Channel buoys are all numbered in sequence from the sea inward, the red ones with even, and the black ones with odd numbers, and the larger ones are anchored with “mushrooms” while the smaller have “sinkers” of iron or stone. They are made of iron plates in water-tight compartments, so that if punctured by an over-running ship or some other accident, they will not be likely to sink. In harbors where ice forms in winter, large summer buoys are replaced in winter by a smaller sort less liable to be torn adrift. Buoys do go adrift, however, now and then, and sometimes take a voyage across the ocean or far down the coast before they can be found by the tenders of the Lighthouse Service, which is constantly looking after these and other marks. Lieutenant Ellicott tells us that all changes in the position of buoys or lightships, or the placing of new buoys to mark a change of channel, or an obstruction, are published promptly in pamphlets called “Notices to Mariners,” which are distributed as quickly as possible through well organized means of communication. A few years ago one of the largest of our handsome new cruisers was approaching New York harbor from the West Indies in a light fog. Sandy Hook Lightship had been found, the usual course laid for Gedney Channel, and the ship was steaming onward at full speed, her captain, having been inspector of that very lighthouse district but a short time before, feeling that he knew his way into that port better than the most experienced pilot. Presently, however, he was startled by the alarming cry of _breakers ahead_! A large hotel also loomed up, and, as the ship was backed full speed astern, all hands realized that they had barely escaped running high and dry on Rockaway Beach. When the vessel got into port it was learned that Sandy Hook Lightship had been moved considerably from its old position, and that the notice of this change had failed to reach the captain of the cruiser before he sailed from the West Indies. [Illustration: A WHISTLING BUOY, OUT OF COMMISSION.] Shipwrecks still occur, however, in spite of lighthouses and sirens and buoys and coast-surveys; therefore we add to our precautions arrangements to help those cast away. Societies to save wrecked persons have existed, it is said, for many centuries in China, but in Europe they are hardly a hundred years old. The early humane societies, like that of Great Britain, placed life-boats and rescuing gear in certain shore towns, and organized crews, who promised to go out to the aid of any lost ship, and to take good care of the persons rescued. In America, however, our coasts are so extensive, and so much of the dangerous part of them is far away from villages, or even a farmhouse, that the government has been obliged to do whatever was necessary. Thus came about the Life Saving Service, which now has its stations close together along our whole sea-coast, and upon the great lakes, covering more than ten thousand miles in all.