158 ELEMENTS OF GENERAL SCIENCE 



have become railway centers also. In many cases the railways 

 have followed the routes which were earlier used by water- 

 borne commerce. Thus the New York Central Railway paral- 

 lels the Hudson River, Erie Canal, and Lake Erie, and two 

 railways follow the route of the Illinois and Michigan Canal. 



172. Harbors, lights, buoys, and life-saving stations. A 

 good harbor is a necessity for any city which carries on com- 

 merce by water. There must be some place where vessels 

 may lie in quiet water while unloading or taking on cargo. 

 Harbors need more or less constant dredging. They need 

 properly constructed breakwaters to check the force of the 

 waves and produce a fairly quiet area behind them in which 

 vessels can lie in security. Since the harbor is open to all 

 vessels, it is the business of the government to make these 

 improvements. 



Lighthouses are placed at the harbor entrances and at 

 other places to guide the master of a vessel safely into the 

 harbor or to warn him of danger. Important lighthouses are 

 equipped with foghorns, which are sounded at intervals of a 

 number of seconds during rainy or foggy weather, when the 

 lighthouse may not be visible. Obstructions, shallow places, 

 and other dangers are commonly marked by buoys of different 

 shapes and colors. 



Life-saving stations are maintained at many places. Each 

 station is in charge of a crew of trained and experienced 

 men and is equipped with boats and other special apparatus 

 for the saving of life in case of wrecks or other accidents. It 

 is better, however, to prevent wrecks than to save life after 

 a wreck, and one of the measures taken for this purpose con- 

 sists in maintaining storm-signal stations, which are frequently 

 connected with the life-saving station. 



More has been said of Chicago than of other ports, since 

 it is the largest city on the Lakes and the port closest to the 

 heart of the country. Other lake and ocean ports, if carefully 

 studied, will show interesting facts of a similar nature. 



