RECENT WONDERS OF ELECTRICITY. 791 



up in the air between the carbon points, and the arc is formed. This 

 light is due to the passage of an infinitely rapid succession of particles 

 of carbon which are projected across the air-space, which, in their high 

 state of incandescence, produce light, and which in brilliancy would 

 not compare unfavorably with that of the sun. The light from a 

 larger arc-lamp would be far more brilliant than this, but I do not 

 want to damage your eyes or my own. I have experimented on the 

 electric light so much, that I have suffered great tortures from the 

 irritating and exciting influence of its bright rays upon the retina of 

 the eyes, and I advise all people who have an opportunity of examin- 

 ing the arc-light, not to look at it too much, or the eye-sight may be 

 unfavorably affected. The arc-light is used principally for lighting 

 large areas : for instance, Charing Cross station is lit by one form of 

 arc-light, called the Brush ; Cannon Street station is lit by what is 

 known as the Brockie lamp ; the space in front of the Royal Exchange 

 is lit up by the Siemens arc-lamp ; King's Cross station is lit up by 

 the Crompton plan ; and so on. A very brilliant arc-lamp at Paris, 

 which attracted a great deal of attention, was called the Jasper light. 

 But all arc-lamps play upon one string, similar to the plan I have just 

 shown, viz., that when two pieces of carbon are maintained at a cer- 

 tain distance from each other, and electricity passed between them, 

 great heat and brilliant light are the result. There are certain difficul- 

 ties in arc-lamps which militate against their employment for domestic 

 and internal use generally. The light is very intense ; the effect is 

 irritating ; the ladies do not like it (and they are a powerful influence 

 in this country), because it does not suit their complexion, nor their 

 style of costume for evening wear : they have set their faces against it 

 for internal illumination, and, that being so, it is all up with it. Now, 

 the light that is going to supplant the arc light for domestic purposes 

 is the incandescent light. The principle of the incandescent lamp is 

 exactly the same as that I showed you in Mr. Becker's lamp, viz., that 

 a suitable substance is inclosed in a glass bulb, from which the air has 

 been extracted, and is brought to a high state of temperature by the 

 passage through it of currents of electricity. The lamps illuminating 

 this room are Mr. Edison's incandescent lamps, whose representative, 

 Mr. Johnson, has been most indefatigable in his assistance for these 

 lectures. The Edison lamp consists of a single curl, or loop, of a fine 

 carbon filament (instead of platinum wire) placed in an exhausted glass 

 bulb. The carbon is extremely thin as thin as a human hair but, in 

 spite of its extreme tenuity, you see [knocking a lamp on the table] 

 that concussion or shaking does not cause it to break, but it possesses 

 great resilience, and vibrates like a steel spring ; and it is so refractory 

 that it will stand electric currents of enormous strength. As I have 

 said, the lamps before you are worked by electric currents generated 

 by an Edison dynamo-machine on the Thames embankment, but each 

 lamp is self -regulating and can be turned on and off by turning 



