227 



" It is well known nowadays that the disease-resisting power of 

 a plant seems largely a function of its vitality, and when grown 

 under unsuitable conditions the less virile plants seem more easily 

 to succumb to the parasitic attack. It is hence, perhaps, worthy 

 of note that on one or two occasions in the cucumber houses at 

 Bitton, electrified houses seem to have shown indication of greater 

 resistance both to the ordinary Cercospora spot disease and to 

 other occasional outbreaks of disease. From the nature of the 

 trials, howerer. I fear no very definite statement is possible, and 

 the question is not easily decided by experiments in the labo- 

 ratory. 



APPLICATION OF THE METHOD OF OVERHEAD 

 ELECTRIC DISCHARGE. 



" A) In the Open. In considering the method of applying the 

 overhead discharge it should be clear that many points in regard 

 to its use are at present not decided, and that any rules followed 

 in regard to times of electrification, strength of current, etc. are 

 of an empirical character. 



The system is capable of use upon a large scale, and the Evesham 

 installation charges some twenty acres; similar installations could 

 easily be established to charge a still larger area, and a device 

 which would be quite possible is to charge at, alternate periods in 

 the 24 hours, two different areas of some twenty acres each. The 

 first necessity is a supply of current for the induction coil. A con- 

 tinuous current, any^voltage from 10-250 and at about 100-500 watts 

 is necessary; a current at no volts and 2-5 amperes is quite satisfac- 

 tory. If this is not available from some power-station in the neigh- 

 bourhood it can be generated by means of a dynamo and small 

 oil engine, which can be placed upon any convenient spot upon 

 the farm, and the power may probably also be employed for other 

 purposes. The high-tension generating apparatus needs to be placed 

 in a building a watertight shed will do near the area to be 

 electrified, as while it is possible to lead the lower tension current 

 any distance without appareciable loss by leakage, this is not the 

 case with the high-voltage current. The high-tension apparatus can 

 hardly be satisfactorily described in a non-technical article ; Sir Oliver 

 Lodge has briefly described it in a paper published privately in 1908, 

 but anyone thinking of adopting the system would need to consult 

 Sir Oliver Lodge, Mr Newman, or other electrical expert, unless 

 he is himself acquainted with the working of the mercury break 



