202 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1910. 



present and prospective commerce of the Mississippi River ; the said dry dock 

 and its appurtenances shall be such as to give space, facilities, and conven- 

 iences for the repair of vessels at least equal to those afforded by the existing 

 Government dry dock aud shops at the Des Moines Rapids Canal. 



Other conditions provide for further approval by the Secretary of 

 War and upon completion place in the .United States the ownership 

 and control of the lock, dry dock, and their appurtenances, and the 

 operation and maintenance thereof. 



As still further protection to navigation, and in the interest of 

 fisheries, section 2 of the act requires: 



That the withdrawal of water from the Mississippi River and the discharge 

 of water into the said river, for the purpose of operating the said power stations 

 and appurtenant works, shall be under the direction and control of the Secre- 

 tary of War, and shall at no time be such as to impede or interfere with the 

 safe and convenient navigation of the said river by means of steamboats or 

 other vessels, or by rafts or barges : Provided, That the said company shall 

 construct such suitable fishways as may be required from time to time by the 

 Secretary of Commerce and Labor. 



Under authority of this act, after the delay of preparing to finance 

 the construction, in 1909 work was actually begun to continue until 

 completion, it is estimated, some time before July 1, 1913. 



In direct charge of the hydraulic construction is Mr. Hugh L. 

 Cooper, of New York. The Stone & Webster Engineering Corpora- 

 tion, of Boston, has direct charge of the electrical installation, includ- 

 ing the transmission and distributing lines. 



CHARACTER OF RIVER BED. 



The site of this dam and hydro-electric plant, as a glance at the 

 map will show, is above the junctions with the Mississippi, of 

 the Ohio, Missouri, and Illinois Rivers. It is at a point where 

 the three States of Iowa, Missouri, and Illinois touch, 140 miles 

 from Des Moines, 140 miles from St. Louis, and 220 miles from 

 Chicago. 



The dam itself is being built upon a river bed of blue limestone in 

 a region stable from a geological point of view. The surface of the 

 river bed at this point is naturally clean and free from the cracks and 

 fissures of rock of igneous origin. The average depth of the river 

 at this point is from 5 to 6 feet and the variation is slight. 



Under an act of Congress July 25, 18G6, a bridge joining Keokuk 

 and Hamilton was built. This bridge crosses the river at a point 

 1,066 yards below the location of the Keokuk Dam. The following 

 description of the river bed in the vicinity of this bridge is taken 

 from page 1006 of the Report of the Chief of Engineers, United 

 States Army, for the year 1878, Part 2 : 



