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ot all the ordinary operations of cultivation, including harvesting, 

 being carried on without interference and without damage to the 

 overhead system. 



Thus Mr Newman tells that, in the three years' work at Evesham, 

 only one wire has been broken. 



B) Under Glass. Under these conditions it is possible either (i) to 

 use a smaller and cheaper method of generating electrical discharge, 

 the influence machine, with, however, the attendant disadvantages 

 of smaller output and liability to interruption owing to the un- 

 suitability of most forms of influence machines for continuous running, 

 or (2) to adopt the high-tension system described for work in the 

 open. 



Along the first lines ran the early experiments at Mr Newman's 

 nurseries at Bitton, and with remarkably good results on the whole, 

 the occasional failure being probably to be attributed to causes 

 which could easily be controlled. 



In applying the other method in use at Evesham to work under 

 glass, several points had to be considered. The main difficulty was 

 the great tendency to leakage under these conditions, and in practice 

 it was never possible to keep up such a high charge on the wires 

 running through the greenhouse, as, with the same apparatus, could 

 be obtained in the open field. At the same time it was quite pos- 

 sible to keep up an effective discharge, Mr Newman and myself 

 testing the point on several occasions by carrying a long test wire 

 into the houses and testing the distribution of the charge. 



To avoid leakage where the current entered the house, a pent 

 roof was put up to prevent the water dripping on to the insulators 

 used, and under this pent roof was placed, first a large porous 

 cylinder or perhaps an ebonite tube, and within this a tube of fused 

 silica, some two feet long, through which the charged wire (gutta- 

 percha covered wire) ran. These fused quartz or silica tubes are 

 easily obtainable nowadays, and seem the most satisfactory type of 

 insulator, 



Within the house, the wire was simply hooked .on to another 

 wire, running the whole length of the house, and supported by 

 ebonite insulators attached to either door by lengths of paraffined 

 string running through holes in an ebonite rod. This single wire 

 was of comparatively small diameter and acted as the discharge wire. 



The houses are arranged in groups of five, without walled parti- 

 tions separating them, and hence it was possible to run the charge 

 from house to house within the same block by simply carrying a 



