north and the other south latitude; as New-York and Cape St. Antonio. The antæci have noon at the same time, but contrary seasons of the year; so that when it is summer with one, it is winter with the other, &c.; consequently the length of the days with one is equal to the length of the night with the other. They have different poles elevated, and the stars that never set to the one are never seen by the other. Those who live at the equator have no antæci. 7. The periaci, or periæcians, are those who live under the same parallel of latitude, but under opposite meridians; their difference of longitude being 180 degrees. The periœci have the same seasons of the year, and also their days and nights of the same length; but when it is noon with the one, it is midnight with the other. Those who live at the poles of the earth, have no periœci. 8. The antipodes are those inhabitants of the earth who live under opposite meridians, and opposite parallels of latitude; their difference of longitude being 180 degrees, and the one having the same degrees of north latitude as the other has of south latitude. The antipodes are diametrically opposite to each other, the zenith of the one being the nadir of the other, and, consequently, they walk feet to feet; they have the same seasons and length of days and nights; but all of these at contrary times, it being day to the one when it is night to the other, summer to the one when it is winter to the other, &c. 9. The inhabitants of the earth have also particular names assigned to them from their shadows falling different ways at noon, and are called Amphiscii, Heteroscii, and Periscii. 10. Amphiscii, or Amphiscians, are the people who inhabit the torrid zone; so called, because they cast their shadows both north and south at different times of the year; the sun being sometimes to the south of them at noon, and at other times to the north. When the sun is vertical, or in the zenith, which happens twice in the year, the inhabitants have no shadow, and are then called Ascii, or shadowless. 11. Heteroscii is a name given to the inhabitants of the temperate zones, because they cast their shadows at noon only one way. Thus the shadow of an inhabitant of the north temperate zone always falls to the north at noon, because the sun is then directly south; and an inhabitant of the south temperate zone casts his shadow towards the south at noon, because the sun is due north at that time. 12. Periscii, or Periscians, are those people who inhabit the frigid zones, so called because their shadows, during a revolution of the earth on its axis, turn quite round to all points of the compass, without disappearing. For as the sun does not set to the inhabitants of the frigid zones during several revolutions of the earth on its axis, but moves quite round; so do their shadows also. These distinctions of the inhabitants of the earth from the direction of their shadows, are of little, or, perhaps, of no importance. 13. The right ascension of the sun, or a star, is that degree of the equinoctial which rises with the sun, or a star, in a right sphere, and is reckoned from the equinoctial point, Aries, round the globe. 14. Oblique ascension of the sun, or a star, is that degree of the equinoctial which rises with the sun, or a star, in an oblique sphere, and is likewise counted from the point Aries round the globe. 15. Oblique descension of the sun, or a star, is that degree of the equinoctial which sets with the sun, or a star, in an oblique sphere. 16. The ascensional or descensional difference is the difference between the right and oblique ascension, of the difference between the right and oblique descension; and with respect to the sun, it is the time he rises before six o'clock in the summer, or sets before six in the winter. 17. The longitude of the sun, which is usually called the sun's place in the ecliptic, is reckoned on the ecliptic from the point Aries, eastward, round the globe. 18. The time from the first dawn or appearance of the morning, or between the setting of the sun and the last remains of day, is called the crepusculum, or twilight. The twilight, it is supposed, usually begins and ends when the sun is about 18 degrees below the horizon; for then the stars of the 6th magnitude disappear in the morning, and appear in the evening. It is of longer duration in the solstices than in the equinoxes, but it is longer in an oblique sphere than in a right one; because, in those cases the sun, by the obliquity of his path, is longer in ascending through 18 degrees of altitude. 19. Angle of position between two places on the terrestrial globe, is an angle at the zenith of one of the places, contained by the meridian of that place, and a vertical circle passing through the other place. The vertical circle, as has already been observed, may be represented by the quadrant of altitude screwed in the zenith of one of the places, and passing cver the other; and the angle of position is usually measured on the horizon, from the elevated pole towards the quadrant of altitude. 20. Rhumbs are the divisions of the horizon into 32 parts, usually called the points of the compass. The ancients, according to Pliny, were acquainted only with the four cardinal points, and the wind was said to blow from that point to which it was nearest. 21. The path which a ship describes, while she sails on the same point of the compass, and cuts all the meridians at the same angle, is called a rhumb line. This angle is usually called the course, and sometimes the proper angle of the rhumb. If the rhumb line, which is a loxodromic or spiral curve, be continued, it will never return into itself so as to form a circle, except it happens to be due east and west, or due north and south; and it can never be a straight line upon any map, except the meridians be parallel to each other, as in Mercator's and the plane chart. Hence the difficulty of finding the true bearing between two places on the terrestrial globe, or on any map but those above mentioned. The bearing found by a quadrant of altitude on a globe, is only the measure of a spherical angle upon the surface of that globe, as defined by the angle of position, and not the real bearing or rhumb, as shown by the compass; if a place A bear due east from a place B, the place B will bear due west from the place A; but this is not the case when measured with a quadrant of altitude. QUESTIONS. How many positions of the sphere are there? What is a right sphere, and what inhabitants of. the earth have this position? What is a parallel sphere, and what inhabitants of the globe have this position? What is an oblique sphere, and what inhabitants of the globe have this position? What inhabitants are called antæci to each other, and what do you observe with respect to their latitudes, longitudes, &c. ? What inhabitants are called periæci to each other, and what is observed with respect to their latitudes, longitudes, hours, &c. ? What are the antipodes, and what observed with respect to their seasons of the year, &c. ? What parts of the globe do the amphiscii inhabit, and why are they so called ? When do the amphiscii obtain the name of ascii? What parts of the globe do the heteroscii inha bit, and why are they so called? What parts of the globe do the periscii inhabit, and why are they so called? What is the right ascension of the sun? What is the ascensional or descensional differ ence? What is the crepusculum, or twilight, and when. does it begin or end? What is an angle of position? What are rhumbs and rhumb lines ? CHAPTER. IX. Astronomical and Geographical Problems performed by the Terrestrial Globe. PROBLEM I. A Place being given, to find its Latitude and Longitude. RULE. Bring the given place to the graduated side of the brazen meridian, which is counted from the equator towards the poles; the degree directly over the place is the latitude, and the degree on the equator, under the edge of the meridian, is the longitude. The longitude is either east or west. Thus, if it be on the east side of the first meridian, it is called east longitude; if on the west side, west longitude, and is reckoned 180 degrees each way. On Wilson's American globes there are two rows of figures on the north side of the equator. When the place lies on the east side of the meridian of London, the lon |