38o THE POPULAR SCIENCE MONTHLY, 



(8,G72 Falir.). A number of ingenious appliances have been adopted 

 to obtain steadiness and uniformity in the action of the arc, which is 

 liable to variations arising from the irregularity in the character and 

 consequently in the consumption of the carbon, and from variations in 

 the strength of the current. AVe want brilliancy combined with abso- 

 lute steadiness, and a durability equal to the length of a winter's night. 

 All the improvements that have been made in the arc have not given a 

 silent and steady light. 



The incandescent light is free from many of the defects of the arc- 

 light. In it we have something that is beautifully soft, absolutely 

 noiseless a light that brightens up Nature in all her true colors and 

 purity. It, however, requires a considerable expenditure of power, 

 and is at present an expensive luxury. Sir William Armstrong finds 

 that six horse-power will supply thirty-seven lights, giving altogether 

 the illumination of nine hundred and twenty-five candles. The same 

 power applied to arc-lights would give more than six thousand candles. 

 But rapid progress has been made in this field. Maxim, Edison, etc., 

 in America Swan, Lane-Fox, and others, in England are working 

 hard ; while Gordon and Joel are working in an intermediate field, in 

 w^hich a prospect appears of a happy compromise being effected be- 

 tween the arc and incandescence. 



Some wild statements, involving wonderfully divergent estimates, 

 have been made about the light-giving power of the different lights. 

 A standard sperm-candle, although it may be a good unit to measure 

 gas by, is a very poor standard for the electric light. None of the 

 various modes of measurement in use seem to apply exactly to this 

 light, and the standard of measurement of the future has yet to be 

 found. Much is said about the subdivision of the electric light by 

 certain gentlemen, who hope to distribute it throughout our houses 

 from one central sj^ot, and furnish it cheaply and abundantly in our 

 cities. I am one of those who do not believe in the impossible, but 

 I say that, with our present knowledge, this problem is unsolvable. 

 Sir William Armstrong can only keep thirty-seven lamps going ; Lane- 

 Fox could only show twelve lights ; Professor Adams could only pro- 

 duce from the most powerful dynamo-electric machine, by calculation, 

 one hundred and forty lamps. Where is the subdivision ? The advo- 

 cates of subdivision assume an inexhaustible source of electricity. 

 Their opponents reply that there is but a very limited source of energy 

 in every dynamo-electric machine. It may be that more jDOwerful 

 machines and lamps of lower resistance may enable us to light up a 

 greater number on one circuit, but this is not subdivision, it is multi- 

 plication. 



For application to external illumination, we have, first, the central- 

 ized system of Dr. Siemens, in which one machine works one powerful 

 light, raised like a small moon on the top of a high mast ; and, secondly, 

 the distributed system of the Brush Company, who utilize the existing 



