xlvi PROCEEDINGS OP THE GEOLOGICAL SOCIETY. [vol. lxxix, 



experimentation, and brilliance in interpretation. Incidentally, 

 I may add that botanists also owe you a debt of gratitude for the 

 distinguished part that you played, in conjunction with Prof. H. H. 

 Dixon, in contributing to our knowledge of the ascent of sap in 

 trees. The publication of your work on ' Radioactivity and 

 ■Geology ' marks an epoch in the history of our science. By your 

 quantitative determination of the distribution of radium and, later, 

 thorium, you were able to liberate Geology from the narrow limits 

 of time imposed upon it by inadequate knowledge. Your investi- 

 gation of the mysterious haloes of biotite and other minerals is a 

 model of scientific research : in its later stages it afforded unex- 

 pected evidence of a change of rate in the disintegration of 

 uranium dependent on time. At an earlier date you attacked the 

 problem of the Earth's age by another method of investigation, 

 with results not inconsistent with your latest estimate. You have 

 greatly extended the use of the microscope as an instrument of 

 scientific research ; by an original method you have measured the 

 expansion which rocks undergo on fusion, using for observation 

 minute spherules of material not contained in an enclosing vessel. 

 That you still take a keen interest in geological problems is shown 

 by your recent suggestion of a vera causa for the movements of 

 the land imagined by Wegener. 



It is not often that one finds in combination powers of imagina- 

 tion such as you possess, and sufficient patience and critical faculty 

 to exercise the necessary control ; nor are there many scientific men 

 who are able, as you are, to express the results of research in 

 language which is also literature. 



Prof. Joly replied in the following words : — 



Mr. President,— 



I find it difficult to exjiiress how much I feel the honour that 

 you, Sir, and the Council of this Society have conferred upon me 

 in awarding to me the Murchison Medal. I am sincere when I 

 say that I never anticipated so great a distinction. 



I have — so far as I was able — consistently worked in that 

 domain of science where Geology and Physics meet. Drawn into 

 physical lines of thought by early training and associations, I have 

 always looked with a certain longing at that delightful aspect of 

 the geologist's mission which leads him to the field and to the 



