go GARDEN DESIGN 



By merely taking an average of all the levels an 

 approximate result is obtained, but it comes out 

 rather more than the correct mean. An average 

 of the levels on Diagram 26 works out to 5.56, 

 and it will be found that such calculation usually 

 work out slightly greater than the correct figure. 



If the levels have not been taken at even dis- 

 tances the working is complicated in the same way 

 as when the example of a strip was irregular. Un- 

 less there are strong reasons against it, levels 

 should always be taken regularly. 



An even line between two points, whether slop- 

 ing or horizontal, can conveniently be laid by the 

 use of " boning " or " borning " rods. These are 

 three pieces of wood, preferably shod with metal, of 

 uniform length with a cross piece. Four feet is a 

 good length. The first and last levels being deter- 

 mined, a rod is held at one end, and an observer 

 goes to the other extremity with a second rod, 

 while an assistant holds the third wherever a level 

 is required. The first and last rods are fixed, and 

 the intermediate one has to be raised or lowered 

 according as the observer directs in order to bring 

 its top in a line with the other two. As many 

 intermediate stations can be taken as may be 

 wanted. 



This is a quick way of testing the surface of a 

 lawn or of a sloping path. 



When drawing sections it is customary to make 

 the vertical distances at double the scale of the 



