| Popis: |
The history of incandescent lighting has been characterized by a succession of advances in the efficiency of light production. Through various steps in development from the early carbon lamps to the gas-filled MAZDA types of today, efficiency increases have come one after another. There have been major improvements in filament materials as when tantalum and tungsten were introduced, and minor changes which produced less spectacular increases. Neglecting the lower cost of electrical energy, and taking all sizes of lamps into consideration, the public receives over ten times as much light for the same power as it did when incandescent lighting was first introduced. The highest wattage lamps regularly used today give seventeen times as much light per watt as did the early carbon lamps. Electrical energy costs much less today than in past decades and lamp prices are but a fraction of what they once were. The effect of all these factors is that on the average, electric lighting costs but one-sixteenth as much as in 1890, and for the largest lamp the cost is only one-nineteenth. |
