ELECTRIC LIGHTING. 75 



of the larger proportion, and the varied compounds,, of 

 earth-metals it contains. 



For the volcanic phenomena alone he need simply watch 

 what occurs when in the ordinary course of puddling the 

 cinder is run into a large bogie, and the bogie is left to 

 cool standing upright. I need scarcely add that these phe- 

 nomena strikingly illustrate and confirm Mr. Mallett's the- 

 ory of earthquakes, volcanoes, and mountain-formation. 



In merely passing through an iron-making district one 

 may see the results of what I have called the volcanic action, 

 by simply observing the form of those oyster-shaped or 

 cubical blocks of cinder that are heaped in the vicinity of 

 every blast furnace that has been at work for some time. 

 Radial ridges or consolidated miniature lava-streams are 

 visible on the exposed face of nearly, if not quite all of 

 these. They were ejected or squeezed up from below while 

 the mass was cooling, when the outer crust had consolidated 

 but the inner portion still remained liquid. Many of these 

 are large enough, and sufficiently well-marked, to be visible 

 from a railway carriage passing a cinder heap near the 

 road.* 



A CONTRIBUTION TO THE HISTORY OF 

 ELECTRIC LIGHTING. 



As the subject of lighting by electricity is occupying so 

 much public attention, and the merits of various inventors 

 and inventions are so keenly discussed, the following facts 

 may have some historical interest in connection with it. 



In October, 1845, I was consulted by some American 

 gentlemen concerning the construction of a large voltaic 

 battery for experimenting upon an invention, afterwards 

 described and published in the specification of "King's 

 Patent Electric Light ' (Letters Patent granted for Scotland, 

 November 26, 1845 ; enrolled March 25, 1846 ; English 

 Patent sealed November 4, 1845). 



* See Chapter on " The Origin of Lunar Volcanoes." 



