3. Arided, midnight.

4. Capella, 8 p.m. 5. Castor, 10 p.m.

7. Menkar, 11 p.m.

8. Atair, 9 p.m.

9. Vega, 9 p.m.

6. Algenib (a, Perseus), 8 p.m. 10. Arcturus, 7 p.m. Required the altitude and azimuth of the following stars, at London, December 21st, at 4 in the morning.

11. Spica Virginis.

12. Sirius.

13. Deneb (Leo, B).

14. Cor Hydræ.

15. Procyon.

16. Pleiades (Taurus, «).

17. Arided (Cygnus, a).

Give the altitude and azimuth of the following stars, at

C. Good Hope June 21st, at midnight.

18. Spica Virginis.

19. Antares (Scorpio, a).

20. Arcturus.

21. Ras Alhague.

22. Fomalhaut (S. Fish, a).

23. Achernar (Eridanus, a).

What are the altitude and azimuth of the following stars, at Jerusalem, August 9th, at 4 o'clock, a.m.?

24. Menkar (Cetus, «).

25. Algol.

26. Dubhe (Ursa Major, a).

27. Phoenix, a.

28. Fomalhaut (S. Fish, a).

Required the altitude and azimuth of the following

stars at Quito, on March 22nd, at 10 p.m.

The Azimuth of any Star and Day of the Month being given, to find the Hour of the Night and the Altitude of the Star, in a given Latitude.

1. Rectify the globe as in the last problem, fix the quadrant of altitude upon the zenith, and bring it to the given azimuth.

2. Turn the globe round till the star come to the quad

rant, then the index will show the hour, and the altitude of the star will be found upon the quadrant.

N. B. Some of the examples admit of two answers.

EXAMPLES.

1. The azimuth of Regulus, the Lion's Heart, at London, May 11, was S. 76° W.; required the altitude and hour of the night. Ans. Hour, 11 p.m. Alt. 27o.

2. The azimuth of Capella, at Rome, on Dec. 2d, was N. 60o W.; required the altitude and hour of the night. Ans. Hour, 5 a.m. Alt. 42°.

Having the azimuth of the following stars, required their altitude, and the hour for London, on Sept. 1st.

3. Ras Alhague, S. 47o W. 4. Dubhe, N. 23 W. Having the azimuth of the castle, Oct. 6th, required the 7. Seven stars, S. 8810 E. 8. Arcturus, N. 81 W. 9. Aries, a, S. 65 E. 10. Capella, N. 40 E.

5. Delphinus, a, S. 20 E.

6. Cygnus, a, S. 55 E. following stars for Newhour and the altitude. 11. Auriga, ß, N. 52 E. 12. Betelguese S. 80 E. 13. Cancer, a. S. 70 E. 14. Procyon, S. 29. E.

PROBLEM VIII.

The Altitude of a Star, the Day, and the Latitude being given, to find the Azimuth and Time of the Night.

1. Rectify the globe as in the former problems.

2. Having screwed the quadrant upon the zenith, turn the globe and move the quadrant till the star cut the quadrant at the given altitude; the index will show the hour, and the quadrant the azimuth on the horizon.

The stars having the same altitude twice a day, it is necessary to know whether the given star is E. or W. of the meridian; or whether the hour required is in the evening or morning.

EXAMPLES.-1. The altitude of Rigel, in Orion, was observed at Boston (America) to be 15° in the evening

of December 8th; what were the hour and azimuth, Ans., 8 hrs. 1 min.; azimuth, S.E. by E. 7° E.

2. At Jerusalem, on the morning of August 9, the altitude of Alderamin (Cepheus, a,) was 41°; required the hour and the azimuth. Ans. Az. N. 34o W.; hour 4.

Having the altitudes of the following stars at London, on the days given, required the time and azimuth.

Having the altitudes of the following stars at Grand

Cairo, required the hour and azimuth.

Having the Azimuth of a Star, the Latitude, and Hour, to find the Star's Altitude and Day of the Month.

1. Elevate the globe for the latitude,-fix the quadrant on the zenith, and bring it to the given azimuth.

2. Bring the star to the edge of the quadrant, and set the index to the given hour; the altitude of the star will then be found upon the quadrant.

3. Turn the globe till the index point to noon; and the day of the month answering to the degree of the ecliptic cut by the brass meridian, is the day required.

EXAMPLES.

1. At London, 11 o'clock p.m., the azimuth of Spica Virginis was observed to be S. 17° W.; required its altitude and the day of the month. Ans. May 11th; alt. 27°.

2. At London, 9 p.m., the azimuth of a, N. Crown, was S. 89° W.; what were the alt. and day of the month? Ans. Sept. 1st.; alt. 38°.

3. At Newcastle, 10 p.m., the azimuth of Almaach (Andromeda, y) was S. 84° E.; required the alt. and day.

4. At Jerusalem, 4 a.m., the azimuth of Markab was S. 71° W.; what were the day and altitude?

5. At Jerusalem, at 4 a.m., the azimuth of Alderamin was N. 34° W.; required the day and altitude.

6. At the Cape of Good Hope, at midnight, the azimuth of the star Fomalhaut was S. 73° E.; required the day of the month and the altitude of the star.

7. At Rome, 5 a.m., the azimuth of Capella was N. 60° W.; required the day and the altitude of the star.

PROBLEM X.

To find the Hour of the Night, by observing when any two

Stars have the same Azimuth.

1. Rectify the globe as in the preceding problems. 2. Move the globe and the quadrant, till the quadrant come over both stars; the index will shew the hour.

It may be found when two stars have the same azimuth, by holding up a small line, with a plummet, between the eye and the stars; or, by observing when any two stars are in a line with the end of a house or wall, that is known to be perpendicular.

EXAMPLES.-1. May 11th, at London, Vega and Atair were observed to have the same azimuth; what was the hour? Answ. 2 hrs. 15 min. a.m.

2. March 29th, Atair and Vega had the same azimuth at Stockholm; required the hour. Answ. 4 o'clock a.m. Required the hour at London when the following stars have the same azimuth on the annexed days.

3. January 3,

4. February 6, 5. May 12,

6. November 15,

Algol and Aldebaran.

Cor Caroli and Arcturus.
a, Cygnus, and a, Pegasus.
Castor and Cor Hydræ.

7. Procyon and Sirius were observed to have the same azimuth at Rome, December 2nd; what was the hour?

PROBLEM XI.

To find the rising, setting, and culminating of any Star,its continuance above the Horizon,-its oblique Ascension and Descension,—and its eastern and western Amplitude for any given Day and Place.

Rectify the globe as in the preceding problems.

2. Bring the given star to the eastern horizon, and the index will shew the hour of rising; the degree of the equinoctial that rises with the star is its oblique ascension; and the distance of the star from the east point of the horizon is its eastern or rising amplitude.

3. When the star is brought to the meridian, the index will shew the time of culminating.

4. Bring the star to the western horizon, and its setting, oblique descension, and western amplitude, will be found in the same manner as its rising, eastern amplitude, and oblique ascension.

5. The number of hours from rising to setting will be the time of its continuance above the horizon.

EXAMPLE. Required the time when the following stars rise, come to the meridian, and set; how long they continue above the horizon; likewise their oblique ascension and descension, and their eastern and western amplitude, at the respective places and days.

1. Sirius at London, on March 14th.

Answ. Rises at 2h. 24m. p.m.; Culminates, 6h. 57m. p.m.; Sets, 11h. 30m. p.m.; Above the horizon, 9h. 6m.; Oblique ascension, 120° 47′; Oblique descension, 77° 17′; Amplitude, 27° S.

2. Fomalhaut, at the Cape of Good Hope, on Dec. 10th. Answ. Rises, 10h. a.m.; Culminates, 5h. 30m. p.m.; Sets, lh. a.m. Above the horizon, 15h.; Oblique ascension, 317°; Oblique descension, 5o; Amplitude, 38° S.

3. Achernar in Eridanus, at Otaheite, on June 4th. 4. Arcturus, at Newcastle, on March 11th.