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The National Geographic Magazine 



of the breakers. Nearly all masonry in 

 engineering constructions is of Dutch 

 brick, which is of a very superior qual- 

 ity. In breakwaters or piers, however, 

 concrete blocks are used exclusively, as 

 neither bricks nor basalt would furnish 

 a bond strong enough to withstand the 

 impact of the waves. 



ENGINEERING PROBLEMS 



From a hydrographic point of view, 

 the Netherlands present a very unusual 

 spectacle. While the eastern elevated 

 portion has a natural topography of its 

 own, and consequently natural lines of 

 drainage, the western lowlands are de- 

 void of all drainage whatever, and every 

 drop of rain water that falls, as well as 

 all seepage water, must either evaporate 

 or be pumped up and discharged through 

 artificial means into the ocean, if accu- 

 mulations and inundations are to be 

 prevented. 



Statistics show that in i8g6, 2,519 

 square miles of polder land were being 

 maintained with the aid of 444 steam- 

 engines and 247 windmills; i , 234 square 

 miles were being maintained with the 

 aid of 1,706 windmills, or in all 2,397 

 pumping plants were required to drain 

 3,753 square miles. 



What at one time were natural chan- 

 nels and water-courses have been since 

 inclosed between dikes, and the level of 

 their waters is now higher than that of 

 the adjacent land. The large rivers 

 that flow through these low districts are 

 therefore here no longer rivers in the 

 strict sense of the word, as the features 

 and problems which thej'^ present are 

 very distinct from those characteristic 

 of natural streams. The smaller streams 

 have in reality ceased to exist as such. 

 For instance, the northern branch of 

 the Rhine, along which general Drusus 

 caused a levee to be built, is no longer 

 a river; its waters no longer flow; it is 



Forest Growth on the Dunes 



