DRAINAGE OF WET LANDS OF SOUTHERN LOUISIANA. 79 



As the headings in the table on page 78 are necessarily much abbreviated a 

 short explanation of those that may seem obscure will be given. The first 

 column gives the water horsepower of the plant of the assumed capacity. The 

 second column states the type of plant, and also whether the engine is belted or 

 direct connected to the pump. Under efficiencies, the third column gives the 

 mechanical efficiency of the engine, the fourth that of the belt, if any, and the 

 fifth the combined efficiency of engine and belt. The sixth column gives the indi- 

 cated horsepower of the steam engine and the brake horsepower of the gasoline 

 engine. The seventh column shows the pounds of water consumed by the 

 engine, in the form of steam, per indicated horsepower hour; then the total 

 steam used per hour would be the product of the two next preceding columns, 

 plus 20 per cent for use of the usual auxiliaries and oil burners; these figures 

 are shown in column 8. The ninth column gives the amount of fuel oil per 

 hour necessary, assuming that 1 pound of oil will evaporate 12 pounds of 

 water. In like manner column 10 indicates the number of gallons of gasoline 

 required per hour, on the basis of 1 pint of gasoline per brake horsepower hour. 

 The total cost of the fuel per hour (columns 11 and 12) is found by multiply- 

 ing the total amount used per hour by the unit cost, which is here taken as 

 $1.25 per barrel of 320 pounds for the fuel oil and 12 cents per gallon for the 

 gasoline. The total cost per year is found by multiplying the cost per hour by 

 270, this being the number of hours the plant will be required to run to remove 

 a depth of 1 foot of water from the 1,000 acres. Under this heading the first 

 column gives the cost for a pump efficiency of 100 per cent. The figures in the 

 other columns are derived by dividing the first column by the various pump 

 efficiencies. 



It will be noted in the above table that efficiencies of pumps are given from 

 30 to 100 per cent. Of course, the higher limit will never be attained, but the 

 lower one doubtless will be reached when such pumps are worked under a heavy 

 overload. The usual efficiency for average-size plants probably will vary 

 between 55 and 65 per cent. In using this table it must be remembered that 

 the higher-class engines can not be purchased in smaller sizes than 75 horse- 

 power. 



In the following table the above summary has been applied to a special case 

 of a tract of 3,500 acres, showing the fuel costs per year for removing depths 

 of water from 2 to 6 feet at the rate of 1 inch in depth per 24 hours. The 

 greater depth of water might be encountered when the tract is first reclaimed, 

 but the usual rate would be about 24 inches in depth per year. 



