CHAPTER XX 

 LIGHTING 



Candle power. The candle is the unit by which light is 

 measured. A standard candle is one that burns a fixed 

 quantity of a specific quality of sperm oil in an hour. An 

 ordinary candle is a little stronger than a standard candle. 

 A 1 6-candle-power light will give illumination equal to 

 sixteen standard candles, or about fifteen ordinary tallow 

 candles. It does not follow that the 1 6-candle-power lamp 

 will produce a better light in a room than the fifteen or six- 

 teen candles if the latter are properly distributed. To 

 illuminate a room satisfactorily by candles is considered too 

 expensive. The secret of the economy is that the large unit 

 is in all cases more economical than the small, though the 

 distribution may not be as satisfactory. 



Kerosene lamps. Kerosene lamps have been equipped 

 with mantles producing a good light, and at a price which 

 would keep all others out of the field. The mantle is frail, 

 however, and a portable lamp using a mande of the soft- 

 fabric construction is not satisfactory. 



GAS 



Oil gas. Gas for lighting purposes has been known for 

 many years. The common name applicable to all gases 

 so used is air gas. This implies a mixing of air with a small 

 quantity of vapor from a volatile oil — in short, a carbu- 

 reting of the air. This gas is not satisfactory when burned 

 in a flat frame or open burner. It requires a mantle in order 

 that reasonably constant results may be obtained with the 

 varying quality of the gas. The most common of air-gas 

 plants is the one that uses gasoline. This system has fallen 

 into disfavor because of the gradual lowering of the grade 



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