DRAINAGE AND VENTILATION 



51 



Windmills. Holland. 





From our study of geography we have already learned that 

 Holland owes its wealth and importance to its progressive engineers, 

 who have success- 

 fully grappled with 

 its drainage prob- 

 lems. The land 

 is lower than the 

 sea and ordinarily 

 would be deluged 

 with water, but 

 thanks to the skill 

 of its practical en- 

 gineers, Holland is 

 a country where, by 

 dykes and ditches, 

 thousands of acres have been reclaimed, from the sea, and made to 

 yield rich harvests. The Dutch first built walls or dykes around 

 the low, swampy land and then pumped out the water by wind- 

 mills into canals which carry the water away to the sea. Thou- 

 sands of windmills as well as steam pumps are required to keep 

 Holland dry. 



Methods of Drainage. The efficiency of various systems and 

 kinds of drains is the first thing to be considered in the question 

 of drainage. This will be determined largely by the free passage 

 of water through them. Measured by this standard, tile drains 

 seem to be the best and cheapest. Some of the reasons advanced 

 for their use are as follows: 



1. Durability. Good drains last for years and are always clear. 



2. When properly laid, they are out of the reach of the cultivat- 

 ing tools of the farmer. 



3. Cheapness. No other material suitable for this purpose can 

 be found which is so cheap. 



Where the land is level the drains should be gradually sloped 

 towards the lowest portion of the land. The grade should be at 

 least one foot in five hundred. The depth to which the water should 

 be lowered by drainage need seldom exceed four feet, but it is gov- 

 erned by the character of the land. On light, open soils they should 

 be deep, and on heavy land they should be near the surface. The 





