474 REPORT — 1881. 



vation of electricity, that a change in the position of a magnet will, under 

 snch circumstances, produce motion of the static charge of electricity. 



When the air becomes charged up to discharging point, then we may 

 get the sudden discharges, such as the aurora in the air and the earth-cur- 

 rents in the earth ; and since the conductiiig layer of air approaches nearer 

 to the earth in the colder polar regions — possibly within less than twenty 

 miles of the earth's surface — it may bo found that the discharge of the 

 aurora may even take place from earth to air by gradual slow discharge, 

 aided, as it may be, by the state of moisture, and by change of tempera- 

 ture, and other causes. 



In addition to the European stations the principal Observatories for 

 photographic registi-ation of the magnetic elements are at Toronto, Zi- 

 ka-Wei, Bombay, and Melbourne. The fact that there are so fcAv such 

 Observatories will be sufficient to show how important it is that there 

 should be additional Magnetic Observatories — more especially in America, 

 in the eastern parts of Siberia, and in the southern hemisphere. Practi- 

 cally we have to rely on one excellent Observatory (Melbourne) for the 

 whole of the southern hemisphere. Seeing that the Fi-ench Government 

 have decided to establish a Magnetic Observatory at Cape Horn next 

 year, where photographic records of the changes of the magnetic elements 

 are to be taken, surely it is time that a fully-equipped Magnetic Observatory 

 should be established at the Cape of Good Hope, where there is already an 

 excellent Astronomical Observatory and a staff of observers ready to 

 carry on the work. 



On some applications of Electric Energy to Horticultural and 

 Agricultural purposes, by C. Wm. Siemens, D.G.L., LL.D.^ 

 F.R.S., Mem. Inst. C.E. 



[A communication ordered by the General Committee to be i^rinted in extenso 



among the Reports.] 



On March 1, 1880, I communicated to the Royal Society a paper ' On 

 the influence of electric light upon vegetation, &c.,' in which I arrived at 

 the conclusion that electric light was capable of producing upon plants 

 effects comparable to those of solar radiation ; that chlorophyl was pro- 

 duced by it, and that bloom and fruit rich in colour and aroma could be 

 developed by its aid. My experiments also went to prove that plants do 

 not as a rule require a period of rest during the twenty-four hours of the 

 day, but make increased and vigorous progress if subjected (in winter 

 time) to solar light during the day and to electric light during the 

 night. 



Dui'ing the whole of last winter I continued my experiments on an 

 enlai'ged scale, and it is my present purpose to give a short account of 

 these experiments, and of some further applications of electric energy to 

 farming operations (incliiding the pumping of water, the sawing of 

 timber, and chaff- and root-cutting) at various distances not exceeding 

 half a mile from the source of power, giving useful employment during- 

 day-time to the power-producing machinery, and thus reducing in- 

 directly the cost of the light during night-time. 



