616 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1914. 
The development of the gas mantle by Von Welsbach, in 1884, 
was the beginning of a new era in gas lighting.t. When the mantle 
burner was introduced there were available the flat-flame burner, 
producing 1 to 2 candlepower per cubic foot of 16-candlepower coal 
gas; the Argand burner, producing perhaps 3 candlepower per cubic 
foot; the regenerative burners, producing as much as 7 to 10 candle- 
power. The Welsbach lamp made available at first 10 and, later, 
something like 15 candlepower per cubic foot of gas. Since the 
early developments of the modern Welsbach lamp in, say, 1891, no 
material improvements have been made in the efficiency of light 
production from small mantle burners, though burners, mantles, and 
auxiliaries have been further developed along lines which make for 
better operating qualities. Beginning with about 1901, the number 
of sizes of lamps employing mantles was increased and the produc- 
tion of an inverted burner was undertaken. By 1906 the inverted 
burner had attained a point of commercial success, and there had 
been produced a variety of sizes of upright mantle lamps, ranging 
from those consuming 1} cubic feet of gas up to the multiple burner 
lamps employed for lighting large areas and consuming 12 to 18 
cubic feet of gas per hour. Since that time this range of lamps has 
been realized in the inverted type, and various improvements have 
been made in structural features and operating qualities. Regen- . 
erative lamps have been produced and. have entered to a limited 
extent into service in this country. These attain efficiencies of 
the order of 28 candlepower per cubic foot per hour. Highest 
efficiencies from illuminating gas have been obtained by the use of 
pressed gas systems, used largely abroad for street hghting, but not 
as yet introduced extensively in this country. These yield light- 
producing efficiencies of the order of 35 candlepower per cubic foot 
per hour. - 
The progress in efficiency of light production indicated by the 
record of the manufacturer of gas illuminants is shown in figure 5. 
Among other illuminants? the kerosene oil lamp is, of course, 
the most important. Its earlier form was improved by the substi- 
tution of a round-wick, center-draft lamp for the flat-wick burner. 
The incandescent mantle has been applied to the kerosene lamp, 
but without such success as to command general substitution in 
oil-lamp lighting. Acetylene lighting, filling a limited part of the 
general illumination field, is not understood to be making any con- 
siderable advance in efficiency of light production. The same is true 
of gasoline lighting. 
1Gas lamps: “Inverted gas lighting;’”? Whitaker; Trans. Illg. Eng. Soc., 1907, p. 764. ‘‘Modern gas 
lighting conveniences;” Litle; Trans. Illg. Eng. Soc., 1908, p. 418. “Symposium on Ligh-pressure gas 
lighting;’? Goodenough, Klatte and Zeek; Trans. Ilg. Eng. Soc., 1912, p. 506. 
2 Miscellaneous illuminants: ‘‘The progress of the gas industry;’’ Morrison; Trans. Ig. Eng. Soc., 1909, 
p. 36. 
