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Bill Thayer

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This webpage reproduces a correspondence over several issues of
The Observatory

The text is in the public domain.

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and I believe it to be free of errors.
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Vol. VII, No. 87  p198  The Eclipse of Pericles

Sir, —

In his excellent and useful little book, 'Eclipses Past and Future,' the Rev. S. J. Johnson refers amongst others to the solar eclipse which occurred in the first year of the Peloponnesian war, and in reference to which Plutarch tells us that Pericles endeavoured by an illustration to remove the superstitious fears of the pilot of his boat. The date generally accepted for this event is B.C. 431; and an eclipse of the Sun occurred on the 3rd of August in that year, which is usually supposed to be the one in question. Mr. Johnson, however, on the ground that this eclipse was more partial than had been thought (the obscuration not exceeding seven tenths of the Sun's diameter), proposes to substitute for it that of March 30, B.C. 433, thus carrying back the outbreak of the Peloponnesian war to a date two years earlier. Now without entering into a dispute about the exact season of the year implied in the word θέρος, which Mr. Johnson thinks may in that country have been taken to include a time as early as the end of March, I would submit that it is quite impossible that all the events of the campaign as narrated by Thucydides could have occurred before that time. We have the attempt of the Thebans to surprise Plataea and its failure; the march of the Spartan army into Boeotia under King Archidamus; the long and ineffectual siege of Oenoe; the slow march into Attica; the long encampment at Acharnae; the final retreat of Archidamus, on finding that he could not succeed in drawing the Athenians, restrained by Pericles, into an engagement. It was only after the retreat had actually begun that the latter fitted out a naval force to ravage the coasts of Peloponnesus; and it was at the embarkation of this that Pericles, according to Plutarch, held up his cloak to re-assure the pilot, frightened by the eclipse, and told him the only difference between  p199 that and the phenomenon was that something larger than his cloak (he does not seem to have explained what) caused the obscuration of the Sun. Now all these events could not have taken place before the 30th of April, whilst the beginning of August appears to be about the time required by the history; so I contend that we need have little doubt on these grounds that the eclipse of August 3rd, B.C. 431, is the one alluded to.

Perhaps, for the full appreciation of other points, you will allow me to quote the passage of Thucydides in which the eclipse is mentioned. We need not stop to smile at the shrewdness which that historian evidently thought that he showed in noticing that an eclipse of the Sun always occurred about the time of New Moon. He says (book II c.28):—

Τοῦ δ’ αὐτοῦ θέρους νουμενίᾳ κατὰ σελήνην, ὥσπερ καὶ μόνον δοκεῖ εἶναι γίγνεσθαι δυνατόν, ὁ ἥλιος ἐξέλιπε μετὰ μεσημβρίαν καὶ πάλιν ἀνεπληρώθη, γενόμενος μηνοειδὴς καὶ ἀστέρων τινῶν ἐκφανέντων.

The reason I have quoted this passage is that Mr. Johnson argues that the circumstances agree better with the eclipse of March 30, B.C. 433, than with that of August 3, B.C. 431, both because the former eclipse was larger in amount of obscuration, and because it occurred earlier in the day (soon after noon, whilst the latter was towards evening). But surely this last argument (which appears of most weight, as both eclipses were only partial), might much more forcibly be used the other way. For a partial eclipse would be much more likely to be noticed and thus described when the Sun was rather low in the heavens than when near the meridian; and, we may add, the visibility of a few stars (perhaps the expression is exaggerated, and only the planet Venus was really seen) would also be more easily explained during an eclipse, which, although partial, occurred whilst the Sun was at a small altitude in the sky. I for one see, therefore, no reason in this account for seeking to alter the ordinary historic date of the commencement of the Peloponnesian war, viz. B.C. 431.

Yours faithfully,

W. T. Lynn

Blackheath, 1884, May 22.

Vol. VII, No. 88  p232  The Eclipse of Pericles

Sir, —

In an interesting communication in the July number of the 'Observatory,' Mr. Lynn takes exception to certain doubts I have expressed about the solar eclipse of B.C. 431 being that of Pericles.

W. D. Snooke, in his little work on this subject (published by Highley and Son, 32 Fleet Street) 1852, refers to the position of the brightest stars at the time. He remarks, "Lyra was high in the east or near the zenith, Arcturus high in the south-west, and Spica nearer the horizon; farther west were Regulus, and the planet Venus a little eastward of the Sun." A writer so accurate as Thucydides would hardly have said that "some of the stars shone out" if only Venus was meant; and it is perfectly certain that an eclipse of seven-tenths of the Sun's disk could bring out no star except the planet Venus: nor would this be even the case if she were only "a little eastward of the Sun." It seems impossible, therefore, that the magnitude of the eclipse of B.C. 431 was sufficient to cause any of the stars to shine out.

Faithfully yours,

S. J. Johnson

Melplash Vicarage, Bridport,

July 8.

Vol. VII, No. 89  p261  The Eclipse of Pericles

Sir, —

In his letter to you on this subject, Mr. Johnson still contends for the eclipse of March 30th, B.C. 433, rather than that of August 3rd, B.C. 431, as the one in question (which occurred in the first year of the Peloponnesian war), on the ground that Thucydides was too accurate a writer to say that several stars appeared (ἀστέρων τινῶν ἐκφανέντων) if the obscuration was only sufficient (and barely sufficient) to bring out the planet Venus. I must confess this seems to me a literal clinging to his words, almost like the αὐτὸς ἔφη which we are told the disciples of Pythagoras repudiated any calling in question what their master said. I think I can call to mind many instances in which it has been said to me, "The stars are out!" when in the dusk of evening twilight one star only has actually been seen. It is to be remembered that, in any case, a star or stars can only be seen momentarily during an eclipse. Nor is it likely that more stars were visible at the eclipse of B.C. 433.

But, however that be, there are two arguments which, unless I can see them rebutted, will continue to lead me to give the preference to that of B.C. 431.

One of these (which I mentioned in my previous letter, but do not see that Mr. Johnson has noticed) is the number of events that took place in the campaign before the eclipse, which could not have occurred before March 30, and point rather to such a date as August 3.​a

The other is mentioned by Mr. Johnson himself (p18 of his 'Eclipses Past and Future') as a difficulty, and seems to me to be a fatal one. Another eclipse of the Sun is mentioned by Thucydides (book IV c.52), which appears to have occurred in the eighth year of the war. He calls it a small eclipse (τοῦ τε ἡλίου ἐκλιπές τι ἐγένετο), and says that it took place at the beginning of the summer (as before, it would seem that he uses the word θέρος as almost equivalent to the period of time which would be covered by the campaign). There seems to be little or no doubt that this was the eclipse of the 21st of March, B.C. 424; and if this was the eighth year of the war, B.C. 431 must have been the first.

Mr. Johnson refers to a small pamphlet published in 1852 by W. Drew Snooke, formerly of Ryde, Isle of Wight, in which the author gives the places of Venus and of several of the brightest stars at the time of the eclipse of August 3, B.C. 431. It does not appear, however, that Mr. Johnson has verified Snooke's result, which makes Venus only "a little eastward of the Sun." An approximate calculation made by myself indicates that she was not far from greatest eastern elongation, and therefore considerably to the east of the Sun. At any rate, there can be, I think, little doubt that the planet would be visible during the eclipse (although partial), especially in the atmosphere of Greece, and with the Sun low in the heavens.

Yours faithfully,

W. T. Lynn

Blackheath, 1884, Aug. 16.

Vol. VII, No. 90  p298  The Eclipse of Pericles,
and the Eclipses of A.D. 1191 and A.D. 1733

Sir, —

(1) Eclipse of Pericles. In addition to the difficulty involved in supposing an eclipse of about three-fourths of the Sun's disk to cause some of the stars to shine out as Thucydides records, it appears there are historical difficulties which render it probable that we must look for some other eclipse than that of B.C. 431 as the eclipse of Pericles. Parker in his 'Chronology' (1858), p783, admits that the eclipses of B.C. 431, 424, 413, agree with the account which Thucydides has given of his three eclipses, but adds "they place the end of the Peloponnesian war only at the distance of 81 years about death of Alexander. We need not again go over our manifold testimonies to show that this is utterly incredible."

(2) Eclipse of 1191. In an article headed 'Historical Sun-darkenings' by Dr. Hind, in 'Nature' of June 26, 1879, we have the following:— "A century later, in June 1191, according to Schnurrer, the Sun was again darkened with certain attendant effects upon nature: here the cause is easily found; on June 23 there was a total eclipse in which the Moon's shadow traversed the continent of Europe from Holland to the Crimea: the eclipse was total in this country between the coasts of Cumberland and Yorkshire." Instead of being total, I find the Moon's semidiameter was very small at the time, so that the eclipse could only have been widely annular.

(3) Eclipse of 1733. This was the last of a nine-year series of four fine eclipses in our land, of which the two middle ones, 1715 and 1724, were total in England. Weaver's Ephemeris for 1733 makes the line of totality in May 1733 to run across the northern isles of Shetland. My own rough calculations make the northernmost of the Shetland Islands (Unst) to lie a good way south of the total phase, according to which the inhabitants would have to make a very considerable excursion out to sea to get involved in total darkness. But if any record should exist which would lead to the supposition that totality touched the northern point of these islands, it would be extremely interesting to bring it forward, as in this case the eclipse of 1733 would be the last total eclipse of the Sun visible in Great Britain; and the next nearest approach to totality in our kingdom is that of 1954, only just escaping the northernmost of the Shetlands (if we omit that of 1927, total for a very few seconds).

 p299  The above eclipse of 1733 was the last one in Europe that was total for a period of 109 years, no other taking place till 1842 — something like the interval between two transits of Venus. Query: When did a whole century go by before without one total solar eclipse in Europe? Vassenius, at Gottenburgh, says:—

"7.14.6 adparebat ♃.

7.14.46 incepitº totus tegi solis discus.

7.15.50 maximae tenebrae, cum stellae omnes Ursae Majoris, cor , Procyon, Sirius, oculus , et nonnullae aliae videri poterant."

It lasted 2m 8s. He speaks of "subrubicundae nonnulaeº maculae extra peripheriam disci lunaris."

Faithfully yours,

S. J. Johnson

Melplash Vicarage, Bridport,

Sept. 19.

Thayer's Note:

a To me, the arguments advanced by Lynn seem conclusive, and this particular one determinant; I'm in luck, since the modern consensus, based in part on much refined eclipse path calculations produced by better orbital elements and the use of computers, is that the traditional date of August 3, 431 B.C. is indeed that of the actual eclipse. For full details, see NASA's page, Annular Solar Eclipse of ‑0430 Aug 03.

The same conclusion was arrived at in a more literary way by J. A. R. Munro, Thucydides on the Third of August, 431 B.C. (CQ 13:127‑128): the author feels that Thucydides actually witnessed the eclipse while he was on a diplomatic mission to the capital of Thrace, somewhere near Adrianople — an idea that dispels Johnson's objections above, since that would have put the Greek historian much closer to the path of maximum obscuration, and thus, to quote the concluding sentence of Munro's article, "Thucydides would certainly have seen the stars on the afternoon of the 3rd of August, 431 B.C."

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