Christian æra). They occur in the prophecy of Amos, near the same period; and Arcturus, Orion, and the Pleiades are mentioned twice, even in the book of Job).*

*

*

*

*

"The similarity of the constellations recognised in different countries, is very remarkable. The Chaldean, the Egyptian, and the Grecian skies, have a resemblance which cannot be overlooked. Some have conceived that this resemblance may be traced also in the Indian and Arabic constellations, at least in those of the Zodiac. * It is clear that fancy, and probably superstition, had a share in forming the collection of constellations. The stars were supposed to influence the character and destiny of man; and to be, in some way, connected with superior natures and powers.† We may, I conceive, look upon the formation of the constellations, and the notions thus connected with them, as a very early attempt to find a meaning in the relations of the stars, and as an utter failure.”‡

7. MORNING OR EVENING STAR. Venus and Jupiter, as the most conspicuous of the planets, receive the names of Morning or Evening Stars, according as they are situated westward of the sun, and are therefore seen to rise before him; or are eastward of that luminary, and therefore appear in the evening after he has set in the west.

8. THE TERRESTRIAL GLOBE is a model of our earth, the third planet in order of distance from the sun; and is designed to exhibit the relative situations of its several countries and seas, and their varying positions in the light of any heavenly body, as our planet revolves on its axis and in its orbit.

Not more than one half of the surface of any globe can be enlightened, at any instant, by the direct beams of a distant luminary.

9. AXIS OF THE EARTH is the diameter about which it revolves with a uniform motion from west to east, (C on page 8).

10. POLES OF THE EARTH are the points where its axis meets its surface, (F on page 8). The northern extremity of the earth's axis is called the Arctic Pole, because it is situated nearly beneath that part of the heavens occupied by the constellation of the Bear, (аρктоç, arctos). Hence also the southern or opposite Pole is called Antarctic.

For great Circles and small Circles, see D on page 8. 11. THE CELESTIAL GLOBE is a model of the apparent

* See" Rhymes on the Constellations," Appendix.

+ See "Astrology."

Whewell's Hist. of the Inductive Sciences, pp. 134, 136.

sphere of stars, formed on the supposition of the observer's being situated at its centre, and viewing the stars on its concave surface.

12. POLES OF THE CELESTIAL SPHERE are those points which are exactly vertical to the two poles, or stationary points, of the earth's surface; and which, therefore, are not affected with that apparent westward motion which is common to all other points in the Celestial Sphere, as our earth's surface rotates eastward within it.

13. EQUATOR of the earth, or terrestrial globe, is a great circle passing, or supposed to pass, through all those parts of the surface which are equally distant from both poles; and which, being most distant from the axis, are carried the most rapidly eastward by the rotation of the globe.

14. EQUINOCTIAL of the celestial globe or heavens, is a line passing, or supposed to pass, over all those stars or points in the sphere which are equally distant from both Polar points; and to which, successively, the head of any Equatorial inhabitant is pointed as he is carried eastward by the earth's diurnal rotation.

When the earth is so situated in space, as that its inhabitants behold the sun coinciding with this line of stars, our nights are equal to our days; hence the name Equinoctial.

15. LATITUDE OF A PLACE is its distance northward or southward of the Equator, and is reckoned in degrees and parts of a degree.

For "Latitude of a Heavenly body," (see Index).

16. Parallels oF LATITUDE are small circles parallel to the Equator, which, on globes and in maps of the world, are generally drawn through every ten degrees.

17. DECLINATION OF A HEAVENLY BODY is its distance northward or southward of the Equinoctial, reckoned in degrees and parts of a degree.

Since the Equinoctial stars appear to pass vertically over the Equator, and the Polar points are vertical to the Poles, it is evident that the declination of any star, shows the latitude in which that star appears to pass vertically.

18. PARALLELS OF DECLINATION are small circles parallel to the Equinoctial, and corresponding to the parallels of latitude of the terrestrial globe.

19. PLANE OF THE MERIDIAN of any place, is an ima

DEFINITIONS, ETC.

29

ginary plane, which, passing through the place and the whole axis of the earth, passes likewise through all situations northward and southward of that place, and through their several Antipodes, (Note to G on p. 9).

20. BRAZEN MERIDIAN is the circle of brass within which the artificial globe is suspended by its poles.

On the terrestrial globe, the flattened and graduated surface of the Brazen Meridian represents a portion of the plane of a meridian extending beyond the earth's surface, and serves to find what places agree in meridian and time.

On the Celestial globe, this graduated surface of the brass meridian represents a portion of the plane of a meridian extended beyond the Heavens; and serves to show what heavenly bodies are situated in the same plane with our whole axis, and are therefore brought by the earth's rotation into the plane of a meridian at the same instant of time.

21. Divisions of the Brazen Meridian. The brazen meridian of either globe, is divided into semicircles, which have different uses. The upper semicircle has its quadrants graduated from the Equator or Equinoctial, northward and southward, and is used to point out latitude and declination. The under semicircle has its quadrants graduated from the Poles, to enable the student to elevate them above the wooden circle, as may be required.

22. MERIDIANS (or, "Semi-meridians," or "Meridional Lines,") of the terrestrial globe, are semi-circumferences, passing through the poles, and showing what portions of the surface have a common meridian plane. They are sometimes drawn through every 15°, and sometimes, but less conveniently, through every 10° of the globe's circumference.

23. LONGITUDE OF A PLACE is the inclination of the plane of its meridian towards the east or towards the west, of a given standard meridian plane; and is reckoned in degrees and parts of a degree. For this purpose, the Equator of the terrestrial globe is divided into semicircles, one of which is graduated eastward and the other westward. The greatest longitude any place can have, is 180°, or half the circumference of the globe.

24. THE FIRST MERIDIAN is that from which geogra

phers reckon in assigning the longitudes of places. The ancient geographers measured their longitude from the meridian passing through Ferro, one of the Canary isles. The Dutch also reckon from the Peak of Teneriffe in that group; but foreigners generally, count longitude from the observatories of their respective nations; and the first meridian of English maps and globes, is that which passes through the Royal Observatory at Greenwich.

For "Longitude of a Heavenly body," see Index.

25. THE HOUR CIRCLE on the artificial globe, is a small circle of brass, attached to the extremity of the axis, and divided into parts corresponding to the twenty-four hours of the day, and their subdivisions; in order to adjust the proposed time to any proposed meridian.

There are various arrangements of the Hour Circle in various editions of the globes. Some have a double row of figures, others but one. Some have the hour circle placed under the brass meridian, which is used as its index : others have the hour circle attached to the brazen meridian on its outside, and stationary, whilst the time is shown by an index moving with the globe. The more simple and less expensive arrangement of an hour circle placed at each pole, under the brazen meridian, and with a double row of figures to that only which is attached to the terrestrial globe, is indispensable to the free use of the globes.

26. " HOUR CIRCLES," OR "HORARY CIRCLES," is a term also sometimes applied to those meridians which, on many terrestrial globes, are drawn through every 15° of longitude, and thus very conveniently divide the Equator on which it is reckoned, into twenty-fourths, or hours.

The Horizon (opiw, horizo, I limit,) is either Sensible or Rational.

27. The SENSIBLE HORIZON is that circular limit of a view of the earth's surface, (taken at sea, or on extended plains,) which is caused by the convexity of its figure.

A man of six feet stature, standing on the sea-shore, has his view limited by a circumference, distant only three miles. The greatest altitude, above the average surface, ever attained by man, was that of M. Guy-Lussac's balloon; viz., rather less than five miles; when his view comprehended of the earth's surface, (F on p. 10).

28. THE RATIONAL OR TRUE HORIZON is an imaginary plane, parallel to the sensible horizon, and passing through the earth's centre to and beyond the heavens.

DEFINITIONS, ETC.

31

These two Horizontal Planes, (the Sensible and Rational,) although thus separated by 4000 miles, (the semi-diameter of the earth,) will appear to coincide when considered as extending to the stars, because the earth's diameter is but a point when compared with that extension, (B on p.10).

29. The HORIZON OF THE CELESTIAL GLOBE is the flat wooden ring, or portion of a circular plane which surrounds the globe and is concentric with it. It represents a portion of the plane of the rational horizon of any latitude to which the celestial globe is adjusted, and thus affords the means of determining the rising and setting of the heavenly bodies, their altitudes, bearings, &c.

30. THE TERMINATOR is the flat wooden ring surrounding the terrestrial globe, and concentric with it; and is designed to exhibit the position of the earth's surface, in the light of a heavenly body of any declination; but especially the seasonal distribution of sunlight arising from the position of the earth's axis with respect to the sun, on any day and hour for which the globe is adjusted.

31. Markings of the Horizon or Terminator. The different editions of the globes vary somewhat in their markings of this wooden circle.

It is divided into several concentric circles :

The outermost contains the twelve months, printed underneath their days and the degrees of the signs of the Zodiac which correspond to those days.

Between the globe and these Signs, (which are given with their symbols and sometimes with their stars,) are the thirty-two Points of the Compass; and, still nearer the globe, are two circles of figures, of which the innermost always shows the Amplitude or degrees of distance from the east or west; and the other the Azimuth, or degrees of distance from the north or south. Several editions of the globes omit this Azimuth graduation.

32. HEMISPHERE, (μov hemisu, half, and opaipa, a globe,) the half of a sphere when divided by a great circle or the plane which passes through its centre. Thus, the Celestial Sphere is divided into Hemispheres by the rational horizon the Equator divides the earth into the northern and southern, and the plane of the first meridian divides it into the eastern and western Hemispheres.

33. DIURNAL ARC is the arc described by any heavenly