| XXX | (479) | XXX |
4)79 AST R O N O M Y. panfuvt. And as this 36 degrees is not gone through in From thefe remarks on the entire revolution of this may gather, that a thoufand years, more Or lefs than 77 periods, which takes up 1388 years, the eclipfe,(forwethere are fome irregularities that may protradfc remaining 324 degrees cannot be fo gone through in lefs, or lengthen this period too years), complete the whole lefs than 12492 years. For, as 36 is to 1388, fo is terredrial phenomena of any fingle ecliple : and iince 20 324 to 12492. 54 years each, and about 33 days, compreTo illuftrate this a little farther, we fliall examine periodstheofentire extent of their revolution, it is evident, Tome of the mofl: remarkable circumftances of the returns hend of the eclipfe which happened July 14th 1748, about that the times of the returns will pafs through a circuit of one year and ten months, every Chaldean period being noon. This eclipfe, after traverfing the voids of fpace ten days later, and of the equable appearances, from the creation, at laft began to enter the Terra Au- aboutor 32eleven or 33 days. Thus, though this eclipfe hapftralis Incognita about 88 years after the conqueft, which was the laft of king Stephen’s reign ; every Chal- pens about the middle of July, no other fubfequent ecdean period it has crept more northerly, but was dill in- lipfe of this period will return till the middle of the fame vifible in Britain before the year 1622 ; when, on the month again ; but wear conftantly each period 10 or 11 30th of April, it began to touch the fouth parts of Eng- days forward, and at laft appear in winter, but then it land about 2 in the afternoon ; its central appearance ri- begins to ceafe from affedting us. ling in the American fouth feas, and traverfing Peru and Another conclufion from this revolution may be the Amazon’s Country, through the Atlantic ocean into drawn, that there will feldom be any more than two Africa, and fetting in the ^Ethiopian continent, not far great echpfes of the fun in the interval of this period, and thefe follow fometimes next return, and often at from the beginning of the Red fea. Its next vifible period was after three Chaldean revo- greater diftances. That of 1715 returned again in 1733 lutions in 1676, on the firft of June, riling central in the very great; but this prefent eclipfe will not be great till Atlantic ocean, palling us about 9 in the morning, with the arrival of 1820, which is a revolution of four Chalfour digits eclipfed on the under limb, and fetting in the dean periods.; fo that the irregularities of their circuits muft undergo new computa ions to aflign them exa&ly. gulf of Cochinchina in the Eaft Indies. It being now near the folftice, this eclipfe, was vilible Nor do all.eclipfes come in at the fourh pole : That dethe very next return in 1694, in t‘ie evening; and in pends altogether on the pofition of the lunar nodes, which two periods more, which was in 1730, on the 4th of will bring in as many from the expanfum one way as the July, was feen about half eclipfed jult after fun-rife, and other ; and fuch eclipfes will wear more foutherly by obferved both at Wirtemberg in Germany, and Pekin in degrees, contrary to what happens in the prefent cafe. The eclipfe, for example, of 1736 in September, had China, foon after which it went off.. Eighteen years more afforded us the eclipfe which fell its centre in the expanfum, and let about the middle of its obfeurity in Britain; it will wear in at the north pole, on the 14th of July 1748. The next vifible return happened on July 25th 1766, and in.the year 2600, or thereabouts, go off into the in the evening, about four digits-eclipfqd; and after two expa?fum-on the fouth fide, of the earth. periods more, will happen on Auguft 16th 1802, early in The eclipfes therefore which happened about the crethe morning, about five digits, the centre coming from the ation are little more than, half way yet of their etherial north frozen continent, by the capes of Norway, through circuit; and will be 4000 years before they, enter the Tartary China and Japan, to the Ladrone ifldncTs, where earth any more. This grand revolution feems. to have it goes off. been intirely unknown to the ancients.Again, in 1820, Au.guff 26thi between one-and two, It is particularly^ to be noted, that eclipfes.which have there will be another great eclipfe at London, about 10 happened many centuries ago, will not be. found by our digits; but, happening fo near the equinox, the centre prefent tables to agree exadtly with, ancient obfervations, will leave every part of Britain to, the welt, and enter by reafon of (he great anomalies in. the lunar motions ; Germany at Emden, palling by Venice, Naples, Grand which appears an inconteftable demonftration. of the non^ Cairo, and let in the, gulf of Baffora near that city. eternity of the univerfe. For it feems confirmed, by unIt will be no more vifible till 1874, when five digits deniable proofs, that the moon now finilhes her period in will be obfeured (the centre being now about to leave lefs time than formerly, and will'continue, by the centhe earth) on September 28th. In 1892, the fun will go tripetal law, to approach nearer and nearer the earth, down eclipfed in London; and "again, An 1928, the paf- and to go fooner and fboner round it: Nor will the cenfage of the centre will b$ in the expanfum, though there trifugal power be fufficient to compenfate the different will be two digits eclipfed-at London, October the 31ft gravitations of fuch an affemblage of bodies as conftitute of that year, and’ about the year 2090 the whole pe- the folar fyftem, which would come to ruin of itfelf, withnumbra will be wore off; whence no more returns of out fome new regulation and adjuftment of their original this ecliple can happen, till after a revolution of io.ihou- motions *.. fand years. We
- There are two ancient ecllpfes of the moon, recorded by Ptolemy from Hipparchus, which afford an undentable proof of the moon's acceleration. The firft of thefe was obferved at Babylon, Decern, it 2d, in the year before Chrift 383; when tie,moon began to be eclipfed, about half an hour before the fun rofe, and the eclipfe was
not
