REPORT ON RADIANT HEAT. aM 
© On the ice formed under peculiar circumstances at the bottom 
of running water’, by the Rev. J. Farquharson, F.R.S. of Al- 
ford, Aberdeenshire. In this paper the author details various 
new and highly interesting particulars as to the mode of the 
formation of the spongy masses of spiculz of ice at the bottom 
of certain rivers in his neighbourhood, and the peculiar cir- 
cumstances under which alone it is formed. He examines acutely 
the several explanations which have been suggested, which he 
shows are all insufficient to explain the whole of the circum - 
stances, and then proceeds to suggest his own theory, which is 
grounded essentially on the assumption that the radiation of 
heat from substances at the bottom goes on through the water ; 
and partly also on the supposed greater radiation from dark- 
coloured surfaces. Neither of these assumptions, it appears to 
me, are admissible ; the former especially is directly at variance 
with the experiments of Melloni. Some suggestions at least 
towards a theory not open to these objections, are given by an 
anonymous writer in the Magazine of Popular Science, vol. i. 
p- 157. 
Division [I].—Pouarizep HEAT. 
Polarization of Heat: Forbes. 
The original statement by Berard, of the polarization of heat 
by reflexion, and the attempts to verify it, are mentioned in my 
former report*. In 1833, Melloni tried to repeat the experiment 
with tourmalines, but unsuccessfully+. 
In 1834, Nobili attempted it by reflexion, employing the 
thermo-multiplier, but without success t. The disbelief in such 
aresult, at least with dark heat, seems now to have prevailed 
generally. Mrs. Somerville, in the second edition of her “‘ Con- 
nexion of the Sciences ’’ (in 1833), speaks of it as altogether 
without experimental proof. 
Prof. Forbes took up the inquiry in November, 1834; and in 
his first memoir, already referred to in Section 2, announced his 
complete success, after having in the first instance failed from 
ee influence of secondary radiation, which disguised the real 
effect. 
(1.) He proved distinctly the stoppage of a considerable pro- 
portion of heat when the tourmalines were crossed, not only 
with a lamp, but with brass heated below luminosity. 
(2.) In the third section of the same memoir, he details his 
* British Association Report, vol. i. pp. 262. 276. 
+ Second Memoir, dnn.de Chim. 55. Taylor’s Scientific Memoirs, Part I, 
p. 59. t Biblioth. Univ., Sept. 1834. 
