114 



THE IRKIGATION AGE. 



it will usually be found that the cost of repairs ia 

 about in proportion to the speed. 



Nearly all engines on the market are four-cycle, 

 but there are a few two-cycle, meaning four strokes or 

 two strokes respectively, per cycle of operation. A 

 cycle means the interval of time between explosions, 

 and you will notice that four strokes, or two revolu- 

 tions, are required for each explosion in most engines, 

 while in some there is an explosion every revolution. 

 In a four-cycle engine the first stroke draws in the 

 gasoline, the next (back) compresses the mixture of 

 gasoline and air ready for ignition at the back end; 

 the third stroke is just after the explosion, and the 

 fourth (back) serves to expel the gases of the explo- 

 sion. In two-cycle engines the forward stroke follow- 

 ing the explosion is the first, a combination of ports 

 being so arranged that the exploded gases pass out 

 at the end of the stroke, the new mixture of gasoline 

 and air being quickly forced into the cylinder, com- 

 pressed on the back stroke and ignited. Some two- 

 cvcle engines give very good, results, although it can 

 scarcely be claimed that they will operate with as little 

 fuel as a four-cycle engine, since it is evident that 



decreased atmospheric pressure, which prevents the 

 engine from getting as much active air in its cylinder 

 at a high altitude as it does at sea level. It gets a 

 cylinder full, but there is less oxygen in it, and it is 

 the oxygen that combines with the gasoline to make the 

 explosion. FUEL CONSUMPTION. 



An engine of 10 H. P. or more will give one horse- 

 power for ten hours with one gallon of gasoline, while 

 with the sizes below 10 H. P. between 1 and l-*4 gal- 

 lons will be required. Distillate or alcohol can be used 

 in most engines, without any change, the quantity re- 

 quired being about the same as for gasoline. If fuel 

 must be hauled very far the advantages of a gasoline 

 engine are plainly shown when compared with steam. 

 One pound of gasoline will give one horsepower for 

 an hour, but with a steam engine from five to eight 

 pounds of fuel- are required. It must also be remem- 

 bered that when a boiler and engine are used, fuel is 

 consumed in getting up steam for about an hour before 

 work can be commenced, and that after the engine is 

 shut down there is always a great deal of coal left in 

 the fire box that is wasted. There is no such loss with 



Haying Scene in the North Platte Valley, Nebraska. 



some portions of the exploded gases will remain in the 

 cylinder after the new mixture enters, even though the 

 incoming mixture forces out some remnants of the 

 exploded gases left in the cylinder. Two-cycle engines 

 give an explosion at every revolution, and thus more 

 power is secured from a cylinder of certain size than 

 from a four-cycle engine. It is, therefore, evident that 

 a two-cycle engine can be bought for less money than 

 a four-cycle, as less metal is required to build it, but 

 the cost of operation and the amount of fuel used will 

 be more. Probably ninety-five percent of all gasoline 

 engines on the market are four-cycle. It is seldom 

 that a good gasoline engine of size below 25 H. P. can 

 be bought for less than $35 or $40 per horsepower. 



EFFECT OF ALTITUDE. 



Since a gasoline engine cannot give its full quota 

 of power at an altitude greater than that at which it 

 was made and tested, it is necessary to make proper 

 allowances for this loss of power, which is equal to 

 about three percent for each one thousand feet of alti- 

 tude. At five thousand feet altitude, a 10 H. P. engine 

 will give about 8y 2 H. P., while at ten thousand feet 

 it will give but 7 H. P. This loss is occasioned by the 



gasoline, as no fuel is consumed when the engine is not 

 running. 



ATTENTION REQUIRED. 



With a properly installed plant it is unnecessary 

 to remain close to the engine, a visit in a couple of 

 hours or so being sufficient. If the lubricators are of 

 ample capacity, and the circulating water properly ar- 

 ranged, the engine will run until the gasoline supply 

 is exhausted. 



ENGINES FOR PUMPING. 



When buying an engine to run a pump, be sure 

 that it is of ample capacity. Take the power recom- 

 mended by the pump manufacturer, and add 15 percent 

 or 20 percent. Then select an engine that will give 

 this amount of power when the proper allowance has 

 been made for altitude. If a pump requires 3y 2 

 H. P. theoretically, the pump manufacturers will usu- 

 ally recommended double thus, or 7. H. P. A gasoline 

 engine to run this pump should give at least 8 H. P., 

 and if the altitude is 5,000 feet a 10 H. P. engine 

 should be selected, giving 8y 2 actual H. P. It will 

 then be found that the engine will run the pump read- 

 ily, taking an explosion not more often than two times 



