PLANS FOR OBTAINING SUBTERRANEAN TEM- 

 PERATURES. 



On November 19, 1902, 1 submitted to the Trustees of the Carnegie 

 Institution a memorial proposing an investigation of subterranean 

 temperature gradient b)' means of a deep boring in plutonic rock. 

 On December 1 1 , 1903, I was notified that an appropriation of $1 ,000 

 had been made by the Institution for the expense of preUminarj'' work 

 and the preparation of plans, and was requested to take general charge 

 of the preparations of plans. 



I now have the honor to submit the following report of progress : 

 (i) Mr. F. H. Newell, Hj^drographer of the United States Geo- 

 logical Survey, has at m}^ request considered the question of cost, 

 securing from establishments engaged in the manufacture of well- 

 drilling machinery estimates of the expense of putting down borings 

 to great depths. These estimates indicate that the cost of a boring 

 in granite to the depth of 10,000 feet would be very large — so large 

 as to be prohibitory. The Sullivan Machinery Company estimates 

 the cost of a boring to the depth of 6,000 feet at $110,000, and is 

 willing to enter into a contract on the basis of that estimate. Esti- 

 mate for a 6,000-foot boring has been requested from another re- 

 sponsible company, but has not yet been received. If the general 

 plan is approved bj^ the Institution, bids will be solicited from parties 

 making a business of sinking wells under contract. 



(2) I have investigated the question of a suitable site {a) by form- 

 ulating the conditions to be satisfied, {b) by a series of inquiries and 

 consultations with geologists familiar with the structure of various 

 districts east of the Great Plains, (r) by a personal visit to the dis- 

 trict which appeared from description most likely to afford a satis- 

 factory site. As a result of this investigation I beg to report that 

 the Lithonia district, Georgia, both appears preferable to all other 

 districts of which I have secured information and does in fact well 

 satisfy the conditions requisite for a successful boring. No effort 

 was made to choose a precise spot, but the natural conditions are 

 there favorable over so large an area that the selection of a partic- 

 ular spot can be made in view of local economic conditions. 



(3) By favor of the Director of the United States Geological Sur- 

 vey, the cooperation of Mr. Newell and other members of the Survey 

 has been secured without expense to the Carnegie Institution, and 

 the only draft thus far made on the allotted fund has been for the 



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