494 
Journal of Agricultural Research 
Vol. XXIX, No. 10 
two factors and the months or critical 
periods can be shown at one time. 
In these graphs the temperatures are 
represented on the vertical scale to 
the left, and the tenths of inches of rain¬ 
fall and the per cent of relative humid¬ 
ity on the horizontal scale at the top. 
(For a more detailed method of con¬ 
struction, see Taylor (25)). When 
3a, and lb). Graphs can thus be made 
of any section to compare with the 
composite. 
A comparison of the graphs of the 
important sheep countries shows simi¬ 
larity in rainfall, temperature, and 
humidity (2, 5, 10, . 11, 12, 20, 29). 
In general, the winters are mild and the 
summers cool, with a moderate amount 
o sxomm. /s&ma o 5:00mm ioikmm 
Eigs. 4 to 9.—4, limits for February, March, April, May, and June of a good sheep year in England; 5, 
good year, Reading, England, 1909; 6, bad year, Hastings, England, 1911, due to high temperature and 
humidity during July and August; 7, bad year, Reading, England, 1914, due to wet March and De¬ 
cember; 8, bad year, Rounton, England, 1917, due to cold spring period of critical months; 9, bad year, 
Croyden, England, 1921, due to lack of rain, high temperature, and humidity in summer 
possible, records from several stations 
with averages over as long a period of 
years as possible were selected for each 
section. 
These graphs, representing the mean 
monthly temperature, rainfall, and hu¬ 
midity of the important (densest) sheep 
centers in the world, were made into a 
composite graph, made by tracing one 
graph on top of another and by con¬ 
necting all the outer points (figs, la, 2a, 
of rainfall, sufficient to afford a good 
growth of forage; and the humidity is 
considerably lower in’summer than in 
winter. 
On the composite graph the rutting 
and lambing seasons have been plotted 
because sheep seem sensitive during 
•these periods. The lambing season, 
which extends over three or four months, 
was obtained for each country and then 
plotted. The middle month (or months) 
