192 



FORESTRY AND IRRIGATION 



April 



place. The maximum flood discharge 

 is about 50,000 second feet. The con- 

 struction plant now on the ground con- 

 sists of an air compressor for driving 

 rock drills, cableways for transporting 

 and placing the material in the dam, 

 a dredge for excavating the gravel 

 and earth to be used for back-filling, 

 a railroad half a mile long for hauling 

 this material to the dam, and a high 

 trestle built across the river from 

 which the major portion of the back- 

 filling will be done. There are two 

 cableways placed parallel to each other 

 and having spans of 1,100 feet. They 

 are suspended from towers, the tops 

 of which are about 1,000 feet above 

 the river. These cables are arranged 

 so that the rock which will be exca- 

 vated from the upper section of the 

 canal can be transported readily and 

 dumped into the dam. The steei skips 

 or boxes in which the material is load- 

 ed when convenient on the cableways, 

 have a capacity each of more than 3 

 cubic yards, or a weight when loaded 

 with rocks of about 5 tons. These 

 skips are dumped by the tower man, 

 who drops the material into the water 

 from a height of from 40 to 60 feet, 

 thus forming very compact embank- 

 ments which, when the back filling is 



added, will be practically water tight. 



The construction plant is now in full 

 operation, and the embankments con- 

 stituting the first section of the coffer- 

 clam will soon be ready for the con- 

 struction of the core walls. The con- 

 tract provides for the completion of 

 the dam and spillways by November 

 17, 1905, and the construction of the 

 dam will provide splendid facilities 

 for the development of power. The 

 minimum discharge of the rive.r at this 

 point which will be available for this 

 purpose, is 2,100 second feet. This 

 can easily be increased to 3,000 second 

 feet by storage on the headwaters of 

 the stream. This water can be passed 

 through walls under a head of about 

 50 feet, which will provide for the de- 

 velopment of more than 17,000 horse 

 power. It is proposed to use the major 

 portion of this power for pumping wa- 

 ter to lands situated above the gravity 

 system of canals which will be con- 

 structed during the coming season. 

 From 50,000 to 75,000 acres can be 

 reclaimed at a reasonable cost by 

 pumping. 



Bids are also asked for the construc- 

 tion and completion of a pole line and 

 telephone system about 18 miles in 

 length in connection with this project. 



RECENT PUBLICATIONS 



The Prickly Pear and Other Cacti as Food 

 For Stock. Bulletin No. 74, Bureau of 

 Plant Industry, U. S. Department of 

 Agriculture. By DAVID GRIFFITHS. Pp. 

 46, with five half-tone plates and several 

 line drawings. Washington, Government 

 Printing Office, 1905. 



An investigation of the forage value of 

 different species of cactus was undertaken 

 by the Bureau of Animal Industry, in re- 

 sponse to numerous letters requesting such 

 information. The investigation revealed the 

 fact that certain cacti have long been in use 

 as forage, and the Bulletin noted here con- 

 . tains descriptions of the varieties most suit- 

 ed, and methods of preparing the same. A 

 large part of the investigation is still under 

 way in regard to the chemical composition 

 of the most useful forms, methods of plant- 

 ing, yield, varieties, methods of preparation, 

 and feeding, etc., but this preliminary Bulle- 

 tin contains some very valuable information 



for the stockman. In view of the recent 

 "spineless cactus" achieved by Luther Bur- 

 bank, it is interesting to note that the 

 Agrostologist says that "if it were not for 

 the spines on this class of plants they would 

 probably have been exterminated long ago, 

 and there is some doubt whether there 

 would be any use for spineless forms." 



The Luquillo Forest Reserve, Porto Rico. 



Buletin No. 54, Bureau of Forestry, U. S. 

 Department of Agriculture. By DR. 

 JOHN GIFFORD. Pp. 52, illustrated. Wash- 

 ington, Government Printing Office, 1905. 

 The Bulletin noted here embodies the in- 

 vestigations made by Dr. Gifford recently 

 on a special trip undertaken for the purpose 

 of determining the general conditions, forest 

 wealth, accessibility, and industrial condi- 

 tions of the Luquillo Forest Reserve, which 

 was set aside by proclamation of President 

 Roosevelt on January 17, 1903. 



