102 HANDT-BOOK OP HUSBANDRY. 



Next, survey the boundaries of the land, and all of the lines, 

 and note the position of each stake on the map, having reference 

 to some permanent landmarks, so that the exact position of any 

 point of the drains may at any future time be found, in order that 

 repairs and alterations maybe made without loss of time in hunting 

 for lines vv^hose exact location is forgotten. Such a map of drains, 

 vi'hich are entirely hidden, is always satisfactory and often useful. 



Levels. — Except on land which has a rapid descent, drains 

 should be laid with more accuracy as to the depth than is possible 

 by the aid of the eye alone, and in order to do this, the elevation 

 of the ground at each stake should be measured and recorded. 

 First, drive in a grade stake (a peg eight or ten inches long) at the 

 side of each stake, until its top is nearly even with the surface 

 of the ground; then imagine a horizontal plane above the ground, 

 at such height as will be above the highest grade stake of the 

 whole system of drains, and by the aid of a leveling instrument, 

 such as is used by railroad surveyors, ascertain the distance from 

 the imaginary plane, down to the top of each grade stake, and 

 mark it in pencil, near its proper stake on the map. This will 

 give perfect data from which to compute the depth at which the 

 tiles are to be laid, or the grade of the drains. 



On nearly level land this process is indispensably necessary, 

 while its importance diminishes as the surface inclines more 

 steeply ; where the fall is as much as one foot in fifty feet, an 

 ordinary carpenter's level will do sufficiently accurate work , and 

 on steeper slopes the eye is a sufficient guide. Generally, how- 

 ever, the main drains (having less fall) should be very accurately 

 leveled ; and the leveling of the whole tract is in all cases satis- 

 factory, and is essential to perfect drainage, while its cost is 

 trifling, as it may be done by the surveyor at the time of mapping 

 the lines. 



Grading. — The proper adjustment of the grades on which 

 the tiles are to be laid, is, by far, the most important question 

 connected with draining. Not only must we make sure that the 

 outlet is lower than the head of the drain ; it is necessary that 

 the whole line pursue a well-regulated descent, and equally 



