Perhaps it would have been impossible at another time; but just at this very juncture it chanced that Lone Rock Lighthouse was vacant, and indeed the post of caretaker had actually been offered to Nathaniel Carey, because he was known to be a steady respectable man, who could be relied upon to do his duty there. Lone Rock Lighthouse was always changing its keeper, for the life there was so solitary that men could not long stand the strain of it; and by the end of a year, or a couple of years, almost always resigned the post, in spite of the regular pay and comfortable home. It was not a post that Nat would have cared to accept under ordinary circumstances, for he was a sociable man, and liked to have other men about him; but when the life of his only child was at stake, and his wife, with wan drawn face and piteous eyes, pointed to the little figure on the bed and told him what the doctor had said, the only thing to be done was to go and accept the post without any more hesitation; and the next business was to get the sick child removed there upon the first calm and suitable day. For Lone Rock was not to be approached at all times and seasons, even in summer weather, and often was cut off from communication with the shore in winter for many weeks together. It was built upon a very dangerous sunken reef, round which the sea boiled and surged and raged from year's end to year's end. And herein lay the chief peril and the chief drawback of the keeper's life. If anything were to go wrong with him or with his home--if he were to be ill, or in want of some necessary of life, or if the structure of the lighthouse needed attention, it might be long weary days, or even weeks, before he could receive the help he had signalled for. It is true that every precaution was taken to ensure his safety. The structure was carefully examined by competent persons at short intervals. A large store of dried and salted provisions was always kept under the roof of the building, so that the keeper and his assistant might never be put to actual shifts for food, and stores of oil, for the great lamp, were likewise kept--stores which could scarcely run out, however long a spell of bad weather might last. Every care and precaution was taken; but for all that the life there was one of singular isolation, and men had been known to go mad during the long dreary winter months; and once a terrible crime had been committed there through this very cause--a crime of which men whispered still sometimes with 'bated breath, though Pat's mother always resolved that the child should never hear the gruesome tale.