"The pleasure we felt on discovering the southern Cross was warmly shared by such of the crew as had lived in the colonies. In the solitude of the seas, we hail a star as a friend, from whom we have long been separated. Among the Portuguese and the Spaniards peculiar motives seem to increase this feeling; a religious sentiment attaches them to a constellation, the form of which recalls the sign of the faith planted by their ancestors in the deserts of the new world. "The two great stars which mark the summit and the foot of the Cross having nearly the same right ascension, (see No. 64,) it follows hence, that the constellation is almost perpendicular at the moment when it passes the meridian. This circumstance is known to every nation, that lives beyond the tropics, or in the southern hemisphere. It has been observed at what hour of the night, in different seasons, the Cross of the south is erect, or inclined. It is a time-piece that advances very regularly near four minutes a day, and no other group of stars exhibits to the naked eye an observation of time so easily made. How often have we heard our guides exclaim in the savannas of Venezuela, or in the desert extending from Lima to Truxillo, Midnight is past, the Cross begins to bend! How often those words reminded us of that affecting scene, where Paul and Virginia, seated near the sources of the river of Lataniers, conversed together for the last time, and where the old man, at the sight of the southern Cross, warns them that it is time to separate."

4

Many of the facts stated above, with some others relating to the bodies which compose the solar system, are arranged in the following tables, useful for reference, but not necessary to be learned.

TABLE I.

Of the Sun and Primary Planets.

The earth being 1.

Dist. Time

of Time of

Diame

Heat

Greatest Hourly Eccen

in revolving turning mill. round the on their

ter in miles.

Bulk.

and Den- distance

motion, tricity. Light. sity. from the in miles. Mean

Sun.

Axis.

ecliptic.

Dist. 1.

CHAP. II.

LATITUDE AND LONGITUDE.

55. When latitude and longitude are applied to places on the earth, they properly belong to geography. But as the method of finding them is purely astronomical, it is proper to treat of them as used both to designate the situation of places on the earth, and of the heavenly bodies. Before any thing can be understood of latitude and longitude, definite ideas must be obtained of the poles, the equator, parallels of latitude, and meridians. (The earth turns round on an imaginary line, passing through its centre, called its axis; the extremities of this axis are, as before stated, called poles; one north pole, the other south. If the axis be supposed to extend both ways to the starry heavens, its places or points among the stars are the celestial poles, one north, and the other south, directly over or beyond the poles of the earth of the same name. The north celestial pole is very near a particular star, which on that account is called the pole star.

56. (The equator is a circle surrounding the earth from west to east, at equal distance from the poles. Hence the equator divides the earth's surface into two equal parts, called hemispheres. If the plane of the equator were extended every way to the starry heavens, the circle it would make among the stars is called the celestial equator. It is 1.om the equator that latitude on the earth is reckoned. All places between the equator and the north pole are in north latitude, and all. places between the equator and the south pole are in south latitude. The latitude is greater, as the place is farther from the equator and nearer the poles. All circles, passing round the earth from west to east between

the equator and the poles, are called parallels of latitude; and when two places, as Boston and Philadelphia, differ in latitude, they are said to be on different parallels. There may be as many parallels as there are places not equally distant from the equator.

57. A line passing over the earth from the north to the south pole, and crossing the equator at right angles, is called a meridian. Every place on the earth's surface may be supposed to have such a line or circle passing through it; consequently, when a place lies more easterly or westerly than another, it is said to have a different meridian. Hence there may be as many meridians, as there are places lying eastwardly and westwardly of each other. When places are on different meridians, they are said to be in different longitude. Celestial meridians are lines passing among the stars from one celestial pole to the other, crossing the celestial equator at right angles. When it is noon at any place, the sun is in the celestial meridian directly over the meridian of that place.

Let the instructer explain right angles.

58. To illustrate what has been said, let Pl. III. fig. 1. represent the earth. The line NS is its axis; the extremities of which, N and S, are the north and south poles of the earth. EQ shows the equator. The lines 10 10, 20 20, 30 30, &c. are parallels of latitude; and the lines NAS, NBS, &c. are meridians. If each of these meridians be supposed to extend quite round the earth, (as they do on the artificial globe,) each would divide it into an eastern and western hemisphere; just as the equator divides it into northern and southern.

Much of what is said in this chapter may be illustrated with a terrestrial and celestial globe, if at hand, far better than by any figure.

59. Latitude and longitude are expressed in degrees