PROBLEM V.

To find the distance between two places on the globe. With a pair of dividers gently applied to the globe, or the straight edge of a piece of paper, take the extent between the places. With this extent applied to the equator, note the number of degrees, which, multiplied by 694, give the distance in statute miles; by 60, the distance in geographical miles.

When a globe has a quadrant of altitude, the number of degrees between places may be ascertained by only taking the distance on the quadrant, without reference to the equator.

What is the distance from Boston to London? About 3340 miles.

What is the distance from Cape St. Roque to Cape Verd? 1900 statute miles, 1640 geographical miles.

PROBLEM VI.

The hour of the day at a place being given, to find the time at any other place.

The place where the hour is given being brought to the brazen meridian, and the index set at the hour, turn the globe till the other place comes to the meridian; the index will show the hour.

What is the time at Cairo, in Egypt, when it is 9 o'clock, A. M., at Boston? 3 h. 47 m., P. M.

When it is noon at Washington, what is the time at the Sandwich Islands? 6 h. 45 m., A. M.

PROBLEM VII.

To find the Sun's place in the ecliptic.

The day of the month being found on the horizon, opposite to this, in the adjacent sign, is the degree of the Sun's place. The same sign and degree found in the ecliptic show the Sun's place.

The Sun's place in the ecliptic on the 4th of July is 120 of Cancer.

PROBLEM VIII.

On a given day to find the declination of the Sun. On the brazen meridian, directly over the Sun's place in the ecliptic, brought to that meridian, is the Sun's declination.

On the 1st day of May, the declination of the Sun is 15° N.

There is an analemma on the globe, where the declination for each day is set against the days of the months.

PROBLEM IX.

To find on a given day at what places the Sun is vertical.

The degree of the Sun's declination being found on the brazen meridian, turn the globe round, and to all places coming under that degree the Sun is vertical.

On the 28th of August, the Sun is vertical to the northern part of the Colombian republic, to Guinea, Abyssinia, the southern part of Hindostan, and Malacca.

PROBLEM X.

To find at any given hour where the Sun is vertical. The place where the hour is given being brought to the brazen meridian, and the index set at the given hour, turn the globe westward for the forenoon, eastward for the afternoon, till the index points to 12; under the degree of the Sun's declination is the place sought.

Where is the Sun vertical on the 16th of April, when the time is 11 o'clock, A. M., at Washington?

Near the mouth of the river Oronoco, in the Colombian republic.

PROBLEM XI.

To find, at any given place, and time of year, what hour the Sun rises and sets; also the length of the day and night.

The globe being rectified for the latitude of the place, find the Sun's place in the ecliptic, and bring it to the brazen meridian. Set the index at 12. Turn the globe eastward till the Sun's place comes to the horizon, the index will point to the time of the Sun's rising. Turn the Sun's place westward to the horizon, the index will show the time of his setting.

Double the time of the Sun's setting for the length of the day; of his rising, for the On the 1st of June, the Sun 4 h. 30 m., sets about 7 h. 30 m. is 15 hours; of the night, 9 hours.

length of the night. rises at Boston about The length of the day

PROBLEM XII.

At any place, to find at a given time where the Sun is rising, and where setting; where it is noon, and where midnight.

When the Sun is north declination, elevate the north pole, when it is south declination, the south pole, equal to the declination, and bring the place where the Sun is vertical at the hour to the meridian. The Sun appears rising to places at the western semicircle of the horizon; setting, at the eastern. It is noon at the meridian above the horizon; midnight at the meridian below.

On the 1st of January, Ŏ h. 30 m., P. M., at Washington, the Sun is rising at the western Sandwich Islands; also a little to the west of the Friendly Islands, and New Zealand. It is noon at Hudson's Bay, Upper Canada, Michigan Territory, Indiana, Kentucky, Tennessee, Western Georgia, Gulf of Mexico, and Guatimala. The Sun is setting at Cape Farewell; in Africa, near the mouth of the Gambia, Liberia, and the Cape of Good Hope.

PROBLEM XIII.

To find, by the globe and the table of longitude, how fast any place moves by the revolution of the Earth on

its axis.

Find the latitude of the place by the globe, and the number of miles in a degree by the table. These, multiplied by 15, give the answer required.

Caraccas moves 1025 miles an hour.
Nova Zembla moves 217 miles an hour.

Problems to be solved by the Celestial Globe.
PROBLEM I.

To find the declination of a star.

Bring the star to the brazen meridian; directly over it, on the meridian, is the degree of its declination. The declination of Sirius is 160 30' S.

The declination of Arcturus is 20° 20' N.

The declination of the Sun is found on this as on the terrestrial globe.

PROBLEM II.

To find the right ascension of a star or the Sun. Bring the star or the Sun's place to the brazen meridian. At the intersection of the equator and the meridian, on the equator, is the degree of right ascension. The right ascension of Regulus is 149° 30'. The right ascension of the Sun, on the 4th day of July, is 1020.

PROBLEM III.

To find a star on the globe, when its declination and right ascension are given.

Bring the right ascension to the brazen meridian. Under this, at the declination, the star will be found. What star is 5° 40′ N. declination, 1120 right ascension? Procyon.

PROBLEM IV.

At any place, the time of year being given, to find at what hour any star will rise, be on the meridian, and set.

The globe being rectified for the latitude of the place, bring the Sun's place in the ecliptic to the brazen meridian, and set the index at 12. Turn the globe till the star comes to the horizon eastward, the index will show the time of its rising. Bring it to the meridian, the index will point to the time. Turn it to the horizon westward, the index will show the time of its setting.

At Boston, on the 20th of January, Sirius rises at 5 h. 45 m.,P. M., is on the meridian at 10 h. 30 m., P. M., and sets at 3 h. 15 m., A. M., of the 21st.

PROBLEM V.

The altitude of a star being given, to find the time of night at a place proposed.

Rectify the globe for the latitude of the place. The Sun's place in the ecliptic being brought to the brazen meridian, set the index at 12. Turn the globe till the star comes to the altitude proposed; the index will point to the time.

When Arcturus is 100 above the western horizon on 31st of August, what is the time of night at Boston? 9 h. 45 m., P. M.

PROBLEM VI.

The latitude of a place being given, to adjust the globe so as to represent the appearance of the heavens at any proposed hour of the night.

The globe being rectified for the latitude of the place, and the Sun's place in the ecliptic brought to the brazen meridian, set the index at 12. Turn the globe eastward for the forenoon, westward for the afternoon, till the index points to the given hour. The ap