180 
PROFESSOR G. B. AIRY ON THE ECLIPSES 
of Mr. Baily’s astronomical publications) must be considered as possessing the 
highest value ; for its due appreciation of the characteristic circumstances of a total 
eclipse for its accuracy of computation, and for the caution and goo ait wit 
which the results are announced. Mr. Bailv, in the first place, pointed out that on y 
a total eclip.se could satisfy the account of Herodotus, and that a total eclipse would 
suffice He lived to witness the total eclipse of 1842, but he observed it from a room 
of a house, where probably he could scarcely remark the general effect of the 
eclipse I have myself seen two total eclipses (those of 1842 and of 185 1 ), being on 
both occasions in the open country ; and I can fully testify to the sudden and aw ul 
effect of a total eclipse. I have seen many large partial eclipses, and one annular 
eclipse concealed by clouds; and I believe that a body of men, intent on military 
movements, would scarcely have remarked on these occasions anything unusua . 
Mr. Baiev then, adopting Burg’s tables, exhibited in detail the results of computation 
of the eclipses of b.c. 685, May 28; 583, October 1 ; 60/, July 30; o97, July 9; 
601, September 20; 603, May 18; 626, February 3 ; and 610, September 30; and 
stated that he had computed all the eclipses which seemed likely to have been visible 
in Asia Minor from b.c. 650 to b.c. 580. He found that only the eclipse of 610, 
September 30, passed over Asia Minor ; that the centre of its shadow crossed the 
river Halys at its mouth, passing a short distance south of the Caspian 8ea ; and he 
adopted it as the true eelipse of Thales. But he then subjoined a computation 
which threw doubt on the whole. Upon applying the elements of the same tables to 
the computation of the eelipse of Agathocles, b.c. 310, August 15, he found that 
they would not give a total eclipse for any place in which it was possible to locate 
Agathocles at the time when, according to the historieal record, the shadow passed 
over him. Mr. Baily inferred from this that the tabular motion of tbe moon s node 
must be altered ; and he admitted, as a probable effect of such an alteration, that the 
eclipse of b.c. 610 might be found insufficient for the history of Herodotus. But 
he confidently believed that no other eclipse between b.c. 650 and 580 would be made 
to pass centrally over any part of Asia Minor. 
4. Since I first read this paper, I have always attached greater importance to the 
last portion of it than to any other part. It has always appeared to me that not the 
eclipse of Thales but that of Agathocles ought to be considered as the true cardinal 
eclipse for chronology and lunar astronomy. And I have long since contemplated 
the recalculation of the latter eclipse with the view of obtaining correct elements for 
the computation of the former. 
5. About the same time in which Mr. Baily w^as employed in his calculations, 
Mr Oltmanns was also engaged (apparently without any knowledge of Mr. Baily s 
labours) on the same subject. His paper was presented to the Berlin Academy on 
1812 , November 26, and is printed in the Berlin Memoirs 1812-1813. He points 
out (as Mr. Baily had done) that a total eclipse is required: he insists also that it 
must have been visible as a large eclipse in Ionia; be then, using his own tables 
