20 



JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



network sags and sparks to the ground. If the door opens outward then 

 this support may be attached to a handle outside the door, in such a 

 manner that the door can be opened only by releasing the tension on 

 it by letting the wire sag and discharge. 



Some precaution of this sort is necessary so that people working 

 in the houses may not get unnecessary shocks ; with a large system oi 

 wires the shocks are as bad as those received from large Leyden jars, 

 and an unpleasant addition to the other vicissitudes of a horticultural 

 occupation. 



My experience with the system inside a greenhouse leads to the 

 conclusion that it will be far more efficacious in the case of crops 

 grown in pots all over the floor of a large house, than in the case of 

 plants such as vines and cucumbers which are grown climbing up the 

 sides of the house. The latter plants are so insulated as they grow 

 up behind their system of supporting wires that very little discharge 

 can effectively reach them. 



In the cases where I have seen cucumbers electrified all effect 

 seemed to be produced in the first month or so, during which time the 

 leaves and shoots were still chiefly below these supporting wires and 

 therefore under the influence of the discharge. 



A great difficulty in the case of greenhouse electrification is the 

 problem of getting the charged wires into the house. This should be 

 done beneath a pent roof, but the insulation need not necessarily be 

 quite so elaborate as suggested for the exit from the high tension 

 shed. 



At Bitton they entered through ebonite tubes packed into earthen- 

 ware pipes, placed over the door and under a pent roof; the charged 

 wure then dropped down upon the single insulated wire suspended down 

 the centre of the greenhouse. 



At Bitton there was no complete partition between one cucumber 

 house and the next, it was therefore possible to take a loop of insulated 

 wire from one house to the next, the leak not being too serious. These 

 loops of wire were carried through glazed earthenware tubes half an 

 inch to an inch in diameter, suspended from the partition wall above 

 by paraffined string. 



If this cannot be done then it will be necessary to lead a charged 

 wire down the front of the series of houses which it is desired to elec- 

 trify, and from this to take short lengths of wire down into each green- 

 house through some such insulated aperture as previously described. 



Testing the Discharge. 



In some such way as this it is possible to arrange to produce a dis- 

 charge upon almost any crop, but if the experiment is to be of any 

 value it is necessary to carefully test the discharge system when work- 

 ing, to see whether electricity is leaking away as desired on to the 

 plants beneath the wires. 



For this purpose a long insulated wire is held beneath the charged 

 wires and just above the level of the crop that is being electrified. If 



