VARIETIES OF THE ELECTRIC LIGHT. 777 



plan in preference to having a whole house full of property damaged or spoiled 

 by the supply of water to a fire occurring in an upper room. — The Builder and 

 Wood- Woi'ker. 



VARIETIES OF THE ELECTRIC LIGHT. 



Many persons are waiting before adopting the electric light until there shall 

 Le a demonstration which lamp is the best. The various accounts of the lights 

 in the Paris Exhibition indicate that the competition is not estabUshing decided 

 superiority of either the arc or the incandescent method, but rather is showing 

 that each has peculiar advantages for particular situations. Very probably the 

 arc light, which is the more powerful, yet more simply produced, may come to 

 be preferred for engineering operations, for light-houses and vessels, and for 

 streets and parks, while the incandescent method which gives a milder, steadier 

 effulgence, may win favor for use in halls, shops and dwellings. In the main 

 hall of the exhibition lamps of all kinds have been in use and, to promote com- 

 parison, twenty-nine apartments in the gallery have been lighted, each by a single 

 system. The nature of the arc method has been made familiar in this country 

 by the Brush lamp, the Fuller, the Wallace and the Weston, and by the arc lamp 

 of Maxim. Its light is emitted by the electric current as this flows from one to 

 the other of two carbon points ; but unless these two points can be made to ap- 

 proach each other precisely as fast as they are consumed by the heat, a disagree- 

 able flicker is the result. In the incandescent method, which is that of the Edi- 

 son lamp, the Sawyer, and the incandescent lamp of Maxim, the light is emitted 

 by a carbonized fibre, raised to white heat by passage of the current through it, 

 but to protect the fibre from being consumed, it must be hermetically sealed in a 

 glass globe. The arc method allows the carbon to be slowly consumed; the pur- 

 pose of the mechanism is to replace it steadily; the incandescent seeks to prevent 

 the consumption. The long effort to devise means of avoiding the flicker with- 

 out incurring the mechanical difficulties incident to the exhausted globe, has de- 

 veloped many forms of lamp, and several as yet little known in this country are 

 in the exhibition. 



In the Compton lamp a vertical metallic rod is held pinched more or less 

 strongly, according to the force of the current, between two pieces of metal, the 

 friction on the rod being varied according to the strength of the current, and the 

 friction regulates the approach of the points. In the Pilsen a piece of iron of 

 spindle form is made the common core of two electro magnets, one placed above 

 the other, and is drawn up or down, according to the variation in the current. 

 In the Serrin, clock-work, regulated by the current, moves the points toward 

 each other. In the Werdermann the purest carbon which can be obtained is 

 used. In order to avoid accumulation of ash, a rod of it is passed from beneath 

 against a block of carbon, and as fast as the point is consumed the rod ascends. 

 The Reynier, in its most recent models, is like this, except that the block is un- 



