QUANTITATIVE ESTIMATES OF SENSORY EVENTS 277 



by 47r AjX times the normal gradient. Numerical solutions for a number of 

 actual bores have been made by Dr. BuUard and published in the Geophysical 

 Supplement ; the biggest disturbance found is for the Simplon Tunnel, where 

 the observed gradient requires to be increased by 14 %. 



Dr. JeflFreys has investigated the disturbance of the temperature gradient 

 produced by the casing in a bore. If a long rod of radius a and conductivity 

 K is introduced into a solid of conductivity k with a temperature gradient p 

 in a direction parallel to the rod, the temperature gradient within the rod 

 at a distance s from the end differs from p by an amount Sp given by 



8plp = UK - k) a^k s^ 



If K = 100^ the error is less than 1 % if afs = 50, the effect of the casing 

 is therefore always negligible except within a few feet of the end. 



Future Programme. — Owing to the difficulty of obtaining satisfactory 

 temperature measurements in rotary drilled holes it is desirable to make the 

 best possible use of data obtained when other systems of drilling were in 

 vogue. A great mass of temperature data exists from bores in the U.S.A., 

 in Persia and elsewhere, much of which has been taken with every pre- 

 caution ; efforts should therefore be made to obtain specimens of the 

 strata passed through by these bores in order that conductivity determina- 

 tions may be made. Requests for specimens have been sent to various 

 organisations who might be able to assist. It is easy to obtain odd specimens 

 from bores but difficult to get a representative selection. 



Temperature measurements should be made whenever bores are available. 

 Any bore over 500 ft. deep is suitable, and any dry bore over 100 ft. is 

 worth testing. 



No grant will be required for this work. 



QUANTITATIVE ESTIMATES OF SENSORY EVENTS. 



Interim Report of the Committee appointed to consider and report upon the 

 possibility of Quantitative Estimates of Sensory Events (Prof. A. 

 Ferguson, Chairman ; Dr. C. S. Myers, F.R.S., Vice-Chairman ; 

 Mr. R. J. Bartlett, Secretary ; Dr. H. Banister, Prof. F. C. 

 Bartlett, F.R.S., Dr. Wm. Brown, Dr. N. R. Campbell, Prof. 

 J. Drever, Mr. J. Guild, Dr. R. A. Houstoun, Dr. J. C. Irwin, 

 Dr. G. W. C. Kaye, O.B.E., Dr. S. J. F. Philpott, Dr. L. F. 

 Richardson, F.R.S., Dr. J. H. Shaxby, Mr. T. Smith, F.R.S., 

 Dr. R. H. Thouless, Dr. W. S. Tucker, O.B.E.). 



Introduction. 



This Committee, whose title indicates its terms of reference fairly 

 accurately, was appointed at the York meeting in 1932, and has met since 

 at irregular intervals, much of its work having been carried out by corre- 

 spondence between members of different views and the circulation of 

 statements made by members. 



In the early stages of the Committee's existence, it seemed impossible 

 to reach an agreement, and it soon became obvious that it was necessary 

 to investigate the general imphcations of the term measurement and of the 

 processes involved in the making of measurements, and that it would be 



