Proceedings of the Ro^al Society of Edinburgh. 407 
At the same meeting, an extract of a letter from M. Berze- 
lius to Dr Brewster, was read, on the Composition of Water, 
and on the Weight of an Atom of Hydrogen Gas. 
April 19.' — Dr Brewster presented a notice respecting the 
extension of his theory of double refraction, to crystals with 
more than one axis ; and respecting a general law, relative to 
the composition of any number of polarizing and doubly re- 
fracting axes placed symmetrically round a given line. 
At the same meeting, James Russel, Esq. presented a notice 
respecting a cow from Guernsey. This cow had one calf in 
June 1806, and for several years, she ceased to give milk at 
the usual time that cows with calf generally lose it. At the 
end of nine, or nine and a half months, after she had been with 
the bull, the milk re-appeared in as great a quantity, and of 
as good a quality, as at any former period, although she had 
no calf. After this was observed to take place for several years, 
it was thought unnecessary to make any farther trials for a 
calf ; but notwithstanding the change of circumstances, the ces- 
sation of her milk, and its re-appearance, took place exactly as 
before. 
May 3. — Mr Leonard Horner laid before the Society an ac- 
count of the art of lithography, and an analysis of some of the 
limestones generally employed. 
May 17. — Mr Lizars exhibited to the Society several speci- 
mens of his new style of engraving on copper in alto relievo. 
At this meeting Dr Brewster laid before the Society an ab- 
stract of his experiments on the structure of the crystalline lens 
in man, quadrupeds, birds, fishes, and whales, the results of 
which were illustrated by models. 
The Society adjourned till November. 
Art. XXXVII . — Proceedings of the Wernerian Natural His- 
tory Society. 
Feb. 20. 1819- — Dr Hibbert continued" the reading of his 
geognostical description of Shetland. — The first part of an ab- 
