30 REPORT—1852. 
of the sea, between it and the promontory of Bengore; the inhabitants asserting that 
many of them had distinctly seen it, crowded with people selling yarn, and en- 
gaged in various other occupations common toa fair. The notes to the second book 
of Dr. Drummond’s poem on the ‘ Causeway’ were also glanced at, as containing an 
account of other cases of the Fata Morgana, by the Bushfoot Strand and Tor-point. 
So, a person still living (and whose name; &c. were given) conceived that he had a 
sight of the floating isle off Fair-Head; that it seemed to be well-wooded; and that 
he could distinguish upon it the forms of buildings, and a woman laying out clothes, 
Mr. M‘Farland then mentioned that, in June 1833, he himself and a party of friends, 
when stariding on a tock at Portbalintrea, perceived a small rothdish island as if in 
the act of emerging from the deep, at a distance of a mile from the shore; at first it 
appeared but as 4 green field, afterwards it became fringed with red, yellow and 
blue; whilst the forms of trees, men and cattle rose upon it slowly and successively ; 
and these continued for about a quarter of an hour, distinct in their outlines, shape 
and colour; the figures, too, seemed to walk across it, or wandered among the trees, 
the ocean bathed it around, the sun shone upon it from above; and all was fresh, 
fair, and beautiful, till the sward assumed a shadowy form, and its various 
objects, mingling into one confused whole, passed away as strangely as they came. 
Further, Morgana had occasionally assumed the semblance of a beautiful bridge 
that spanned the Sound between the Skerry rocks and the strand at Portrush, 
and having people passing and repassing over it. A particular instance of 
this was Stated, as well as of the appearance of the sea, at Ballintoy, of what 
resembled a city with its streets; houses, spires, &c. Two occasions were then spe- 
cified, in which the Fata had been seen in the sky—the one in the summer of 1847, 
over the Ferry at Lough Foyle, and the other on the 14th of December 1850, near 
to the Bannmouth; and in the course of which the images of troops, ships, &c. 
were reflected on the clouds. Four other cases of the Aérial Morgana were adduced, 
as witnessed about the town and coast of Waterford in 1644, and at the close of the 
last arid commencement of the present centuries, atid taken from the ‘ Voyages and 
Observations’ of M. le Gown, Brewer’s “‘ Beauties of Ireland ” (vol. ii. p. 307; n.), 
and the 13th volume of the Phil. Mag., Old Series. Mr. M‘Farland considéted that 
these various exhibitions of the Fata Morgana might all be accounted for by apply- 
ing to those parts of the coast on which they had been displayed; the theories of 
Minasi and M. Honel, as advanced by them in explanation of similar phenomena 
seen on and about the Strait of Messina. The Northern Channel of Ireland presents, 
to a very great degree, the same data as regards shape, indentations, currents, and 
bituiien, as that strait does, and on which their theories rest; and he believed that, 
to some extent at least, so did the sea in the neighbourhood of the isles of Arran 
~ afid towh of Waterford. Where the Marine Morgana was found, the Aérial might 
be expected, aiid the Prismatic was a mere corollary to the first. 

————w 
On the Causes of the Excess of the Mean Temperature of Rivers above that of 
the Atmosphere, recently observed by M. Renou. By W. J. Macquorn 
Rankine, C.F, F.RSE. 
M. Renow having for four years observed the temperature of the River Loir at 
Vendéme, as compared with that of the atmosphere, has found that the mean teim- 
perature of the river invatiably exceeds that of the air, by an amount varying from 
14 to 3 Centigrade degrees, and averaging 2°24 Centigrade; anda similar result has 
been deduced from obsetvations made by M. Oscar Valin on the Loire at Tours. 
M. Renou and M. Babinet account for this fact by the re-radiation from the bed of 
the river of solar heat previously absorbed by it. 
Mf. Rankine thinks this supposition inadequate to account for the facts ; because 
the excess of temperature of the river over the air was considerably above its mean 
amount in November, and very near its maximum in December; and because the 
mean diurnal variation of temperature of the river was much less than that of 
the air. He cofisiders that friction is probably one cause of this elevation of 
temperature; for if water descends in a uniform channel, with a uniform 
eaams from a higher level to a lower, the whole power due to its descent is 
expended in overcoming friction; that is to say, is converted into heat, as the expe- 

