ELECTRIC CULTIVATION IN RELATION TO HORTICULTURE. 411 



Showing an average increase of 35* 5 per cent, of productivity per 

 unit of area. Analysis shows 14 \ per cent, increase of glucose. 



Mr. Priestley gives the following information concerning experiments 

 made at Bristol in 1906 to determine the value of earth-current electric 

 stimuli, employing the Speschnew system of plates embedded in the soil 

 (see fig. 65, 6). Copper and zinc plates were used. 



Beans were planted on February 21, 1901, and weighed in June. 



Electrified Non-electrified 

 Average volume of bean . . 2 c.c. 1*5 c.c. 



Average weight . . . 2*26 gr. 1*71 gr. 



The plates had an area of 200 square inches and were placed 4 feet 

 apart. A current strength was recorded of '12 milli-ampere. 



The Voltaic Aec Stimuli. 



Faraday's laboratory machine was transformed into a practical and 

 fairly efficient machine by a sequence of improvements. The shunting 

 of part of the current on to the magnet is claimed by two inventors, 

 one an Englishman, Cromwell Varley, whose claims for recognition have 

 never yet secured from his countrymen the reward they deserve ; the 

 other, Werner Siemens of Berlin. 



Gramme also made specific improvements, and the Siemens family of 

 distinguished inventors finally evolved a thoroughly practical machine. 

 Sir William Siemens, a brother of Werner, was probably the first to 

 recognise the full possibilities of the voltaic arc as a supplement to, or 

 substitute in winter time for, the rays of the sun. 



It may here be stated that whereas the electro-static application is 

 applicable to field service in the ordinary periods of natural cultivation in 

 summer time, the voltaic arc is available if desired for use all through 

 the winter months. 



In the year 1861 Herve Mangon had noticed the effect of the voltaic 

 arc light in stimulating the growth of plants ; but Siemens pioneered the 

 practical application for the specific purpose of cultivating fruit and 

 flowering plants in the glass house in winter months. The results * of 

 these trials have passed into history. Although the apparatus employed 

 by Siemens, compared with those available to-day, were primitive, his 

 papers and the discussions lead the way to the modern attempts to 

 secure results that we all require — viz., electric cultivation associated with 

 profit possibilities. 



Objections have been raised on the score of the hard and burning 

 intensity of the fixed electric beam. On the other hand a summary of the 



* Siemens found that peas sown in October produced a harvest of ripe fruit on 

 February 16 ; raspberry stalks put into the house on December 16, produced ripe 

 fruit on March 1 ; strawberry plants put in at the same time, produced ripe fruit of 

 excellent flavour and colour on February 14 ; vines which broke on December 26 

 produced ripe grapes of stronger flavour than usual on March 10 ; peas gathered on 

 February 16 from the plant were replanted on February 18, and vegetated in a few 

 days ; bananas and melons were produced of remarkable size and aromatic flavour. 



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