Fig. 135. 
Ships in the harbor of Naples. 
In the background is Mt. Vesuvius. 
CHAPTER FIFTEEN 
THE USE OF SHIPS 
Not many decades ago, wooden sailing vessels carried the whole of 
the world’s commerce on the high seas, but now steel steamships carry 
the greater part of it. In almost every large harbor a few sailing ves- 
sels may indeed be seen ; they are still extensively used to carry heavy, 
bulky goods, such as jute from Calcutta, grain and lumber from the 
west coast of North America, and nitrate of soda from Chile. But 
many of the sailing vessels now built have auxiliary steam power to 
take them through calms and into harbors. Only in small harbors or 
for the purposes of purely local trade is the wooden vessel still the prin- 
cipal carrier. 
OCEAN TRAFFIC 
No civilized country produces a sufficient variety of goods to satisfy 
all its own needs; every such country must draw upon other parts of 
the earth. Since three fourths of the earth’s surface is water and the 
other fourth consists of detached land masses, the commodities from 
distant lands generally have to cross the water. If there is a choice 
between a land and a water route, the water route is generally chosen, 
because it is cheaper. 
How ocean liners differ from tramp steamers. Just as express 
trains and locals, fast freights and slow freights, all run on the same 
189