74 REPORT — 1882. 



into four lengths by a new and special tool, and three of these were 

 raised ; but the fourth was so broken and jammed that the extracting 

 tool could not remove it. Dynamite was tried, but its explosive violence 

 was so deadened by the superincumbent pressure, that it proved power- 

 less, and a special engine had to be constructed for crushing the broken 

 pieces. This task has now been successfully accomplished, and the work 

 is accordingly just as forward as it was before the tubing was com- 

 menced. The Municipal Council of Paris have now ordered the con- 

 tinuance of the operations, and the tubing will be recommenced. Owing 

 to the difficulties above described, the well is now no deeper than it was 

 when the last observations of temperature were taken in it nine years 

 ago. 



Two slow-action thermometers have been sent to Mr. "W. Galloway 

 (Member of the Committee and Inspector of Mines, Cardilf), for obser- 

 vationa in mines. 



One slow-acting and one Negretti maximum thermometer have been 

 sent to Mr. T. W. Rumble, Engineer of the Southwark and Vauxhall 

 Water Company, for observations in a deep well now sinking at Tooting. 



A slow-acting thermometer has also been supplied to Mr. Grifi&th, 

 Manager of a Colliery at Wrexham. 



This, the iifteenth Report of the Committee, is accompanied by a 

 summary, which has been made by the Secretary, of the fourteen pre- 

 ceding Reports, together with as much as it was possible to include of 

 the present Report. 



Summary of Results contained in the First Fifteen Reports of the 

 Underground Temperature Committee. By Professor Everett {Secre- 

 tary). 



The fourteen reports hitherto published are contained in the consecu- 

 tive volumes of British Association Reports, commencing with that for 

 1868, except that the report for 1874 having been by mistake omitted 

 from the volume for that year, is inserted in the volume for 1875 instead. 



The following Table, showing the page at which each report com- 

 mences, will facilitate reference : — 



Eeport 



I. . 



II. . 



ni. . 



IV. . 



V. . 



VI. . 



VII. . 



Volume 



1868 , 



1869 , 



1870 , 



1871 . 



1872 . 



1873 , 



1874 . 



Page 



510 



176 



29 



14 



128 



252 



14 



In the references which we shall have to make, the number of the 

 report will be indicated by Roman, and the page by Arabic figures. 



We shall classify the results as follows : — 



A. Instruments. B. Methods of observation. C. Questions afiect- 

 ing correctness of observations. D. Questions affecting deductions from 

 observations. E. Comparison of results. F. Mean rate of increase of 

 temperature with depth, and mean upward flow of heat. 



A. Instruments. — Under this head we have — 



1. Instruments for observing temperature. 2. Subsidiary apparatus. 



1. The thermometers which the Committee have employed have been 



