i9io.] 



Overhead Electrical Discharges. 



23 



wires, but with this high voltage it is possible without this 

 provision to detect a quite appreciable discharge from the 

 wires when the apparatus is running properly. 



It is, of course, very necessary to have some simple method 

 of ascertaining that effective discharge is really occurring. 



The arrangement adopted is to have an insulated wire which 

 receives a charge when the overhead wire is giving off elec- 

 tricity, and this charge can be detected quite simply, either 

 by touching the wire with the finger, when a slight shock is 

 felt as the current passes through one's body to the earth. At 

 night a different method may be adopted ; a vacuum tube, 

 which will show a bright glow as the slight current passes, 

 may be used. 



Using this method it is possible to test to what extent the 

 wires are distributing the charge over the field, and hence 

 at what distance apart they may be effectively put, a distance 

 that varies with height of crop and of the wires above the 

 ground. 



It can also be shown that the treated area will not be 

 sharply delimited from the untreated if growing side by side, 

 for it is found that on windy days the discharge is carried 

 considerably further over the crop in the direction in which 

 the wind is blowing. 



As it is possible by the method described to detect quite 

 close to the ground an appreciable discharge from a wire 

 raised some 10-16 feet above it, it is clear that this height is 

 preferable, as it permits of all the ordinary operations of 

 cultivation, including harvesting, being carried on without 

 interference and without damage to the overhead system. 



Thus Mr. Newman tells me that, in the three years' work 

 at Evesham, only one wire has been broken. 



As to the results of the treatment given under these con- 

 ditions, probably most readers will be accustomed to large 

 scale trials, as for instance with manure, and will be able to 

 form their own conclusions from the table given at the end 

 of this article. 



For my own part I consider they give justification for the 

 verdict that the method is worthy of further trial. 



B. Under Glass. — Under these conditions it is possible 

 either (1) .to use a smaller and cheaper method of generating 



