B B Xi FA S T 



NATURAL HISTORY & PHILOSOPHICAL SOCIETY 



SESSION 1892-93. 



I si November , 1892. 



Professor M. F. FitzGerald, B.A., C.E., in the Chair. 



John H. Greenhill, Esq., Mus.Bac, (Member of the Institute 



of Electrical Engineers), gave a lecture on 



ELECTRICITY AS AN ILLUMINANT. 



A LARGE number of electric lamps, supplied from a storage 

 battery, were arranged in the hall for the purpose of illustration 

 and experiment, with a number of other electrical appliances, 

 including a very powerful coil, designed and constructed by 

 Mr. John Brown, who exhibited its power in a series of in- 

 teresting experiments. Various kinds of oil and gas lamps to 

 aid the work of illustration and comparison of the different 

 illuminants in common use were lent by Messsrs. Richard 

 Patterson & Co., R. Paiterson & Son, W. Coates & Son, T. E. 

 Osborne, and Riddell & Co. 



Mr. Greenhill, after referring to the scientific principles of 

 lighting by such illuminants as gas and oil, proceeded : — In the 

 case of electric light the luminosity may, and does, occur in 

 some instances from the combustion of minute particles of 

 carbon, as in the arc lamp, or it may arise from the intensely 

 heated condition of a substance due to the flow of the electric 

 current through it, as in the incandescent or glow lamp, in 

 which no combustion practically takes place at all. 



The lecturer, after given a brief history of the development 



