117 



una noting the rate of filliiig, indicate a capacity of 12,000 gallons per 

 (lay, under a head of Cfteen feet, the water-table being depressed five 

 feet when the test was made. This is probably about the usual dry 

 weather depression. Allowing 50 per cent, interference of wells, this 

 Aalley should produce 50,000 gallons of water per day during the driest 

 year. Sucli a supply would be sufficient for a town of 1,000 population, 

 and would be of first-class quality. 



There arc many valleys of this type in the Knobstone region, that 

 would be good water producers for small towns, or for manufacturing 

 l)lants. The water would be of excellent character and exceptional purity. 

 The larger valleys, such as Bean Blossom, should furnish sufficient well- 

 water for cities of 10,000 inhabitants or less, or for extensive industrial 

 plants. 



The conditions affecting the impounding of water in the Knobstone 

 region can not be adequately discussed without introducing cerl^ain cli- 

 matological data. Since these data will also serve for the limestone 

 region, they may properly be discussed in full at this point. 



The following climatological data are obtained principally from the 

 publications of the U. S. Weather Bureau. Between the coldest and 

 warmest portions of this section of the State there is a difference of 

 about 5 degrees in the mean annual temperature. The wannest locali- 

 ties are in the Wabash and Ohio valleys, the temperature increasing quite 

 regularly from the upper to the lower portion of each valley. The mean 

 annual temperature varies from about 52 degrees at the north end of 

 the area, to nearly 57 degrees at Evansville. 



The length of the growing season is somewhat greater in the south- 

 ern than in the northern portion of the area under consideration. It 

 is from two to three weeks longer at the Ohio River than in the northern 

 part of Indiana. 



The mean annual precipitation varies from about 40 inches to 55.21 

 inches (at Marengo). The maximum precipitation for any one year 

 within the area was 97.38 inches at Marengo, in 1890. The maximum 

 for any one month is 18.00 inches, also at Marengo, in August, 1888. The 

 minimum for one month is a trace in October, 1908, at Mt. Vernon. Pre- 

 cipitations of 10 inches or more in one month are not uncommon, 

 having been recorded an aggregate of 35 times at the seven stations 

 reporting within the area, Teii of these were in the month of Marah, 



