What star is that whose longitude is 200° 80', and whose latitude is 2o south?

If a comet appear in that part of the heavens whose longitude is 125°, and latitude 64°, to what constellation must I look for it?

Def. The declination of any heavenly body is measured upon the meridian from the equator. PROBLEM III.—To find the declination of the sun or stars.

Rule.-Bring the sun or star to the brazen meridian; and then its distance in degrees from the equator is its declination.

Ex. Thus, the sun's declination, April 19, is 11° 19' north. On the 1st of December, it is 21° 54' south.

Examples for practice.

What is the declination of the sun on the 10th of February, and the 15th of May ?-on the 11th of August, and the 21st of September?-on the 10th of November, and the 21st of December?

What is the declination of ẞ in Draco, and of the Pole Star?

What is the declination of a in Lyra, and of y in the Dragon's Head?

Def. The right ascension of any heavenly body, is its distance from the first meridian (or that which passes through the first point of Aries,) counted on the equator.

PROBLEM IV. To find the right ascension of the sun, or any star.

Rule.-Bring the sun's place, or the star, to the brazen meridian; and the number of degrees on the equator between that brass meridian and the first point of Aries, is the right ascension.

Ex. Thus, the sun's right ascension on April 19 is 27° 30'; on the 1st of December 247° 50',

Examples for practice.

What is the sun's right ascension on the 15th of January,

and the 18th of March?

What is the sun's right ascension on the 24th of May, the 16th of September, and the 19th of December?

What is the right ascension of the star ẞ in Auriga's shoulder?

What is the right ascension of Dubhe on the back of the Great Bear?

What is the right ascension of the Bull's eye?

What is the right ascension of Rigel in Orion's foot? What is the right ascension of ẞ in the Northern Scale?

PROBLEM V.-The latitude of the place, the day and hour being given, to represent the face of the heavens at that time, by the celestial globe, so as to find and point out all the constellations, and principal stars, there visible.

Rule.-Elevate the globe to so many degrees above the horizon as are equal to the latitude of the place, and set the globe due north and south: find the sun's place in the ecliptic, bring it to the brazen meridian, and set the index to twelve at noon; turn the globe westward till the index points to the given hour; then the surface of the globe represents the exact face of the heavens at the given place.

Examples for practice.

Let the learner now represent the face of the heavens for six and ten o'clock in the evening of the 5th of November ; and for nine and twelve at night of the 10th of May, and the 16th of October.

PROBLEM VI.-To find the time when any of the heavenly bodies rise, set, or come to the meridian. Rule.-Rectify the globe to the latitude of the place; bring the sun's place in the ecliptic to the meridian, and set the index to XII. Then

turn the globe till the given body comes to the eastern part of the horizon; and the index shows the time of its rising. Bring the body to the meridian, and the index shows the time of its coming to it. Bring the body to the western horizon, and the index shows the time of its setting. Thus the time of the sun's rising and setting may be found. Turn the globe about its axis: all those stars which do not descend below the horizon never set at that place; and those which do not ascend above it never rise there.

Examples for practice.

At what time does the sun rise and set on the 10th of May?

At what time does Aldebaran come to the meridian on the 12th of November?

When will Arcturus set on the 21st of June?

At what time will y in Draco be vertical over London this day?

PROBLEM VII.-To find how many hours any star is above the horizon, from its rising to its setting, in any latitude.

Rule.-Rectify the globe, and bring the star to the eastern edge of the horizon, and note the time of rising: turn the globe to the western side; and the number of hours that the index passes over to the dial-plate, answers to the time that the star is above the horizon. Thus, Aldebaran, at Londor, continues about fifteen hours above the horizon, and Rigel about ten hours and a half.

Examples for practice.

How long does Aldebaran continue above the horizon at Copenhagen, and at Jamaica ?

How long is Sirius above the horizon at St. Petersburg?

227

OF MAPS.

DEFINITIONS.

1. LATITUDE is the distance of a place, in degrees north or south, from the equator.

The latitude of places upon maps is expressed by the figures which run up or down the sides. If the figures increase upward, the latitude is north; if they increase downward, the latitude is south.

2. LONGITUDE is the distance of a place, in degrees, from the meridian of another place; as from the meridian of London, or Ferro, or Paris, &c.

The longitude of places upon maps is expressed by the figures which run along the top and the bottom. When the figures increase from right to left, the longitude is west; and when they increase from the left to the right, the longitude is east.

3. In maps, in general, the top is northward, the bottom southward, the left hand westward, and the right hand eastward. When otherwise, the bearings of the map are expressed by a small compass, with a fleur-de-lis pointing to the north, and a cross pointing to the east.

4. Distances upon maps are measured by means of a scale, which is generally placed in one of the corners.

QUESTIONS AND EXERCISES,

To be answered by the Pupil in writing.

ON THE MAP OF THE WORLD.

1. How many degrees is the equator from each pole?

2. Does Cape Horn or the Cape of Good Hope stretch further to the south?

3. How is the Mediterranean sea situated ? 4. How is Madagascar situated?

5. Between what countries is the Bay of Bengal ?

6. Where is St. Helena?

7. How are Arabia and Thibet situated with regard to Persia?

8. In what zone is Nova Zembla?

9. Do the New Hebrides, the Friendly, or the Society Islands, lie most westward? 10. Where is the Caspian Sea?

11. What is the longitude of the most easterly part of South America?

12. Is there more land in the northern or southern hemisphere?

13. Which of the four general divisions or quarters of the earth is the largest?

14. How is America separated from Europe and Africa?

15. Where are the Fox Islands?

16. What is the longitude of the most easterly part of Africa?

17. How is the island of Sumatra situated with regard to the equator?