THE IRRIGATION AGE. 



base wall. This core consists of a double thickness of 

 two inch plank, spiked to uprights two feet apart 

 Above this core or fence, all -the material is carefully 

 puddled with water; below it, the rock is loose and 

 open and free to drain out any water that may find 

 its way through the ponderous mass of puddled earth 

 behind it, and through the core. All the possible leak- 

 age water is thus robbed of its velocity head and has 

 no power to do harm to the structure, even should it 

 appear. 



INTERESTING FEATURES OF HEAD GATES. 



Among the_ interesting engineering features of 

 the works are the canal head gates, which are being 

 built by the American Bridge Company. They are 

 radial gates, a segment of a cylinder, hung on the side 

 walls or piers between the gates, where the axle goes 

 through each wall. These walls have a steel frame 

 fastened on bed rock. The gates and frame are all of 

 structural steel, the facing only of wood, with a rubber 

 flap, or belt, connecting the division walls and the 

 gates against which the water presses and makes them 

 water tight. The gates are twelve feet wide by eleven 

 feet high, hoisted by chains and windlass from bridge 

 above. With this form of gate the pressure is not 

 felt, as the force resisting is at right angles to the 

 surface and transferred to the axle and only the weight 

 of the gate is considered. This type of gate is to be 

 used throughout for waste gates, lateral gates, head 

 gates, controlling gates, etc. 



TUNNELS UNDER THE DAM. 



Another novel feature is the great tunnel under 

 one of the islands and under the battery of waste gates, 

 by which the river is to be diverted from its present 

 bed, while the north dam foundation is being laid. 

 From that time until the completion of the dam, the 

 water will necessarily have to flow through the tunnels. 

 The tunnels are four in number 10x10x80 feet, lined 

 with concrete, which are now under construction, and 

 under the level of the river, but coffer dammed to keep 

 the water out and about fifty feet under the surface. 

 The average flow of the river is 6,000 second feet while 

 the tunnels will have a capacity of 10,000 second feet 

 and are to be closed by eight large steel gates, brass or 

 bronze mounted, and each gate is 5x10 feet in the clear 

 and strong enough to withstand a pressure of seventy 

 tons. The controlling device or capstan for raising 

 is ball bearing and made by the Coffin Valve ^Com- 

 pany, of Boston. The approximate cost of tunnels 

 and gates is $50,000. The gates can be raised or 

 lowered by one man, but probably will only be used 

 at the time when the third dam or last opening is 

 being closed. When, however, these gates are closed, 

 the water will form a large reservoir which will extend 

 up the river six or seven miles and take two days to 

 fill. It is expected to be a busy time for placer miners 

 in the canyon below, as it will give a chance for the 

 examination of the bottom of Snake river, which has 

 placer gold of considerable quantity that has never 

 been exposed. This will also be an interesting time 

 for those curious to see the perpetual stream, once held 

 at bay. 



THE CONSTRUCTION PLANT. 



' The construction of the dam is being carried on 

 by Messrs. Faris & Kesl, of Boise, Idaho, who have 

 built a private temporary dam across Snake river, 800 

 feet long. A channel in the middle, sixty feet wide 

 by twenty deep was filled by large cribs filled with 



rock. This dam raised the water about five feet and 

 forced it into a canal of about one-half a mile in 

 length, made by clearing the loose rock and debris 

 from bed rock, and anchoring a fence with bolts to 

 the same. This conducts the water to a platform of 

 rock in the canyon, where a power plant is established. 

 A turbine wheel operated by 100 second feet of water 

 falling thirty-one feet which drives a 200 kilowatt 

 direct current generator. The current is used to run 

 electric drills, to blast the two miles of rock in the 

 canal, which is used in construction of the dams. 

 Electric shovel is used as a derrick to hoist rocks of a 

 yard and more into cars hauled by electric trolley 

 motors. These cars are hauled to the dam and raised 

 with a Ledgerwood cable. A cable stretched on toweiv 

 lengthwise of the dams, with a clutch carriage oper- 

 ated by smaller cables and when the skip or body of 

 the small car is in midair is tripped and the rock 

 comes down on the other rock with great force, as- 

 suring the settlement of the whole mass. All this is 

 done by electric power furnished by the contractors. 

 This has been a large expense to the contractors, but 

 will be money well expended in the long run. 



CANALS. 



The main canal now under construction is eighty 

 feet on the bottom and is to carry a depth of ten feet 

 of water. The slopes of banks are two to one and 

 thirteen feet high above the center of the canal. The 

 canal on an average, banks and all, takes up a width 

 of almost 200 feet. The first four miles have con- 

 siderable solid rock, but from there on it is excavated 

 in a lava ash soil, very fine and mellow. One fill is 

 thirty-four feet high, and there is to be no flume on the 

 entire length. About twenty-five miles of canal will 

 be completed this year and is expected to be com- 

 pleted by Christmas. One place on the main canal, 

 eight miles below the head, a dam of earth is being 

 constructed across a large draw called Dry Creek, to 

 avoid a long detour of three miles. The dam is forty- 

 eight feet high in the lowest place in the draw and 

 one mile long. To make the dam firm and have it 

 settle, water has been piped three and one-half miles 

 from a warm spring, and as the earth is put in, it is 

 sprinkled and rolled. Fifteen per cent of moisture is 

 used in the earth. This dam will form a reservoir 

 which will hold a supply for three days run, in case 

 of break or repairs. The grading is done with Fresno 

 scrapers drawn by four horses, and wheel scrapers and 

 slips in the usual way. As the canal is through a 

 desert the construction camps exceed thirty in number. 

 On the whole there are about 400 teams and 500 men 

 engaged upon the canal and dam. These camps, al- 

 though most of them are near water, it is yet so far 

 to the river, down in the impassible canyon, 500 feet 

 deep, that in order to get water, a steam or gasoline 

 hoist raises it in a barrel suspended on a cable 600 

 feet long, on an incline into the canyon. In this way 

 water is hoisted to the rim and then hauled in tank 

 wagons some five or six miles. The grading of the 

 twenty-five miles of canal is under contract with Nel- 

 son Bennett Company, of Tacoma, Wash. The first 

 twenty-five miles of large canal reaches a point from 

 which 30,000 acres of land can be reclaimed and are 

 already thrown open for settlement. 



Several thousand acres have been filed upon and 

 some of the settlers are clearing and breaking ground 

 in advance of the coming of the water next spring. 

 The land has a very gentle slope. 



