ELECTRICITY IN RELATION TO HORTICULTURE. 



21 



the discharge is effective this test wire should then accumulate a small 

 charge from the electricity passing through ihe air. 



The accumulation of this charge can be detected by touching the 

 wire with a moistened finger or with the tongue and thus detecting the 

 slight shock as the charge passes away through one's body to the earth. 

 At night the discharge may be tested by placing against the test wire one 

 terminal of a small vacuum tube, the other terminal being connected 

 by a wire to earth. Through the vacuum tube a faint glow will occur 

 as the charge passes away through it to earth. 



For an experiment to be satisfactory, whether with the outdoor or 

 indoor system it is essential that this test be made at times to see that 

 an effective discharge is maintained. With the greenhouses at Bitton 

 it was uncomfortable but necessary work. 



Mr. Newman and I crawled through a considerable length of the 

 houses, holding the test wire stretched between two ebonite rods, and 

 thus it was possible to show that the discharge was effective except 

 behind the hot water pipes and behind the wires put up to support 

 the plants. 



Application and Eesults. 



Having now described the method it would seem desirable to go on 

 to prescribe times for its application, etc., but unfortunately such rules 

 cannot be laid down at present, the action of the current is so little 

 understood. The following provisional hints are given in the light of 

 what is at present known in the matter, and experiments are in pro- 

 gress. 



In the first place it is certainly undesirable to apply the discharge 

 in very dry weather, for by so doing crop yield is decreased; on the 

 other hand, during rain the overhead wires leak too much to render 

 discharge practicable. 



The discharge then can be applied effectively only when the 

 weather is fine and the soil contains sufficient moisture. Applied at 

 any time when these conditions hold it seems probable that the yield 

 of the crop would be accelerated, but it may be that it is only by appli- 

 cation at certain times that this yield may not only be accelerated but 

 also increased. 



Unfortunately as to what those times may be very little is known. 

 Some experiments suggest that early morning and evening would be the 

 best times. Some useful experiments might be carried out by using 

 one apparatus to electrify different networks for different periods 

 within the twenty-four hours and comparing the results. 



The results obtained in previous experiments are not referred to in 

 any detail here — they have been given so fully elsewhere : good lists 

 will be found in the Journal of the Board of Agriculture, vol. 17, p. 14, 

 in the Field for September 24, 1910, and in my lecture before 

 the Farmers' Club on April 3, 1911. 



Probably the most striking result of previous experiments from 

 the horticultural point of view is the almost constant occurrence of 



