THE HOSE-LEVEL 183 



on the inner edge of stake 1. In this case the depth of 

 the ditch at stake 1 is to be 40 inches as previously stated. 

 Forty inches equals 3 feet 4 inches, and this subtracted 

 from 5 feet 6 inches gives us 2 feet 2 inches, and this 

 height above grade stake is now marked on the inner 

 edge of the long stake at 1, as it was on stake 9. 



239. To determine fall by hose-level. Referring now 

 to Fig. 76, if we draw a straight line connecting points 

 L g and LI, this line passes through all the other level 

 marks on the several other stakes. It is level. If we 

 connect the point Z 9 , which is also the height of the grade 

 bar on stake 9, with the point B\, which is the height of 

 the grade bar on stake 1, with a straight line, that line 

 represents the fall of the drain from stake 9 to stake 1. 

 (It shows the location of the boning line.) 



240. Computations. The distance from the point 

 LI to the point BI represents the actual fall or drop of 

 the drain between stake 9 and stake 1. This measuring 

 may be done with an ordinary rule or yardstick. In 

 this case the distance from L l to BI is found to be 2 feet 

 If inches, or 2-1-4. This is the total fall whether it 

 is regular or broken. 



The length of drain is 400 feet, divided by the grade 

 stakes into eight 50-foot intervals or sections. If the 

 fall is constant and the total fall from stake 9 to stake 1 

 is 2 feet 1-f- inches, the fall from stake 9 to stake 8 indeed 

 the fall from any stake to the stake next below it is one 

 eighth of 2 feet 1-f- inches. Dividing, we find that fall to 

 be 3 inches and 1^ eighths (2-1-4) -r-8 = (0-3-1-J). At 

 stake 8, then, the grade bar will stand 3 inches and 1-^ 

 eighths below the level mark. At stake 7 the grade bar 

 will stand twice 3 inches and 1^ eighths below the level 

 mark ; at stake 6 the grade bar will stand three times 3 



