156 



dimensions of the drain can be accurately determined. The levelling 

 sight being moveable, can be taken off when the guage is required for 

 measuring the drains. 



This instrument is extremely useful for laying out drains, and also for 

 levelling them before they are filled. 



In draining swamps and running sands, it is very diflScult to con- 

 struct drains that will not be choked by the loose sand or mud of such 

 places. In such cases the bottoms of the drains should be lined with 

 tough sods, so as to make a firm bed for the stones or tiles, and to keep 

 them from being choked with mud or sand; stiff clay will sometimes 

 answer. 



A farmer in England succeeded in draining a running sand, by in- 

 serting small pipes inside large ones. Narrow stone drains do not suc- 

 ceed well in sandy land, they are very apt to be choked in such places 

 unless proper precautions are taken. Some writers recommend the use 

 of stones and tiles in the same drain, and state that the water running 

 down through the stones has a better chance of entering the tiles. 

 Since the discovery of the fact that water enters from the bottom and 

 sides, instead of from the top of the drain, this system of filling has 

 been abandoned. 



Open sewer drains, and double tile main drains are sometimes neces- 

 sary where large springs exist and much water is to be conveyed ?.way^ 



The following figures represent open sewer and double tile drains : 



There are but few farms which do not require draining, indeed a cer- 

 tain amount of drainage is necessary on every farm. If we want to 

 plant an orchard or lay out a garden, the site of either will be wonder- 

 fully improved by draining and subsoiling. Fruit trees of any kind will 

 not thrive well in soil saturated with water. Do we wish to build a 

 house, and expect the locality to be healthy ? if so we must drain ; as 

 stagnant water whether above or beneath the surface tends to produce 

 ague and fever, and several other diseases. 



