I am a light, set up to warn and guide mariners. In dark and stormy nights I exhibit

I am a light, set up to warn and guide mariners. In dark and stormy nights I exhibit my red light, which shows that danger lies here, and thus prevent ships from running into destruction. In fair weather I display a white light, which marks out the channel, and directs them into safety. Besides, I exhibit two lights, which exhibit a green light, when I am to be passed on the starboard side, and a red light, when I am to be passed