The latter were introduced in the early 1880s and required "trimming" maintenance just about every day. Around 1900 enclosed arc lights started to become popular for street lighting service. They needed arc-rod replacement/adjustment only once every seven to ten days; were somewhat more energy efficient and provided more of a steadier light than the open arc variety which had some noticable flicker to them at times. The color of these arc lights when illuminated was a bright bluish-white....a lot like modern metal halide lamps and LEDs used for today's automotive headlights, flashlights, etc, etc.