378 



GAS-LIGHTING, REGENERATIVE SYSTEM OF. 



expression by a simple formula. All bodies 

 begin to be self-luminous (so that they can be 

 seen in the dark) at a temperature a little un- 

 der 1,000 Fahr., while 2,500 Fahr. is proba- 

 bly the temperature of a gas-flame. In this 

 case, while the temperature has been increased 



FIG. i. 



2$ times, the light has increased more than a 

 hundred-fold. This ratio of increase does not 

 hold as the temperature is still further in- 



creased, but within the limits of increase at 

 our command the light certainly augments in a 

 vastly greater ratio than the temperature. Dr. 

 John W. Draper found that the light yielded 

 by a strip of platinum-foil at a temperature of 

 2,600 Fahr. was 36 times that given by the 

 same body when raised to only 1,900 ; and 

 experiments with the incandescent electric 

 light have shown that an increase of the 

 current energy which in this case is all ex- 

 pended in the production of heat of from 

 28 to 37 per cent, was sufficient to double 

 the light of a 16-candle lamp. The exceed- 

 ing brilliance of the arc-light is due to the 

 enormous temperature to which a small 

 mass of matter is raised. 



In the electric light, whether arc or in- 

 candescent, the temperature attainable is 

 limited solely by the power of the incan- 

 descent material to resist the disintegrating 

 effect of high temperatures, but in all forms 

 of lights due to combustion this limit is im- 

 posed by the combustible itself. The maxi- 

 mum temperature which can be obtained 

 with a hydrogen-flame burning in air is 

 about 2,000 C., and with carbonic oxide a 

 few degrees less, while, as stated above, the 

 actual temperature attained in a gas-flame 

 as ordinarily burned does not much exceed 

 2,500 F., or 1,371 C. The lower temper- 

 ature in this latter case is largely due to the 

 cooling of the flame by its exposure to the 

 air, and consequently, if this cooling can be 

 avoided, the amount of light yielded by a 

 given flame ought to be greatly increased. 

 This the regenerative burners have shown 

 to be the case, and further, that the in- 

 creased effect is in proportion to the com- 

 pleteness with which this is accomplished. 

 Large burners, in which the surface of flame 

 exposed is smaller in proportion to the gas 

 burned, and the cooling effect consequently 

 less, give results considerably higher than 

 those realized in smaller burners. 



While the principle might seem easy of 

 application, practically it has not been found 

 to be so, and it is only in the past few years 

 that satisfactory commercial apparatus has 

 been constructed, A burner, in which a 

 portion of the air supplying the flame was 

 heated, was described by an Englishman 

 named Young as long ago as 1854; and ex- 

 periments were conducted by Frederick Sie- 

 mens, to whom the successful application in 

 recent years is due, fully twenty years ago. 

 Mr. Siemens did not succeed in his early 

 experiments, and the subject was aban- 

 doned by him, until the advent of the elec- 

 tric light turned his attention to the pro- 

 duction of powerful foci of light by means 

 of gas. In a lecture delivered in the lat- 

 ter part of 1879 before the Society for the 

 Promotion of Industry in Prussia, Mr. Sie- 

 mens describes several forms of apparatus in 

 which he had endeavored to carry out the prin- 

 ciple. The lamp shown in Fig. 1 illustrates the 



