Deg. Miles. Min.

Equator. 52 37

Deg. Miles. Min. 72 18. 32

53

36

S. What is that Pofition of the Globe denominated a right Sphere ?

M. The Inhabitants of the Earth are fometimes diftinguished according to the various Pofition of their Horizon, as they are fituate in a right Sphere, a parallel Sphere, or an oblique Sphere. Vide Plate 3.

Sphere.
A right

In a right Sphere the Equator paffes thro' the Zenith and Nadir, and the parallel Circles fall perpendicularly on the Horizon, which is the Case of those People who live under the Equinoctial Line. In a parallel Sphere, the Poles are in the Zenith and Nadir; the Equator is parallel to, and coin- Sphere. cides with the Horizon, and the parallel Circles are parallel to the Horizon, which can only be faid of People under either Pole.

A parallel

An oblique

Sphere.

In an oblique Sphere, the Inhabitants have one of the Poles above, and the other under the Horizon, and the Equator and parallel Circles cutting the Horizon obliquely, as is the Cafe of all People that do not live under the Equinoctial or the Poles.

S. How is the Globe to be rectified in order to find the true Situation of any Place upon it?

M. Let the Globe be set upon a level Table, and the brazen Meridian ftand due North and South, then bring the given Place to the brazen Meridian, and let there be 90 Degrees between that Place and the Horizon both North and South, and the given Place will be in the Zenith; the Globe being thus rectified, you may proceed to folve any Problem.

S. How fhall I find the Longitude and Latitude of the given Place?

La itude found

by the Globe.

Longitude and found by numbering on the Equator fo many DeM. The Longitude of fuch a Place will be grees as the Place lies Eaft or Weft of the first Meridian: And the Latitude will be found by counting fo marry Degrees on the brazen Meridian, as the Place lies North or South of the Equator. You must turn the Globe therefore either Eaft or Weft, till the given Place is brought to the brazen Meridian, and you will fee the Degree of Longitude marked on the Equator; and the Latitude is found at the fame time, only by numbering the Degrees on the brazen Meridian either North or South of the Equator, till you come to the given Place.

S. How fhall I find what Places are under the fame Meridian with the given Place?

Places under

the fame Me. ridian.

M. This is done only by bringing the given Place to the brazen Meridian, and obferving what Places lie under that Meridian, either North or South of the Equator.

S. How fhall I find what Places have the fame Latitude?

Places under

the fame Parallel.

M. This is done only by turning the Globe round, and obferving on the brazen Meridian what Places come under the fame Degree of Latitude as the given Place is.

S. How fhall I find the Sun's Place in the Ecliptic at any time of the Year?

The Sun's Place in the Ecliptic.

M. When you know the Month, and Day of the Month, you will find upon the wooden Horizon the Sign in which the Sun is oppofite to the Day of the Month, which is the Sun's Place in the Ecliptic at that time.

S. How fhall I know the Length of the Days at any Time, and at any Place?

Length of the
Day.

M. Bring the given Place to the Zenith; then bring the Sun's Place in the Ecliptic to the Eaft Side of the Horizon, and fet the Index of the Hour Circle to 12 at Noon, or the upper Figure of 12, and turn the Globe till the faid Place in the Ecliptic touch the

Western

Western Side of the Horizon, and the Number of Hours between the upper Figure of 12, and the Hour the Index points to, fhew how many Hours the Day is long, and confequently the Length of the Night; because fo many Hours as the Day falls fhort of 24, muft be the Length of the Night; as when the Day is 16 Hours long, the Night muft of courfe be 8 Hours long.

S. How fhall I find thofe Places on the Globe where the Sun is in the Meridian at any time?

To find in

That Places the Sun is in

the Meridian.

M. The Globe being rectified, and the Place where you are brought to the brazen Meridian, fet the Index of the horary Circle at the Hour of the Day at that Place, then turn the Globe till the Index points to the upper 12, and you will fee all thofe Places where the Sun is in the Meridian; as for Example, if it be II in the Morning at London, and you fet the Index at 11, turn the Globe till the Index points at the upper 12, and you will find Naples, which is an Hour or 15 Degrees Eaft of London. And in all Places under the fame Meridian as Naples is, it must confequently be 12 at Noon at that Time.

In like manner, if it be 4 in the Afternoon at London, and you fet the Index at 4, and turn the Globe till the Index points at the upper 12, you will find Barbadoes, which is four Hours or 60 Degrees Weft of London, and at all Places under the fame Meridian as Barbadoes is, it must confequently be 12 at Noon at that Time.

S. How fhall I discover where the Sun is vertical at any time of the Year?

M. The Sun can only be vertical in fuch Places

the Sun is vertical.

as lie between the Tropics; and to know this, To find where you are only to find what Place the Sun is in the Ecliptic, and bringing that Place to the brazen Meridian, obferve what Degree of Latitude it has, for in all Places in that Latitude the Sun will be vertical that Day, and you will find all thofe Places only by turning the Globe round, and obferving them as they come to the brazen Meridian.

S. How may I find where the Sun is above the Horizon, or fhines without fetting all the 24 Hours in the Northern Hemisphere?

M. The Day given must be when the Sun is in the Northern Signs, and having found the Sun's Place in the Ecliptic, you must bring that Place to the brazen Meridian, then count the fame Number of Degrees from the North Pole towards

P 3

To find where

the Days are 24 Hours long.

the Equa

tor

tor, as there is between the Equator and the Sun's Place in the Ecliptic, then turn the Globe round, and in all the Places paffing under the laft Degree counted from the North Pole, the Sun begins to fhine conftantly without fetting on the given Day: And the Rule will ferve vice verfa for any Place fet in the Southern Hemisphere, when the Sun is in the Southern Signs.

S. How do we difcover the Length of the longest and fhorteft Days and Nights at any Place in our Northern Hemisphere?

1 To find the Length of the longest Day in any Place,

M. Rectify the Globe according to the Latitude of the given Place, or which is the fame thing, bring the given Place to the Zenith, then bring the first Degree of Cancer to the Eaft Side of the Horizon, and fetting the Index of the Hour Circle to the upper Figure of 12, turn the Globe till the Sign of Cancer touch the Weft Side of the Horizon, and obferve the Number of Hours between the upper Figure of 12, and the Hour the Index points to, and that is the Length of the longest Day, and the shortest Night confequently confifts of fo many Hours as the Day falls fhort of 24; and as for the Length of the Days and Nights in Southern Latitude, they are juft the reverse of thofe in Northern Latitude, and the Table of the Climates fhews both the one and the other.

S. How may I find in what Places the Sun is rifing or fetting, or in its Meridian: Or what Parts of the Earth are enlightened at any particular time?

To find where

the Sun is rifing, fetting, or in the Me ridian.

M. Firft find where the Sun is vertical at the given Hour, and bring that Place to the Zenith, under the brazen Meridian; then obferve what Places are in the Eaftern Semi-circle of the Ho

rizon, for there the Sun is fetting, and in those Places in the Western Semi-circle of the Horizon the Sun is rifing, and in all Places under the brazen Meridian it is Noon Day: All thofe Places in the upper Hemisphere of the Globe are enlightened, and thofe in the lower Hemisphere are in Darkness.

S. How fhall I find the Distance of one Place from another upon the Globe?

M. If both Places lie under the fame Meridian, bring them to the brazen Meridian, and count thereon how many Degrees of Latitude the two Places are from each other, which being reduc'd to Units is the true Diftance. Every Degree of Latitude containing 60 Geographical Miles, as has been obferv'd already; and 60 Geographical Miles make near 70

English

English Miles. If the two Places lie under the fame Parallel of Latitude, then obferve on the Equator how many Degrees of Longitude they are afunder, and obferve in the Table A, how many Miles a Degree of Longitude makes in that Latitude, and then numbering the Degrees of Longitude on the Equator, reduce them to Miles, and that will give the Diftance of the two Places. For Inftance, fuppofe Rotterdam lies in 52 Degrees of North Latitude, and 4 Degrees of Eaftern Longitude and Pyrmont lies under the fame Parallel 5 Degrees Eaft of Rotterdam, and I find that every Degree of Longitude in this Latitude makes 37 Miles, then I multiply 37 by 5, which makes 185, being the Number of Miles between Rotterdam and Pyrmont.

Where the two Places differ both in Longitude and Latitude, the Distance may be found by measuring the Number of Degrees they are afunder by the Quadrant of Altitude, and reducing those Degrees to Miles. For Example, if I find the two Places are the Length of 10 Degrees afunder by the Quadrant, they muft neceffarily be 600 Miles diftant from each other; because 60 Miles which is the Extent of I Degree of Latitude, multiplied by 10, makes 600 Miles on the Globe, in whatever Direction one Place lies from another, as the North, Eaft, South, Weft, &c.

S. How may I find how one Place bears of another, that is, whether it lies North-Eaft, South-Weft, or on any other Point of the Compafs from another Place?

To find bow

one Place bears of another.

M. Bring one of the Places to the Zenith, and fix the Quadrant of Altitude there, then extend it to the other Place whofe bearing you would know, and the lower Part of the Quadrant will interfect the wooden Horizon at the Point of the Compass infcrib'd on the wooden Horizon, which is the true Bearing of the given Place.

S. How fhall I find on what Point of the Compass the Sun rifes or fets at any

Place?

To find on what Point of the Comas the Sun pass

M. Bring the given Place to the Zenith, and having found the Sun's Place in the Ecliptic, bring the fame to the Eastern Side of the Horizon, and it will fhew on what Point of the Compafs the Sun rifes. On the other hand, if you bring the Sun's Place in the Ecliptic to the Weft Side of the Horizon, it will fhew on what Point of the Compafs the Sun

fets.

rifes.