Page:Encyclopædia Britannica, first edition - Volume I, A-B.pdf/578

 ASTRO N O M Y. We are credibly informed from the teftimony of the than fix. For the fun pafles by both the nodes but onc^ ancients, that there was a total eclipfe of the fun pre- a-year, unlefs he paffes by one of them in the beginning didted by Thales to happen in the fourth year of the of the year ; and if he does, he will pafs by the fame 48th Olympiad, either at Sardis or Miletus in Aha, node again a little before the year be finilhed ; becaufe, where Thales then redded. That year correfponds to as thefe points move 19^ degrees backward every year, the 585th year before Chrift ; when accordingly there the fun will come to either of them 173 days after the happened a very dgnal eclipfe of the fun, on the 28th of other. And when either node is within 17 degrees of May, anfwering to the prefent 10th of that month, cen- the fun at the time of new moon, the fun will be etral through North America, the fouth parts of France, clipfed. At the fubfequent- oppofition, the moon will Italy, fee. as far as Athens, or the ides in the Aegean be eclipfed in the other node, and come round to the next fea ; which is the fartheft that even the Caroline tables conjundion again ere the former node be 17 degrees paft carry it; and confequently make it invifible to any part the fun, and will therefore eclipfe him again. When of Afia^ in the total charafter ; though there are good rea- three eclipfes fall about either node, the like-numbef gefons to believe that it extended to Babylon, and went nerally falls about the oppofite ; as the fun comes to it down central over that city. We are not however to in 173 days afterward; and fix lunations contain but imagine, that it was fet before it pad Sardis and the four days more. Thus, there may be two eclipfes of Afiatic towns, where the predidlor lived ; becaufe an in- the fun, and one of the moon, about each of her nodes. vilible eclipfe could have been of no fervice to demon- But when the moon changes in either of the nodes, {he ilrate his ability in aftronomical fciences to his country- cannot be near enough the other node at the next full to be eclipfed ; and in fix lunar months afterward Ihe will men, as it could give no proof of its reality; For a farther illudration, Thucydides relates, That a change near the other node : in thefe cafes there can be folar eclipfe happened on a fummer’s day in the after- but two eclipfes in a year, and they are both of the fun. noon, in the firft year of the Peloponnedan war, fo A longer period than the above mentioned, for comgreat, that the ftars appeared. Rhodius was viftor in paring and examining eclipfes which happen at long inthe Olympic games the fourth year of the faid war, be- tervals of time, is 557 years, 21 days, 18 hours, 30 miing alfo the fourth of the 87 th Olympiad, on the 428th nutes, 11 feconds ; in which time there are 6890 mean year before Chrift. So that the eclipfe muft have hap- lunations ; and the fun ancLnode meet again fo nearly as pened in the 43 ift year before Chrift ; and by computa- to be but 11 feconds diftant; but then it is not the fame tion it appears, that on the third of Auguft there was a eclipfe that returns, as in the ftiorter period above menfignal eclipfe which would have part over Athens, cen- tioned. tral about 6 in the evening, but which our prefent tables bring no farther than the ancient Syrtes on the African A Lift of EdipfcS) and hiftorical Events, coaft, above 400 miles from Athens ; which differing in which happened about the fame times, from that cafe but 9 digits, could by no means exhibit the remarkable darknefs recited by this hiftorian ; the centre Ricciolus. therefore feems to have part Athens about 6 in the evening, and probably might go down about Jerufalem, or Before Christ. But, according to an old kalennear it, contrary to the conftruiftion of the prefent tables. July dar, this eclipfe of the fun was on Thefe things are only obviated by way of caution to the 21ft of April, on which day the the prefent aftronomers, in re-computing ancient efoundations of Rome were laid ; if clipfes ; and they may examine the eclipfe of Nicias, fo fatal to the Athenian fleet; that which overtye may believe Taruntius Firmanus. threw the Macedonian army, &c. A total eclipfe of the moon. The In any year, the number of eclipfes of both luminaries 721 March Afi'yrian empire at an end ; the Bacannot be lefs than two, nor more than feven ; the moft bylonian eftablifhed. ufual number is four, and it is very rare to have more

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not over before the moon fet: But, by mojl of our aftronomical tables, the moon ivas fet at Babylon half an hoar before the eclipfe began ; in •which cafe, there could have been no pojjibility of obferving it. The fecond eclipfe was ohferved at Alexandria, Septem. 22d, the year before Chrift 201; where the moon rofe fo much eclipfed, that the eclipft muft have begun about half an hour before fhe rofe: Whereas, by meft of our tables, the beginning of this eclipfe was not till about 10 minutes after the moon rofe at Alexandria. Had thefe eclipfes begun and ended while the fun was below the horizon, we might have imagined, that as the ancients had no certain way of meafuring time, they might have been fo far miflaken in the hours, that we could not have laid any ftrefs on the acounts given by them. But as, in the firft eclipfe, the moon was fet, and confequently the fun rifen, before it was over; and in the fecond eclipfe the fun was ft, and the moon not rifen, til! fome time after it began ; thefe are fuch circumftances as the obfervers could not poffibly be miftaken in. Mr Struyk, in the following catalogue^ notwithftanding the exprefs words of Ptolemy, puts down thefe two eclipfes as obferved at Athens; where they might have been feen as above, without any acceleration of the moon's motion, Athens being 20 degrees weft of Baby lon, and 7 degrees weft of Alexandria. An