1880.] Influence of Electric Light upon Vegetation. 



213 



exposed to both day and electric light have made great progress, and 

 my gardener, Mr. D. Buchanan, says that he could not have brought 

 on the latter, without the aid of electric light, during the early winter. 

 Some of these commenced to blossom on the 14th of February. 



These preliminary trials go to prove that electric light can be 

 utilized in aid of solar light by placing it over greenhouses, but the 

 loss of effect in such cases must be considerable. I, therefore, directed 

 my observations, in the next place, to the effect of electric light upon 

 plants, when both were placed in the same apartment. A section of the 

 melon house, already referred to (7' 3" x 3' 3", 2*21 m. X 0'19 m.), was 

 completely darkened by being covered in with thick matting, and was 

 whitewashed inside. The electric light was placed over the entrance 

 door, and shelves were put down, in a horse-shoe form, to receive the 

 pots containing the plants to be exposed to the action of electric 

 light, the plants being placed at distances from the lamp varying from 

 0'5 metre to 2 metres. Upon the first occasion of trying the naked 

 electric light in this manner, some of the plants, and especially some 

 melon and cucumber plants, from 20 centims. to 40 centims. in height, 

 which were within a metre distance from the lamp, commenced to 

 suffer ; those leaves which were directly opposite the light turning up 

 at the edges and presenting a scorched appearance. On subsequent 

 nights, therefore, the stands were so arranged that the distance of the 

 plants from the light varied from 1*5 metres to 2*3 metres. The 

 plants under experiment were divided into three groups ; one group 

 was exposed to daylight alone, a second similar group was exposed 

 to electric light during eleven hours of the night, and were kept in 

 the dark chamber during the day time, and the third similar group 

 was exposed to eleven hours' day and eleven hours' electric light. 

 These experiments were continued during four days and nights con- 

 secutively, and the results observed are of a very striking and decisive 

 character, as regards the behaviour of such quick-growing plants as 

 mustard, carrots, &c. The experiment was unsatisfactory in this one 

 respect, that during the third night the gas-engine working the 

 dynamo-machine came to a standstill, owing to a stoppage in one of 

 the gas channels, and thus more than half the electric-light influence 

 that night was lost to the plants. But, notwithstanding this draw- 

 back, the two groups of plants showed unmistakably the beneficial 

 influence of electric light. The plants that had been exposed to day- 

 light alone (comprising a fair proportion of sunlight) presented their 

 usually healthy green appearance ; those exposed to electric light 

 alone were, in most instances, of a somewhat lighter, but, in one 

 instance; of a somewhat darker hue than those exposed to daylight ; 

 and all the plants that had the double benefit of day and electric 

 light far surpassed the others in darkness of green and vigorous 

 appearance generally. A fear had been expressed that the melon and 



VOL. xxx. Q 



