THE HOSE-LEVEL 181 



depth subtracted from 5 feet 6 inches 1 

 gives the height of the top of the grade 

 bar above the grade stake. Let us sup- 

 pose that in this case the depth of the 

 drain is to be 3 feet; 3 feet subtracted 

 from 5 feet 6 inches gives 2 feet 6 inches 

 as the height of the bar above grade 

 stake. On the inner edge of the long 

 stake, by pencil, chisel, or some other 1 

 mark, the height of the grade bar is in- K t^ ij 

 dicated (2 feet 6 inches in this case). 1 x ^ 



237. Leveling. With the hose-level, I 3 Jf 1 

 the leveling begins at the end stake 

 (stake 9 in this case). In this case the 

 leveling proceeds down instead of up the 

 drain. The hose-level is stretched be- 



K t$ 



tween stakes 9 and 8 and the tubes of Jj^ g 



the level are placed one against the tall 



stake 9 and one against tall stake 8. 



The tube at 9 is brought into position 



so that the top of its water column 



stands even with the mark on the edge 1 o 



of the stake indicating the proper height 



of the grade bar. The man at stake 8 



now carefully marks on the edge of stake 



8 the height of water column in the tube 



at his end of the level. The level is 



now placed between stakes 8 and 7, and 



the tubes brought against the edges of 



the stakes ; the tube against the edge of 



8 is brought into position so that the top 



1 In the computations for this drain, feet, 

 inches, and fraction of the inch will be used. 



