Deep Artesian Wells in the Dakotas. 165 



the United States Indian Agents at these points ; the well 25 

 miles southeast of Chamberlain is on the authority of the well 

 driller, Mr. Kaufman, and the well at Tripp is stated by the 

 chairman, Mr. Hassett, of the Town Board as " about 63° F." 

 A 2500-foot boring on the Rosebud Reservation, 65 miles 

 southwest of Pierre, was tested by a pair of self-registering 

 maximum thermometers, sent to its bottom by my assistant, Mr. 

 F. H. Ainsworth. The mean annual temperatures which have 

 been used for the comparisons are based on observations which 

 have been made by the IT. S. Signal Service as follows :* 



Jamestown, North Dakota 3*7° F. 



Huron, South Dakota 42° 



Kimball " ._ 43° 



Fort Meade " _.. 45° 



Fort Randall, South Dakota 41° 



Fort Sisseton, " 48° 



Fort Sully, " 45° 



Webster, " 43° 



Valentine, Nebraska 46° 



Yankton, South Dakota 46° 



For the wells not very near these places I have assumed the 

 most probable mean temperature in comparison with the 

 nearest localities at which observations were made. It is real- 

 ized that there is of course some chance for error in this pro- 

 cedure, but the small difference does not greatly affect the final 

 product of calculation. It would of course have been much 

 safer to have observed the temperature of the earth at a mod- 

 erate depth at all the localities to determine the differences of 

 temperature, but this was not practicable. In most cases it has 

 been possible to take for the depth the middle of the water- 

 bearing bed as far as pierced by the well. The rate of tem- 

 perature-increase has been calculated from the surface down to 

 this depth and without deducting the usual 40 feet at the sur- 

 face, as has been done sometimes in making such calculations. 

 In considering the data I have selected only wells over 400 

 feet in depth and yielding large flows. They are all cased 

 from the top to the bottom. The deep well at Highmore was 

 excluded on account of its small flow, for in this instance the 

 water loses much of its heat before reaching the surface. The 

 temperature of the Highmore water, however, is 72° F., accord- 

 ing to Nettleton, the flow is 9 gallons and the source is about 

 1550 feet below the surface. At Aberdeen one of the earlier 

 city wells was reported by Nettleton to yield water at a tem- 

 perature of 66° F., from a depth of from 905 to 918 feet, 



* " Certain Climatic Features of the two Dakotas," by J. P. FiDlay (Weather 

 Bureau), page 119, Washington, 1893. 



