172 TRANSACTIONS OF THE 
THE PRESSURE-WATT CHARACTERISTICS 
OF DRAWN WIRE TUNGSTEN LAMPS. 
By C. ARTHUR SMITH. 
Perhaps no industry in the country ever had so phe- 
nominal a growth as that of the incandescent lamp. Al- 
though its history covers only the brief period of thirty-five 
years, it has in that time been developed to such a high 
state of perfection that it has practically crowded out 
every competitor from the field of electric lighting. In 
less than three years after the first incandescent lamp 
made its appearance, the arc lamp industry began to show 
signs of uneasiness, and scarcely five years had gone by 
when the manufacturers of the arc lamp were forced to 
improve their designs in order to hold their place in indoor 
lighting. 
The first incandescent lamp was of the carbon fila- 
ment type, very fragile, of low efficiency as expressed in 
watts per candle power, and of uncertain duration. For 
nearly twenty years it was the only incandescent lamp on 
the market. In 1899 the tantalum lamp was invented by 
a German scientist and immediately entered the field as 
a strong competitor because of its excellent illuminating 
qualities and high efficiency. For atime it looked as though 
it would displace the carbon lamp entirely, but within a year 
from its introduction a new process of preparing the carbon 
filament was discovered. The result of this discovery 
brought forth what is known as the metallized carbon fila- 
ment, and the carbon lamp henceforth became the Gem lamp. 
Its durability was greatly increased, its efficiency was 
raised to nearly that of the tantalum lamp, and the first 
cost was considerably less as it was a cheaper lamp. It 
thus continued to hold first place for indoor lighting un- 
til the year 1908 which was one of supreme importance in 
electric lighting industry. It marks the advent of the 
tungsten lamp. This lamp immediately took first rank on 
account of its excellent illuminating properties and high 
efficiency, and this in spite of the fact that it was extremely 
