247 
had lost by evaporation the preceding week. These latter, therefore, 
show us the maximum effect that water can have on vegetation in the 
climate of Paris. The proportion of water that is consumed is 
exaggerated, but the crop increases at the same time, but less rapidly 
_ than the consumption of water. We may, therefore, say that to 
a certain extent, water can with the aid of the sunshine supplement 
the fertilizers, although we can not say that a deficiency of fertilizer 
is a good thing. 
In general, all the observations recorded in France, Switzerland, 
and England show that the total annual evaporation from cultivated 
soils is 70 to 80 per cent of the total annual rainfall. A large part 
of the rain falls in the autumn and winter when vegetation has 
ceased. The rains of these seasons partly filter into the earth and 
feed the subterranean springs, but they must first return to the soil its 
own water supply. Now the more the soil is impoverished by cutting 
the crops the more it will take up of the autumn rains and the less 
will be received by the subterranean water beds. It is then easy to 
understand that in cultivated lands the mean flow in the water 
courses diminishes in proportion to the progress of the cultivation. 
It seems certain that in France, and especially in the central portions, 
the grains do not find in the soil all the water that they could 
profitably use to the advantage of the crop and that irrigation would 
be advantageous in these and many other crops wherever there is a 
good soil and an abundance of sunshine. 
Notwithstanding this necessity for water, the rainy years are 
frequently bad for cereals. Rainy summers are deficient in light 
and dry summers have too much. It is the relative chassis “ot 
heat, sunshine, and moisture from day to day throughout the whole 
season that is important. 
From a meteorological point of view we should say that from the 
sowing to the formation of the embryo grain sunlight is indis- 
pensable, but from the formation to the maturity it is far less 
important. 
In his Annuaire for 1878 (p. 468) Marié-Davy gives a summary 
of the meteorological data, month by month, for several years, as a 
sample of what may be done by way of explaining the general rela- 
tions between meteorology, as hitherto pursued, and the crops of the 
agriculturist. He says: 
Meteorology, as seen from the agricultural point of view, has for 
its ultimate “object to enable the farmer to anticipate the future of 
his current crop. This.explains why we think it necessary to study 
the influence that each of the meteorological elements has on the 
progress of the development of the plants in the successive phases 
