SECT. II.
Geographical Definitions.
Of the Situations of Places upon the Earth; of the different Situations of its Inhabitants; of Zones and Climates.
Thesituations of places upon the Earth, are determined by their Latitude and Longitude.
Latitude.
1. TheLatitudeof any place (upon the Earth) is its nearest distance, either North or South from the Equator; and if the place be in the (Northern/Southern) hemisphere, it is accordingly called (North/South)Latitude; and is measured by an arch of the meridian intercepted betwixt the zenith of the said place, and the equator. And all places that lie on the same side, and at the samedistance from the equator, are said to be in the same parallel of latitude: the parallels inGeography, being the same with the parallels of declination inAstronomy.
From this definition arise the following Corollaries.
(1.)That no place can have above 90 degrees of latitude, either North or South.(2.)Those places that lie under the equinoctial (or thro’ which the equator passes) have no latitude, it being from thence that the calculation of latitudes is counted; and those places that lie under the Poles have the greatest latitude, those points being at the greatest distance from the equator.(3.)The latitude of any place is always equal to the elevation of the Pole in the same place above the horizon; and is therefore often expressed by the Pole’s height, or elevation of the Pole; the reason of which is, because from the equator to the Pole there is always the distance of 90 degrees, and from the zenith to the horizon the same number of degrees, each of these including the distance from thezenith to the Pole: That distance therefore being taken away from both, will leave the distance from the zenith to the equator, (which is the latitude) equal to the distance of the Pole to the horizon.(4.)The elevation of the equator in any place is always equal to the complement of the latitude of the same place.(5.)A ship sailed directly (towards/from) the equator (lessens/augments) her latitude, (or (depresses/raises) the Pole) just so much as is her distance sailed.
(1.)That no place can have above 90 degrees of latitude, either North or South.
(2.)Those places that lie under the equinoctial (or thro’ which the equator passes) have no latitude, it being from thence that the calculation of latitudes is counted; and those places that lie under the Poles have the greatest latitude, those points being at the greatest distance from the equator.
(3.)The latitude of any place is always equal to the elevation of the Pole in the same place above the horizon; and is therefore often expressed by the Pole’s height, or elevation of the Pole; the reason of which is, because from the equator to the Pole there is always the distance of 90 degrees, and from the zenith to the horizon the same number of degrees, each of these including the distance from thezenith to the Pole: That distance therefore being taken away from both, will leave the distance from the zenith to the equator, (which is the latitude) equal to the distance of the Pole to the horizon.
(4.)The elevation of the equator in any place is always equal to the complement of the latitude of the same place.
(5.)A ship sailed directly (towards/from) the equator (lessens/augments) her latitude, (or (depresses/raises) the Pole) just so much as is her distance sailed.
Difference of Latitude.
2.Difference of latitudeis the nearest distance betwixt any two parallels of latitude, shewing how far the one is to the Northward or Southward of the other, which can never exceed 180 degrees. And when the two places are in the same hemisphere (or on the same side of the equator) the lesser latitude subtracted from the greater, and when they are on different sides of the equator, the two latitudes added, gives the difference of latitude.
Longitude.
3. TheLongitudeof any place (upon the Earth) is an arch of the equator, contained betwixt the meridian of the given place, and some fixed or known meridian; or, it is equal to the angle formed by the two meridians, which properly can never exceed 180 degrees, tho’ sometimes the Longitude is counted Easterly quite round the globe.
Since the meridians are all moveable, and not one that can be fixed in the heavens, (as the equinoctial circle is fixed, from whence the latitudes of all places are determined to be so much either North or South) the longitudes of places cannot so well be fixed from any other meridian, but every Geographer is at his liberty to make which he pleases his first meridian, from whence to calculate the longitudes of other places. Hence it is that geographers of different nations reckon their longitudes from different meridians, commonly choosing the meridian passing through the metropolis of their own country for their first: Thus, theEnglishgeographers generally make the meridian ofLondonto be their first, theFrenchthat ofParis, and theDutchthat ofAmsterdam, &c. and mariners generally reckon the longitude from the last known land they saw. This arbitrary way of reckoning the longitude from different places, makes it necessary, whenever we express the longitude of any place, that the place from whence it is counted be also expressed.
From the preceding definitions arise the following corollaries:
1.If a body should steer directly North, or directly South, quite round the globe, he’ll continually change his latitude; and pass through the two Poles of the world, without deviating the least from the meridian of the place he departed from; and consequently on his return will not differ in his account of time from the people residing in the said place.2.If a body should steer round the globe either due East, or due West, he’ll continually change his longitude, but will go quite round without altering his latitude; and if his course should be due East, he’ll gain a day compleatly in his reckoning, or reckon one day more than the inhabitants of the place from whence he departed; or if his course had been West, he would have lost one day, or reckon one less.
1.If a body should steer directly North, or directly South, quite round the globe, he’ll continually change his latitude; and pass through the two Poles of the world, without deviating the least from the meridian of the place he departed from; and consequently on his return will not differ in his account of time from the people residing in the said place.
2.If a body should steer round the globe either due East, or due West, he’ll continually change his longitude, but will go quite round without altering his latitude; and if his course should be due East, he’ll gain a day compleatly in his reckoning, or reckon one day more than the inhabitants of the place from whence he departed; or if his course had been West, he would have lost one day, or reckon one less.
The reason of which is evident; for admitting our traveller steers due East; so many miles in one day as to make his difference of longitude equivalent to a quarter of an hour of time, it is evident that the next day the Sun will rise to him a quarter of an hour sooner than to the inhabitants of the place from whence he departed; and so daily, in proportion to the rate he travels, which in going quite round, will make up one natural day. In like manner, if he steers due West after the same rate, he’ll lengthen each day a quarter of an hour, and consequently the Sun will rise to him so much later every day; by which means, in going quite round, he’ll lose one day compleat in his reckoning. From whence it follows,
3.If two bodies should set out from the same place, one steering East, and the other West, and so continue their courses quite round, until they arrive at the place from whence they set out, they’ll differ two days in their reckoning at the time of their return.4.If a body should steer upon an oblique course (orany where betwixt the meridian and the East or West points) he’ll continually change both latitude and longitude, and that more or less, according to the course he steers; and if he should go quite round the globe, he’ll differ in his account of time, as by the second Corol.5.The people residing in the Easternmost of any two places, will reckon their time so much the sooner than those who live in the other place, according to the difference of longitude betwixt the two places, allowing one hour for every 15 degrees, &c. and the contrary.
3.If two bodies should set out from the same place, one steering East, and the other West, and so continue their courses quite round, until they arrive at the place from whence they set out, they’ll differ two days in their reckoning at the time of their return.
4.If a body should steer upon an oblique course (orany where betwixt the meridian and the East or West points) he’ll continually change both latitude and longitude, and that more or less, according to the course he steers; and if he should go quite round the globe, he’ll differ in his account of time, as by the second Corol.
5.The people residing in the Easternmost of any two places, will reckon their time so much the sooner than those who live in the other place, according to the difference of longitude betwixt the two places, allowing one hour for every 15 degrees, &c. and the contrary.
Zones,Torrid,Temperate, andFrigid.
4.Zonesare large tracts of the surface of the Earth, distinguished by the tropics and polar circles, being five in number;viz.oneTorrid, twoTemperateand twoFrigid.
TheTorrid, orBurning Zone, is all the space comprehended between the two tropics; the ancients imagined this tract of the Earth to be uninhabitable, because of the excessive heat, it being so near the Sun. All the inhabitants of the torrid zone have the Sun in their zenith, or exactly over their heads twice in every year; excepting those who liveexactly under the two tropics, where the Sun comes to their zenith only once in a year.
The twoTemperate Zoneslie on either side of the globe, between the tropics and the polar circles.
The twoFrigid Zonesare those spaces upon the globe that are included between the two polar circles.
Amphiscians.Ascians.
The inhabitants of the Earth are also distinguished by the diversity of theirShadows. Those who live in the torrid zone, are calledAmphiscians, because their noon-shadow is cast different ways, according as the Sun is to the northward or southward of their zenith; but when the Sun is in their zenith, they are calledAscians.
Heteroscians.Ascians Heteroscians.
Periscians.
The inhabitants of the temperate zones, are calledHeteroscians, because their noon-shadow is always cast the same way: But those who live under the tropics are calledAscians Heteroscians; those who live in the frigid zones are calledPeriscians, because sometimes their shadow is cast round about them.
These hard names are onlyGreekwords, importing how the Sun casts the shadow of the several inhabitants of the Earth; which would be a too trifling distinction to be made here, was it not for the sake of complying with custom.
The inhabitants of the Earth are also distinguished into three sorts, in respect to their relative situation to one another, and these are called thePeriœci,Antœci, andAntipodes.
Periœci.
5. ThePeriœciare those who live under opposite points of the same parallel of latitude. They have their seasons of the year at the same time, and their days and nights always of the same length with one another, but the one’sNoonis the other’sMidnight; and when the Sun is in the equinoctial, he rises with the one, when he sets with the other. Those who live under the Poles have noPeriœci.
Antœci.
6. TheAntœcilive under the same meridian, and in the same latitude, but on different sides of the equator; their Seasons of the year arecontrary, and the days of the one are equal to the nights of the other, but the hour of the day and night is the same with both; and when the Sun is in the equinoctial, he rises and sets to both exactly at the same time. Those who live under the equator have noAntœci.
Antipodes.
7. TheAntipodesare those who live diametrically opposite to one another, standing, as it were, exactly feet to feet: Their days and nights, summer and winter, are at direct contrary times.
The surface of the Earth is by some distinguished intoClimates.
Climates.
8. AClimateis a tract of the surface of the Earth, included between two such parallels of latitude, that the length of the longest day in the one exceeds that in the other by half an hour.
The whole surface of the Earth is considered, as being divided into 60 climates,viz.from the equator to each of the polar circles 24, arising from the difference of ½ hour in the length of their longest days; and from the polar circles to the Poles themselves, are six,arising from the difference of an entire month, the Sun being seen in the first of these a whole month without setting; in the second two; and in the third, three months,&c.These climates continually decrease in breadth, the farther they are from the equator. How they are framed,viz.the parallel of latitude in which they end (that being likewise the beginning of the next) with the respective breadth of each of them, is shewed in the following table:
ATABLEof theClimates.
Cosmical,Acronical, andHeliacal risingandsetting.
The ancient Poets make frequent mention of the Stars rising and setting, eitherCosmically,Acronically, orHeliacally; whence these distinctions are calledPoetical.
A Star is said toriseorset Cosmically, when it rises or sets at Sun-rising; and when itrisesorsetsat Sun-setting, it is said to rise or setAcronically. A Starrises Heliacally, when first it becomes visible, after it had been so near the Sun as to be hid by the splendor of his rays: And a Star is said toset Heliacally, when it is first immersed, or hid by the Sun’s rays.
TheFixed Stars, and the three superior Planets,Mars,Jupiter, andSaturn, riseHeliacallyin the morning; but the Moon risesHeliacallyin the evening, because the Sun is swifter than the superior Planets, and slower than the Moon.
The Earth consists naturally of two parts, Land and Water, and thereforeit is called theTerraqueous Globe. Each of these elements is subdivided into various forms and parts, which accordingly are distinguished by different names.
I.Of the Land.
The land is distinguished intoContinents,Islands,Peninsula’s,Isthmus’s,Promontories,Mountains, orCoasts.
Continent.Main Land.
9. AContinentis a large quantity of land, in which many great countries are joined together, without being separated from each other by the sea: such areEurope,Asia,Africa, and the vast continent ofAmerica; which four are the principal divisions of the Earth. A continent is sometimes called theMain Land.
Island.
10. AnIslandis a country, or portion of land, environed round with water: such areGreat-BritainandIreland;Sardinia,Sicily, &c. in theMediterranean Sea; theIslesofWight,Anglesey, &c. nearEngland. Also a small part of dry land, in the midst of a river, is called an island, when compared to a lesser, is called the continent;as if we compare theIsleofWighttoEngland, the latter may be properly called the continent.
Peninsula.
11. APeninsulais a part of land almost environed with water, save one narrow neck adjoining it to the continent; or which is almost an island: such isDenmarkjoining toGermany; alsoAfricais properly a large peninsula joining toAsia.
Isthmus.
12. AnIsthmusis a narrow neck of land joining a peninsula to the continent; as theIsthmusofSues, which joinsAfricatoAsia, that ofPanama, joining North and SouthAmerica, &c.
Promontory.Mountain.
13. APromontoryis a high part of land stretching out into the sea, and is often called aCapeorHeadland: such is theCapeofGood Hopein the South ofAfrica;Cape Finistreon the West ofSpain; also theLizard Point, and theLand’s End, are two Capes or Headlands on the West ofEngland. AMountainis a high part of land in the midst of a country, over topping the adjacent parts.
A CoastorShore.Inland.
14. ACoastorShoreis that part of land which borders upon the sea, whether it be in islands or a continent: And that part of the land which is far distant from the sea, is called theInland Country. These are the usual distinctions of the land.
The Water is distinguished intoOceans,Seas,Lakes,Gulfs,Straits, andRivers.
The Ocean, orMain Sea.
15. TheOcean, orMain Sea, is a vast spreading collection of water, not divided or separated by lands running between; such is theAtlanticorWestern Ocean; betweenEuropeandAmerica; thePacific Ocean, orSouth Sea, &c.
Note, Those parts of the ocean which border upon the land, are called by various names, according to those of the adjacent countries; as, theBritish Sea, theIrish Sea, theFrenchandSpanish Sea.
A Lake.
16. ALakeis a collection of deep standing water, inclosed all round with land, and not having any visible and open communication with thesea: But when this lake is very large, it is commonly called a sea; as theCaspian SeainAsia, &c.
A Gulf.CreekorHaven.
17. AGulfis a part of the sea almost encompassed with land, or that which runs up a great way into the land; as, theGulfofVenice, &c.But if it be very large, ’tis rather called anInland Sea; as theBaltic Sea, theMediterranean Sea, theRed Sea, or theArabian Gulf, &c.And a small part of sea thus environed with land is usually called aBay. If it be but a very small Part, or, as it were, a small arm of the sea, that runs but a few miles between the land, it is called aCreekorHaven.
A Strait.
18. AStraitis a narrow passage lying between two shores, whereby two seas are joined together; as, theStraitsofDover, between theBritish Channeland theGerman Sea; theStraitsofGibralter, between theAtlanticand theMediterranean Sea. TheMediterraneanitself is also sometimes called theStraits.
These are all the necessary terms commonly used inGeography. The names of the several countries and seas, and all the principaldivisions of the Earth, the reader will find expressed upon the Terrestrial Globes. To give a tolerable account of the produce of each country, the genius of the people, their political institutions,&c.is properly a particular subject of itself, and quite foreign to our design. We shall next proceed to the use of the Globes; but first it may not be amiss to take a shortreviewof their appurtenances.
Those circles of the sphere that arefixed, are (as has been already said) drawn upon theGlobesthemselves; those that aremoveable, are supplied by theBrass Meridian, theWooden Horizon, and theQuadrant of Altitude.
Brass Meridian.
1. That side of theBrazen Meridian, which is divided into degrees, represents thetrue Meridian; this side is commonly turned towards the East, and ’tis usual to place the globe so before you, that the North be to the right hand, and the South to the left. The meridian is divided into 4 quadrants, each being 90 degrees, two of which are numbered from that part of the equinoctial, which is above the horizon, towards each of the Poles; the other two quadrants are numbered fromthe Poles towards the equator. The reason why two quadrants of the meridian are numbered from the equator, and the other two from the Poles, is because the former of these two serve to shew the distance of any point on the globe from the equator, and the other to elevate the globe to the latitude of the place.
Wooden Horizon.
2. The upper side of the wooden frame called theWooden Horizon; represents the true horizon; the circles drawn upon this plane have been already described; we may observe, that the first point of ♈ is the East, and the opposite being the first point of ♎ is the West, the meridian passing through the North and South points.
Quadrant of Altitude.
3. TheQuadrant of Altitudeis a flexible plate of thin brass, having a nut and screw at one end, to be fastened to the meridian of either globe, as occasion requires. The edge of this quadrant which has the graduations upon it, called the fiducial edge, is that which is always meant whenever we make mention of the quadrant of altitude.
Hour Circle.
4. TheHoraryorHour Circle, is divided into twice twelve hours,the two XII’s coinciding with the meridian; the uppermost XII is that atNoon, and the lowermost towards the horizon is XII atNight. The hours on theEastside of the meridian are theMorning Hours, and those on theWestside theHoursafterNoon. The axis of the globe carries round theHandorIndexwhich points the hour, and passes through the center of the hour circle.
The things above described are common to both globes; but there are some others which are peculiar or proper to one sort of globe. The twoColures, and theCirclesofLatitudefrom the ecliptic, belong only to theCelestial Globes; also the ecliptic itself does properly belong only to this globe, tho’ it is always drawn on the Terrestrial, for the sake of those that might not have the other globe by them. The equinoctial on the celestial globe is always numbered into 360 degrees, beginning at the equinoctial point ♈; but on the terrestrial, it is arbitrary, where these numbers commence, according to the meridian of what place you intend for your first; and the degrees may be counted either quite round to 360, or both ways, ’till they meet in the opposite part of the meridian, at 180.
The USE of theGlobes.
1.
Turnthe globe round its axis, ’till the given place lies exactly under the (Eastern side of the brass) meridian, then that degree upon the meridian, which is directly over it, is theLatitude; which is accordingly North or South, as it lies in the Northern or Southern hemisphere, the globe remaining in the same position.
That degree upon the equator which is cut by the brazen meridian, is theLongituderequired from the first meridian upon the globe. If thelongitude is counted both ways from the first meridian upon the globe, then we are to consider, whether the given place lies Easterly or Westerly from the first meridian, and the longitude must be expressed accordingly.
TheLatitudesof the following places: and upon a globe where the longitude is reckoned both ways from the meridian ofLondon, their longitudes will be found as follow:
2.The Latitude and Longitude being given to find the Place.
Seek for the given longitude in the equator, and bring that point to the meridian; then count from the equator on the meridian the degree of latitude given, towards the arctic and antarctic Pole, according as the latitude is Northerly or Southerly, and under that degree of latitude lies thePlacerequired.
Bring each of the places proposed successively to the meridian, and observe where they intersect it, then the number of degrees upon the meridian, contained between the two intersections, will be theDifference of Latituderequired. Or, if the places proposed are on the same side of the equator, having first found their latitudes, subtract the lesser from the greater; but if they are on contrary sides of the equator, add them both together, and the difference in the first case, and the sum in the latter, will be the difference of latitude required.
Thus the difference of latitude betwixtLondonandRomewill be found to be 9¾ degrees; betwixtParisandCape Bona Esperance83 degrees.
Bring each of the given places successively to the meridian, and see where the meridian cuts the equator each time; the number of degreescontained betwixt those two points, if it be less than 180 degrees, otherwise the remainder to 360 degrees, will be the difference of longitude required. Or,
Having brought one of the given places to the meridian, bring the index of the hour circle to 12 o’clock; then having brought the other place to the meridian, the number of hours contained between the place the index was first set at, and the place where it now points, is the difference of longitude in time betwixt the two places.
Thus the difference of longitude betwixtRomeandConstantinoplewill be found to be 19 degrees, or 1 hour and a quarter; betwixtMexicoandPekininChina, 240 degrees, or 9⅓ hours.
The latitude of any given place being marked upon the meridian, turn the globe round its axis, and all those places that pass under the same mark are in the same latitude with the given place, and have their daysand nights of equal lengths. And when any place is brought to the meridian, all the inhabitants that lie under the upper semicircle of it, have their Noon or mid-day at the same point of absolute time exactly.
1.To find the Sun’s Place: Look for the day of the month given in the kalendar of months upon the horizon, and right against it you’ll find that sign and degree of the ecliptic which the Sun is in. The Sun’s place being thus found, look for the same in the ecliptic line which is drawn upon the globe, and bring that point to the meridian, then that degree of the meridian, which is directly over the Sun’s place, is theDeclinationrequired; which is accordingly either North or South, as the Sun is in the Northern or Southern signs. Thus,
1.For the Latitude: If the place be in the Northern hemisphere, raise the arctic Pole above the horizon; but for the South latitude you must raise the antarctic; then move the meridian up and down in the notches, until the degrees of the latitude counted upon the meridian below the Pole, cuts the horizon, and the globe is adjusted to the latitude.
2.To rectify the Globe for the Zenith: Having elevated the globe according to the latitude, count the degrees thereof upon the meridian from the equator, towards the elevated Pole, and that point will be the zenith or the vertex of the place; to this point of the meridian fasten the quadrant of altitude, so that the graduated edge thereof may be joined to the said point.
3. Bring the Sun’s place in the ecliptic to the meridian, and then set the hour index to XII at Noon, and the globe will be rectifiedto the Sun’s Place. If you have a little mariner’s compass, the meridian of the globe may be easily set to the meridian of the place.
Lay the quadrant of altitude over both the places, and the number of degrees intercepted between them being reduced into miles, will be the distance required: Or, you may take the distance betwixt the two places with a pair of compasses, and applying that extent to the equator, you’ll have the degrees of distance as before.
Note, Ageographical mileis the ¹/₆₀th part of a degree; whereof if you multiply the number of degrees by 60, the product will be the number of geographical miles of distance sought; but to reduce the same intoEnglishmiles, you must multiply by 70, because about 70Englishmiles make a degree of a great circle upon the superficies of the Earth.
Thus, the distance betwixtLondonandRomewill be found to be about 13 degrees, which is 780 geographical miles.
If you rectify the globe for the latitude and zenith of any given place, and bring the said place to the meridian; then turning the quadrant of altitude about, all those places that are cut by the same point of it, are at the same distance from the given place.
Having rectified the globe for the latitude and zenith of one of the given places, bring the said place to the meridian, then turn the quadrant of altitude about, until the fiducial edge thereof cuts the other place, and the number of degrees upon the horizon, contained between the said edge and the meridian, will be the angle of position sought.
Thus, the angle of position at theLizard, between the meridian of theLizardand the great circle, passing from thence toBarbadoesis 69 degrees South-Westerly; but the angle of position between the same places atBarbadoes, is but 38 degrees North-Easterly.
SCHOLIUM
The angle of position between two places is a different thing from what is meant by the bearings of places; theBearingsof two places is determined by a sort of spiral line, called aRhumb Line, passing between them in such a manner, as to make the same or equal angles with all the meridians through which it passeth; but theangleorpositionis the very same thing with what we call the azimuth in astronomy, both being formed by the meridian and a great circle passing thro’ the zenith of a given place in the heavens, then called the azimuth, or upon the Earth, then called the angle of position.
From hence may be shewed the error of that geographical paradox,viz.If a place A bears from another B due West, B shall not bear from A due East. I find this paradox vindicated by an author, who at the same time gives a true definition of a rhumb line: But his arguments are ungeometrical; for if it be admitted that the East and West lines make the same angles with all the meridians through which they pass, it willfollow that these lines are the parallels of latitude: For any parallel of latitude is the continuation of the surface of aCone, whose sides are the radii of the sphere, and circumference of its base the said parallel; and it is evident, that all the meridians cut the said surface at right (and therefore at equal) angles; whence it follows, that the rhumbs of East and West are the parallels of latitude, though the case may seem different, when we draw inclining lines (like meridians) upon paper, without carrying our ideas any farther.
Bring the given place to the meridian; and having found its latitude, count the same number of degrees on the meridian from the equator towards the contrary Pole, and that will give the place of theAntœci. The globe being still in the same position, set the hour index to XII at noon, then turn the globe about ’till the index points to the lower XII; the place which then lies under the meridian, having the same latitude with the given place, is thePeriœcirequired. Asthe globe now stands, theAntipodesof the given place are under the same point of the meridian, that itsAntœcistood before: Or, if you reckon 180 degrees upon the meridian from the given place, that point will be theAntipodes. Let the given place beLondon, in the latitude of 51½ degrees North, that place which lies under the same meridian and the latitude 51½ degrees South, is theAntœci; that which lies in the same parallel withLondon, and 180 degrees of longitude from it, is thePeriœci, and theAntipodesis the place whose longitude fromLondonis 180 degrees, and latitude 51½ degrees South.
The difference of time betwixt two places is the same with their difference of longitude; wherefore having found their difference of longitude, reduced into time (by allowing one hour for every 15 degrees,&c.) and if the place where the hour is required lies(Easterly/Westerly) from the place where the hour is given, (add/subtract) the difference of longitude reduced into time (to/from) the hour given; and the sum or remainder will accordingly be the hour required. Or,
Having brought the place at which the hour is given to the meridian, set the hour index to the given hour; then turn the globe about until the place where the hour is required comes to the meridian, and the index will point out the hour at the said place.
Thus when it isNoonatLondon, it is