The latter is seen on the extreme left and utilized an incandescent lightbulb. These bulbs had a carbon filament. Around 1912 tungsten-filament light bulbs for all purposes were introduced. These were much more energy-efficient, "whiter" in light output and lasted longer than their carbon-filament predecessors. The forementioned tungsten lightbulbs basically are the same as those we see today except for specialty ones such as halogen bulbs.