Overhead Electrical Discharges. [april, 



OVERHEAD ELECTRICAL DISCHARGES AND 

 PLANT GROWTH. 



J. H. Priestley, B.Sc, F.L.S. 



Department of Economic Biology, University of Bristol. 



In giving a brief account of recent developments in this 

 subject which show some likelihood of being of practical 

 importance, I propose to refer chiefly to what would be called 

 the practical side of the subject, the actual method of appli- 

 cation of such discharge, and its effect upon the growing 

 crop. 



I have dealt elsewhere * with the historical side of the 

 subject, and hope to do so at greater length at some future 

 time, but on this occasion I would only refer to the 

 pioneer work of Lemstrom which has been brought before 

 the English-speaking public by the small book mentioned 

 below, f 



In Lemstrom 's work the wires above the crop were charged 

 with electricity by means of an influence machine specially 

 designed for the work, and the method suffered from several 

 defects in consequence. 



It is difficult to get an influence machine to run satis- 

 factorily when kept going continuously in the manner 

 required in this work, and the quantity of electricity obtained 

 from Lemstrom 's machine was not sufficient to enable his 

 overhead wires to be raised very high above the crop, on 

 account of the fact that, if this were done, the discharge on 

 to the plants would then cease. Consequently, in all his 

 experiments, operations upon the growing crops were some- 

 what hampered by the wire network which impeded the men 

 when trying to move among the plants. 



In recent times it has been possible, owing to the use of 

 Sir Oliver Lodge's high-tension valves in connection with 

 a Ruhmkorf or induction coil, of a type similar to that used 

 in X-ray work, to develop a method of generating continuous 

 high-tension current which could be trusted to give a satis- 

 factory output of current with only occasional attention, and 



* Priestley, " The Effect of Electricity upon Plants," Bristol Naturalists' Society's 

 Proceedings, Fourth Series, vol. i, part iii, 1907. 



t Lemstrom, Electricity in Agriculture and Horticulture. — The "Electrician" 

 Series. 



