550 SECTIONAL TRANSACTIONS.— C. 



where M= thickness (in feet) of ice melted per month (30 days), and <°= average 

 monthly temperature (F.). 



This would become -2 inches of ice melted per day for each degree (F.) above zero 

 under normal atmospheric conditions, wind and rain producing deviations from the 

 normal. With the object of testing further this relationship, observations were 

 conducted on the Rhone Glacier 1927 over a period of twenty days. A hole 3 feet deep 

 was bored in the ice and a rod inserted from which a shaded standardised maximum 

 and minimum thermometer was suspended. It was found that when hourly records 

 of temperature were recorded the relationship given above was corroborated. As 

 the recording of hourly temperatures, however, was impracticable, late morning or 

 early afternoon temperatures only were recorded, in addition to the maximum and 

 minimum. 



An inspection of the tables of Zurich air-temperatures (Das Klima de Schweiz, 

 1864-1900) shows that the average of the maximum and minimum temperatures 

 gives too high a value to the summer mean, whereas if the mean between the noon 

 and maximum temperatures be first obtained, and then the mean calculated between 

 this figure and the minimum temperature, the approximation to the true mean is more 

 correct. This method was accordingly adopted. The average temperatures (July 26 

 to August 16) were as follows : maximum 50-6° F., minimum 34-5° F., noon 44° F., 

 giving a daily average of 8'9° F. above zero. Assuming the rate of "2 inches of ice 

 melted per day for each degree, the total amount melted would be 35-6 inches. The 

 actual amount was 35-2 inches. The expenses of this investigation were defrayed 

 by a grant from the Royal Society, for which the author expresses his thanks. 



Dr. W. K. Spencer. — The Starfish of the Scottish Palceozoic Beds. "■'* f 



Afternoon. 



Excursion to Barnley, Barrhead, and Paisley. (Leaders : Mr. P. 

 Macnair and Mr. B. Hilton Barrett.) 



Saturday, September 8. 



Excursion to Pinwherry and Girvan. (Leaders : Prof. J. W. Gregory, 

 r.R.S., and Dr. Ethel Currie.) 



Monday, September 10. 



Presidential Address by Mr. E. B. Bailey, M.C, Ldg. d'Hon., on 

 The Palceozoic Mountain Systems of Europe and America. (See p. 57.) 



Discussion on Problems of Highland Geology. (Dr. Gertrude L. 

 Elles, Dr. H. H. Read, Dr. E. Greenly, and others.) 



Dr. Geetrtjde L. Elles. — The main problems of Highland geology at the present 

 are those relating to (1) the age of the beds ; (2) the actual succession ; (3) the relative 

 ages of the various rock groups ; (4) the metamorphism ; (5) the complex of structures ; 

 (6) the age of the movements. 



Most of these are intimately related but definiteness may be given to the discussion 

 if arguments are directed along one or more of these lines. 



Available evidence to date seems to indicate a close connection between the 

 metamorphism and the fundamental folding which are regarded as part of the same 

 story though the effects may be somewhat obliterated by the more obvious later 

 folding. 



Barrow was the pioneer in 1912 to show the significance of the metamorphic changes 

 in the pelitic members of the Highland Schists, and his work holds, and has been 

 extended though in some degree re-interpreted by Tilley and others, for his zones (or 

 belts) of metamorphism are now regarded rather as due to depth than to contact with 

 a body of igneous rock, though should the depth be reached at which permeation on a 

 large scale by an igneous magma takes place, a superadded effect may result. The 



