"Has that ever happened that the light went out?" Frank asked.
"Not since father has been in charge," said Lucy proudly, "and that is over fourteen years, now. He came here when he was first married, and has been here ever since."
"What is this for?" asked Bob, as they passed a curious bit of machinery in the tower, on their way up to the lamp itself.
"That is what turns the lenses," the girl explained. "You see this is a revolving light. It flashes around once every two seconds, and it is regulated by clock-work. This big weight that hangs down is used instead of a spring or an engine, to turn the lenses."
"I see!" exclaimed Sammy. "It's like a cuckoo clock."
"Yes," answered Lucy. "Father winds the weight up every day, by a crank and windlass, as in an old-fashioned well. Then it is caught by a sort of trigger. At night when the lantern is lighted, the weight is allowed to slide slowly down. That pulls the wheels around and the light flashes.
"You see each lighthouse in this section has a different sort of lantern. That is, some are fixed lights, some are revolving lights, some are red and some are white. Sailors can tell, by the difference in the lights, just where they are, even on the darkest night."
"A lighthouse is quite important," murmured Frank.
"We think so," laughed Lucy.
Then the girl took them up into the light chamber itself, a small room, with glass sides. The glass was really in the shape of lenses, as in an automobile lamp, only it was cut in another form, called a prism, in order to better cast out the direct rays, and magnify them.
The lantern was an oil one, and it burned brightly, for it was kept clean, and the wicks were often trimmed. The boys
