THE HOSE-LEVEL 175 



226. The reading. When the top of the water column 

 stands at zero on the short rod : 



(a) If the top of the water column stands at zero on 

 the long rod, the stakes stand at the same height above 

 datum, and the reading is zero. 



FIG. 74. Nearer view of the hose-level in use. 



(b) If the top of the water column stands above zero, 

 on the long rod, it is because stake 2 stands higher above 

 datum than stake 1, and the reading is a positive reading. 



(c) If the top of the water column stands below zero 

 on the long rod, it is because stake 2 does not stand so 

 high above datum as stake 1 (is lower than stake 1) 

 and the reading is a negative one. 



227. Moving. After the reading has been made and 

 properly recorded, the short-rod man, grasping his end 

 of the level, moves to stake 3 and places the short rod 



