40 REPORT — 1879. 



requesting some qualified person to report upon it — a function which 

 hitherto has been discharged by the Sectional Committees of the Asso- 

 ciation. 



Considering all the difficulties of the undertaking and the extent to 

 which it is rendered unnecessary by existing (chiefly German) publica- 

 tions, the present Committee came to the conclusion that it is not at 

 present desirable for the Association to attempt to obtain reports in the 

 nature of compilations of abstracts of the papers published upon 

 mathematics or physics. 



With regard to the other more critical class of reports, many have 

 already been obtained which are recognised as among the most valuable 

 results of the existence of the British Association ; and the Committee 

 hope for a continuance of these valuable contributions. They are happy 

 to state that two such reports have already been promised. Professor 

 Stokes has undertaken to draw up the plan of a report on physical 

 optics, especially in reference to the theory of reflection, the theory of 

 dispersion, and the theory of phosphorescence and fluorescence. Pro- 

 fessor Balfour Stewart has also undertaken, in conjunction with Mr. J. 

 Allan Brown, to draw up the heads of a report on terrestrial magnetism. 



Twelfth Report of the Committee, consisting of Professor Everett, 

 Professor Sir William Thomson, Professor J. Clerk Maxwell, 

 Mr. G. J. Symons, Professor Kamsay, Professor Geikie, Mr. J. 

 G-laisher, Mr. Pengelly, Professor Edward Hull, Professor 

 Ansted, Dr. Clement Le Neve Foster, Professor A. S. Herschel, 

 Mr. G, A. Lebour, Mr. A. B. Wynne, Mr. Galloway, Mr. 

 Joseph Dickinson, and Mr. G. F. Deacon, appointed for the pur- 

 pose of investigating the Rate of Increase of Underground Tem- 

 perature downwards in various Localities of Dry Land and 

 under Water. Draivn up by Professor Everett (Secretary). 



Dr. Stapfp has forwarded to the Secretary a summary of his observa- 

 tions of temperature made in the St. Gothard Tunnel in 1878, in con- 

 tinuation of those of previous years, the places of observation being 

 always those which have been newly opened up. At the Swiss end the 

 portion reported on begins at 5000 and ends at 6400 metres from the 

 north portal ; and at the Italian end the limits are 4600 and 5900 metres 

 from the south portal. In the former the temperatures (Centigrade) 



25-5 26-6 27-8 27-9 28-8 



were observed in the rock, at the distances from north portal (in 

 metres) 



5157 5456 5593 5725 6297 



and at the depths below the surface vertically overhead (in metres) 



945 971 983 1012 1250 



The temperature of water was found to be higher than that of rock ; 

 whence Dr. Stapff infers the existence of hot springs in the Serpentine 

 and the rocks immediately to the south of it. 



