In the late 1800s Moon Towers were a real thing. Gas lantern streetlamps were common but not very bright. Electric carbon arc lights were very bright but too large to put in streetlamps (incandescent bulbs were still experimental). So these really tall, very bright carbon arc towers were used to light areas of several square blocks. See more
Now who can tell me the common denominator of these two fractions?
You don't know or you're just bored?
Hey listen, you know, if we're all bored over here, wouldn't the common denominator be you?