274 REPORTS ON THE STATE OF SCIENCE, ETC. 



precautions, be measured with considerable accuracy, using thermo- 

 junctions. It is possible to measure the temperature gradient to a few 

 per cent, in a hole loo ft. deep. The conductivity can be determined by 

 burying heaters in the hole and noting the temperature distribution round 

 them. Two values may be obtained, one from the final temperature 

 distribution and one from the rate of rise and the specific heat. In pre- 

 liminary experiments in a 15 -ft. hole the method was found to work well ; 

 no attempt was made to get the highest accuracy, but the values obtained 

 by the two methods at different distances above and below the heater agreed 

 to 3 per cent., which is within the experimental error. The boring of a 

 loo-ft. hole has been postponed till after Dr. Bullard's return from America 

 in September. 



The cost of boring the hole is estimated at about £40, and the Committee 

 asks for reappointment with a grant of that amount. 



PHOTOGRAPHS OF GEOLOGICAL INTEREST. 



Twenty-eighth Report of the Committee (Prof. E. J. Garwood, F.R.S., 

 Chairman ; Prof. S. H. Reynolds, Secretary ; Mr. H. Ashley, 

 Mr. G. Macdonald Davies, Mr. J. F. Jackson, Dr. A. G. Mac- 

 GREGOR, Dr. F. J. North, Dr. A. Raistrick, Mr. J. Ranson, Prof. 

 W. W. Watts, F.R.S.) 



At the Norwich meeting in 1935, at which the 27th report was presented, 

 Mr. H. Ashley and Drs. A. G. Macgregor, F. J. North and A. Raistrick 

 were added to the Committee. During the past year the Committee has 

 lost one of its oldest and most valued members, Mr. R. J. Welch, whose 

 photographs for uniform excellence, technical and scientific, have probably 

 never been excelled. Mr. Welch contributed 287 photographs to the Com- 

 mittee's collection and 10 of these were reproduced in the series published 

 by Prof. Watts. Mr. Welch's contributions to the collection were practically 

 all pre-war, the earliest being included in the Committee's first report 

 (Leeds 1890). In 1897 he sent as many as 93. All his photographs were 

 whole-plate platinotypes. 



In the present report 154 photographs are listed, bringing the number in 

 the collection to 8,865. The series includes a fine set by a new member of 

 the Committee, Mr. H. Ashley ; Norfolk is the county best represented 

 in this set, but there are others from Lincoln and Nottingham. Mr. A. G. 

 Stenhouse sends an excellent series from Fife, Orkney, Shetland and the 

 Isle of Eigg. The Hon. Secretary contributes photographs from the North 

 of Scotland and the Bristol and Belfast districts. Mr. G. Macdonald Davies 

 sends a series from Dorset and Mr. D. E. Owen from Cornwall. 



ENGLAND. 



Cornwall. — Photographed by D. E. Owen, B.Sc, Geological Dept., 

 Public Museums, Liverpool 3. P.C. 



8712. I Duckpool, 4 m. N. of Rugged weathering of hard band 



Bude. in Upper Culm. 1933. 



8713. 2 Boscastle harbour. Blowhole. 1934. 



8714. 3 Boscastle harbour. Blowhole. 1934. 



