1880.] Influence of Electric Light upon Vegetation. 215 



a banana palm, and a few other small palm trees are planted, the sides 

 of the honse all ronnd being occnpied with a considerable variety of 

 flowering plants. The electric light was fixed as high as practicable 

 at the south corner of the house, in order that its rays might fall upon 

 the plants from a direction and at an angle coincident with those of 

 the sun during the middle of the day. A metal reflector was 

 placed behind the lamp in order to utilize the electric rays as 

 much as possible. Along the eastern side of the house are some 

 young vines, having their roots in a bed outside. Three pots of 

 nectarine plants, just beginning to bud, were placed on the floor at 

 various distances from the electric light, and also some rose plants, 

 geraniums, orchids, &c. The temperature of the house was maintained 

 at 65 F., and the electric lamp was kept alight from 5 p.m. to 6 a.m., 

 for one week, from February 18th to February 24th, excepting 

 Sunday night. The time was hardly sufficient to produce very strik- 

 ing effects, but all the plants continued to present a healthy ap- 

 pearance. Of three Alicante vines, the one nearest the electric light 

 made most progress, and the same could be said of the nectarines and 

 roses. It was observed that other plants, such as geraniums, con- 

 tinued to exhibit a vigorous appearance, notwithstanding the heat of 

 the place. The electric light appeared to impart the vitality neces- 

 sary to prevent a collapse of the organism through excessive tempera- 

 ture. This experiment is of importance in showing that the electric 

 light if put into conservatories or greenhouses does not injure the 

 plants, but rather improves their appearance and growth. The leaves 

 assume a darker and more vigorous appearance, and it seems that 

 the colouring of the flowers becomes more vivid, but a further period 

 of time is necessary to establish this observation absolutely. The 

 effects producible by electric light in conservatories is very striking, 

 owing to the clear definition of form and colour produced, far exceeding 

 that of ordinary daylight. 



No further results of any particular interest could be expected from 

 a continuance of this experiment, and I decided to try the effect of 

 electric light as a means of promoting growth in the open air and 

 under glass at the same time. The regulator was put back into its 

 first position, 2 metres above the ground, with a sunken melon house 

 on one side, and a sunken house containing roses, lilies, strawberries, 

 and a variety of other plants on the other. The space of ground 

 between these, about 1 metre broad, and 7 metres long, was covered 

 with boxes sown with early vegetables, including mustard, peas, beans, 

 and potatoes, and in order to prevent cold winds from injuring the 

 plants, low protecting walls were put up across the openings of the 

 passage between the two houses. The effect of electric light could 

 thus be observed at the same time, upon the melon and cucumber 

 plants in the one house, upon the roses, strawberries, &c, at an 



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