan ’s Church, Fleet Street . MDCCLXXIII. Advertisement. The great encouragement Mr. Wright has had for many years past in making large Orreries , with

Of the Order and Periods of the Primary Planets revolving about the Sun; and of the Secondary Planets round their respective Primaries. The Sun is placed in the midst of an immense space, wherein six opaque spherical bodies revolve about him as their center. These wandering globes are called the Planets , who, at different distances, and in different periods, perform their revolutions from West to East, in the following order: 1. ☿ Mercury is nearest to the Sun of all the planets, and performs i

Of the Fixed Stars . The fixed Stars are those bright and shining bodies, which in a clear night appear to us every where dispersed through the boundless regions of space. They are term’d fix’d, because they are found to keep the same immutable distance one from another in all ages, without having any of the motions observed in the Planets. The fixed Stars are all placed at such immense distances from us, that the best of telescopes represent them no bigger than points, without having any appare

An Explanation of the Circles of the Sphere, and of some Astronomical Terms arising therefrom. In order to determine the relative situations of places upon the Earth, as well as the positions of the fixed Stars, and other Celestial phænomena, the Globe of the Earth is supposed to be environed by several imaginary circles, and these are called the Circles of the Sphere . These imaginary circles are either fixed, and always obtain the same position in the Heavens, or moveable, according to the pos

Geographical Definitions. Of the Situations of Places upon the Earth; of the different Situations of its Inhabitants; of Zones and Climates. The situations of places upon the Earth, are determined by their Latitude and Longitude. 1. The Latitude of any place (upon the Earth) is its nearest distance, either North or South from the Equator; and if the place be in the (Northern/Southern) hemisphere, it is accordingly called ( North / South ) Latitude ; and is measured by an arch of the meridian int

4. Zones are large tracts of the surface of the Earth, distinguished by the tropics and polar circles, being five in number; viz. one Torrid , two Temperate and two Frigid . The Torrid , or Burning Zone , is all the space comprehended between the two tropics; the ancients imagined this tract of the Earth to be uninhabitable, because of the excessive heat, it being so near the Sun. All the inhabitants of the torrid zone have the Sun in their zenith, or exactly over their heads twice in every year

The ancient Poets make frequent mention of the Stars rising and setting, either Cosmically , Acronically , or Heliacally ; whence these distinctions are called Poetical . A Star is said to rise or set Cosmically , when it rises or sets at Sun-rising; and when it rises or sets at Sun-setting, it is said to rise or set Acronically . A Star rises Heliacally , when first it becomes visible, after it had been so near the Sun as to be hid by the splendor of his rays: And a Star is said to set Heliacal

The Earth consists naturally of two parts, Land and Water, and therefore it is called the Terraqueous Globe . Each of these elements is subdivided into various forms and parts, which accordingly are distinguished by different names. I. Of the Land. The land is distinguished into Continents , Islands , Peninsula’s , Isthmus’s , Promontories , Mountains , or Coasts . 9. A Continent is a large quantity of land, in which many great countries are joined together, without being separated from each oth

The USE of the Globes . 1. Turn the globe round its axis, ’till the given place lies exactly under the (Eastern side of the brass) meridian, then that degree upon the meridian, which is directly over it, is the Latitude ; which is accordingly North or South, as it lies in the Northern or Southern hemisphere, the globe remaining in the same position. That degree upon the equator which is cut by the brazen meridian, is the Longitude required from the first meridian upon the globe. If the longitude

Having put on the handle, push in the pin which is just above it, and place a small black patch (or bit of wafer) upon the middle of the Sun (for instance) right against the first degree of ♈; you may also place patches upon Venus , Mars , and Jupiter , right against some noted point in the ecliptic. If you lay a thread from the Sun to the first degree of ♈, you may set a mark where it intersects the orbit of each Planet, and that will be a help to note the time of their revolutions. One entire

The primary Planets, as they all turn round the Sun, at different distances, and in different times, appear to us from the Earth to have different motions; as sometimes they appear to move from West to East, according to the order of the signs, which is called their Direct Motion ; then by degrees they slacken their pace, until at last they lose all their motion, and become Stationary , or not to move at all; that is, they appear in the same place with respect to the fixed Stars for some time to

We shall instance in the Planet Mercury , because his motion round the Sun differs more from the Earth’s than that of Venus does. When Mercury is in his superior conjunction (or when he is in a direct line from the Earth beyond the Sun) fasten a string about the axis of the Earth, and extend it over Mercury to the ecliptic; then turning the handle, keep the thread all the while extended over ☿, and you will find it move with a direct motion in the ecliptic, but continually slower, until Mercury

The Earth in her annual motion round the Sun, has her axis always in the same direction, or parallel to itself; that is, if a line be drawn parallel to the axis, while the Earth is in any point of her orbit, the axis in all other positions of the Earth will be parallel to the said line. This parallelism of the axis, and the simple motion of the Earth in the ecliptic, solves all the phænomena of different seasons. These things are very well illustrated by the Orrery . Plate 3. If you put on the l

The orbit of the Moon makes an angle with the plane of the ecliptic, of above 5¼ degrees, and cuts it into two points, diametrically opposite (after the same manner as the equator and the ecliptic cut each other upon the globe, in ♈ and ♎) which points are called the Nodes ; and a right line joining these points, and passing through the center of the Earth, is called the Line of the Nodes . That node where the Moon begins to ascend Northward above the plane of the ecliptic, is called the Ascendi

An Eclipse is that deprivation of light in a Planet, when another is interposed betwixt it and the Sun. Thus, an eclipse of the Sun is made by the interposition of the Moon at her conjunction, and an eclipse of the Moon is occasioned by the shadow of the Earth falling upon the Moon, when she is in opposition to the Sun. Let S be the Sun, T the Earth, and ABC its shadow; now if the Moon, when she is in opposition to the Sun, should come into the conical space ABC, she will then be deprived of the

The apparent diameters of the inferior Planets are so small, that when they pass betwixt us and the Sun, they only appear like small spots upon the Sun’s surface, without depriving us of any sensible quantity of his light. The shadow of the Earth likewise terminates before it reaches any of the superior Planets, so that they are never eclipsed by us; and the Earth when she is in conjunction with the Sun, only appears like a black spot upon his surface. But Jupiter and his Moons mutually eclipse