HYDROLOGY. 171 



The question then, "What facilities for manufacturing does our state 

 present? becomes one of the highest importance, especially so to our 

 preponderating agricultural interests. Chief among these is water 

 power. 



In the district ur.der consideration there is a vast amount of water 

 power situated in the heart of an exceedingly rich farming country, 

 with abundant facilities for transportation, and, not by any means a 

 subordinate consideration, in the midst of an intelligent, cultured so- 

 ciety. The object of this chapter will be to give trustworthy facts for 

 the guidance of capitalists, who may have the prescience to foresee 

 that the natural facilities for manufacturing in the interior must in 

 the immediate future be utilized to their utmost capacity and must 

 become correspondingly valuable. 



Water Power of Rock river. For a portion of the facts here 

 given, credit is due the report of Brevet Maj. Gen. James H. Wilson, 

 on the survey of Rock river, under the direction of the U. S. Engi- 

 neer Department, and for another portion to a very careful survey of the 

 lower portion of the river by Edward Ruger, C. E., made to deter- 

 mine the availability of Lake Koshkonong as a storage reservoir. I 

 am indebted for the use of the latter to the kindness of J. M. Cobb, 

 Esq., through whose efforts the enterprise has been brought to a suc- 

 cessful issue. The remaining data have been gathered during the 

 progress of the present survey. 



The entire area drained by Rock river and its tributaries in Wis- 

 consin is 3,635 square miles. From the Table of Rainfall at Milwau- 

 kee, given in Dr. Lapham's report, this volume, it appears that the 

 average rainfall for the past thirty years is 30.27 in., which may be 

 assumed as at least approximately correct for the Rock river valley. 

 The average fall for some portions of Wisconsin is given in Gen. 

 Humphrey's work on the hydraulics of the Mississippi at 35 inches. 

 But reckoning at 30 inches, the rainfall upon the drainage area under 

 consideration would be 253,344,960,000 cubic feet. Now it is asserted 

 by varidus authorities, based on experience, that one-half the rainfall 

 can be utilized. This would give 126,672,480,000 cubic feet per an- 

 num. Mr. Ruger says: "From personal observations, and after con- 

 sulting many authorities as to rainfall, springs, evaporation, filtration, 

 etc., I estimate that the total annual quantity of water passing in 

 Rock river at the state line, including Turtle Creek, is 98,4-37,536,000 

 cubic feet," which may be regarded as a safe estimate. The daily 

 supply, by this estimate, would be 269,691,879 cubic feet. We need 

 next to ascertain what is the average descent of this volume. Some 

 of it falls over 600 feet, while other portions practically no distance. 



