ON UNDERGROUND TEMPERATURE. 75 



Underground Temperature. — Twenty-first Report of the Committee, 

 consisting of Professoi- J. D. Everett (Chairman and Secretary), 

 Lord Kelvin, Mr. G. J. Symons, Sir A. Geikie, Mr. J. Glaisher, 

 Professor E. Hull, Professor J. Prestwich, Dr. C. Le Neve- 

 Foster, Professor A. S. Herschel, Professor G. A. Lebour, 

 Mr. A. B. Wynne, Mr. W. Galloway, Mr. Joseph Dickinson, 

 Mr. G. F. Deacon, Mr. E. Wethered, Mr. A. Strahan, and 

 Professor Michie Smith. (Draivn up hy Professor Everett.) 



Information as to underground temperature in the southern hemisphere 

 has hitherto been very scanty. Importance therefore attaches to observa- 

 tions which have recently been taken in a deep bore in New South Wales 

 by T. W. Edgeworth David, Professor of Geology in Sydney University, 

 and E. F. Pittman, Government Geologist. The following account is 

 derived from a paper by these gentlemen to the Royal Society of N.S.W., 

 read December 6, 1893, supplemented by letters from Professor David to 

 the Secretary of the Committee. 



The bore is 2,929 ft. deep, and is the second of two which have been 

 sunk at Cremorne on the shores of Port Jackson. 



A protected maximum thermometer had been furnished by the sec- 

 retary to Professor David when he went out to Sydney in 1882 ; but it 

 had passed through several hands, and was not forthcoming when the 

 opportunity for observation occurred. Professor David had accordingly 

 to avail himself of such instruments as were accessible, and he borrowed 

 four maximum thermometers, including two inverted Negretti's belonging 

 to Mr. H. C. Russell, the Government Astronomer, which had Kew certi- 

 ficates. They were similar in pattern to those adopted by the Committee, 

 except that there was no outer glass-case. In place of this, ' a strong 

 piece of wrought iron water-pipe, about two feet three inches in length,' 

 was employed. ' A cap-piece was sweated on to the lower end of this tube, 

 the threads of the screw in the cap-piece and pipe being filled with molten 

 solder, and the cap-piece being screwed on while the solder was still 

 molten.' ' The lower end of the pipe was then filled to a depth of about 

 two inches with Drass tui-nings. The thermometers were next carefully 

 lowered into the tube.' They had their bulbs uppermost, as usual. ' Brass 

 turnings were then packed around them in order that the heat might be 

 conducted rapidly to their bulbs from the water in the bore. Strings 

 were fastened to the bulbs to facilitate the withdrawal of the thermo- 

 meters from the tube after the experiment of taking the temperature had 

 been completed. The ends of these strings were carried close up to the 

 top of the pipe, the brass turnings being packed aroiind them like tamping 

 around a fuse in a shot-hole. A few cardboard wads and a layer of loose 

 paper two inches in thickness were inserted in the upper portion of the 

 tube, to prevent the conduction downwards of the artificial heat, which 

 would otherwise travel down to the thermometers from the upper end of 

 the tube when it was dipped in the molten solder, previous to the upper 

 cap-piece being sweated on. A ring-bolt for attaching the lowering cord 

 was screwed into the upper cap-piece, with molten solder sweated into it ; 

 and the whole cap-piece was then screwed and sweated on to the upper 

 end of the tube in the same manner as the lower cap-piece.' 



