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1. Terrestrial Globes. Though the earth be not exactly a sphere, it deviates very little from the spherical form. The polar diameter is less than the equatorial by about 1334th of the latter, while the height of the highest mountain is not equal to the 2000th part of it. Upon the largest globe that is ever constructed, these differences of the earth from an exact sphere could not be perceived; and the artificial globe, therefore, is always exactly spherical. Through the centre of the globe let a straight wire pass, this will represent the axis, and the points where it cuts the surface, the north and south poles. A circle drawn at the distance of 90 degrees from either pole is the equator, and another circle drawn from any point of the equator, and at right angles to it, will be the first meridian.

The equator and the first meridian are divided into degrees and minutes, which are numbered, beginning at the point where the circles intersect each other. The degrees upon the first meridian are numbered on both sides of the equator, and do not exceed 90. They point out the latitude. The degrees upon the equator are numbered completely round the circle, and extend therefore to 360. They enable us to find out the longitude.

The equator and first meridian are distinguished from parallels of latitude and other meridian lines, by their being graduated. They are also sometimes denoted by double lines.

We shall now suppose, that the artificial globe exactly represents the surface of the earth, and proceed to explain the lines which are commonly drawn upon the globe, besides the equator and first meridian, and to describe the apparatus usually attached to it.

In order that we might be able to find out from the globe itself, the latitude and longitude of any place, a parallel to the equator and a meridian line would require to be drawn through that place. It is impossible that such lines could be drawn through every point on the globe, and it is unnecessary, for the brass circle placed around it, enables us to find out the latitude and longitude. In this circle, which is placed at right angles to the equator, and is there fore a meridian, the globe is suspended by the axis. One of the sides of the meridian is graduated, or divided into degrees, minutes, and seconds. The globe can be turned round its axis, while the general meridian remains stationary, so that every point of the surface of the globe must pass under some point of the meridian. To find out the latitude and longitude of any place, therefore, we have only to turn the globe round till the given place be brought to the meridian. The number of degrees, minutes, &c. under which the place lies will be its latitude, and the number intercepted upon the equator its longitude.

In addition to the general meridian, meridians and parallels of latitude are usually drawn upon the globe, through

every 5th or 10th degree of latitude and longitude, according to the size of the globe. These lines point out accurately the latitude or longitude of those places which are situated upon them, and give us a general idea of the situation of other places.

Besides meridians and parallels of latitude, the ecliptic is usually drawn upon globes, and also the tropics and polar circles. All these last are commonly drawn with double lines to distinguish them from other meridians and parallels of latitude.

The globe suspended in the general meridian, is placed upon a wooden frame. The upper surface of this frame divides the globe into two hemispheres, one superior, and the other inferior, and represents, therefore, the rational horizon of any place which is brought to the zenith point of the meridian. There are two notches for the meridian to slide in, by which different elevations of the pole may be exhibited. The horizon has commonly drawn upon it the points of the compass, the twelve signs of the zodiac, the months of the year, &c.

There is attached to the general meridian a quadrant, composed of a thin pliable plate of brass, answering exactly to a quadrant of the meridian. It is graduated, and has a notch, nut, and screw, by which it may be fixed to the brazen meridian in the zenith of any place. When so fixed, it turns round a pivot, and supplies the place of vertical circles. It is hence denominated a quadrant of altitude.

A small circle of brass is placed on the north pole. It is divided into 24 equal parts, and is termed an hour-circle. On the pole of the globe is fixed an index, which turns round the axis, and points out the hours upon the hourcircle.

There is also often attached to the globe a compass, which is placed upon the pediment of the frame, parallel to the horizon.

2. Problems solved by the Globe. Having thus described the globe and its apparatus, we shall now explain some of the problems that may be resolved by it.

1. To find the latitude and longitude of any place. We have already seen, that this is done by bringing the place to the graduated side of the general meridian; the degree of the meridian cut by the place being equal to the latitude, and the degree of the equator then under the meridian being the longitude.

II. To find a place upon the Globe, its latitude and lon. gitude being given. Find the degree of longitude on the equator, and bring it to the brass meridian; then find the degree of latitude on the meridian, either north or south, and the point of the globe under that degree of latitude is the place required.

III. To find all the places on the Globe that have the same

latitude as a giren place, suppose New York.-Turn the globe round, and all the places that pass under the same point of the meridian as the given place does, have the same latitude with it.

IV. To find all the places that have the same longitude or hour with a given place, as New York. - Bring the given place, New York, to the meridian, and all places then under the meridian have the same longitude.

V. To find the difference in the time of the day at any two giren places, and their difference of longitude. Bring one of the places to the meridian, and set the hour-index to twelve at noon, then turn the globe till the other place come to the meridian, and the index will point out the difference of time. By allowing 15 degrees to every hour, or one degree to four minutes of time, the difference of longitude will be known. The difference of longitude may also be found without the time, in the following manner:- Bring each of the places to the meridian, and mark the respective longitudes. Subtract the one number from the other, and we obtain the difference of longitude sought.

VI. The time being known at any given place, as New York, to find what hour it is in any other part of the world. -Bring the given place, to the meridian, and set the index to the given hour; then turn the globe till the other place come to the meridian, and the hour at which the index points will be the time sought.

VII. To find the distance of two places on the Globe. If the two places be either both on the equator or both on the same meridian, the number of degrees is the distance between them, reduced into miles, at the rate of 69 to the degree, will give the distance nearly. If the places be in any other situation, lay the quadrant of altitude over them, and the degrees intercepted upon it by the two places, and turned into miles, as above, will give their distance.

VIII. To find the antæci, periæci, and antipodes of any giren place, suppose New York. - Bring New York to the eridian, and find by the meridian the point upon the g, of which the latitude is as much south as that of New York is north. The place thus arrived at will be the situation of the anteci, where the hour of the day or night is always the same as at New York, and where the seasons and lengths of the days and nights are also the same, but at opposite times of the year. New York being still under the meridian, set the hour-index to 12 at noon, or pointing towards New York, then turn the globe half round, till the index points to the opposite hour, or 12 at night. The

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Ascii, Amphiscii, Heteroscii, and Periscii. The inhabitants of the different regions of the earth are sometimes distinguished by the ancient geographers, according to the direction of their shadows. When the sun at mid-day is vertical to any place, the inhabitants of that place were said to be asci, that is, without shadow. All the inhabitants between the tropics must be ascii twice a year.

The inhabitants of the torrid zone, having the sun sometimes to the north, and sometimes to the south, will project shadows directed by turns towards either pole, and they were therefore said to be amphiscii, that is, having both kinds of

shadows.

Those who inhabit the temperate zones were called heteroscii, because their shadows fall in opposite directions. Within the polar circles the inhabitants must, for a while, project shadows in all directions, and they are therefore said to be periscii.

Perioci and Antoci, and Antipodes. The seasons which the inhabitants of opposite places on the earth enjoy at the same time, as well as the hours of the day at these places, being contrasted, give rise to certain distinctions with which it is also necessary to be acquainted.

Those who live under opposite meridians, at equal distances from the equator, and upon the same side of it, are termed perioci. They have the same seasons, but reckon at the same instant opposite hours: it being midnight with the one when mid-day with the other.

Those who live under the same meridian on opposite sides of the equator, and at equal distances from it, are called an

teci. They have the seasons at opposite times, but reckon at

the same instant the same hours.

The people who live at equal distances from the equator, and under opposite meridians, are termed antichthones, or antipodes. They have both the seasons and the hours of the day at opposite times.

place that comes under the same point of the meridian where New York was, is where the periceci dwell, or people that have the same seasons, and at the same time, as New York, and the same length of the days and nights, but have an opposite hour, it being midnight with the one when noon with the other. Lastly, While the place of the pericci is at the meridian, count by the meridian the same degree of latitude south, and that will give the place of the antipodes of New York. They have all their hours and seasons opposite to those of New York, being noon with the one when midnight with the other, and winter with the one when summer with the other.

IX. To find the sun's place in the ecliptic and also on the Globe at any given time. Find in the calendar, on the wooden horizon, the given month, and day of the month, and immediately opposite will be found the sign and degree which the sun is in on that day. Then in the ecliptic drawn upon the globe, find the same sign and degree, and that will be the place of the sun required.

X. The time being given at any place, to find the place on the earth to which the sun is then vertical. - Find the sun's place on the globe by the last problem; and turn the globe about till that place come to the meridian; mark the degree of the meridian over it, which will show the latitude of the required place. Then turn the globe till the given place come to the meridian, and set the index of the hour-circle to the given moment of time. Lastly, Turn the globe till the index points to twelve at noon, and the place of the earth corresponding to that upon the globe, which stands under the meridian at the point marked as before, is that which has the sun at the given time in the zenith.

XI. To find all those places on the earth to which the sun is vertical on a given day. - Find the sun's place in the ecliptic on the globe, as in the last problem, and bring that place to the meridian. Turn the globe round, and note all the places which pass under the same point. These will be the places sought. This problem enables us to determine what people are ascii on any given day. It is evident, that in a similar manner we may also find to what places on the earth the moon or any other planet is vertical at a given time: the place of the planet on the globe at that time being found by its declination and right ascension. XII. A place being given in the torrid zone, to find on what two days of the year the sun is vertical at that place.Bring the given place to the meridian, and note the degree it passes under. Turn the globe round, and note the two points of the ecliptic which pass under the same degree of the meridian. Then, find by the wooden horizon on what days the sun is in these two points of the ecliptic, and on these days he will be vertical to the given place.

XIII. To find how long the sun shines without setting in any given place in the frigid zone. Subtract the degrees of latitude of the given place from 90, which gives the complement of the latitude, and count this complement upon the meridian from the equator towards the pole, marking that point of the meridian; then turn the globe round, and observe what two degrees of the ecliptic pass exactly under the point marked on the meridian. It is evident, that the sun will shine upon the given place without setting while it is in these, and all the points of the ecliptic that are nearer to the given place. Find, therefore, upon the wooden horizon the months, and days of the months in which the sun is in the two points in question, and the intermediate time will be that during which the sun constantly shines at the given place.

XIV. To find how long the sun never shines upon any given place in the frigid zones.— - Count the complement of latitude towards the south, or farthest pole, and then proceed exactly as in the last problem.

XV. To rectify the globe to the latitude of any place. Move the brass meridian in its groove, till the elevation of the pole above the horizon be equal to the latitude.

XVI. To rectify the globe to the horizon of any place. Rectify the globe to the latitude of the place by the last problem; and then turn the globe on its axis till the given place come to the meridian. The place will then be exactly on the vertex of the globe, 90 degrees distant every way from the wooden horizon; and that horizon, therefore, will represent the horizon of the given place.

XVII. To find the bearing of one place from another, and their angle of position. - Rectify the globe to the horizon of one of the places. Screw the quadrant of altitude to the zenith point of the meridian, and make it revolve till the graduated edge passes through the other place. Then look on the wooden horizon for the point of the compass, or number of degrees from the south, where the quadrant of altitude meets the horizon, and that will be the bearing of the latter place from the former, or the angle of position sought.

XVIII. To find all those places on the earth to which the sun at a given time is rising or setting; also what places are then illuminated by the sun, or in darkness; and where it is noon, or midnight. — Find the place to which the sun is vertical at the given time, and rectify the globe to its horizon, in which state the place will be in the zenith point of the globe. Then is all the hemisphere above the wooden horizon enlightened, or in daylight, while the hemisphere below the horizon is in darkness, or night; lastly, to all these places by the eastern side of the horizon, the sun is just setting, and to those by the western side, he is just rising.

XIX. The time of a solar or lunar eclipse being given, to find all those places at which the eclipse will be visible.— Find the place to which the sun is vertical at the given time, and rectify the globe to the horizon of that place. Then, by the last problem, it is evident, that if the eclipse be solar, a part of it at the beginning only will be seen in places which are not far above the eastern side of the horizon; while, in the rest of the upper hemisphere, the

whole of the eclipse will be visible. A part of it at the end will be seen in places which are near to the lower side of the western part of the horizon. If the eclipse be lunar, the moon will be in the opposite point of the ecliptic to the sun, and vertical to that point of the earth which is opposite to the place to which the sun is vertical. The eclipse, therefore, will be visible in the lower hemisphere. XX. To find the beginning and end of twilight, on any day of the year, for any latitude. It is twilight in the evening from sunset till the sun is 18 degrees below the horizon; and in the morning from the time the su is within 18 degrees of the horizon till the moment of his rising. Therefore, rectify the globe to the given lati tude, set the index of the hour-circle to 12 at noon, and screw on the quadrant of altitude. Find the point of the ecliptic which is opposite to the sun's place, and turn the globe on its axis westward along with the quadran of altitude, till that point cut the quadrant in the 18th degree below the western side of the horizon. The in dex will then show the time of dawning in the morning Next turn the globe and quadrant of altitude towards the east, till the same opposite point of the ecliptic meet the quadrant the 18th degree below the eastern side of the horizon. The index will then show the time when twilight ends in the evening.

XXI. To rectify the globe to the present situation of the earth. - Rectify the globe to the horizon of the place. Its situation will then correspond to that of the earth; and, if it stand in the sun, it will be illuminated as the earth is.

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DESCRIPTIVE GEOGRAPHY.

CHAPTER I. GENERAL VIEWS OF THE GLOBE.

1. Northern and Southern Hemispheres. The terraqueous globe is divided by the equator into two equal parts, called the Northern and Southern Hemispheres. But the slightest glance at a map of the world will show, that there is a much greater accumulation of dry land in the former than in the latter; recent voyages have, indeed, shown, that this inequality is not so great as was thought by geographers of the last century, large masses of land having been discovered in the Antarctic Seas, and the northern coasts of Asia and America having been shown not to extend so far north as was once supposed. The following statement will show the comparative distribution of land and water in the two hemispheres. If we divide the whole surface of the earth into 1000 parts, we shall find

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The whole of Asia, Europe, and North America, much the greater part of Africa, and a part of South America, lie north of the equator, and large masses of land advance to within 25 degrees of the north pole, and considerable tracts much nearer. While only a small portion of Africa, with New Holland, the bulk of South America, and some islands, rise above the

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waters in the south. There is, indeed, a much larger tract about the south than around the north pole, that has not been explored, and it is now ascertained that an Antarctic continent lies in that quarter. America reaches only to 56° South Lat., Africa to 34°, and New Holland to 45°, while on the north, Asia, Europe, and America, project above the 70th parallel of latitude.

2. Eastern and Western Hemisphere. The two great continents of which the land is composed, are commonly so projected on maps as to form two separate hemispheres. The eastern then includes, in addition to the continental portion, New Holland and the islands around it; and the western com

The distribution

prises most of the small islands of the Pacific with the American continent.
of land and water is not less unequal in this than in the former division. Thus we have

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Another striking circumstance in the conformation of the two continents, is the different disposition of the land in each. In the old continent, the principal extension is to the west and east, the breadth from north to south being comparatively inconsiderable, particularly if we leave out the southern tongue of Africa; in the new, the great extension is from north to south. In the former, we may draw continuous straight lines over land of great extent, but in the latter, in order to draw lines of much length, it will be necessary to make them winding. Thus a straight line from the Gulf of Guinea to the northwestern coast of Siberia is 9,000 miles in length; the longest straight line we can draw on the new continent is from Cumana to Terra del Fuego, 5,400 miles. Conformable to this general extension of the land, is the

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direction of the great mountain chains in the two hemispheres. The Rocky Mountains, the Cordilleras, and the Andes, stretch north and south; while starting with the Pyrenees and the Alps in Europe, we may follow an almost unbroken chain of lofty mountains, comprising the Tauro-Caucasian, Himalaya, and other Asiatic chains, to the shores of the Pacific ocean. Even

the direction of the smaller portions of both continents, as their islands - and peninsulas, nearly coincides with the general course of the great mountain chains.

We shall now proceed to describe the different countries and states of the globe under the following heads and in the following order;

1. North America.-2. West Indies.-3. South America.-4. Europe.-5. Africa. 6. Asia. —7. Oceanica.

Giving first a general description of each division, sketching its physical and political features, and pointing out its minerals, plants, animals, and inhabitants, we shall then pass to a more particular consideration of the separate parts of which it consists.

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