10 LANDSCAPE GARDEN SERIES 



this nature is considered 1 to 2 (one foot of rise to each two feet of 

 horizontal distance) while a slope of 1 to 3 is better and easier to 

 maintain. 



Terrace embankments that do not have to conform with steps may 

 be as steep as a 1 to 1 slope which is the minimum slope in which 

 most soils will maintain themselves. It should be remembered that 

 terraces are always hard to maintain and where they are not a neces- 

 sary means to an end they should be avoided. Where the difference 

 of elevation is not too greajt for the distance an attractive way of 

 handling the slope is found in the use of the ogee curve. 



Grading should be done when the soil is in good workable shape 

 and not wet and heavy. Fills made with frozen soil will settle more 

 than soil not frozen and ample allowance should be made for this. 

 All fills will settle in proportion to their depth and the nature of the 

 material used. Hauling and working over the fills will help to settle 

 them as the work progresses. 



When it becomes necessary to establish an exact grade of known 

 levels it is necessary to use some implement of a fair degree of pre- 

 cision. The surveyor's spirit level is used when absolute accuracy is 

 required. Stakes can be set with their tops coinciding with the level 

 of the desired grade or may be marked and a notation made as to the 

 amount of cut or fill. A more accessible way of determing levels is 

 to drive all the stakes and then sight from one to another of them by 

 means of a carpenter's level. Two stakes of the same elevation 

 will establish a plane or line of sight from which the elevation of the 

 others can be regulated. A carpenter's level and a level board, 12 

 to 14 feet long, will provide a means of carrying a grade from one 

 stake to another. This method is commonly used in laying sidewalks. 



In all grading operations where teams are employed all existing 

 trees should be protected by heavy guard stakes or by fastening a cov- 

 ering direct to the tree. 



DRAINAGE 



The removal of surface and ground water is accomplished artifi- 

 cially by drainage. Drainage warms soils, thus increasing fertility and 

 enabling the plant growth to start earlier (a benefit particularly favor- 

 ing lawns and gardens) ; it makes soils moist instead of wet and in- 



