1906 



FORESTRY AND IRRIGATION 



317 



in a forest policy, and, among the va- 

 rious conditions studied from which 

 to draw conclusions, the status of the 

 people whom it most concerns is not 

 the least important. 



The wasteful custom of making 

 clearings in these islands is deeply 

 rooted and is one that has been prac- 

 ticed for rears with scarcely any re- 



straint. Very satisfactory results are 

 ensuing from making arrests, which 

 seems to be the most effective way of 

 solving the problem. During the past 

 two years many arrests have been 

 made, which has resulted in an appre- 

 ciable decrease in the making of clear- 



ings. 



PUMPING WATER 



Fourth Paper Suggestions for the Construction of Small Pumping Plants 

 for Irrigation Kind of Wells Adopted for Securing Water from Gravels 



KIND OF WELLS ADAPTED EOR SECUR- 

 ING WATER FROM GRAVELS. 



The most economical well for se- 

 curing water in the quantities needed 

 for irrigation is a well from 12 to 15 

 inches in diameter, extending into the 

 water-bearing gravels 30 to 60 feet, 

 according to the thickness of the 

 gravels at the place where the well is 

 drilled. Strainers for these wells can 

 be made of slotted galvanized iron. 

 The perforated metal should be placed 

 opposite all the coarse gravels, or at 

 a depth of 10 feet below the surface 

 of the water. These- strainers can be 

 made by any mechanic by punching 

 y% by 1 inch slots into heavy galvan- 

 ized iron and then riveting the sheets 

 into cylinders of the proper diameter. 

 The cylinders should be rolled in such 

 a way that the burr made by punch- 

 ing the slots will come on the outside 

 of the finished casing, so that the slots 

 will be vertical. A much better strainer 

 can be made by purchasing the metal 

 in sheets already perforated. For this 

 purpose steel sheets 48 by 120 inches 

 in dimensions, perforated with hit 

 and miss slots, 3-16 by 1 inch, and gal- 

 vanized after the perforations are 

 made, will make ideal strainers. When 

 rolled into cylinders these sheets form 

 a casing about 15 inches in diameter. 

 In constructing the well the perfor- 

 ated sections should be put in place, 

 one above another, to within about 10 



feet of the w T ater level ; from this 

 depth upward the casing should not 

 be perforated. 



AMOUNT OE WATER THAT CAN BE OB- 

 TAINED FROM THE WELLS. 



Wells constructed as above, in 

 gravels similar to those in the South 

 Platte and Arkansas valleys, will fur- 

 nish at least l /\ gallon of water per 

 minute for each square foot of strain- 

 er surface in the well, when the water 

 in the well is lowered I foot by pump- 

 ing. If the water in the well is low- 

 ered 10 feet by pumping, the amount 

 of water recovered should amount to 

 at least ten times as much, or 2^ gal- 

 lons per minute per square foot of 

 strainer. If a 15-inch well is drilled 

 in good water bearing gravel to a 

 depth of 40 feet, the lower 30 feet of 

 which is strainer surface, and if the 

 pump lowers the water in the well 10 

 feet, the amount of water supplied by 

 the well should amount to at least 

 300 gallons per minute. A careful test 

 of the water works at North Platte, 

 Nebr., showed that the strainers in the 

 wells were furnishing 3-10 gallon of 

 water per minute per square foot of 

 strainer surface, when the water in 

 the wells was lowered 1 foot by pump- 

 ing. The average of eleven pumping 

 plants in the Arkansas valley kas 0.33 

 gallon of water per minute for each 

 square foot of strainer surface under 

 one foot head. 



