Part 5

The _Babylonians_ began their day at Sun-rising, and reckoned 24 hours ’till he rose again! This way of computation we call the _Babylonish Hours_. In several parts of _Germany_ they count their hours from Sun-setting, calling the first hour after the Sun has set, the first hour, _&c._ ’till he sets the next day, which they call the 24th hour: These are commonly called the _Italian Hours_. According to both these ways of computation, their hours are commonly either a little greater or less than the ¹/₂₄ part of a natural day, in proportion as the Sun rises or sets sooner or later in the succeeding days. They have also this inconvenience, that their mid-day and midnight happen on different hours, according to the seasons of the year.

[Sidenote: _Jewish Hours._]

[Sidenote: _Planetary Hours._]

The _Jews_ and the _Romans_ formerly divided the artificial days and nights each into 12 equal parts; these are termed the _Jewish Hours_, and are of different lengths, according to the seasons of the year; a _Jewish Hour_ in summer being longer than one in winter, and a night-hour shorter. This method of computation is now in use among the _Turks_, and the hours are stiled the _first hour_, _second hour, &c._ of the day or night; so that _Mid-day_ always falls on the sixth hour of the day. These hours are also called _Planetary Hours_, because in every hour one of the seven Planets were suppose to preside over the World, and so take it by turns. The first hour after Sun-rising on _Sunday_ was allotted to the _Sun_; the next to _Venus_, the third to _Mercury_; and the rest in order to the _Moon_, _Saturn_, _Jupiter_, and _Mars_. By this means on the first hour of the next day, the Moon presided, and so gave the name to that day; and so seven days by this method had names given them from the Planets that were supposed to govern on the first hour.

[Sidenote: _A Week._]

A _Week_ is a system of seven days, in which each day is distinguished by a different name. In most countries these days are called after the names of the seven Planets, as above noted. All nations that have any notion of religion, lay apart one day in seven for public worship; the day solemnized by _Christians_ is _Sunday_, or the first day of the week, being that on which our saviour rose from the grave, on which the apostles afterwards used more particularly to assemble together to perform divine worship. The _Jews_ observed _Saturday_, or the seventh day of the week, for their sabbath, or day of rest, being that appointed in the fourth commandment under the Law. The _Turks_ perform their religious ceremonies on _Friday_.

[Sidenote: _A Month._]

[Sidenote: _Periodical_ and _Synodical Month_.]

A _Month_ is properly a certain space of time measured by the Moon in his course round the Earth. A _Lunar Month_ is either _Periodical_ or _Synodical_. A _Periodical Month_ is that space of time the Moon takes to perform her course from one point in the ecliptic ’till she arrives to the same again, which is 27 days, and some odd hours; and a _Synodical Month_ is the time betwixt one new Moon, and the next new Moon, which is commonly about 29½ days. But a _Civil Month_, is different from these, and consists of a certain number of days, fewer or more, according to the laws and customs of the country where they are observed.

[Sidenote: A _Year Sydereal_ and _Tropical_.]

The compleatest period of time is a _Year_, in which all the variety of seasons return, and afterwards begin anew. A _Year_ is either _Astronomical_ or _Civil_. An _Astronomical Year_ is either a _Sydereal_ wherein the Sun departing from a fixed Star, returns to it again; or _Tropical_, which is the space of time the Sun takes to perform his course from any point of the ecliptic, ’till he returns to it again.

A _Tropical Year_ consists of 365 days, 5 hours, and 49 minutes; this is the time in which all the seasons compleatly returns, which is a small matter less than a Sydereal Year.

[Sidenote: _Egyptian Year._]

The _Civil Year_ is the same with the _Political_ established with the laws of a country; and is either moveable or immoveable. The moveable year consists of 365 days, being less than the tropical year by almost six hours, and is called the _Egyptian Year_, because observed in that Country.

The _Romans_ divided the year into 12 kalendar months, to which they gave particular names, and are still retained by most of the _European_ nations, _viz. January_, _February_, _March_, _April_, _May_, _June_, _July_, _August_, _September_, _October_, _November_, and _December_. The number of days in each month may be known by the following verses:

_Thirty Days hath_ September, April, June, _and_ November; February _hath Twenty-eight alone_, _And all the rest have Thirty-one_.

The year is also divided into four quarters or seasons, _viz._ _Spring_, _Summer_, _Autumn_, and _Winter_. These quarters are properly made when the Sun enters into the equinoctial and solstitial points of the ecliptic; but in civil uses they are differently reckoned, according to the customs of several countries. In _England_, we commonly reckon the first day of _January_ to be the first in the year, which is therefore vulgarly called _New-Year’s-Day_; but in political and ecclesiastical affairs, the year is reckoned to commence on _Lady-day_ which is the 25th of _March_; and from thence to _Midsummer-day_, which is the 24th of _June_, is reckoned the first quarter; from _Midsummer-day_ to _Michaelmas-day_, which is the 29th of _September_, is the second quarter; the third quarter is reckoned from _Michaelmas-day_ to _Christmas-day_, which is the 25th of _December_; and from _Christmas-day_ to _Lady-day_, is reckoned the last quarter in the year. In common affairs, a quarter is reckoned from a certain day to the same in the fourth month following. Sometimes a month is reckoned four weeks, or 28 days, and so a quarter 12 weeks. To all the inhabitants in the (Northern/Southern) Hemisphere, their _Midsummer_ is properly when the Sun is in the tropic of (_Cancer_,/_Capricorn_,) and their _Midwinter_ at the opposite time of the year; but those who live under the equinoctial have two winters, _&c._ when the Sun is in either tropic; tho’ indeed properly, there is no season that may be called winter in those parts of the world.

[Sidenote: _Bissextile_, or _Leap-Year_.]

The _Egyptian_ year of 365 days being less than the true solar year, by almost six hours, it follows, that four such years are less than four solar years by a whole day; and therefore in 365 times four years, that is, in 1460 years, the beginning of the years move through all the seasons. To remedy this inconveniency, _Julius Cæsar_ (considering that the six hours, which remain at the end of every year, will in four years make a natural day) ordered that every fourth year should have an intercalary day, which therefore consists of 366 days; the day added was put in the month of _February_, by postponing St. _Matthias_’s day, which in common years fall on the 24th, to the 25th of the said month, all the fixed feasts in the year from thenceforwards falling a week-day later than otherwise they would. According to the _Roman_ way of reckoning, the 24th of _February_ was the sixth of the kalends of _March_, and it was ordered that for this year there should be two sixths, or that the sixth of the kalends of _March_ should be twice repeated; upon which account the year was called _Bissextile_, which we now call the _Leap-Year_.

To find whether the year of our Lord be leap-year, or the first, second, or third after; divide it by four, and the remainder, if there be any, shews how many years it is after leap-year; but if there be no remainder, then that year is leap-year: Or, you may omit the hundreds and scores, and divide the residue by 4, _Examp._ 1757, omitting the hundreds and the twenties, I divide the residue 17, by 4, and the remainder 1, shews it to be the first after leap-year.

[Sidenote: _Julian Account_ or _the Old Style_.]

This method of reckoning the year, _viz._ making the common year to consist of 365 days, and every fourth year to have 366 days, is now used in _Great-Britain_ and _Ireland_, and some of the Northern parts of _Europe_, and is called the _Julian Account_, or the _Old Style_. But the time appointed by _Julius Cæsar_ for the length of a solar year is too much; for the Sun finishes his course in the ecliptic, in 365 days, 5 hours, and 49 minutes, which is 11 minutes less than the civil year; and therefore he again begins his circuit 11 minutes before the civil year is ended; and so much being gained every year, amounts in 131 years, to a whole day. So that if the Sun in any year entered the equinox upon the 20th of _March_ at noon, after the space of 131 years, he’ll enter the same point on the same hour, on the 19th of _March_. And therefore the exquinoxes will not always fall on the same day of the month, but by degrees will move towards the beginning of the year.

[Sidenote: _Gregorian Account_, or _New Style_.]

At the time of the _Council of Nice_, when the terms were settled for observing of _Easter_, the _Vernal Equinox_ fell upon the 21st of _March_; but by its falling backwards 11 minutes every year, it was found that in _Anno_ 1582, when the kalendar was corrected, the Sun entered the equinoctial circle on the 11th of _March_, having departed ten whole days from its former place in the year: and therefore Pope _Gregory_ the XIIIth, designing to place the equinoxes in their situation with respect to the year, took these ten days out of the kalendar, and ordered that the 11th of _March_ should be reckoned as the twenty-first: And to prevent the seasons of the year from going backwards for the future, he ordered every hundredth year, which in _Julian_ form was to be a _Bissextile_, should be a common year, and consist only of 365 days; but that being too much, every fourth hundred was to remain _Bissextile_. This form of reckoning being established by the authority of Pope _Gregory_ XIII. is called the _Gregorian Account_, or the _New Style_; and is observed in all the countries where the authority of the Pope is acknowledged, and likewise by several nations of the reformed religion. There being now above an hundred years past, since the reformation was made in the kalendar, the _Gregorian_ account has accordingly got before the _Julian_ one day more than it was in the time of its institution, the difference between these two accounts being now eleven days; so that the first day of any month, according to that way of reckoning, is the 12th of the same month, according to the New Style.

I shall conclude this section with a brief account of the Atmosphere.

[Sidenote: _Atmosphere._]

The _Atmosphere_ is that thin body of air which surrounds the Earth, in which the clouds hover, and by which in their descent they are broke into drops of rain; which sometimes, according to the warmth or coldness of air, are froze into _Snow_, or _Hailstones_. _Thunder_ and _Lightning_ are also made in the _Atmosphere_, and wind is nothing else but a percussion of the air, occasioned by its different density in different places. The benefits we receive from the atmosphere are innumerable; without air no earthly creature could live, as is plainly proved by experiments made by the _Air-Pump_; and the wholsomeness of a climate chiefly depends upon that of its air: If there was no atmosphere to reflect the rays of the Sun, no part of the heavens would be lucid and bright, but that wherein the Sun was placed; and if a spectator should turn his back towards the Sun, he would immediately perceive it to be quite dark, and the least Stars would be seen shining as they do in the clearest night; and the Sun immediately before his setting would shine as brisk as at noon, but in a moment, as soon as he got below the horizon, the whole hemisphere of the Earth would be involved in as great a darkness as if it were midnight.

But by means of the atmosphere it happens, that while the Sun is above the horizon, the whole face of the heavens is strongly illuminated by its rays, so as to obscure the faint light of the Stars, and render them invisible; and after Sun-setting, though we receive no direct light from him, yet we enjoy its reflected light for some time: For the atmosphere being higher than we are, is a longer time before it is withdrawn from the Sun (as if a man was to run to the top of a steeple, he might see the Sun after it had been set to those at the bottom.) The rays which the atmosphere receives from the Sun, after he is withdrawn from our sight, are by refraction faintly transmitted to us; until the Sun having got about 18 degrees below the horizon, he no longer enlightens our atmosphere, and then all that part thereof which is over us becomes dark. After the same manner in the morning, when the Sun comes within 18 degrees of our horizon, he again begins to enlighten the atmosphere, and so more and more by degrees, until he rises and makes full day.

[Sidenote: _Twilight_, or _Crepusculum_.]

This small illumination of the atmosphere, and the state of the Heavens between day and night, is called the _Twilight_, or the _Crepusculum_.

The duration of twilight is different in different climates, and in the same place at different times of the year. The beginning or ending of twilight being accurately given, we may from thence easily find the height of the atmosphere, which is not always the same. The mean height of the atmosphere is computed to be about 40 miles; but it is probable, the air may extend itself a great deal further, there being properly no other limits to it, as we can conceive, but as it continually decreases in density the farther remote it is from the Earth, in a certain ratio; which at last, as to our conception, must in a manner terminate.

SECT. II.

Geographical Definitions.

_Of the Situations of Places upon the Earth; of the different Situations of its Inhabitants; of Zones and Climates._

The situations of places upon the Earth, are determined by their Latitude and Longitude.

[Sidenote: _Latitude._]

1. The _Latitude_ of 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 same distance from the equator, are said to be in the same parallel of latitude: the parallels in _Geography_, being the same with the parallels of declination in _Astronomy_.

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 the zenith 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._

[Sidenote: _Difference of Latitude._]

2. _Difference of latitude_ is 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.

[Sidenote: _Longitude._]

3. The _Longitude_ of 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, the _English_ geographers generally make the meridian of _London_ to be their first, the _French_ that of _Paris_, and the _Dutch_ that of _Amsterdam_, &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._

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 (or any 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._

II. _Of Zones and Climates_, &c.

[Sidenote: _Zones_, _Torrid_, _Temperate_, and _Frigid_.]

4. _Zones_ are large tracts of the surface of the Earth, distinguished by the tropics and polar circles, being five in number; _viz._ one _Torrid_, two _Temperate_ and two _Frigid_.

The _Torrid_, or _Burning 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 live exactly under the two tropics, where the Sun comes to their zenith only once in a year.

The two _Temperate Zones_ lie on either side of the globe, between the tropics and the polar circles.

The two _Frigid Zones_ are those spaces upon the globe that are included between the two polar circles.

[Sidenote: _Amphiscians._]

[Sidenote: _Ascians._]

The inhabitants of the Earth are also distinguished by the diversity of their _Shadows_. Those who live in the torrid zone, are called _Amphiscians_, 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 called _Ascians_.

[Sidenote: _Heteroscians._]

[Sidenote: _Ascians Heteroscians._]

[Sidenote: _Periscians._]

The inhabitants of the temperate zones, are called _Heteroscians_, because their noon-shadow is always cast the same way: But those who live under the tropics are called _Ascians Heteroscians_; those who live in the frigid zones are called _Periscians_, because sometimes their shadow is cast round about them.

These hard names are only _Greek_ words, 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 the _Periœci_, _Antœci_, and _Antipodes_.

[Sidenote: _Periœci._]

5. The _Periœci_ are 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’s _Noon_ is the other’s _Midnight_; 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 no _Periœci_.

[Sidenote: _Antœci._]

6. The _Antœci_ live under the same meridian, and in the same latitude, but on different sides of the equator; their Seasons of the year are contrary, 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 no _Antœci_.

[Sidenote: _Antipodes._]

7. The _Antipodes_ are 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 into _Climates_.

[Sidenote: _Climates._]