130 LANDSCAPE-GARDENING 



at the third stake being directed to drive it until 

 the line over the tops of the rods is satisfactory. 

 When the stake is driven to the proper grade, each 

 assistant and the observer move forward along the 

 line to the next stake and thus continue until all 

 the stakes in the line are driven to the desired grade. 

 When the profile of the grade is straight, the tops 

 of the three T's will be in line. When it is con- 

 vex up\vard, the third stake will be driven until 

 the top of the T resting upon it is below the line 

 over the tops of the other two, the distance below 

 the line depending on the rate of vertical curvature. 

 When the grade is concave upward, the third stake 

 will be driven so that the T resting upon it will 

 show above the line over the tops of the other two 

 T's. By repeating the trials for grade in a way 

 similar to that used in determining horizontal curves, 

 a satisfactory profile can be found quickly. With 

 a hand level, it is easy to determine when the grade 

 is within proper limits. 



It has been stated that when a walk is curved, 

 the curve should continue from end to end. It is 

 a mistake to introduce a complete circular walk 

 inclosing a flower-bed, fountain, or statue, with the 

 center of this circle in the center of the direct walk 



