AND HORTICULTURE. 4I 
its solution; but the experiments have led to an admissible 
explanation, founded on facts, showing the way in which 
this influence is exercised. They have also effected some 
advance in our knowledge, which has not yet attained the 
necessary degree of exactness, but which possesses some 
importance both to science and to the practical application 
of our scientific knowledge. We may therefore summarise 
our present knowledge as follows :— 
(a) The real increase per cent. due to electrical treat- 
ment has not yet been exactly determined for the different 
vegetables which have been under experiment. But we 
are approaching its smallest value in fixing it at 45 per 
cent. for land of average fertility. 
(4) The better and more scientifically a field is cultivated 
and manured, the greater is the increase per cent. On 
poor soil it is so small as to be scarcely perceptible. 
(c) Some vegetables cannot endure the electrical treat- 
ment if they are not watered, but then they will give very 
high percentage increases. Among these are peas, carrots 
and cabbage. 
(@) Electrical treatment when accompanied by hot sun- 
shine is damaging to most vegetables, probably to all; 
wherefore, if favourable results are aimed at, the treatment 
must be interrupted in the middle of hot and sunny days. 
(e) As it is very difficult to determine the’ effect of 
electricity on most plants, a special arrangement must be 
made to get an approximate determination of the increase. 
In this connection we have already set out (page 33) what 
must be done in order to avoid the uncertainty which arises 
from the want of homogeneousness in the soil. 
Since the preceding part of this book was written, the 
following experiments have been carried out during the 
summers of 1902 and 1903 :— 
In all the experiments mentioned hereafter, the new 
type of influence machine, described on page 21 (see Fig. 5), 
