128 BRITISH ASSOCIATION TOE THE 



the island will depend on Wo principal terms : one, a function of the distance of 

 the point from the coast, and capable of being expressed in some cases as a func- 

 tion of the difference of latitude of that point and the nearest point on the coast, 

 and, secondly, of a term depending on the latitude and on an elliptic function of 

 the second order, having for its modulus the line of the obliquity of the equator. 

 The effect of solar radiation will therefore be to transport the centres of all the 

 closed isothermals towards the pole of the hemisphere in which the island lies ; 

 and some of these lines may thus ultimately terminate at the coast with their 

 convex sides turned towards the equator, while others may still continue as closed 

 curves in the interior of the island. The observations collected by Dr. Lloyd in 

 his " Meteorology of Ireland " confirm this theory. 



Dr. Lloyd remarked that the influence of the Gulf Stream in elevating the tem- 

 perature of the coast-stations in Ireland was one ot the first results that presented 

 itself in the discussion of the observations referred to, but the inland stations 

 were not numerous enough to form the basis of deduction as to the law of the 

 actual distribution of temperature. He had therefore formed the isothermals 

 from the coast observations, and had compared the inland temperature calculated 

 from these with the observed. This comparison had shown that the effect of the 

 Gulf Stream was even greater than had been anticipated, the temperature over 

 the sea exceeding that over the land by neai'ly 4° Pah., being more than the utmost 

 due to geographical position alone. Hence it was plain that the actual isother- 

 mals must bo closed curves, but the case of Ireland, bathed as it was by the waters 

 of a heated sea, cannot be taken as a type of the geueral phenomena of island 

 temperature. According to Dufresney, the temperature of the sea was generally 

 higher than that of the air above it, but the difference was very small except in 

 the regions of heated currents flowing from a warmer zone. 



ON THE ECLIPSE OF THE SUN IN HERODOTUS. 



The Rev. Dr. Hincks has introduced a discussion on the eclipse that Herodotus 

 describes as terminating a battle between the Medes and Lydians. This was sup- 

 posed by Bayer in 1*728, to have been the eclipse of May 18th, 603 B.C., but this 

 view was opposed by Baily in 1811, who argued for the eclipse of Sept. 30, 610 B.C. 

 Baily was, however, confuted by Mr. Hind, who has shown that the shadow would 

 fall nearly 10° to the north of Baily's computation, and who falls back on the 

 eclipse of May 28th, 585 B.C. Dr. Hincks conceived this to be an error, and was 

 in favor of the original eclipse of Bayer, viz, — on May 18th, 603 B.C., and intim- 

 ated a desire to learn what the actual track of this eclipse was according to the 

 most modern tables of the moon. 



Dr. Whewell on this remarked that this very eclipse and the whole ground over 

 which Dr. Hincks had travelled had already been fully investigated by the Astron- 

 omer Royal in the R. S. Transactions for 1850. M. Bosanquet writes to the 

 Athenozum (Aug. 23rd) that " not only the track of the eclipse of 603 B.C. but 

 of every eclipse bearing upon the question between the years 630 and 580 B.C. 

 has been examined by the Astronomer Royal, and the result of his investigations 

 published in the Phil. Trans, for 1852, which had been entirely overlooked by 

 Dr. Hincks:" also, that Mr. Hind in 1852 had shewn the eclipse of 585 B.C. to be 

 the only one satisfying all the conditions : that, however, a short time back, the 

 error discovered in Planche's tables had led to a re-calculation of the path for 

 585 B.C. and the alteration necessary was found to be very slight, so as not to 



