32 ELECTRICITY IN AGRICULTURE 
§9. Comparing the results for both the years 1899 and 
1900, they appear to be alike for barley and oats, or an 
increase of 25 to 30 per cent.; for peas the decrease of 7 per 
cent. has grown to an increase of 55:7 per cent.; and for 
carrots from 37°5 to 92°7 per.cent. In general, the per- 
centage of increase was greater during the summer of 1900. 
During the summer of 1899 the machine was at work, on 
an average, for 6'5 hours dazly; during the summer of 1900, 
principally during ¢he night, for to hours. The longer time 
during which the machine was at work in the latter summer 
will suffice to explain the higher increase, so we cannot 
conclude from these results whether day or night is more 
favourable for the electrical treatment. 
When all the results received are taken into considera- 
tion, the increase appears greater if the application of 
electricity is continued by day and night. So we seem 
entitled to suppose that there is a certain dependence 
between the percentage of increase and the period during 
which electrical treatment takes place ; but any declaration 
that they are proportional to each other cannot be made 
from the experiments hitherto carried out. 
As above ‘mentioned, the electric current which goes 
from the wire net through the plants to the earth is 
different during the day and the night: during the day, 
high potential and great resistance; during the night, low 
potential and little resistance. It must be understood that 
we here take normal conditions for granted—that is to say, 
clear days and clear nights. During moist weather the 
potential is low, and in case of rain the machine can be 
continued at work only when a nearly constant spark is going 
on in a gap (Imm.) of the circuits to the earth. This was 
not applied in the above-mentioned experiments, but the 
machine was stopped. 
It might now happen that the changes in the potential 
and the resistance were such that the intensity of the 
current was constant, or nearly so; but upon this point our 
