156 LOUIS BELL 



fact, would be difficult to surpass in this particular. It is 

 interesting to note that it has continued in hmited use even 

 up to the present time. 



The arc lamp therefore did the pioneering for the incan- 

 descent lamp. It educated the public to the appreciation 

 of the importance of color values in illumination, drew once 

 for all a line between weak illuminants and powerful ones, 

 and caused all eyes to be turned to electricity as the coming 

 source of illumination. 



Then came the incandescent lamp in response to the 

 demand for smaller electric hghts. The subdivision of the elec- 

 tric hght was the problem of the day, and very fortunately 

 this problem was solved by the glow lamp instead of by arcs 

 of small candle power, which could not then have been, and, 

 in fact, never have been, satisfactory illuminants. The 

 incandescent lamp nearly equalled the arc in rendering color 

 values, and enormously surpasses it in convenience and 

 steadiness. 



It was far less economical than the arc and was not for 

 some time on pubhc circuits able to compete with gas, but 

 made its way by reason of its better color, its steadiness and 

 its freedom from vibration of the air, and from overheating. 

 These good quahties carried it ahead in spite of all opposition. 

 It is hard to realize to-day how much these gains meant in 

 the way of exterior illumination, but they were fully reahzed 

 at the time, and they unquestionably won the day for electric 

 hghting. Looking over some ancient history recently the 

 writer came across a printed letter reporting results from one 

 of the early isolated plants, that in the Pemberton mills, in- 

 stalled in October, 1881. Although in this case two four-foot 

 gas jets were replaced by each ''A" lamp of 16 candle power, 

 a great improvement was noted in the conditions of illumina- 

 tions, especially in regard to color vision in work on colored 

 fabrics, and in the purity of the atmosphere. Further, it was 

 shown that the cost of the electric hght, including interest 

 and depreciation at 12 per cent, and lamp renewals at $1.00 

 apiece, was less than the cost of gas for the burners replaced 

 by more than a half. 



