1858MNRAS..18..148C
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Mr. Carrington, Notice of some recent Modifications
The title of M. Oltmanns' paper gives some presumption that·
he was inaccurate in his habits of scientific thought:-" Uber die
wahre Epoche der grossen von Herodot erwahnten Sonnenfinsterniss am Flusse Halys." Herodotus does not say a word about the
river Halys; and there is no reason ""hatever for connecting the
battle with the river Halys.
It is pointed out to me, through Mr. Carrington, that the
value which I have assigned to the- daily motion of the p.ode is
incorrect. It is so. The correct value, 3' 1 o''·6, is used in my
private papers: the accurate value is 3' I o''·64; and apparently
the cypher has been lost in transcription.
Before dismissing this subject, I will allude to one point upon
which much discussion has been founded, namely, the asserted
prediction of the eclipse by Thales. I think it not at all improbable that the eclipse was so predicted ; and there is one easy
way, and only one, of predicting it-namely, by the Saros, or
period of I 8 years 1 o days 8 hours nearly. By use of this period,
an evening eclipse may be predicted from a morning eclipse ; but
a morning eclipse can rarely be predicted from an evening eclipse;
(as the interval of 8 hours after an evening eclipse will generally
throw the eclipse at the end of the Saros into the hours of night).
The evening eclipse, therefore, of -5 84, 1\Iay 28, which I adopt
as being most certainly the eclipse of 'fhales, might be predicted
fron1 the morning eclipse of - 6o2, May I 7 ; and a man of astronomical and geometrical knowledge might, from the circumstances
of one, form a shrewd guess on the circumstances of the other,
provided the hours of day were sueh as to make both eclipses
visible. Now the hours were such as to make both eclipses visible;
and moreover, the eclipse of -602 was a large eclipse in .Asia
Minor and the Levant. It is, therefore, very probable that the
eclipse of - 584 was predicted, as is asserted. No other of the
eclipses discussed by Baily and Oltmanns presents the same facility'
for prediction.
_ March 1-7, 18.58.
Notice of some recent Modifications and lmprQvements in Telescopes at Paris. By R. C. Carrington, Esq.
In a recent number of the hfonthly Notices I took occasion
to mention very briefly a helioscope of new construction, by Co-lonel Porro, of No. I o Boulevard D"Enfer, f>aris, a partial
description of which, with some satisfactory results, had pre .._
viously reached me by private correspondenee. Since the last
meeting of the Society, having made a short visit to Paris, I have
had an opportunity of examining one of these instruments more
© Royal Astronomical Society • Provided by the NASA Astrophysics Data System
1858MNRAS..18..148C
1858MNRAS..18..148C