168 LAND DRAINAGE 



an even surface ground or floor preferably upon 

 a slope or incline, and parallel to the slope. The upper 

 end, with tube inserted and clamped in place, should 

 be suspended, or held, tube up, about three feet above 

 the floor. 



The water should be introduced at the lower end (first 

 removing the tube if it has been inserted). At first the 

 end should be held low while the water is being introduced. 

 The water should be poured in slowly, with a care not to 

 introduce air with it. As the filling proceeds and the water 

 fills the hose, the end should be raised until the hose is 

 filled to the upper tube. The tube should now be inserted 

 at the filling end and clamped in place, and enough more 

 water added to bring the water to about the middle of 

 both tubes, which means, of course, that the tubes must 

 be brought to the same level. 



The hose could be better and more quickly filled if an 

 end could be tightly fastened over the end of a water tap, 

 having water free from air, and with some pressure. In 

 this case the water should be allowed to flow through the 

 hose for a few minutes after it is full. 



A funnel properly used would help where the hose is 

 filled by hand, from a receptacle. 



219. Removing air bubbles from the hose-level. - 

 However filled, there is a possibility of the presence of 

 bubbles of air at various points in the hose, and for the 

 purpose of removing them a scheme something like the 

 following should be employed : 



Lower one end of the hose till the water begins to 

 overflow the tube. Place the thumb firmly over the end 

 of the tube and lower to the ground. Having first sus- 

 pended the other end of the hose at a height of 5 or 

 6 feet, have a second party place his hand under the hose 



