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NEW TREATISE

ON

THE USE OF THE GLOBES,

&c. &c. &c.

PART I. CONTAINING,

1: Explanation of the Lines on the artificial Globes, including Geographical and Astronomical Definitions, &c.-2. The Properties of Matter, and the Laws of Motion.-3. The figure and Magnitude of the Earth. 4. The Diurnal and Annual Motion of the Earth.5. The Origin of Springs and Rivers, and of the Saltness of the Sea.-6. The Flux and Reflux of the Tides.-7. The natural Changes of the Earth, caused by Mountains, Floods, Volcanoes, and Earthquakes. -8. Hypothesis of the Antediluvian World, and the Cause of Noah's Flood.-9. The Atmosphere, Air, Winds, and Hurricanes -10. Vapours, Fogs and Mists, Clouds, Dew and Hoar Frost, Snow and Hail, Thunder and Lightning, Falling Stars, Ignis Fatuus, Aurora Borealis, and the Rainbow.

CHAPTER I.

Explanation of the Lines on the Artificial Globes, including Geographical and Astronomical Definitions; with a few Geographical Theorems.

1. THE TERRESTRIAL GLOBE is an artificial representation of the earth. On this globe the four quarters of the world, the different empires, kingdoms and countries; the chief cities, seas, rivers, &c. are truly represented,according to their relative situations on the real globe of the earth. The diurnal motion of this globe is from west to east.

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2. THE CELESTIAL GLOBE is an artificial representation of the heavens, on which the stars are laid down in their natural situations. The diurnal motion of this globe is from east to west, and represents the apparent diurnal motion of the sun, moon, and stars. In using this globe the student is supposed to be situated in the centre of it, and viewing the stars in the concave surface.

3. THE AXIS OF THE EARTH [See Plate I.* Figures I and II.] is an imaginary line passing through the centre of it upon which it is supposed to turn, and about which all the heavenly bodies appear to have a diurnal revolution. This line is represented by the wire which passes from north to south, through the middle of the artificial globe.

4. The POLES OF THE EARTH are the two extremities of the axis, where it is supposed to cut the surface of the earth; one of which is called the north or arctic pole; the other the south or antarctic pole. The celestial poles are two imaginary points in the heavens, exactly above the terrestrial poles.

5. The BRAZEN MERIDIAN is the circle in which the artificial globe turns, and is divided into 360 equal parts, called degrees. In the upper semicircle of the brass meridian, these degrees are numbered from 0 to 90, from the equator towards the poles, and are used for finding the latitudes of places. On the lower semicircle of the brass meridian they are numbered from 0 to 90 from the poles towards the equator, and are used in the elevation of the poles.

*

Figure I. represents the frame of the globe, with the horizon, brass meridian, and axis; figure II. the globe itself, with the lines on its surface.

†The polestar, is a star of the second magnitude, near the north pole, in the end of the tail of the Little Bear. Its mean right ascention, for the beginning of the year 1804, was 130 14′ 43′′ and its declination 800 15' 44" north.

Every circle is supposed to be divided into 360 equal parts, called degrees; each degree into 60 equal parts called minutes; each minute into 60 equal parts called seconds, &c.; a degree is, therefore, only a relative idea, and not an absolute quantity, except when applied to a great circle of the earth, as to the equator, or to a meridian, in which cases it is 60 geographical miles, or 694 English miles. A degree of a great circle in the heavens is a space nearly equal to twice the apparent diameter of the sun; or to twice that of the moon when considerably elevated above the horizon.

6. GREAT CIRCLES divide the globe into two equal parts, as the equator, ecliptic, &c.

7. SMALL CIRCLES divide the globe into two unequal parts, as the tropics, polar circles, parallels of latitude, &c.

8. MERIDIANS, or lines of longitude are semicircles, extending from the north to the south pole, and cutting the equator at right angles. Every place upon the globe is supposed to have a meridian passing through it, though there be only 24 drawn upon the terrestrial globe; the deficiency is supplied by the brass meridian. When the sun comes to the meridian of any place (not within the polar circles,) it is noon or mid-day at that place.

9. THE EQUATOR is a great circle of the earth, equidistant from the poles, and divides the globe into two hemispheres, northern and southern. The latitudes of places are counted from the equator northward and southward; and the longitudes of places are reckoned upon it eastward and westward. The equator when referred to the heavens, is called the equinoctial, because when the sun appears in it, the days and nights are equal all over the world, viz. 12 hours each.

10. THE FIRST MERIDIAN is that from which geographers begin to count the longitudes of places. In English maps and globes the first meridian is a semicircle supposed to pass through London, or the royal observatory at Greenwich.

11 THE ECLIPTIC is a great circle in which the sun makes his apparent annual progress among the fixed stars ;* or it is the real path of the earth round the sun, and cuts the equinoctial in an angle of 23° 28'; the points of intersection are called the equinoctial points. The ecliptic is situated in the middle of the zodiac.

12. THE ZODIAC, on the celestial globe is a space which extends about eight degrees on each side of the ecliptic, like a belt or girdle, within which the motions of all the planets are performed.†

*The sun's apparent diurnal path, is either in the equinoctial, or in lines nearly parallel to it; and his apparent annual path may be tra ced in the heavens, by observing what particular constellation in the zodiac, is on the meridian at midnight; the opposite constellation will shew very nearly, the sun's place at noon on the same day.

Except the newly discovered planets, or Asteroids, Ceres and Pallas.

13. SIGNS OF THE ZODIAC. The ecliptic and zodiac are divided into 12 equal parts, called signs, each containing 30 degrees. The sun makes his apparent annual progress through the ecliptic at the rate of nearly a degree in a day. The names of the signs, and the days on which the sun enters them are as follow:

SPRING SIGNS.

op Aries, the Ram, 21st of

March.

SUMMER SIGNS.

Cancer, the Crab, 21st of June.

8 Taurus, the Bull, 19th of Leo, the Lion, 22d of Ju

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August.

Gemini, the Twins, 20th of my Virgo, the Virgin, 22d of May. The six signs above are called northern signs, being north of the equinoctial; when the sun is in any of these signs his declination is north.

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The six signs above are called southern signs; when the sun is in any of these signs his declination is south.

The spring and autumnal signs are called ascending signs; because, when the sun is in any of these signs, his declination is increasing. The summer and winter signs are called descending signs; because, when the sun is in any of these signs, his declination is decreasing.

It is conjectured, that the figures in the signs of the zodiac are descriptive of the seasons of the year, and that they are Chaldean or Egyptian hieroglyphics, intended to represent some remarkable occurrence in each month. Thus the spring signs were distinguished for the production of those animals which were held in the greatest esteem, viz. the sheep, the black-cattle, and the goats; the latter being the most prolific, was represented by the figure Gemini. When the sun enters Cancer, he discontinues his progress towards the north pole, and begins to return back towards the south pole. This retrograde motion was represented by a Crab, which is said to go backwards. The heat that usually follows in the next month is represented by the Lion, an animal remarkable for its fierceness, and which, at this season, was frequently impelled,. through thirst, to leave the sandy desert, and make its appearance on the banks of the Nile. The sun entered the sixth sign about the time of harvest, which season was therefore represented by a virgin, or female reaper, with an ear of corn in her hand. When the

gun enters Libra, the days and nights are equal all over the world, and seem to observe an equilibrium, like a balance.

Autumn, which produces fruits in great abundance, brings with it a variety of diseases: this season is represented by that venomous animal the Scorpion, which wounds with a sting in his tail as he recedes. The fall of the leaf was the season for hunting, and the stars which marked the sun's path at this time, were represented by a huntsman or archer, with his arrows and weapons of destruction. The Goat, which delights in climbing or ascending some mountain or precipice, is the emblem of the winter solstice, when the sun begins to ascend from the southern tropic, and gradually to increase in height for the ensuing half year.

Aquarius, or the Water-bearer, is represented by the figure of a man pouring out water from an urn; an emblem of the dreary and uncomfortable season of winter.

The last of the zodiacal constellations was Pisces, or a couple of fishes, tied back to back, representing the fishing season. The severity of the winter is over, the flocks do not afford sustenance, but the seas and rivers are open and abound with fish.

The Chaldeans and Egyptians were the original inventers of astronomy; they registered the events in their history, and the mysteries of their religion among the stars by emblematical figures.The Greeks displaced many of the Chaldean constellations, and placed such images as had reference to their own history in their room. The same method was followed by the Romans: hence the accounts given of the signs of the zodiac, and of the constellations, are contradictory and involved in fable.

14. DECLINATION of the sun, a star, or planet, is its distance from the equinoctial, northward or southward. When the sun is in the equinoctial he has no declination, and enlightens half the globe from pole to pole. As he increases in north declination he gradually shines farther over the north pole, and leaves the south pole in darkness: in a similar manner, when he has south declination, he shines over the south pole, and leaves the north pole in darkness. The greatest declination the sun can have is 23° 28'; the greatest declination a star can have is 90°, and that of a planet 30° 28′* north or south.

15. The TROPICS are two small circles, parallel to the equator, at the distance of 23° 28′ from it; the northern is called the Tropic of Cancer, the southern is the Tropic of Capricorn. The Tropics are the limits of the torrid zone, northward and southward.

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Except the planets, or Asteroids, Ceres and Pallas, which are nearly at the same distance from the sun; the former at the time this was written, was out of the zodiac.

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