SOME NP^W MODES OF LIGHTING. 209 



it is concentrated by metal screens the heat rising from the incan- 

 descent mantles. The \iaporized oil escai)es doAvnward through a 

 large tube at the side of- the Itynp and here, mixing with air admitted 

 through a heated chamber, is led from beneath to the burners. 



The light of the (wo-biirner Kitson lamp is dazzling and reaches 

 at least 1,000 candlepowei-. AA'ith specially fa\'orable conditions, such 

 as with a new mantle and a high pressure of oil, 1,500 or even 2,500 

 candlepower is sometimes obtained. Oil is consumed at the rate of 

 about 0.2 liter (one-half pint) per 1,000 candlepower per hour. The 

 light produced has a nudlow, agreeable color, much warmer in tone 

 than that of the electric arc or the incandescent gaslight. As already 

 remarked, the intensity depends on the pressure, which is an inconven- 

 ience for a lamp of small oil capacity, but where thei-e is a reservoir 

 of large dimensions the diminution of pressure during twenty-four 

 hours causes no considerable variation in the intensity of the lamp. 



Of all methods of providing intense light, these which have been 

 described are most economical. It is possible to combine in a single 

 system lamps of great and relatively small intensity, and the material 

 employed is conunon and inexj^ensive and may serve to i)r()duce both 

 lighting and heating, or, indeed, motive power. There are no special 

 dangers to be feared when the combustible liquid is placed outside 

 the dwelling, and both the AA ashington and Kitson systenis include 

 an automatic valve to close off the circulation in case of leakage. The 

 greatest objections are the use of liquid which has a disagreeable odor, 

 tends to creep, and which sometimes yields a foid and disagreeable 

 smoke. Finally, the ])roduction of the gas from the liquid under 

 pressure produces a noticeable roaring sound. But for most |nir- 

 poses these inconveniences are of minor importance as compared with 

 the great advantages of a superb quality of light at minimum cost. 



No other mode of lighting can compar-e in cheai)ness with the 

 ])etroleum incandescent lamp in countries wluM;e kerosen(> may be 

 bought at a cost of from 2 to 4 cents a liter (S to 1<> cents a gallon). 

 It is justto add that in cases where natural gas or water power fur- 

 nishes an almost gratuitous source of energy the electric light may 

 indeed compare in cheapness, but even then there nnist first be ])ro- 

 vided complicated and costly machinery. 



Benzine is employed instead of petroleum in the (irlitsch system, and 

 although somewhat more dangerous, this liquid is cleaner and in cer- 

 tain other respects more suitable for the purpose. It is unnecessary 

 to use pressure greater tiian 1 atmosphere to circulate l)enzine through 

 the capillary tubes, and the lamps may be fed by merely placing the 

 reservoir somewhat above them and depending on the force of gravity. 

 The method of starting combustion is very simple and consists merely 

 in heating the burner for twenty or thirty seconds in an auxiliary 

 flame of alcohol in order to begin the vaporization of the benzine. 



