3. What is the antipodes of the Society Islands ?

Ans. The Red Sea.

4. What is the antipodes of New-York? Of London, of Naples, of the Caspian Sea, of Egypt, of Moscow, of St. Helena, of Spain, of Canton, of Quebec ?

PROBLEM 1X.

To find at what rate per hour the inhabitants of any given place are carried by the revolution of the earth on its own axis.

Find how many miles make a degree of longitude in the latitude of the given place from the following table; which multiply by 15, the product will be the number of miles per hour.*

TABLE,

Showing the length of a degree of longitude for every

degree of latitude, in geographical miles.

* The Sun passes one degree in four minutes, exactly, which is equal to fifteen degrees in one hour.

At what rate per hour are the inhabitants of the following places carried by the motion of the earth on its axis? Washington, New York, Quebec, Calcutta, Canton, Petersburgh, Cape of Good Hope, London, Quito, New Orleans.

PROBLEM X.

The day of the month being given, to find the Sun's place or longitude in the ecliptic, and its declination.

Look for the given day in the circle of months on the horizon, and opposite to it in the circle of signs are the sign and degree in the ecliptic, and it will be the Sun's place of longitude. Bring this place to the meridian, and you will have the declination.

1. What is the Sun's longitude and declination on the 22d of February?

Ans. 337° 30' from Aries, that is in Pisces 4° 30': its declination is 10° south.

2. What is the Sun's longitude and declination on the 5th of April?

Ans. 25 degrees and 30 minutes in Aries; its declination 10° north.

3. When does the Sun enter each of the signs?

4. What is the Sun's place and declination on the 22d of December, on the 21st of June, on the 1st of September, on the 1st of January, on the 4th of July, and the 17th of October?

PROBLEM XI.

To rectify the globe for the latitude, zenith and Suns place on any day.

For the latitude. Elevate the pole till the horizon cuts the brass meridian in the degree corresponding to the latitude; the given place is then in the zenith. Then by problem tenth, find the Sun's place for the given day; bring it to the meridian and set the index 1. Rectify the globe for the latitude of London on the 10th of May. In this case elevate the north pole 51 degrees and 30 minutes, then will London be in the zenith over it; screw the quadrant of altitude: the 10th of May on the horizon, answers to the twentieth degree of Taurus, which find on the ecliptic, and bring it to the meridian, and set the index to 12. This is the position of the globe as it appears to the inhabitants of London on the 10th of May.

2. Rectify the globe for New York January 21st, for Boston April 6th, for Washington June 16th, for Constantinople December 12th, for Petersburgh on the 12th of October, for Jerusalem on the 3d day of April, for New Orleans on the 8th of January, and for Paris on the 22d day of February.

PROBLEM XII.

The month and day of the month being given, to find all those places on the globe which will have a vertical Sun on that day. Find the Sun's place in the ecliptic (by problem 10th and bring it to the meridian, turn the globe round, and all the places that pass under that degree of the meridian, will have a vertical Sun on that day.

1. Find all the places which have a vertical Sun on the 22d day of February.

Ans. Amazonia, Angola, Queen Charlotte's Island, New Guinea and Peru.

2. What places have a vertical Sun on the 6th day of June, on the 4th of July, on the 21st of September, on the 17th of October, and 12th day of March?

PROBLEM XIII.

To find the time of the rising and setting of the Sun at any place, at any given day in the year, and the length of the day and night at that place.

Rectify the globe (by problem 11th,) for the latitude of the place, find the Sun's place in the ecliptic (by problem 10th,) and bring it to the meridian, and set the index to 12. Bring the Sun's place to the eastern edge of the horizon, and the index will show the time of the Sun's rising. Bring it to the western edge of the horizon, and the index will show the time of the Sun's setting. Double the time of the Sun's rising and it will give the length of the night. Double the time of setting, and it will show the length of the day.

At what time does the Sun set and rise at New York on the 10th day of May, and what is the length of the day and night?

Ans. It rises 56 minutes past four, and sets 4 minutes after seven. Length of the day 14 hours and 8 minutes; and length of the night 9 hours and 52 minutes. What is the time of the Sun's rising and setting, and the length of the day and night at Boston on the 8th of September, at Washington on the 10th of June, at London on the 22d of December, at Petersburgh on the 21st of June, at Paris on the 1st of March, and at the Island of St. Helena on the 24th of October?

PROBLEM XIV.

To find the length of the longest and shortest days and nights in any part of the earth.

If the place be in the northern hemisphere, rectify the globe for the latitude of the place, bring the first degree of Cancer to the meridian, and proceed as in the last problem. If the place be in the southern hemisphere bring the first degree of Capricorn to the meridian, and proceed as before.

1. What is the length of the longest day and shortest night at New York.

Ans. Longest day 14 hours and 56 minutes. Short

est night 9 hours and 4 minutes.

2. What is the length of the longest day and shortest night at each of the following places:-Boston, Washington, Albany, Philadelphia, Mexico, Paris, London, Petersburgh, Stockholm, Quebec, Jerusalem, Iceland, Canton, Berlin, Warsaw, Constantinople, St. Helena, Calcutta, and Van Dieman's Land.

PROBLEM XV.

The month and day of the month being given, to find those places where the Sun does not set, and where it does not rise on the given day.

Find the Sun's declination, (by problem 10th,) elevate the pole for the declination in the same manner as for the latitude, turn the globe on its axis, and on the places around the pole, above the horizon, the Sun does not set; and on the places around the other pole, below the horizon, the sun does not rise on that day.

1. How much of the south frigid zone is in darkness, and how much of the north frigid zone is enlightened on the 20th of May?

Ans. 20 degrees round each pole.

2. On which pole does the Sun rise on the 6th of November?

3. Which frigid zone, and how much of it, has constant night on July 4th?

4. What days in the year does the Sun shine equally on both poles ?

5. How much of the north frigid zone has constant day on the following days, namely, March 25th, April 10th, June 21st, July 4th, August Sth, September 12th?

PROBLEMS-TO BE SOLVED BY THE CELESTIAL GLOBE.

PROBLEM XVI.

To find the right ascension of the Sun, or a star. Bring the Sun's place in the ecliptic, or the star, to the brass meridian; then the degrees of the equinoctial under the meridian, reckoning from Aries eastward, is the right ascension.

1. What is the Sun's right ascension on the 19th of April? Ans. 27 degrees and 30 minutes. 2. What is the Sun's right ascension on the 1st day of December? Ans. 247 degrees and 50 minutes. 3. What is the Sun's right ascension on the 7th of