ADVANTAGES OF HARBORS 



549 



a barterer of goods. The sea offers him an unrestricted 

 highway for his traffic. Harbors he must have to load and 

 unload his wares safely. 



Although many of the best harbors of the world are 

 found along depressed coasts, such as the harbors of New 

 York, San Francisco, 

 London, Liverpool, 

 and Bergen, yet there 

 are several other 

 sorts of harbors. 

 The delta of a great 

 river may afford a 

 good harbor, as those 

 of New Orleans and 

 Calcutta. Harbors 

 may be formed by 

 sand reefs and spits, 

 like those of Galves- 

 ton, Provincetown, 

 and San Diego. The 

 atolls of the mid- 

 Pacific and even the 

 submerged craters of 

 volcanic islands af- 

 ford safe resting 

 places where ships 

 may ride out the 

 storms. 



All natural fea- 

 tures have a greater 



. MINOT'S LEDGE LIGHTHOUSE 



or less influence upon 



Situated on a reef about 15 miles southeast 



the inhabitants of of Boston. 



