792 EXPERIMENT STATION RECORD. 



4(t stumps per Mcre. v;ir.viii,ii in diiuiu'tcr from 1 to Hi ft. and from a heavy 

 f,'ro\vth of undorbriisli. The cost was at the rate of $71.90 an acre. 



The author concludes that "a donkey enguie built for logging purposes is not 

 properly constructed for hind clearing. Clearing laud with a donkey engine 

 poorly operated is very expensive, while such a machine properly manned by 

 a good crew is. on the whole, quite satisfactory. The usual way of piling and 

 burning stumps and other debris destroys the soil. The ' windrow ' method Is 

 a more satisfactory way of piling and burning. The clearing of land by the 

 aid of a donkey engine is not as expensive a method as the impression, gained 

 from estimates generally given [indicates]. Stumping powder and the donkey 

 engine are quite satisfactory and rai)id. but rather expensive, agents to use in 

 clearing logged-oft" land." 



Tests of pumping plants in New Mexico, 1908-9, B. P. Fleming and J. B. 

 Stoneking {Nctv AJc.Hco 8ta. Bui. 73, pp. 50, fins. 10). — This bulletin describes 

 a series of tests of seven i)lants made in cooperation with the Irrigation Investi- 

 gations of this Ofhce. 



The methods of making the tests and their details are given and the results 

 summarized. There is also a diagram from which it is possible to determine 

 the practiciibility of pumping under given lifts and given yields and prices of 

 crops. The object of the tests, as stated by the authors, was " to determine as 

 nearly as may be. not only the efficiency of the pumping plant as a machine 

 (which, while of interest to the engineer, is rarely understood by the farmer) 

 but to determine also the fuel use in terms of the head and water pumped and 

 the total cost of ojieration including such items as fuel, lubricating oil. attend- 

 ance, interest, and taxes, estimated depreciation, and wherever possible, the 

 actual area irrigated or capable of being irrigated." 



The power developed by the engines was determined by indicator and Ijrake 

 tests. The lifts were determined by the use of pressure and vacuum gages 

 and the water pumped was measured over weirs, making the results unusually 

 accurate. The authors developed a new method of determining the power 

 developed in the engines, in which, as " all the gasoline engines tested were of 

 the hit-and-miss type, the necessity of using an indicator was obviated by 

 determining l)eforehand the relation between horsepower developed by the 

 engine and the number of explosions per minute, so that during pumping the 

 power delivered to the pump at any time could be determined by simply count- 

 ing the niunber of explosions in a given interval of time. This method was 

 tested thoroughly before trying it in actual pump tests, a small engine being 

 rigged up by attaching a friction brake to a fly wheel and by connecting up the 

 exhaust-valve motion with a stroke counter in such a way that the explosions 

 during a given length of run would be automatically recorded. In addition a 

 small fuel tank was supported on a spring balance weighing to ounces in such 

 a way that the fuel used could be accurately weighed. The engine was then 

 run at several different brake loads during intervals of 10 minutes each and 

 the relation between horsepower developed and number of explosions per 

 minute was platted on cross-section paper." 



Four of the seven plants tested had gasoline engines, one a crude-oil engine, 

 and two steam engines. All of the pumps tested were centrifugal except one, 

 which was a bucket pump. The summaries show the lift, with the fuel cost 

 per acre-foot and per foot-acre-foot. With the gasoline engines the total cost 

 per foot-acre-foot varied from 12.S to 28.6 cents, the high cost being with the 

 bucket pump, and due largely to the low efficiency of this type of pump. The 

 efficiencies of the pumping plants varied from 31.6 per cent for the gasoline 

 engine with bucket pump, to 51.S per cent for one of the gasoline engines and 



