249. The anticipation of the Equinoxes, and consequently of the seasons, is by no means owing to the Precession of the Equinoctial and Solsticial points in the Heavens, (which can only affect the apparent motions, places and declinations of the fixed Stars) but to the difference between the Civil and Solar year, which is 11 minutes 3 seconds; the Civil year containing 365 days 6 hours, and the Solar year 365 days 5 hours 48 minutes 57 seconds. The following table shews the length, and consequently the difference of any number of Sidereal, Civil, and Solar years from 1 to 10,000.

The reason for altering the Style.

250. The above 11 minutes 3 seconds, by which the Civil or Julian year exceeds the Solar, amounts to 11 days in 1433 years: and so much our seasons have fallen back with respect to the days of the months, since the time of the Nicene Council in A.D. 325, and therefore in order to bring back all the Fasts and Festivals to the days then settled, it was requisite to suppress 11 nominal days. And that the same seasons might be kept to the same times of the year for the future, to leave out the Bissextile day in February at the end of every century of years not divisible by 4; reckoning them only common years, as the 17th, 18th and 19th centuries, viz. the years 1700, 1800, 1900, &c. because a day intercalated every fourth year was too much, and retaining the Bissextile-day at the end of those Centuries of years which are divisible by 4, as the 16th, 20th and 24th Centuries; viz. the years 1600, 2000, 2400, &c. Otherwise, in length of time the seasons would have been quite reversed with regard to the months of the years; though it would have required near 23,783 years to have brought about such a total change. If the Earth had made exactly 3651⁄4 diurnal rotations on its axis, whilst it revolved from any Equinoctial or Solstitial point to the same again, the Civil and Solar years would always have kept pace together; and the style would never have needed any alteration.

The Precession of the Equinoctial Points.

251. Having already mentioned the cause of the Precession of the Equinoctial points in the heavens, § [246], which occasions a flow deviation of the earth’s axis from its parallelism, and thereby a change of the declination of the Stars from the Equator, together with a slow apparent motion of the Stars forward with respect to the Signs of the Ecliptic; we shall now describe the Phenomena by a Diagram.

Fig. V.

Let NZSVL be the Earth, SONA its Axis produced to the starry Heavens, and terminating in A, the present north Pole of the Heavens, which is vertical to N the north Pole of the Earth. Let EOQ be the Equator, T♋Z the Tropic of Cancer, and VT♑ the Tropic of Capricorn: VOZ the Ecliptic, and BO its Axis, both which are immoveable among the Stars. But, as [[57]]the Equinoctial points recede in the Ecliptic, the Earth’s Axis SON is in motion upon the Earth’s center O, in such a manner as to describe the double Cone NOn and SOs, round the Axis of the Ecliptic BO, in the time that the Equinoctial points move quite round the Ecliptic, which is 25,920 years; and in that length of time, the north Pole of the Earth’s Axis produced, describes the Circle ABCDA in the starry Heavens, round the Pole of the Ecliptic, which keeps immoveable in the center of that Circle. The Earth’s Axis being 231⁄2 degrees inclined to the Axis of the Ecliptic, the Circle ABCDA, described by the north Pole of the Earth’s Axis produced to A, is 47 degrees in diameter, or double the inclination of the Earth’s Axis. In consequence of this, the point A, which at present is the North Pole of the Heavens, and near to a Star of the second magnitude in the tail of the constellation called the Little Bear, must be deserted by the Earth’s Axis; which moving backwards a degree every 72 years, will be directed towards the Star or Point B in 6480 years hence: and in double of that time, or 12,960 years, it will be directed towards the Star or Point C; which will then be the North Pole of the Heavens, although it is at present 81⁄2 degrees south of the Zenith of London L. The present position of the Equator EOQ will then be changed into eOq, the Tropic of Cancer T♋Z into Vt♋, and the Tropic of Capricorn VT♑ into t♑Z; as is evident by the Figure. And the Sun, in the same part of the Heavens where he is now over the earthly Tropic of Capricorn, and makes the shortest days and longest nights in the Northern Hemisphere, will then be over the earthly Tropic of Cancer, and make the days longest, and nights shortest. So that it will require 12,960 years yet more, or 25,920 from the present time, to bring the North Pole N quite round, so as to be directed toward that point of the Heavens which is vertical to it at present. And then, and not till then, the same Stars which at present describe the Equator, Tropics, polar Circles, and Poles, by the Earth’s diurnal motion, will describe them over again.

A TABLE shewing the Time contained in any number of Sidereal, Julian, and Solar Years, from 1 to 10000.

Sidereal Years. Julian Years. Solar Years.
YearsDaysH.M.S.DaysH.DaysH.M.S.
1Contain 36569141⁄2Contain 3656Contain 36554857
273012182973012370113754
310951827431⁄21095181095172651
4146103658146101460231548
51826646121⁄21826618265445
621911255272191122191105342
72556195411⁄22556182556164239
8292211356292202921223136
93287723101⁄232876328742033
103652 133225365212365210930
207305345073050730420190
301095716371510957121095762830
401461069401461001460916380
50182621942518262121826224730
6021915914302191502191412 570
702556722465525567122556623630
8029220121920252200292199160
903287315145328721232871192530
1003652515241036525 36524535
200730516482073050 730481110
300109576221230109575 1095721645
400146102133640146100 1460962220
5001826285050182625 182621355
6002191532025 219150 219145930
700255679114910255675 255669155
80029220531320292200 2921932010
900328730183730328725 328718215
100036525610140365250 365242750
200073051220320730500 7304841540
3000109576965 1095750 10957262330
40001461025166401461000 1460969720
5000182628228201826250 18262111510
600021915381210 2191500 21914531440
700025567942211402556750 2556696650
80002922051813202922000 29219381440
900032870371815 3287250 32871802230
100003652564416403652500 3652423620
A TABLE shewing the Sun’s true Place, and Distance from his Apogee, for the second Year after Leap-year.
DaysJanuaryFebruaryMarchAprilMayJune
Sun’s Place.Sun’s Anom.Sun’s Place.Sun’s Anom.Sun’s Place.Sun’s Anom.Sun’s Place.Sun’s Anom.Sun’s Place.Sun’s Anom.Sun’s Place.Sun’s Anom.
D.M.S.D.D.M.S.D.D.M.S.D.D.M.S.D.D.M.S.D.D.M.S.D.
111♑76212♒397310♓538011♈409110♉5710010♊46111
21286313407411538112399211551011144112
31396414417512538213389312531021241113
414106515427613538314379413511031338114
515116616 437714538415369514491041435115
61612671743785538516359615471051533116
717146818447916538617349716451061630117
8181569194571017538718339817431071728118
91916610204671118538819329918411081825119
10201761121467121953892030910193910919221110
1121186122247713205281021299112037101020201111
1222196132347714215281122289122134101121171112
1323216142448715225281223269132232101222141113
1424226152548716235281324259142330101323111114
152523616264971724518142524915242810142481115
162624617274971825518152622916252610152561116
172725618285071926518162721917262310162631117
182826619295072027508172819918272110172701118
192927620♓51721285081829189192819101827581118
20♒286211517222949819♉169202916101928551119
21129622251723♈49820115921♊15102029521120
222306233527241488212139221111021♋491121
233316244527252478223119232910221461122
244326255527263478234109243610232441123
25533626652727446824589254410243411124
26634627753728545825669265210254381125
277356288537296458267492755910265351126
28836629953807448278392865610276321127
2993770 8438289192975410287301128
30103871 94282995992985110298271129
31113972 104190 948110