104 ME. SOLLY ON THE 



is found to be generated in a wire of any length suspended in any 

 direction. The only way then in which we can regard such a 

 wire as acting, is in equalizing the electricity of the earth and 

 atmosphere, either assisting in neutralizing the opposite electric 

 states of the earth and air, which, when highly dissimilar, may 

 possibly be hurtful to vegetation, or as discharging electric 

 clouds and fogs, and thus bringing down moisture from the air. 

 If the former be our object, it may be certainly more con- 

 veniently attained by other means; whilst, for the latter object, 

 much more elevated wires would be requisite except in veiy 

 barren places, or countries where there are no trees, which of 

 course would interfere with the action of wires near the earth. 



The arrangement proposed, for the application of galvanic 

 currents to growing plants, is one in which, provided it acts, a 

 feeble current Avill constantly pass across the roots at right 

 angles to their axis of growth : such an arrangement therefore 

 could hardly assist them in a chemical point of view, but could 

 only be expected to aid them, and that in a very imperfect 

 manner, as a stimulant ; the plant next the one plate miglit pos- 

 sibly be assisted in its growth by the gradual decomposition of 

 saline matters in the soil, and consequent evolution of substances 

 either directly or indirectly favourable to vegetation, but the 

 plant at the other end would probably be proportionably injured, 

 whilst the intermediate ones would be neither benefited nor in- 

 jured, unless the electricity in passing across the roots could 

 stinuilate or augment their energy. In the arrangement first 

 proposed, where plates were buried at either end of a row of 

 plants, the electricity would tend to pass from the zinc to the 

 copper through the best conducting part of the soil, and this 

 would naturally be the moistest : the current therefore would pass 

 at a considerable distance below the surface of the ground, and 

 below the roots of young plants altogether. 



In the experiments on these subjects made in the Horticul- 

 tural Society's Gardens, it was not thought necessary to repeat 

 exactly the arrangement described by Dr. Forster ; the more so, 

 as numerous repetitions of his experiments were being made in 

 various parts of the country ; amongst others, one by Mr. Jes- 

 sop on his Grace the Duke of Devonshire's estate, within half a 

 mile of the Gardens. 



In this experiment Dr. Forster 's original statement was fol- 

 lowed as closely as possible. The field was eleven acres, sown 

 with barley, and the portion enclosed by the parallelogram of 

 wire was half an acre. The wire was of iron, and the poles 

 were rather more than fourteen feet in height. No perceptible 

 difi'erence was at any time observed, either whilst growing or at 

 harvest time, between the enclosed part and the rest of the field. 



