No. 4.] IRRIGATION. 413 



cases ponds are so located that water can be conveyed from 

 them to fields on lower ground by means of open ditches, 

 the expense depending upon the distance and the character 

 of the ground to be passed through. This often is the 

 cheapest method for securing water. When the supply is 

 large, the loss of water occasioned by soakage from the ditch 

 or evaporation is not of serious consequence. The fall of 

 many of our small streams is so great that by building a 

 small dam the water may be turned from its natural eourse 

 and conveyed in ditches along the outer edge of the valley, 

 and then allowed to flow over the surface of the fields back 

 to the natural stream. 



Hams. — In many places the source of supply is below 

 the fields to be irrigated, and the water can only be made 

 available by some pumping device. The cheapest sources 

 of power are water and wind, although steam or electricity 

 may be profitably used where the water is wanted only for 

 a short period of time. A ram, under man} r conditions, is 

 the best power. As only a small part of the water that is 

 needed to operate the ram can be pumped, the supply must 

 be quite large and the ram of heavy capacity. If the water is 

 lifted over 40 or 50 feet high, the strain on the ram is quite 

 severe, and all parts must be securely and strongly made. 

 But few styles of rams manufactured in this country are 

 powerful enough to supply water for anything but small 

 areas, perhaps 3 to (> acres. 



Windmills. — If wind is the form of power to be used, 

 the mill should be constructed of the best materials, and be 

 strong and secure in all its parts. Cheap forms of mills 

 should be avoided in all cases. The best steel mills are the 

 cheapest in the end. The mill should be located on hisrh 

 ground, so it will "catch" the wind from all directions, 

 and the place of storage should be sufficiently above the 

 fields to be irrigated to give a good fall. The average 

 velocity of the wind in New England is about 12 miles per 

 hour. A 14 foot wheel will do good work with a wind of 

 10 to 15 miles per hour. Of course the movement of the 

 wind is very irregular, but there is usually sufficient to fur- 

 nish power for pumping water for 3 to 6 acres, by having a 



