The cost of pumping for irrigation, where the well and machinery is used for no other purpose, must be charged up to the crop. The items of expense are interest on the first cost of the pumping machinery, depreciation, upkeep and running expenses. On Eastern farms, however, where diversified farming is the business, this expense may be divided among the different lines of work. Where live-stock is kept, it is necessary to have a good, reliable water supply for the animals. A reservoir on high ground so water may be piped to the watering troughs and to the house is a great convenience. Also the same engine that does the pumping may be used for other work in connection with the farm, so that the irrigation pump engine, instead of lying idle ten or eleven months in the year, may be utilized to advantage and made to earn its keep. Well-water contains many impurities. For this reason, it is likely to be valuable for crop growing purposes in a wider sense than merely to supply moisture. Well-water contains lime, and lime is beneficial to most soils. It has been noticed that crops grow especially well when irrigated from wells. [Illustration: Figure 128.--Power Transmission. Circular motion is converted into reciprocating motion by the different lengths of the two pitman cranks which cause the upper wheel to oscillate. Power is carried to a distance by wires. To reduce friction the wires are supported by swinging hangers. Sometimes wooden rods are used instead of wires to lessen expansion and contraction.] _House and Barns Supplied from a Reservoir._--A farm reservoir may sometimes be built very cheaply by throwing a dam across a narrow hollow between two hills, or ridges. On other farms, it is necessary to scrape out a hole on the highest ground within reach. For easy irrigation a reservoir is necessary, and it is economical because the pump may work overtime and supply enough water so the irrigation may be done quickly and with sufficient water to make it effective. When the cost of the reservoir can be charged up to the different departments of the business, such as irrigation, live-stock and house use, the cost is divided and the profits are multiplied.