24 



lifting 1,000,000 gallons one foot, adding to the above interest on the 

 plant and maintenance, the cost is increased to 8 cts. per million 

 gallons lifted 1 foot 



It may be of interest to mention that Reidler Pumps have been 

 found the most satisfactory for pumping to high elevations, as the 

 valves in these pumps are automatically closed, there is less loss of 

 water from slip. They are usually driven by triple expansion con- 

 densing engines, steam being delivered at 225 lbs. pressure from water 

 tube boilers, fitted with Gre m's economizer or other good system of 

 feed water heater. 



• As has been shown, elevating one million gallons of water one foot 

 costs 8 cts., thea to pump one million gaUons to 100 feet elevation 

 will cost $8.00, 200 feet $16.00, to 300 feet $24.00. 



By carefully conducted experiments made at the Hawaiian Expe- 

 riment Station, where the water used in irrigating was carefully 

 measured, it was found that the amount of water required to produce 

 22,9T4: lbs. of available sugar, equalled 4,751,950 gallons, and to pro- 

 duce 20,900 lbs. of available sugar from the same area, 1,656,394 

 gallons of water were required. That is to say, that by the application 

 of one inch of water per week only 2074 lbs. of sugar less, were 

 produced, than where three inches of water were applied weekly. 

 It was also found that 3 inches of water applied per week gave the 

 maximum yield; but from the foregoing figures it is shown that the 

 most profitable amount of water to be applied between one and three 

 inches weekly will altogether depend on the cost of water delivered 

 on the land. 



In pumping water to the higher lands, these can stand a much 

 greater reduction in the amount of water used than at the lower levels, 

 and in taking water at a certain figure, say, from an irrrigating 

 company, the amount which can be profitably used may from the 

 foregoing figures be closely calculated. 



Cane makes the most rapid growth during the hot months or 

 between May and November, where there is sufficient moisture in the 

 soil. The difference in temperature during this period in Arecibo is 

 about 4 degrees F. A saturation giving about 77% of the soil's capacity 

 for water will give the best results. The maximum of water which can 

 be profitably used in Porto Kico will probably not exceed two inches 

 per week as against three inches in the Hawaiian Islands. 



The average yield of sugar per acre will also fall off in about the 

 same proportion and will not be more than about 4 tons per acre as 

 against 6 tons average in Hawiiii under the same growing peiiod. And the 

 maximum yield under the most favorable conditions in Porto Rico will 

 not exceed 7 tons of sugar per acie as against 10 tons in Hawaii over 

 any large area. This is due to climatic differences and also because the 

 soil in Porto Rico contains more clay and is not so well drained, and 

 consequently not so well aerated. 



Rarinfall is not to any extent affected by the removal of forests 

 but is governed largely by the topography of the ci)unti-y and the 

 direction of the prevailing winds. 



In irrigating cane, water is conserved by having the cane rows 

 not more than 30 feet long, filling these one at a time from the lateral 

 ditch, then closing them off. 



In making any permanent impiovement, the cost, in its relation 

 to the income it will bring, should always be carefully estimated, so 

 the effectiveness of the different systems of delivering watei's for 



