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NEAR VIEW OF THE BOILER DURING THE TEST.
under the intense heat applied during the
The pressure gauges, height of water,
Statistics of the test are of little in-
one which the common type could not
that a boiler so equipped could not, under
the common conditions which cause exfallen about five inches below the crown- plosions, create a disaster such as we so sheet and a temperature of 1,125 degrees often read of in the daily papers. Bein the firebox was recorded by a pyro- cause of the reinforcement of the firebox, meter. In other words, the crownsheet little or no damage could result even if had attained a good working heat. At a blowout should take place in one of this point the fire was shut off and cold the sections, as it would be so small as water turned in the boiler until the steam to amount practically to the opening of a pressure was somewhat reduced. In spite valve for the relief of the unusual presof this terrific treatment, and the fact that at the time the crownsheet was red It is greatly to be hoped, if this form hot, the boiler withheld a pressure of 230 of boiler construction solves the explopounds to the square inch, and showed sion problem, that it may be adopted no ill effects further than a few trifling throughout the world, wherever boilers
DAMMING THE MISSISSIPPI
F. G. MOORHEAD
OT far from the spot where a thousand men are working, beaver like,
last galoot was ashore," a subserviently render up to its master mile-wide dam is being built which will 250,000 horse-power with which to run completely change the contour and the factories, mills, and workshops of the topography of the Mississippi River and very heart of the grain belt. Already, on the historic land thereabouts. Incidentally both sides of the Mississippi, the dam a steamboat canal, nine miles long, built has begun to assume shape. Two gangs forty years ago at a cost of $8,000,000, of men are throwing out abutments and is to be completely drowned out, with creeping toward each other across a not a stick or a stone left to show where watery path. Twenty million dollars will it once made possible the passage of the be spent before the two gangs meet, but treacherous Des Moines rapids.
the investment is considered a good one The sons of the men who damned the by some of the shrewdest financiers of Mississippi a generation ago are now the country. busily engaged in damming it. The work For over sixty years Keokuk has will occupy two years more, but already dreamed of harnessing the turbulent
bottom drops twenty-four feet to the navigable depths of the open river below Keokuk. At an annual cost of $50,000
the government has maintained this canal waters of the Mississippi and making the
for forty years.
Within the next two Des Moines rapids do the work of man. years it will have disappeared under As long ago as 1848 the Mississippi twenty feet of water, part of the bed of River Improvement Association a new inland lake forty miles long and formed, with a capital of $1,000,000, its from one to five miles wide. For the objects being to improve navigation and dream of two-thirds of a century is being harness the water power that might be
realized at last. Five years ago, after developed in the process. The Civil War numberless disheartening failures, a bill passed and still the project remained a was passed through Congress granting dream. The United States government
a franchise and the first glimmerings of went a long ways toward shattering the a realized dream began to appear. dream for all time by building a nine- It was no small task to get both houses mile canal alongside of the perilous of Congress to agree on a franchise rapids where many a steamboat and which establishes the precedent of buildmany a raft had met demolition, estab- ing a dam entirely across the country's lishing three locks for the purpose of largest river. But the Keokuk boosters raising and lowering craft from one level were shrewd. They introduced old river to another. Flowing through the high, pilots and captains before the committees limestone gorges on either side, step by to testify that the dam would improve step the solid lime rock of the river's navigation rather than hinder it; they enlisted the co-operation of the army Mr. Hugh L. Cooper, the engineer in engineers and voluntarily agreed to re- charge, has given Keokuk assurances place the canal and its three locks with a that the work can be completed in thirty single lock, which would answer every months. The first year has been one of purpose, and the twenty-year old dry preparation mainly, but the end of 1911 dock with a new one, and from now to will find the da well under way, exthe end of time to supply the power to tending out from both the lowa and the operate the new lock and the new dry Illinois shores, and the power house dock, absolutely free of charge. On practically completed. January 27, 1905, the lower house passed The project gives to the Mississippi the bill granting the desired franchise. Valley the largest water-power developOn February 2, it passed the Senate and ment in the entire country, with the on February 9, 1905, President Roosevelt single exception of the combined plants signed the bill.
at Niagara Falls, and the largest dam in Immediately there began the hunt for the world, with the single exception of capital. The bill required that the work the Assouan dam across the Nile in begin within five years and be completed Egypt. There will be required in the within ten. It was not until a month or construction 500,000 cubic yards of two before the five-year limit had ex- masonry, 500,000 barrels of cement, and pired that work actually began. Even 7,000 tons of steel. then the doubters remained, crying that The dam, including abutments, will be the limestone cliffs were being uncov- 4,700 feet long. It will extend from a ered simply to keep the franchise and point a little north of the center of the that the dam would never be built. But town of Hamilton, Illinois, due westas the weeks passed and the gangs of ward across the river to a point near workmen grew, from a few score to sev- the Iowa shore, under the bluffs at eral hundred, and the approaches to the Keokuk, where the power house, 1,400 dam on the Illinois shore gradually feet long, will link shore with shore. The began to show, the scoffers fled and all mammoth dam will be of solid concrete, Keokuk joined in such a jubilation as thirty-five feet wide on the bottom and the old Mississippi Valley has not known about thirty feet high. The upper stream since the palmy days of steamboat racing face will be vertical with a rounded top
. On January 8, 1910, definite announce- eight feet wide, the lower side ending in ment was made that the dam would be a curve connecting with the bottom, so built. By the first of February several that the water coming over will not fall, score of men were at work. The con- but slide down the face and be given a struction was continued uninterrupted horizontal direction at the bottom of the from that time, and early in December, river. The whole height is thirty-seven 1910, five hundred men started to work feet, the dam being locked into the rock on the Iowa shore.
bottom seven feet deep, to prevent any water getting underneath. Outside the the main dynamos which are in use on power house there is already consider
the job. able depression in the rock, but the plan Beneath the floor of the power house is to deepen and widen this depression will be a series of forty-seven passages so as to get rid of the water quickly as conducting the water to the turbines. it passes under the power house and These passages will be ali formed in solid through the wheels.
concrete, constructed so as to offer the The long power house will be divided least obstruction to the water. Each into alleys forty-five and thirty-seven generator and turbine is arranged to be feet wide, respectively. Forty feet over- cut off by steel head-gates, which close head in the alley facing the Keokuk side the openings for the water, and allow of the river will be thirty ton cranes, sup
them to be inspected. Heavy screens, ported on the walls, for the handling of consisting of iron bars, will stand in
the heavy machinery. In the alley near- front of each turbine opening, to prevent est the river will be ten ton cranes for the entrance of sticks and stones, which lifting the heavy screens guarding the would injure the blade of the turbines. entrances to the turbines and for the The maximum head of water on the handling of the headgates for shutting wheels will be at low water and will off the water. There will be forty-seven amount to thirty feet. At extreme high immense generators of 4.500 horse- water the head is expected to be twentypower each, working on a vertical shaft one feet. At high water, therefore, the like the generators at Niagara. These plan is to use all three turbines to drive generators will be twelve feet in diam- the generator, when the head is least, but eter. On the same vertical shaft will be the flow is abundant; at low water, when three different turbines, one over the the head is large, two, or even one, of other, about nine feet in diameter, all the turbines in action will be sufficient. working together to drive the generator. The turbines will be made so they can Besides the big 4,500 horse-power gen
be discontinued when not in use. erators, provision is made for three The dam will impound the waters until exciter generators, which are intended to a lake will be formed which will overflow furnish current to excite the magnets of the lowlands along the Iowa and Illinois