848 = 582 Ivfluence of Chemical Discoveries on 
of the permanent general assistants, who at other times undertake 
the botanical work. 
Two or three computers and record-keepers have been occi iii 
pied in calculating and tabulating field, feeding, and laboratoi . 
results, copying, «Scc. iBjisi 
The field experiments, and occasionally feeding experiment -"i 
also employ a considerable but a very variable number of agr a 
cultural labourers. .i 
The investigations may be classed under two heads : — d, 
Experiments I. Field Experiments. — Experiments on Vegetation, ^c. — Tl :tn 
on vegetation, gg^eral scope and plan of the field experiments has been : — ji 
To grow some of the most important crops of rotationj eat i)' 
separately, year after year, for many years in succession, on tl Ji 
same land, without manure, with farmyard manure, and with i 
great variety of chemical manures ; the same description i ijj 
manure being, as a rule, applied year after year on the san .c 
plots. Experiments on an actual course of rotation, with diffe a: 
ent manures, have also been made. J 
In this way field experiments have been conducted as follow! "ie 
On wheat, 34 years in succession, 13 acres, 35 plots, many i in 
which are duplicates of others. 'm 
On barley, 26 years in succession, 4i acres, 23 (or 29) plots- je 
On oats, 9 years in succession, f acre, 6 plots. j 
On wheat, alternated with fallow, 26 years, 1 acre, 2 plots. 
On different descriptions of wheat, 9 years, 7 acres (each ye on 
on a different field), about 20 plots. 'ie 
On beans, 31 years (including 1 year wheat and 5 years fa -ic 
low), 1;^ acre, 10 plots. lic 
On beans, alternated with Avheat, 28 years, 1 acre, 10 plots. 
On clover, with fallow or a corn crop intervening, 28 yeai 
3 acres, 18 plots. fl 
On turnips, 25 years, about 8 acres, 40 plots. jei 
On sugar-beets, 5 years, about 8 acres, 40 plots. i g 
On mangoldwurzel, 1 year (in progress), about 8 acres, 
plots. _ :B 
On potatoes, 1 year (in progress), 2 acres, 10 plots. 
On rotation, 30 years, about 2^ acres, 12 plots. K 
On permanent grass-land, 22 years, about 7 acres, 20 plots. 
Ra iifall. Almost from the commencement of the experiments the rai -.^ 
fall has been measured; for 24 years, in a gauge of one-tho ,[ 
sandth of an acre area, as Avell as in the ordinary small funni 
gauge of 5 inches diameter. From time to time the nitrogen 
as ammonia and as nitric acid — has been determined in t| 
rain-water. 
Drain-gauge?. Three " drain-gauges," also of one-thousandth of an acre e8(j 
for the determination of the quantity and composition of tj 
