PROPOSITION XI.

Having the Jewish Hour in a given Day, to find the Hour with us; or to reduce the unequal Hour to the equal.

DO as in the laft Propofition, and find the equal Hours in the Day; and when the Sun rifeth; then fay, as twelve is to the Jewish Hour given, fo is the Length of the Day to a fourth Number; which add to the Hour of Sun-rifing, and you'll have the Hour from Mid-night if the Number of thefe Hours be above twelve; reject twelve, and you have the Hour from Mid-day.

THE Jewish Hours, mentioned in Christ's Difcourse, cannot be accurately reduced to our Hours, the Day of the Year not being added; therefore that third Hour may be our ninth, tenth, or eighth, and the eleventh Hour may be our fifth, fixth, or feventh, according as the Day was in Summer, Winter, or in the Equinox; but the heat of the Day being mentioned, 'tis likely it was about the Summer Solstice,

PROPOSITION XII.

They who fail to the East, till they come back to the place they left, have feen the Sun rife, pass the Meridian, and fet once more than the People they first left s and thus are one Day before them; the first of January is the fecond to them, and our Saturday they count Sunday; and if they fail round twice or thrice, they will count two or three Days

more,

And

And they who fail to the West, round the Globe, count one Day lefs, fo that 'tis the thirty first of Decem-ber with them, when it is the firft of January with others; and our Sunday, they count Saturday; and they lofe as many Days as they fail Times round that way.

THIS was formerly a great Wonder to Seamen and others: after they had failed Weft and came to the Oriental Islands, and found they differed from other Europeans there by a Day, they accufed one another of Negligence or Sleepiness; but the frequency of the Thing hath now taken away the Wonder, and given Mathematicians occafion to explain the Caufe of it; which is very plain, if Men will but conceive aright the Motion of the Sun, or of the Meridians on the Earth, and fix on fome Beginning of the Day; for it depends on the diurnal Circumvolution of the Sun, (not on it's proper Motion, as fome thought) which may begin at any Meridian Circle, and from thence go round till it come back to the fame Meridian.

AND because they that fail Eastward go to a Meridian to which the Sun comes fooner than to that they left, they therefore begin to count another Day fooner. For Example; if they fail fifteen Degrees Eaftward, they will begin the Day an Hour fooner, and this Anticipation still increases as they go Eastward; and being come to the oppofite Meridian, their Day begins twelve Hours fooner; and having gone round, they begin the Day twenty four Hours fooner than in the Place they came to, where it is Mid-day to both when the Sun is in the South.

AND fo they that go Weft will have the Sun later in their Meridian by a whole Hour, if they fail fifteen Degrees to the Weft, which postpones

the

the Day still an Hour for every fifteen Degrees, which comes to twenty four Hours in failing round.

COROLLARY I

IF one fail Eastward and another Weftward, both round till they meet, the first will count two Days more than the second; and if they fail twice round he will count four Days more, tho they live the fame Number of Days; and the Days of the East Traveller will be fhorter than the Days of the other.

COROLLARY II.

THE fame would happen in whatever Place they fhould meet one another, and from this was the Fact found firft, and often afterwards; for when Ferdinand Magellan had paffed the Straits of Magellan and come to India, he found a Day's difference in his Account, from the Account the Europeans had there, who failed to the Eaft; and fo it was with all others that failed round.

COROLLARY III.

HENCE it is that they differ in a Day in fome Places near one another in the fame Meridian, as in the Philippine Islands, and Macao, a Sea-port in China, poffeffed by the Portuguese, and the Iles by the Spaniards of Caftile, as they fay; for they are under the fame Meridian, yet in Macao it is Sunday, when in the Philippines it is but Saturday; and while in Macao they have Eafter, and eat Flefh, in the Philippines it is but Lent; and they celebrate not the Feaft till the

morrow!

morrow: the Reafon is, the Portuguese came East to India, and from thence to Macao; whereas the Spaniard failed Weft and came from America Weftward to the Philippines; and tho' they met in two Meridians near the fame, yet they differ one Day in their reckoning.

CHAP.

CHA P. XXX.

Of the different rifing and fetting of the Sun, with it's Altitude, and other Appearances, in different Parts of the Earth.

PROPOSITION I.

To place the Globe, fo that the Sun shining on it, thofe Parts may be illuminated which the Sun illuminates any Day; and that it may at the fame Time appear to what People the Sun rifeth every Minute, and to whom it is Mid-day; to whom it fets, and to whom it is Night, and to whom it is vertical; as likewife the Sun's place in the Ecliptic, the Day of the Year, and the Hour of the Day in that place.

L

ET the Place, for which the Globe is to be fo fituated, be mark'd on the Globe, and brought to the Meridian, and the Point on the Meridian above it be marked with Chalk, and on that Point hang the Globe; and if you would have it fast, you must run an Iron Rod thro' that Point, and the Center to the oppofite Point, and have the fame well fixed to fome Plain below.

THEN place the Globe due North and South by a Meridian Line, or by the Compafs: the Globe being thus placed, you may fee every Minute the enlightened Part of the Earth, and that which is dark, and the Places in the middle of the illuminated Part have Mid-day then, and those in the

eaftern