It would appear that the reason why the census does not show the extent of the hydro electric development is that the method of gathering returns from manufacturers did not cover the situation. Probably a very large part of the power credited as electric is hydro electric, and another large part escapes enumera tion under the head of manufacturing or mining, because it is utilized by street railways and lighting companies whose reports do not always indicate the source of their supply. Hence the census figure of 1,823,000 total water power used in manufacturing in 1909 probably repre sents less than half of the total use, and at the present time it is a fair estimate that the total hydro-electric horse power in use in the United States for all purposes is 5,000,000 and the capacity of these plants is fully 9,000,000 horse power.
A description of a few of the hydro-electric power and transmission plants will afford some idea of the actual accomplishments in this field. The Pacific Light and Power Company of Big Creek, Cal., has utilized a small stream for a phenomenal power development. The creek drops 4,000 feet in six miles and by two in stallations the engineers utilized 3,680 feet of this head. The equipment includes three large concrete storage reservoirs that will hold 4,500,000,000 cubic feet of water. From these the water flows first through a 10,360 foot tunnel, and 425 feet of standpipe, arriving at Power Station No. 1 with 1,900 feet effective head. Here are installed two 17,500 k-v-a gen erators and four 10,000 horse power Pelton water-wheels, each of one nozzle. The tail water from this plant runs off through another long tunnel and pipe, and delivers at Power Station No. 2, with 1,780 feet effective head. Here there is another installation of a total of 35,000 k-v-a generators and 40,000 horse power water-wheels. These two stations have an ulti mate capacity of double the power they are now supplying. The dynamos send out the power over a line of 240 miles, made of steel aluminum wires, carried on steel towers, at the enormous pressure of 150,000 volts.
The Pacific Gas and Electric Company, with headquarters at Denver, Cal., have 150 miles of transmission line operated at 110,000 volts, 380 miles at 20,000 volts and many miles of minor lines at 11,000 volts. In 1913 they were equipped with generators for 25,000 kilowatts, but a capacity of 50,000. They use 12,500 k-v-a generators, each driven by two 8,500 horse power Pelton wheels of single nozzle type. They now have in all 11 hydro-electric stations, and their highest head is 1,345 feet. The Sierra and Santa Fe Power Company, at Stanislaus, Cal., in 1907-08 built a plant which
is running at 34,000 kilowatts, the capacity may be increased any time to 75,000 kilowatts, which is the equivalent of about 100,000 horse power. The plant includes four 8,500-kilowatt genera tors, and eight 6,000 horse-power single-nozzle Pelton wheels.
The Tallulah. River plant of the Georgia Railway and Power Company, which supplies Atlanta and vicinity, is one of the most notable in the South. The electric current is sent 90 miles to Atlanta and 50 and 80 miles in other directions, at as high as 110,000 volts. . The storage reservoir has a billion and a quarter feet capacity, and there is a large diversion dam. A tunnel of 6,670 feet carries the water to the six penstocks, each of which serves a 10,000 kilowatt Francis turbine of 514 revolutions per minute. A large medium-head plant is that of the Great Western Power Company at Las Plumas, Cal., which was completed about 1910, and supplied with five 10,000-kilowatt genera tors, each driven by 18,000 horse-power, vertical shaft, single-runner turbines. The head here is 465 feet, and the water is carried 15,168 feet through a pressure tunnel. An illustration of large power obtained from a low head is seen in the plant of the Mississippi Power Com pany, at Keokuk, Iowa, which sells power in Saint Louis at the low rate of $18 per horse power. In 1913 the plant was developed for 112,500 kilowatts, but there is an ultimate capacity of 225,000 kilowatts. They use 7,500 kilowatt generators and 10,000 horse-power Francis turbines, employing 32 feet head. The Alabama Power Company's installation at Coosa Lock, in 1914 totaled 52,000 kilowatts, with 78,000 ultimately available. They use 17,500 horse power single-runner turbines, direct-connected to 13,500 k-v-a generators, and have 68 feet head of water. The No. 3 plant of the Niagara Falls Hydraulic Power and Manufacturing Company uses generators to a total of 130,000 k-v-a, and has 13 10,000 horse power turbines running under 210 feet head. The power projects now under way at Niagara indicate an increased development on the Amer ican side of at least 600,000 horse power, and as much on the Canadian side.
The great trunk line railways of the country are most of them planning for a greater or less electrification of their lines, and naturally will avail themselves of water powers along their routes wherever they can be used economically. Much of the water that is dammed for irriga tion or transported for city supply can be used en route for supplying power without loss, and this is already being done, and is sure to become a common practice.