The seamen aboard fireboats belong to the Fire Department. They do deck work or engine work, and they also handle the pumps and nozzles that shoot enormous streams of water. The pumps suck in water through holes in the side of the boat and force it through hoses and nozzles that can be aimed like big guns. [Illustration] Sometimes fireboats go a little way outside their harbor to help a burning ship. On the way, the fireboat captain guides his vessel between buoys that mark the channels where ships can go. All harbors have these channels, which are really streets for water traffic. The buoys are floating signals anchored to the bottom. On a clear day, seamen can tell by looking at the shape and color what each buoy means. In a fog or at night, they listen for the bells or whistles on some special buoys and watch for the flashing lights on others. Rivers have channels marked with buoys, too, and men who belong to the United States Coast Guard Service have the job of placing and repairing them. The Coast Guard also cares for lighthouses at dangerous points along the shore. Powerful lights and foghorns in the lighthouses warn ships away from rocks or shallow water and also help them find out exactly where they are. In some places, lightships anchored in the sea do this same job. A lightship is really a giant buoy. Seamen live aboard her to care for the safety equipment. They get their food and mail from vessels called tenders. (Any vessel that supplies another is a tender.) Coast Guardsmen help seamen in other ways, too. Suppose a ship is sinking. Fast, tough little Coast Guard cutters race off to the rescue the minute the dreaded SOS signal comes over their radio. (SOS is the code [Illustration] signal for “help!” and every radio man understands it, no matter what language he speaks.) [Illustration] Using a special gun, men on the cutter shoot a lifeline across to the sinking ship, and a breeches buoy is rigged on it. This is a canvas seat, made like a pair of short pants. The seat hangs from a wheel called a block which runs along the line. One by one the seamen sit in the seat and are pulled along to safety. CHARTS FOR SAFETY In the days when the United States was still a very new country, many people in Europe longed for the freedom they were sure they could find here. One of them was Ferdinand Hassler, a young Swiss mathematician. Hassler was no seaman when he set out for the new world in a sailing ship. But luckily he did know a great deal about the stars. After the captain of his vessel collapsed in a terrific storm, Hassler was able to look at the stars and tell the seamen how to steer the ship. [Illustration] The things Hassler knew about mathematics made it easy for him to navigate, but real troubles began when the ship came into Delaware Bay. The map of the bay was old and very inaccurate. Hassler could not tell whether the ship was in shallow water or deep water, except by watching the leadline day and night.