the summer solstice, or 21st of June; the second part, from the 21st of June to the 21st of December.

The months and days correspond with the sun's declination, north or south.

CHAP. III.

Contains fifty Problems on the Terrestrial Globe,* including the Use of the Analemma and Sliding Hour Circle; with a Table showing the Breadth of a Degree of Longitude in any Latitude, a Table of the Equation of Time, and a Table of Climates, &c.

PROBLEM I.

To rectify the globe for any place whose latitude is given.

Elevate the pole that bears the same name with the latitude of the given place, as many degrees above the horizon as are equal to the given latitude, suppose London, in lat. 51° 30' N. First, the north pole must

* It appears necessary to observe here, that the problems on the terrestrial globe are practical geography; hence the absolute neces sity of being well acquainted with that subject in the common way, before an attempt is made to apply it on the globe.

be raised until 51° 30′ on the brass meridian coincide with the upper surface of the horizon, then London must be brought to the meridian, and the quadrant of altitude screwed on it, in the zenith, that is over the given place; place the globe on an horizontal plane, due south and north, which may be done nearly by estimation, or more accurately by the mariner's compass fixed to the horizon, or on the pedestal of the globe, care being taken to correct for the variation of the needle, which has already been observed at p. 29 to have been 24° 16′ W. at London in 1814, therefore turn the globe to the right, or left, till the needle stands over the above degree. Thus the globe will be rectified for London, and correspond, in every respect, with the real position of the earth for the place given.*

*The latitudes and longitudes used in this treatise are, whero practicable, taken from the eighth edition of Moore's Navigation ; but the situation of the interior parts of the most of Africa, Asia, and America, are laid down so differently by geographers, as to raise much difficulty in determining, and cannot be justly depended on. The problems, where calculation is not convenient, are solved from the improved globes of eighteen inches and twelve inches in diameter, lately engraved, and sold under the title of "Bardin's new British Globes." On the terrestrial eighteen-inch globe are included the late discoveries of Captain Cook, Vancouver, Perouse, Mungo Park, &c. to the present time, and on the corresponding celestial globe are depicted the exact positions of more than 6000 stars, clusters, nebulæ, &c. the whole forming the completost globes of any hitherto published.

Ꭰ

Given Cape Horn in 55° 58' S. lat. to rectify the globe for.

Raise the S. pole until 55° 58′ coincide with the upper surface of the horizon, bring the Cape to the meridian, and proceed with the rest as in the preceding example.

PROBLEM II.

A place being given, to find its latitude and longitude.

Bring the place to the graduated side of the brass meridian; and the number that stands over it is the latitude, and the degree cut by the meridian on the equator is the longitude.

Given London; required its latitude and longitude? Answer, lat. 51° 30′ N. lon. 0.

Given Constantinople; required the latitude and longitude? Answer, lat. 41° 1′ N. lon. 28° 57′ E.

Required the latitude and longitude of the Cape of Good Hope? Answer, lat. 34° 29′ S. lon. 18° 29′ E.

PROBLEM III.

The latitude and longitude of a place being given, to find the place on the globe.

Turn the globe until the given longitude comes to

the graduated edge of the brass meridian, then under the given latitude, on the meridian, will be the place required.

A place in 41° 1' N. lat. and lon. 28° 57' E.; required the place? Answer, Constantinople, the capial of Turkey, in Europe.

Given a place in 34° 29′ S. lat. and 18° 29′ E. lon.; required the place? Answer, the Cape of Good Hope. Required the name of the place that has 18° 4 N. lat. and 76° 40′ W. lon.? Answer, Kingston, the capital of Jamaica.

PROBLEM IV.

A place being given, London for example, to find all those places that have the same latitude and longitude.

Bring London to the brass meridian, then all those places that lie under the meridian have the same longitude, viz. 0; mark the latitude of the place on the meridian, turn the globe quite round, and all those places that pass under the mark have the same latitude, viz. 51° 30′ N.*

*The globe may be marked, at any particular part of a problem, by a pencil, a bit of chalk, or small patch of wetted

paper.

PROBLEM V.

To find the Antoci of any place given.

Bring the place to the meridian, note its latitude, find the same latitude, without moving the globe; on the other side of the equator, and under it is the antæci required.

Given London; required its antoci? Answer, under 51° 30' S. lat. in the Southern Ocean.

Given the Island of Malta, in the Mediterranean Sea; required its antoci? Answer, under 35° 53′ S. lat. and 14° 32′ E. lon. near the Cape of Good Hope.

Required the antoci of St. Helena, in lat. 16° 4' S. and lon. 5° 54′ W.? Answer, at 16° 4' N. lat. and lon. 5° 54' W.

PROBLEM VI.

To find the Perioci of any place given.

Bring the place to the meridian, mark the degree of latitude over it, set the index to the upper XII, turn the globe until the index points to the lower XII; and the place under the mark is the periœci required.

Given London; required its periœci? Answer, under 51° 30' N. lat. and 180° E. or W. lon. in the sea of Kamschatka.