1910.] Overhead Electrical Discharges. 



21 



Application of the Method of Overhead Discharge. 



.4. 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, &c, 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. Continuous current, 

 any voltage from 10-250 and at about 100-500 watts is 

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

 satisfactory. If this is not available from some power station 

 in the neighbourhood 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 appreciable 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 and high-tension coil, the Lodge electrical valve, &c, 

 while much of the apparatus is protected by patents. 



Suffice it to say that the whole apparatus is very compact 

 and could easily be stored in a small shed, and when once 

 in good running order requires surprisingly little attention, 

 and as the necessary manipulation to start and stop the 

 discharge is confined to moving a few switches and testing 

 the strength of the discharge by measuring the distance the 



