1817.) during the Year 1816, 87 
adopted during the preceding year. The subject is a copious one, 
had [ taken it up at an earlier part of this historical sketch, 
1. Lighthouse with Parabolic Reflectors.—Lighthouses, scattered 
in such abundance on the coast of Great Britain, now commonly 
consist of an Argand’s lamp attached to a parabolic reflector. But 
probably it is not generally known that the smaller the wick is, the 
greater is the light which the reflector throws out, But this follows 
from a set of observations made by MM. Charles, de Rossel, and 
Arago, Commissioners of the French Academy, on a set of lamps 
with reflectors, made by M. Lenoir. ‘Three lamps were used with 
diameters of 16, 12, and lines, respectively. ‘The last gave the 
best light, and did not consume one half of the oil. (Ann. de 
Chim. xevi. 59.) 
2. The Marquis de Chabanne’s method of ventilating houses, of 
which an account will be found in the Annals, vii. 113, is very in- 
genious, and seems particularly calculated to secure the comfort 
of invalids. 
3. So much has already been said concerning the ingenious 
method of preventing explosions in coal-mines contrived by Sir H. 
Davy, that it seems unnecessary to make any further observations 
on the subject here. 
4. The two papers by Professor Schubler on the physical and 
ehemical analysis of soils, published in the Annals, vii. 207, and 
viii. 115, claim the attention of the farmer, and seem well cal- 
culated to throw light upon the nature of soils. A subject of great 
importance, but still rather obscure. 
5. Mr. Gregor’s remark about Mr. Tennant’s discovery, that 
wootz owes its peculiar qualities to the presence of a small quan- 
tity of arsenic, may probably contribute materially to the improve- 
ment of steel in this country. 
X. PHYSIOLOGY. 
Respecting this branch of science likewise, I am unfortunately 
precluded from entering into details. I shall barely mention a few 
of the most remarkable particulars that have attracted the attention 
of physiologists during 1815. 
1. One of the most curious treatises connected with vegetable 
physiology which has appeared for a long time is, the introduction 
to Humboldt’s Plants of South America. It respects the distribu- 
tion of plants in the different continents, and is scarcely susceptible 
of being epitomized. But I have given a very full account of this 
introduction in the Annals, vii. 473, to which 1 beg leave to refer 
the reader, 
2. In some of the newer formations lying over the chalk both in 
France and England, it is not uncommon to find both fresh and 
salt water shells in the same hed. ‘This circumstance induced M. 
Beudant to make a series of experiments, iv order to determine 
whether fresh water molusca could live in salt water, and vice 
versa. He found that when fresh water molusca were suddenly 
introduced into water containing four per cent. of common salt, 
which is the case with sea water, they die in a very short time. 
