The fifth circle contains the degrees of the signs, each sign comprehending 30 degrees.

The sixth circle contains the days of the month, answering to each degree of the sun's place in the ecliptic.

The seventh circle contains the equation of time, or difference of time, shown by a well regulated clock and a correct sun-dial. When the clock ought to be faster than the dial, the number of minutes, expressing the difference, has the sign + before it; when the clock or watch ought to be slower, the number of minutes in the difference has the sign—before it. This circle is peculiar to the New British Globes.

The eighth circle contains the twelve calendar months of the year, &c.

23. The CARDINAL POINTS of the horizon are east, west, north, and south.

24. The CARDINAL POINTS in the heavens are the zenith, the nadir, and the points where the sun rises and

sets.

25. The CARDINAL POINTS of the ecliptic are the equinoctial and solstitial points, which mark out the four seasons of the year; and the cardinal signs are Aries, Cancer, Libra, and S Capricorn.

26. The ZENITH is a point in the heavens exactly over our heads, and is the elevated pole of our horizon. 27. The NADIR is a point in the heavens exactly under our feet, being the depressed pole of our horizon, and the zenith, or elevated pole, of the horizon of our antipodes.

28. The POLE of any circle is a point on the surface of the globe, 90 degrees distant from every part of that circle of which it is the pole. Thus, the poles of the world are 90 degrees from every part of the equator; the poles of the ecliptic (on the celestial globe) are 90 degrees from every part of the ecliptic, and 23 degrees 28 minutes from the poles of the equinoctial. Every circle on the globe, whether real or imaginary, has two poles diametrically opposite to each other.

29. The EQUINOCTIAL POINTS are Aries and Libra, where the ecliptic cuts the equinoctial. The point Aries is called the vernal equinox, and the point Libra the autumnal equinox. When the sun is in either of these points, the days and nights on every part of the globe are equal to each other.

corn.

30. The SOLSTITIAL POINTS are Cancer and CapriWhen the sun is in, or near, these points, the va riation in his greatest altitude is scarcely perceptible for several days; because the ecliptic near these points is almost parallel to the equinoctial, and therefore the sun has nearly the same declination for several days.When the sun enters Cancer it is the longest day to all the inhabitants on the north side of the equator, and the shortest day to those on the south side. When the sun enters Capricorn it is the shortest day to those who live in north latitude, and the longest day to those who live in south latitude.

31. A HEMISPHERE is half the surface of the globe; every great circle divides the globe into two hemispheres. The horizon divides the upper from the lower hemisphere in the heavens; the equator separates the northern from the southern on the earth; and the brass meridian, standing over any place on the terrestrial globe, divides the eastern from the western hemisphere.

32. The MARINER'S COMPASS is a representation of the horizon, and is used by seamen to direct and ascertain the course of their ships. It consists of a circular brass box, which contains a paper card, divided into 32 equal parts, and fixed on a magnetical needle that always turns towards the north. Each point of the compass contains 11° 15′, or 11 degrees, being the 32d part of 360 degrees.

33. The VARIATION OF THE COMPASS is the deviation of its points from the correspondent points in the heavens. When the north point of the compass is to the east of the true north point of the horizon, the variation is east; if it be to the west, the variation is west.

The learner is to understand, that the compass does not always point directly north, but is subject to a small annual variation. At present, in England, the needle points about 24 degrees to the westward of the north.

The compass is used for setting the artificial globe north and south; but care must be taken to make a proper allowance for the variation.

34. LATITUDE OF A PLACE, on the terrestrial globe, is its distance from the equator; in degrees, minutes or geographical miles, &c. and is reckoned on the brass meridian, from the equator towards the north or south pole.

35. LATITUDE OF A STAR OR PLANET, on the celestial globe, is its distance from the ecliptic, northward or southward, counted towards the pole of the ecliptic, on the quadrant of altitude. The greatest latitude a star can have is 90 degrees, and the greatest latitude of a planet is nearly 8 degrees.* The sun being always in the ecliptic, has no latitude.

36. The QUADRANT OF ALTITUDE, is a thin slip of brass divided upwards from 0 to 90 degrees, and downwards from 0 to 18 degrees, and, when used, is generally screwed to the brass meridian. The upper divisions are used to determine the distances of places on the earth, the distances of the celestial bodies, their altitudes, &c.; and the lower divisions are applied to finding the beginning, end, and duration of twilight.

37. LONGITUDE OF A PLACE on the terrestrial globe, is the distance of the meridian of that place from the first meridian, reckoned in degrees and parts of a degree on the equator. Longitude is either eastward or westward, according as the place is eastward or westward of the first meridian. The greatest longitude that a place can have, is 180 degrees, or half the circumference of the globe.

38. LONGITUDE OF A STAR, OR PLANET, is reckoned on the ecliptic from the point Aries, eastward, round the celestial globe. The longitude of the sun is what is called the sun's place on the terrestrial globe.

39. ALMACANTERS, OR PARALLELS OF ALTITUDE, are imaginary circles parallel to the horizon, and serve to show the height of the sun, moon, or stars. These circles are not drawn on the globe, but they may be described for any latitude by the quadrant of altitude.

*The newly discovered planets, or Asteroids, Ceres and Pallas, do not appear to be confined within this limit.

40. PARALLELS OF CELESTIAL LATITUDE are small circles drawn on the celestial globe, parallel to the ecliptic.

41. PARALLELS OF DECLINATION are small circles parallel to the equinoctial on the celestial globe, and are similar to the parallels of latitude, on the terrestrial globe.

42. The COLURES are two great circles passing through the poles of the world; one of them passes through the equinoctial points, Aries and Libra ;* the other through the solstitial points, Cancer and Capricorn: hence, they are called the equinoctial and solstitial colures. They divide the ecliptic into four equal parts, and mark the four seasons of the year.

43. AZIMUTH, OR VERTICAL CIRCLES, are imaginary great circles passing through the zenith and the nadir, cutting the horizon at right angles. The altitudes of the heavenly bodies are measured on these circles, which circles may be represented by screwing the quadrant of altitude on the zenith of any place, and making the other end move along the wooden horizon of the globe.

44. The PRIME VERTICAL is that azimuth circle which passes through the east and west points of the horizon, and is always at right angles with the brass meridian, which may be considered as another vertical circle passing through the north and south points of the horizon.

45. The ALTITUDE of any object in the heavens, is an arch of a vertical circle, contained between the centre of the object and the horizon. When the object is upon the meridian, this arch is called the meridian altitude.

46. The ZENITH DISTANCE of any celestial object, is the arch of a vertical circle contained between the centre of that object and the zenith; or, it is what the altitude of the object wants of 90 degrees. When the

* In the time of Hipparchus, the equinoctial colure is supposed to have passed through the middle of the constellation Aries. Hipparchus was a native of Nicæa, a town of Bythinia, in Asia Minor, about 75 miles S. E. of Constantinople, now called Isnic; he made his observations between 160 and 135 years before Christ.

object is on the meridian, this arch is called the meridian zenith distance.

47. The POLAR DISTANCE of any celestial object, is an arch of a meridian, contained between the centre of that object and the pole of the equinoctial.

48. The AMPLITUDE of any object in the heavens, is an arch of the horizon, contained between the centre of the object when rising, or setting, and the east or west points of the horizon. Or, it is the distance which the sun or a star rises from the east, and sets from the west, and is used to find the variation of the compass at sea. In our summer, the sun rises to the north of the east, and sets to the north of the west and in the winter, it rises to the south of the east, and sets to the south of the west. The sun never. rises exactly in the east, nor sets exactly in the west, except at the time of the equinoxes.

49. The AZIMUTH of any object in the heavens, is an arch of the horizon, contained between a vertical circle passing through the object, and the north or south points of the horizon. The azimuth of the sun, at any particular hour, is used at sea for finding the variation of the compass.

50. HOUR CIRCLES, OR HORARY CIRCLES, are the same as the meridians. They are drawn through every 15 degrees* of the equator, each answering to an hour; consequently, every degree of longitude answers to four minutes of time, every half degree to two minutes, and every quarter of a degree to one minute.

On the globes these circles are supplied by the brass meridian, the hour circle, and its index.

51. The SIX O'CLOCK HOUR LINE. As the meridian of any place, with respect to the sun, is called the 12 o'clock hour circle; so that great circle passing through the poles which is 90 degrees distant from it on the equator, is called, by astronomers, the six o'clock hour circle, or the six o'clock hour line. The sun and stars are on the eastern half of this circle 6 hours before they come to the meridian; and on the western half, six hours after they have passed the meridian.

* On Cary's large Globes, the meridians are drawn through every 10 degrees, as on a Map.