CONTEN TS. 
I. On the black rete mucosum of the Negro, being a defence against 
the scorching effect of the surds rays. By Sir Everard 
Home, Bart. F. R. S. page i 
II. On the magnetic phenomena produced by Electricity ; in a letter 
from Sir H Davy, Bart. F. R. S. to W. H. Wollaston, 
M.D. P.R.S. p. 7 
III. A Communication of a singular fact in Natural History . By 
the Right Honourable the Earl of Morton, F. R. S. in a Letter 
addressed to the President. p. 20 
IV. Particulars of a fact, nearly similar to that related by Lord 
Morton, communicated to the President, in a letter from 
Daniel Giles, Esq. p. 23 
V. The Croonian Lecture. Microscopical observations on the 
following subjects. On the Brain and Nerves ; showing that 
the materials of which they are composed exist in the blood. On 
the discovery of valves in the branches of the vas breve, lying be- 
tween the villous and muscular coats of the stomach. On the struc- 
ture of the Spleen. By Sir Everard Home, Bart. V. P. R. S. 
p. 25 
IV. On two new compounds of Chlorine and Carbon, and on 
a new compound of Iodine , Carbon, and Hydrogen. By 
Mr. Faraday, Chemical Assistant in the Royal Institution. 
Communicated by W. T. Brande, Esq. Sec. R. S. and Prof. 
Chem. R. I . p. ^7 
VII. An account of the comparison of various British Standards 
of linear measure. By Capt. Henry Kater, F. R. S. p. 75 
