THE water-ea:m. .229 



the waste valve at each pulsation, and prevent the current 

 of water from being thrown backward or up the drive- 

 pipe ; hence, the greater the disproportion between the 

 fall and the required elevation, the longer or larger must 

 be the drive-pipe, in order to obtain sufficient momentum. 

 A descent of only a foot or two is sufficient to raise water 

 to moderate elevations, but the drive-pipe should be of 

 large bore. This pipe should always be very nearly 

 straiglit, so that the water, by having a free course, may 

 acquire sufficient momentum to compress the air in the 

 ram, and push the water up the discharge-pipe. Water 

 may be carried to a distance of a hundred rods or more, 

 but as there is some friction in so long a discharge-pipe, 

 a greater force is required than for short distances. The 

 discharge-pipe should, therefore, be larger, as the length 

 is increased. Half an inch diameter is a common size, 

 but long pipes may be five-eighths or three-fourths ; and, 

 when practicable, it is more economical to reach an eleva- 

 tion with a short and strong pipe, and to use a lighter 

 and weaker one for the upper part. A pit, lined with 

 brick or smooth stone, for placing the ram, protects it 

 from freezing ; and both pipes should be under ground 

 for the same reason. The supply or drive-pipe is usually 

 40 to 50 feet long; but where the fall is 8 or 10 feet, it 

 should be sixty or seventy feet. 



Unlike a pump, there is no friction or rubbing of parts 

 in the water-ram, and, with clean water, it will act for 

 years without repairs, continuing through day and night 

 its constant and regular pulsations, unaltered and unob- 

 served. A small quantity of sand, or of dead grass or 

 other fibre, in the water, will be liable to obstruct the 

 valves, and render frequent attention necessary. 



including those for extinguishing fires and for irrigating 

 gardens, are constructed on a principle quite similar to 



