THE IRRIGATION AGE. 



107 



the surface, the excavation being the exact size of 

 the bottom of the steps. Make sure that the earth 

 is level and compact at the bottom of the excava- 

 tion. Place the largest box in position around the 

 edge of the excavation, staking it in place at two 

 or three points to prevent shifting. Level the first 

 box very carefully by means of a carpenter's spirit 

 level. The concrete, mixed rather dry, should be 

 deposited in the box and thoroughly tamped and 

 compacted until moisture rises to the surface. 

 Work or spade the concrete thoroughly along the 

 sides of the forms so as to produce a smooth sur- 

 face. At the front end of the box, where the con- 

 crete becomes the tread, the surface of the concrete 

 is carefully leveled off and smoothed with a trowel 

 for a distance of about twelve inches from the outer 

 edge. Immediately after this is done the second 

 and smaller box is placed on top of the first one, 

 being fastened thereto by a few nails through the 

 upright cleats shown in the drawing. The nails 

 must not be so long as to project through the 

 forms and into the concrete. Fill the second box 

 with concrete immediately, being careful that no 

 dirt or other foreign matter falls or collects on the 

 surface of the first batch of concrete, as this would 

 prevent a good bond between the two layers. 



Finish this step or slab in exactly the same manner 

 as described for the first step. The last or third 

 step is constructed in exactly the same manner as 

 those previously described. 



The brace between the two back cleats is for 

 the purpose of preventing the boards from spread- 

 ing at the side next to the wall. The outer surface 

 of the top step is carefully leveled off with a 

 straight-edge and finished by troweling to a smooth 

 surface. Excessive troweling, however, must be 

 avoided. Not more than a half hour should elapse 

 between placing the concrete for each step so that 

 the concrete first deposited will not harden and set 

 up before the next form is filled. After the steps 

 are about one week old, the forms may be removed 

 and the steps used. After the forms are removed 

 any roughness or irregularities may be smoothed 

 down and the surface of the entire steps finally fin- 

 ished by rubbing with an old piece of emery wheel 

 and water or carborondum and water. Where the 

 work includes many steps, a hollow space is gener- 

 ally left under the main body of the steps to effect 

 a saving in materials. Where this is done the plat- 

 form and steps are reinforced with steel rods or 

 heavy wire mesh to prevent cracking. 



INDIVIDUAL PUMPING SYSTEMS FOR FARM 



IRRIGATION 



The use of individual pumping plants on irri- 

 gated farms has many advantages and few draw- 

 backs, says an article on this subject in the new 

 Yearbook of the U. S. Department of Agriculture, 

 and the area in the country irrigated in this way 

 is increasing. If a farmer has a dependable supply 

 of water and a well-designed and properly installed 

 pumping plant, he is sure of being able to give 

 his crops the water they need when they need it. 

 The relative cost of individual pumping plants and 

 the gravity supply of water is, of course, a factor 

 of the utmost importance, but in many instances it 

 is now cheaper for a farmer to pump his own water 

 than to buy it delivered by a ditch by gravity. 



Mechanically, it is possible to pump water from 

 greater depths and in greater quantities than com- 

 mercial considerations always make profitable. The 

 amount of money that, from a business point of 

 view, it is wise to expend on a pumping system 

 can not, therefore, be stated unless all the condi- 

 tions which determine the expense of pumping and 

 the price of the resulting crops are known. In the 

 paper already mentioned, it is said that a first-class 

 pumping plant, including the well, with ample ca- 

 pacity to irrigate 160 acres of average forage crops, 

 may be installed at a cost of from $5,000 to $7,000. 

 A plant with a smaller capacity requiring the use 

 of a reservoir may be installed for $2,000, with $500 

 or even $1,000 additional for the reservoir. 



The choice between a pumping plant of large 

 capacity without a reservoir and one of smaller 

 capacity with a reservoir is largely a question of 

 the comparative cost of the larger equipment and 

 of the reservoir. In applying irrigation water, a 

 very small stream can not be used to advantage. 



Where only limited areas are to be irrigated, there- 

 fore, it is customary either to install a pumping 

 plant capable of delivering more water than is ab- 

 solutely necessary, or else to use a smaller plant 

 with a reservoir in which the water can be accu- 

 mulated until an economical stream is available. 

 As the farmer must pay interest on and, to a large 

 extent, depreciation on his investment, whether the 

 pumping plant is in continuous operation or not, he 

 can frequently save money by installing a com- 

 paratively small pump and keeping it in more or 

 less continuous operation. 



The three types of pumping plants principally 

 used for irrigation are the plunger or cylinder 

 pump, the centrifugal pump, and the air-lift. As a 

 general rule, says the article in the Yearbook, the 

 plunger type of pump is well suited for lifting quan- 

 tities of water from 100 to 500 gallons per minute 

 from depths beyond 50 feet. For quantities of from 

 500 to 2,000 gallons per minute at greater depths 

 than 50 feet, the vertical centrifugal pump is better 

 suited. 



In installing a pumping plant, massive and well- 

 built foundations are necessary for proper opera- 

 tion. Weak foundations permit vibration and con- 

 sequent loss of power and unnecessary wear and 

 tear on the machinery. Concrete, thoroughly mixed, 

 and composed ordinarily of one part of cement to 

 two parts of sand and three parts of gravel, is the 

 best material. Another point of importance is to 

 see that the feed water in the engine-cooling system 

 contains no sand or sediment. For the belting used 

 in driving the pump, four materials are in common 

 use leather, rubber, canvas and composition. Of 

 these, leather is to be preferred for dry climates. 



