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But this will eafily be conceived, when it is confidered that the earth attracts all bodies, on or near its furface, towards its centre equally on all fides. If fo, the people who are oppofite to us stand juft as firm as we do.
It is now ten o'clock in the morning, and we now think we are standing upright on the upper part of the earth. We fhall think the fame at ten o'clock this evening, when the earth fhall have turned half round, because we shall then perceive no difference of pofture. We fhall then be exactly in the pofition of thofe perfons who now ftand on the oppofite fide of the earth. Since they are as ftrongly attracted towards the centre of the earth as we are, they can be in no more danger of falling downward, than we are at prefent of falling upward.
a round whofe
equally remote from the centre; and on which the external form of our habitable world is reprefented, and all the parts of the earth and water are defcribed in their natural order, form, distance and fituation.
In order to determine the fituation of places on the globe, it is fuppofed to be circumfcribed by feveral imaginary circles. Each circle is divided into 360 equal parts, called degrees; each degree is divided into 60 minutes, and each minute into 60 feconds.
Axis of the Earth. The axis of the earth is an imaginary line paffing through its centre from north to fouth. The extreme points of the axis are called the poles.
Circles.] A circle paffing through the centre of a globe, and thereby dividing it into two equal parts or hemifpheres, is called a great circle. Of there there are fix. The equator, the meridian, the ecliptic, the horizon, and two colures.
Circles dividing the fphere into unequal parts, are called mall or leffer circles, of which there are four, the two tropics, and the two polar circles.
Equator.] The equator is that line or circle which encompaffes the middle of the earth, dividing the northern half from the fouthern. This line is often called the equinoctial, because, when the fun appears therein, the days and nights are equal in all parts of the world. From this line latitude is reckoned.
Meridian.] This circle is reprefented on the artificial globe by a brafs ring, and is divided into 360 degrees. It paffes through the poles of the earth, and the zenith and the nadir, crofling the equator at right angles, and dividing the globe into eaftern and western hemifpheres. It is called meridian from the Latin meridies, mid-day; because when the fun comes to the fouth part of this circle it is called noon, and the day is half fpent. There are an infinite number of meridians, which vary as you travel eaft or weft. Geographers affume one of the meridians for the first; commonly that which paffes through the metropolis of their own country. The meridian of Philadelphia is the firft for Americans; that of London for the English; and that of Paris for the French.
Ecliptic.] The ecliptic is a great circle, in whofe plane the earth performs her annual revolution round the fun, or in which the sun seems to move round the earth once in a year. This circle is called the Ecliptic, from the word Eclipfe, because no eclipfe of the fun or moon happens, but when the moon is in or near the plane of this circle. It makes an angle with the equator of 23° 30', and interfects it in two oppofite parts called the equinoctial points, because when the fun is in either of these points, he has no declination, and fhines equally to both poles, and the day is then equal to the night all over the world. The times when the fun paffes through these points, are the 21st of March, and the 21st of September: the former is called the vernal, the latter the autumnal equinox.
The ecliptic is divided into twelve equal parts, of thirty degrees each, called figns. Thefe begin at the vernal interfection of the ecliptic with the equator, and are numbered from west to east. The names and characters of the figns, with the months in which the fun enters them, are as follows:
Latin names of
Charac- Months in which the
fun enters them.
Zodiac.] If two circles were drawn parallel to the ecliptic, at the distance of eight degrees on each fide of it, the space, or girdle included between thefe two parallels, fixteen degrees broad, and divided in the middle by the ecliptic, will comprehend within it the orbits of all the planets, and is called the Zodiac.
Horizon. The horizon is reprefented on the artificial globe by a broad wooden circle, dividing it into upper and lower hemifpheres. There are, geographically fpeaking, two horizons, the fenfible and the rational. The fenfible horizon is that circle which limits our profpect; where the fky and the land or water appear to meet. The rational or real horizon, is a circle whofe plane paffes through the centre of the earth, dividing it into upper and lower hemifpheres.
The horizon is divided into four quarters, and each quarter into go degrees. The four quartering points, viz. eaft, weft, north, and fouth, are called the Cardinal points. The poles of the horizon are the zenith and the nadir. The former is the point directly over our heads; the fatter the point directly under our feet.
Colures.] The colures are two meridian lines which divide the globe into four quarters. They are called colures, to diftinguish them from
ather meridians. They both pafs through the poles of the world, and one of them through the equinoctial points Aries and Libra; the other through the folftitial points Capricorn and Cancer: The former is called the equinoctial, the latter the folftitial colure.
Tropics.] The tropics are two circles drawn parallel to the equator, at the diftance of 23° 30′ on each fide of it. Thefe circles form the limits of the ecliptic, or the fun's declination from the equator. That which is in the northern hemifphere, is called the tropic of Cancer, because it touches the ecliptic in the fign Cancer; and that in the fouthern hemifphere, is called the tropic of Capricorn, because it touches the ecliptic in. the fign Capricorn. On the 21st of June the fun is in Cancer, and we have the longest day. On the 21st of December the fun is in Capricorn, and we have the fhorteft day. They are called tropics, from the Greek word TREPŎ, to turn, becaufe when the fun arrives at them, he returns again to the equator.
Polar Circles.] The two polar circles are defcribed round the poles of the earth, at the distance of 23° 30′. The northern is called the Arctic circle, from Arctos, or the bear, a conftellation fituated near that place in the heavens; the fouthern, being oppofite to the former, is called the An tarctic circle.-The polar circles bound the places where the fun fets daily. Beyond them the fun revolves without fetting.
Zones.] The tropics and polar circles divide the globe into five parts, called Zones, or Belts; viz. One torrid, two temperate, and two frigid zones.
The Torrid Zone, 47 degrees broad, is bounded by the tropics, and divided in the middle by the equator. It is called the torrid or burning zone, because the fun, being always over fome part of it, makes it extremely hot.
Each of the Temperate Zones is 43 degrees in breadth. The one which lies between the tropic of Cancer and the arctic circle, is called the worth temperate zone; and the other, lying between the tropic of Capricorn and the antarctic circle, is called the fouth temperate zone. The mildnefs of the weather in thefe fpaces, which are between the extremes of heat and cold, has acquired to them the name of temperate zones.
The two Frigid Zones, fo called on account of the extreme cold of thofe regions, are included between the polar circles and the poles. Each of them is 23° 30′ broad.
Climates.] By a number of other circles, drawn parallel to the equator, the earth is divided into climates.
A Climate is a tract of the earth's furface, included between the equator and a parallel of latitude, or between two parallels of fuch a breadth, as that the length of the day in the one, be half an hour longer than in the other. Within the polar circles, however, the breadth of a circle is fuch, that the length of a day, or the time of the fun's continuance above the horizon without fetting, is a month longer in one parallel, as you proceed northerly, than in the other.
Under the equator, the day is always twelve hours long. The days gradually increase in length as you advance either north or fouth from the equator. The fpace between the equator, and a parallel line drawn at the diftance of 8° 25' where the days are twelve hours and a half long, is called the first climate; and by conceiving parallels drawn in this manner, at the increase of every half hour, it will be found that there B 4
are twenty-four climates between the equator and each of the polar` circles. Forty-eight in the whole.
Under the polar circles, the longeft day is twenty-four hours. The fun, when at the tropics, fkims the horizon without fetting. As you advance from the polar circles to the poles, the fun continues above the horizon for days, weeks and months, in a conftant increase until you arrive at the poles, where the fun is fix months above the horizon; and the whole year may be faid to confift of but one day and one night.
There are thirty climates between the equator and either pole. In the first twenty-four, between the equator and each polar circle, the period of increafe for every climate is half an hour. In the other fix, between the polar circles and either pole, the period of increafe for each climate is a month. Thefe climates continually decrease in breadth as you proceed from the equator, as may be seen by attending to the following table..
17 54 27
17 56 37
Names of countries and remarkable places, fituated in the respective climates, north of the equator.
Within the first climate lie,
I The Gold coaft in Africa, Cayenne and Surinam in S. Amer. 2 Abyffinia, Siam, Madras, Darien, Barbadoes.
3 Mecca, Bengal, Canton, Mexico, Jamaica, Gaudelupe.
4 Egypt, Delhi, Canary Isles, E. Florida, Havanna.
5 Gibraltar, Jerufalem, Nanking, Georgia, and Carolinas.
6 Lisbon, Madrid, Afia-Minor, Virginia, Maryland, Philadel.
Paris, Vienna, Nova-Scotia, Newfoundland, Canada.
12 18 58 29 Iz South Part of Sweden, Siberia. 18/1/ 59 5813 Orkney Isles, Stockholm.
16 South Part of Weft Greenland.
28 4 do.
17 Drontheim in Norway.
18 Part of Finland in Ruffia.
19 Archangel on the White Sea, Ruffia.
21 Northern Parts of Ruffia and Siberia.
25 South Part of Lapland,
27 Zemble Auftralis. 30 28 Zemble Borealis.
0529 Spitsbergen, or E. Greenland.
90 030 Unknown.
Latitude.] The latitude of a place is its diftance from the equator, north or fouth. The greatest latitude is that of the poles, which are ninety degrees distant from the
The elevation of the pole above the horizon, is always equal to the latitude of the place; for to a perfon fituated on the equator, both poles will reft in the horizon. If you travel one, two or more degrees north, the north pole will rife one, two or more degrees, and will keep pace with your distance from the equator.
Longitude.] Every place on the furface of the earth has its meridian. The Longitude of a place, is the diftance of its meridian from fome other fixed meridian, measured on the equator. Longitude is either caft or weft. All places eaft of the fixed or firff meridian, are in east longitude; all weft, in weft longitude. On the equator, a degree of longitude is equal to fixty geographical miles; and of course, a minute on the equator is equal to a mile. But as all the meridians cut the equator at right angles, and approach nearer and nearer to each other, until at laft they crofs at the poles, it is obvious that the degrees of longitude will leffen as you go from the equator to either pole; fo that in the fixtieth degree of latitude, a degree of longitude is but thirty miles, or half as long as a degree on the equator; as is evident from the following table.
Shewing the number of miles contained in a degree of longitude in each parallel of latitude from the equator.