ON THE RATE OF INCREASK OF UNDERGROUND TEMPERATURE. 131 



When these observations are plotted they give a remarkably smooth 

 curve. The portion from 1,835 to 3,232 ft. is nearly straight, with an 

 average gradient of 1° P. for 82*4 ft. It then becomes gradually steeper. 



Beginning at the point where the casing stops, viz., 1,591 ft., the first 

 244 ft. (1,691 to 1,835) give an average gradient of 1° in 92 ft. 



The next 651 ft. (1,835 to 2,486) give 1° in 84-5 ft. 

 The next 746 ft. (2,486 to 3,232) give 1" in 80-6 ft. 

 The next 643 ft. (3,232 to 3,875) give 1° in 62-4 ft. 

 The next 587 ft. (3,875 to 4,462) give 1° in 58-1 ft. 



The mean gradient for these 2,871 ft. (1,591 to 4,462) is 1° in 71-8 ft. 



To determine the surface temperature, advantage was taken of a 

 heading at the depth of 100 ft., which was being driven into new ground 

 in a neighbouring coal-mine. A thermometer inserted in a hole bored 

 3 ft. into the face of the heading showed 51°'3 on five successive days. 

 This is checked by the mean annual temperature of the two neighbouring 

 towns, Marietta and Steubenville, which, according to the Coast Survey, 

 is 51°-5. Comparing the .temperature 51°-3 at 100 ft. with 110°-15 at 

 4,462 ft., we have a mean gradient of 1° T. in 74-1 ft. 



The public spirit shown by the Wheeling Development Company in 

 deepening this bore at great expense for purely scientific purposes cannot 

 be too highly commended. There is reason to hope tbat the boring will 

 be continued, with the aid of a steel rope, to at least 6,000 ft., so as to 

 make this the deepest well in the world. 



Mr. Hallock, by whom the plan of observation was devised and carried 

 out, is senior assistant in the Astrophysical Observatory of the Smith- 

 sonian Institution, Washington. 



[A request for information as to the temperature of the water at the 

 bottom has been answered by Mr. Hallock since the reading of the Report. 

 The temperature of the water was observed in May 1891, and found to 

 be 110°-36 at the depth 4,492 ft., as the mean of three obsei-vations, viz., 

 110°-4, 110°-5, 110° 2, at the respective depths 4,500, 4,500. and 4,475 ft. 



Mr. Hallock adds that this water leaked in at the depth of about 

 2,900 or 3,000 ft. and i-an down, amounting to about ten or fifteen gallons 

 per day.] 



K 2 



