ON LIGHTHOUSE ILLUMINATION — THE ELECTRIC LIGHT. 287 



all tins preparatory education before it could be allowed this practical 

 trial. It is not obtained from frictional electricity, or from voltaic electri- 

 city, but from magnetic action. The first spark (and even magnetic elec- 

 tricity as a whole) was obtained 28 years ago. (Faraday, ' Philosophical 

 Transactions,' 1832, p. 32.) If an iron core be surrounded by wire, and 

 then moved in the right direction near the poles of a magnet, a current of 

 electricity passes, or tends to pass, through it. Many powerful magnets are 

 therefore arranged on a wheel, that they may be associated very near 

 to another wheel, on which are fixed many helices with their cores, like 

 that described. Again, a third wheel consists of magnets arranged like the 

 first ; next to this is another wheel of the helices, and next to this again 

 a fifth wheel, carrying magnets. All the magnet-wheels are fixed to one 

 axle, and all the helix-wheels are held immoveable in their place. The 

 wires of the helices are conjoined and connected with a commutator, 

 which, as the magnet-wheels are moved round, gathers the various electric 

 currents produced in the helices, and sends them up through two insulated 

 wires in one common stream of electricity into the lighthouse lanthorn. 

 So it will be seen that" nothing more is required to produce the electricity 

 than to revolve the magnet-wheels. There are two magneto-electric 

 machines at the South Foreland, each being put in motion by a two-horse- 

 power steam-engine ; and, excepting wear and tear, the whole consumption 

 of material to produce the light is the coke and water required to raise 

 steam for the engines, and carbon points for the lamp in the lanthorn. 



The lamp is a delicate arrangement of machinery, holding the two 

 carbons between which the electric light exists, and regulating their 

 adjustment ; so that whilst they gradually consume away, the place of the 

 light shall not be altered. The electric wires end in the two bars of a 

 small railway, and upon these the lamp stands. When the carbons of 

 a lamp are nearly gone, that lamp is lifted off and another instantly 

 pushed into its place. The machines and lamp have done their duty 

 during the past six months in a real and practical manner. The light has 

 never gone out, through any deficiency or cause in the engine and machine 

 house : and when it has become extinguished in the lanthorn, a single touch 

 of the keeper's hand has set it shining as bright as ever. The light shone 

 up and down the Channel, and across into France, with a power far surpass- 

 ing that of any other fixed light within sight, or anywhere existent. The 

 experiment has been a good one. There is still the matter of expense and 

 some other circumstance to be considered ; but it is the hope and desire of 

 the Trinity-house, and all interested in the subject, that it should 

 ultimately justify its full adoption. 



