variety of books. Thomson's Lectures on Modern History should be read through carefully; ́ it will be found a work of much merit, and its compactness gives it an advantage over more diffuse works. The map, however, should always accompany the book; and every action should be traced carefully in the country where it was performed. SECTION CIII. OF THE GLOBES. AN Artificial Globe is a round body, having every part of its surface equally distant from a point within it, called its Centre. There are two sorts of globes; one called the celestial, and the other the terrestrial. The Celestial Globe has on its surface a proper representation of all the visible stars in the heavens, and the images or figures of all the various constellations into which these stars are arranged, and which are called asterisms. The Terrestrial Globe exhibits on its surface an exact delineation of all the parts of the earth and sea, in their proper situations and distances, just as they are in nature. This curious and entertaining instrument consists of several parts, viz. 1. The Two Poles (being the ends of the axis on which the globe turns to perform its diurnal motion) representing those of the world. 2. The Brass Meridian, divided into four quarters, and each quarter into ninety degrees. This circle surrounds the globe, and is fixed to its axis, at the poles. 3. The Wooden Horizon, or frame which supports the whole globe; the upper part of it represents our true horizon, and has several circles drawn on it. The first* next the globe contains the twelve signs of the Zodiac, through which the sun, apparently, revolves in a year: these are subdivided into single degrees; the next circle exhibits the Julian, and the third circle the Gregorian Calendar (or old and new stile,) divided into months and days; and on the outside of these are generally delineated the thirty-two points of the compass. 4. The Hour Circle divided into thrice twelve hours, fitted to the Brass Meridian round the North Pole: the twelfth hour at noon is upon the upper part of it at the meridian; and the twelfth hour at night upon the lower part, towards the horizon. In the new globes, this circle is moveable, and may be turned round to any hour; but in those that are common mounted, there is an index which shews the hour. 5. The Quadrant of Altitude; which is a thin * The horizons of all globes are not divided alike; this di vision is the same as on Wright's Globes, but different from Adams's, Bardin's New British Globes, and from Cary's Globes. The hours upon Adams's improved globes are counted on the equator, or by means of a brass wire coincident therewith. slip of brass, divided into ninety degrees of the same size with those of the Equator. It may be screwed on occasionally to the top of the brass meridian, to measure the distances of places from one another, &c. 6. The Mariner's Compass: which some globes have fixed at the bottom of the frame. This is a box containing a magnetical needle, freely moving on a fine point, in the centre of a circle, divided into four times ninety degrees, reckoning from the north and south towards the east and west; and also divided into the thirty-two points of the compass, properly marked. SECTION CIV. OF THE CIRCLES DELINEATED ON THE THEIR VARIOUS USES. ON the surface of the Globe are drawn ten cir cles; six of which are called The Great Circles, and four The Less Circles. The Great Circles divide the globe into two equal parts: they are, the Equator, or (Equinoctial,) the Horizon, the Meridians, the Ecliptic, and the two Colures. The Less Circles divide the globe into unequal parts: they are, the two Tropics, the two Polar Circles, and the Parallels of Latitude. 1. The Equator separates the globe into the northern and southern hemispheres. It is divided in 180 degrees each way, from the first or chief meridian; making altogether 360 degrees, if reckoned quite round the globe to the point from whence they begin. 2. The Horizon is that circle you see in a clear day, where the sky and water, or earth, seem to meet; this is called the Visible, or Sensible, Horizon. This circle determines the rising or setting of the sun and heavenly bodies, in any particular place; for when they begin to appear above the eastern edge, we say, "they rise;" and when they go beneath the western, we say, they set," so that each place has its own sensible horizon. That called the Rational Horizon, encompasses the globe exactly in the middle, and is represented by the wooden framé before-mentioned. The Cardinal Points are the four principal points of the horizon; North, South, East, and West. The Zenith is the uppermost pole of the horizon, an imaginary point in the heavens, vertically over our head. On the Artificial Globe, it is the most elevated point on its surface in which the eye of the spectator can be placed. The Nadir is the lower pole of the horizon; that is, an imaginary point, directly under the feet, and consequently diametrically opposite to the Zenith. 3. The Meridians are those circles that pass from pole to pole, and divide the globe into the Eastern and Western Hemispheres. They are so called, because when the Sun comes to the south part part of either of these circles, it is then meridies, or mid-day, to all places lying under that line: the sun at that time has its greatest altitude for that day, which is therefore called its meridian altitude. There are commonly marked on the globes, twenty-four meridians; one through every fifteen degrees, corresponding to the twentyfour hours of the day and night. But every place, though ever so little to the east or west, has its own meridian. The first Meridian with English geographers, is drawn from London. 4. The Ecliptic represents that part in the heavens which the Sun seems to describe by the Earth's annually revolving round it. It is divided into twelve equal parts, called Signs; and each sign contains thirty degrees, corresponding to the twelve months of the year, and the days of the months, It is called the Ecliptic, because the eclipses must necessarily happen in or near this line, where the sun always is. The names and characters of the twelve Signs, with the time of the Sun's entrance into them, are as follow: 1. Aries, or the Ram; in which the Sun 2. Taurus 8, the Bull; April 19. |