Roval Society. 521 
matician and a good linguist—a rare combination. The Memoirs 
and ‘l'reatises in the German and Italian languages, as well as those 
in the French and Latin, have been completely mastered and ana- 
lysed: and some account is given even of a dissertation in the Rus- 
sian language. Of those works which are difficult of access to the 
English student, a more copious account is given; and throughout 
the whole history, ‘‘numerous remarks, criticisms, and corrections 
are suggested relative to the various treatises and memoirs which are 
analysed. The writer trusts that it will not be supposed that he 
undervalues the labours of the eminent mathematicians in whose 
works he ventures occasionally to indicate inaccuracies or imperfec- 
tions, but that his aim has been to remove difficulties which might 
perplex a student’”’ (Preface). We would specially point out the 
last chapter in the book (pp. 505-530) as deserving attention in 
this respect. 
Fully agreeing with Mr. Todhunter as to the “ value of a history 
of any department of science, when that history is presented with 
accuracy and completeness,” we congratulate him on having pro- 
duced a History which so well merits this character of ‘‘ accuracy 
and completeness ;” and we sincerely hope that the success of his 
present contribution to scientific history may induce him to carry out 
the intention expressed in the conclusion of his Preface, viz. ‘‘ to 
undertake a similar survey of some other department of science.” 
ee - ee 
—ee 
LXXVIII. Proceedings of Learned Societies. 
ROYAL SOCIETY. 
(Continued from p. 469.] 
June 21, 1860.—Sir Benjamin C. Brodie, Bart., Pres., in the Chair, - 
tae following communications were read :— 
“Qn the Sources of the Nitrogen of Vegetation ; with special 
reference to the Question whether Plants assimilate free or uncom- 
bined Nitrogen.” By J. B. Lawes, Esq., F.R.S.; J. H. Gilbert, 
Ph.D., F.R.S. ; and Evan Pugh, Ph.D., F.C.S. 
After referring to the earlier history of the subject, and especially 
to the conclusion of De Saussure, that plants derive their nitrogen 
from the nitrogenous compounds of the soil and the small amount of 
ammonia which he found to exist in the atmosphere, the Authors 
preface the discussion of their own experiments on the sources of the 
nitrogen of plants, by a consideration of the most prominent facts 
established by their own investigations concerning the amount of 
nitrogen yielded by different crops over a given area of land, and of 
the relation of these to certain measured, or known sources of it. 
On growing the same crop year after year on the same land, with- 
out any supply of nitrogen by manure, it was found that wheat, over 
a period of 14 years, had given rather more than 30 lbs.—barley, 
over a period of 6 years, somewhat less—meadow-hay, over a period 
of 3 years, nearly 40 lbs.—and beans, over 11 years, rather more than 
50 lbs. of nitrogen, per acre, perannum. Clover, another Leguiminous 
———. 
