\\-ILLIAM SIEMENS, F.R.S. 



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light in the couree of two or three hours, and the stems of 

 cucumber and melon plants also did so, though more slowly. The 

 cucumber and melon plants which have been exposed to both day 

 ami electric light have made great progress, and my gardener tells 

 me that he could not have brought on the latter without the aid 

 of the electric light during the early winter. These preliminary 

 trials go to prove that electric light can be called to the aid of 

 solar light by using it outside of green houses, but the loss of 

 effect in such cases is considerable. 



I next directed my observations to the effect of electric light 

 upon plants, when both were placed in the same enclosure. A 

 portion of the melon-house already referred to was completely 

 darkened with a covering of thick matting, and was whitewashed 

 inside. The electric lamp was placed over the entrance door, and 

 shelves were arranged in a horse-shoe form, with pots containing 

 the plants to be experimented upon, the plants being placed at 

 distances from the source of light varying from O'o metre to 2*3 

 metres. The first time the naked electric light was tried in this 

 manner, some of the plants, and especially some melon and cucum- 

 ber plants, from 20 cm. to 40 cm. in height, less than a metre 

 distance from the lamp, suffered, the leaves nearest the lamp 

 turning up at the edges, and presenting a scorched appearance. 

 In the later experiments the stands were so arranged that the 

 distance of the plants from the light was from 1/5 to 2*3 metres. 

 The plants were divided into three groups ; one group was exposed 

 only to daylight, a second group received only electric light during 

 eleven hours of the night, being in darkness during the day, and the 

 third group had the benefit of 1 1 hours day and 1 1 hours electric 

 light. These experiments were continued during four consecutive 

 days and nights, and the results are very striking and decisive as 

 regards the effect upon such quick-growing plants as mustard, 

 carrots, &c. The trial was unsatisfactory in this one respect, that 

 during the third night the gas-engine working the dynamo machine 

 came to a stand-still, owing to a stoppage in one of the gas 

 channels, and the electric light was only applied half the night. 

 Notwithstanding this drawback the plants were evidently benefited 

 by the electric light. The plants that had only been exposed to 

 daylight (with a fair proportion of sunlight) presented the usual 

 healthy green appearance ; those exposed to electric light alone 



