394 THE NEW GARDENING 



The extra yield was therefore just over six tons, and 

 the cost was 5 igs. 6d., but the same outlay would have 

 electrified fifteen acres, and with a proportionate increase 

 of yield throughout the electrification would prove 

 lucrative. 



Miss Dudgeon tells me that " the electric charge does 

 not do instead of manure. Its action appears to be to 

 break up the component substances of the soil and humus, 

 rendering them more soluble and easy of assimilation by 

 the plants. There is no doubt that the discharge has a 

 stimulating effect on plant growth, as can be easily seen 

 in the greater luxuriance and better quality of vegetables 

 and crops grown under the electric wires. It seems to 

 have a tonic effect on them, and, as Sir Oliver Lodge 

 expresses it, ' the discharge acts like a gentle massage.' ' 

 . In addition to her experimental work with the Oliver 

 Lodge-Newman apparatus in the open, Miss Dudgeon 

 has observed the effect of artificial light on plants under 

 glass, using the mercury- vapour lamp. The object was 

 to grow the plants under summer conditions as to light 

 in winter, that is, giving the house no more heat than out- 

 door summer or spring heat, but using the radiation 

 from the lamp in the place of the sun. The Westing- 

 house Cooper-Hewitt lamp gives a bright blue light, and 

 has a marked effect on plants. Miss Dudgeon says : 



" My idea was to test the effect of the lamp on as many 

 different seeds as possible, which only allowed of my 

 having a few pots of each variety. My greenhouse is 

 twenty feet by ten feet, and by testing the radiation of 

 the lamp by means of photographic paper exposed after 

 dark, I found the most powerful radiation extended to a 

 square of six feet below the lamp. After that it became 

 less, though at the farthest end of the house the paper 

 was distinctly coloured after half an hour's exposure. 



