Anniversary Address by Prof. C. S. Sherrington. 



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co-workers he has importantly extended our knowledge of permeability, and 

 of the influence of anaesthetics on plants. He occupies a leading position 

 amongst plant physiologists, not only by reason of the importance of his 

 discoveries, but also on account of the effective stimulus he has given to the 

 school of investigators who have been trained in Lis laboratory. 



A Eoyal Medal is awarded to Sir Frank Watson Dyson. 



Sir Frank Dyson is distinguished not only for his enlightened and energetic 

 administration of the Eoyal Observatory, but by his many important con- 

 tributions to Astronomy. He has devoted special attention to investigations 

 of the movements and distances of the stars, and of the bearing of these upon 

 the structure of the stellar universe. He has concentrated his energies 

 particularly on the stars surrounding the north celestial pole, and has collected 

 or determined for this region of the sky all the different data which seem 

 likely to aid in the solution of the stellar problem. In a long series of papers 

 he has shown himself able not only to conceive and execute large schemes of 

 observation, but also to deduce by graphical and mathematical analysis the 

 theoretical conclusions which are implicit in the mass of data. Some of his 

 investigations are remarkable for the extensive data which have been utilised ; 

 one of them involves the proper motions of 12,000 stars, and another of 

 26,000 stars. These researches have given Sir Frank Dyson a place in the 

 front rank of workers on stellar distribution and movements. 



He has also given much attention to the accurate determination of stellar 

 magnitudes, and has successfully established a regular programme of work on 

 stellar parallaxes which has yielded results of high precision for a large 

 number of stars. 



Previous to this he had been conspicuously successful in obtaining records 

 of the spectrum of the corona and chromosphere during eclipses of the sun ; 

 his publications on those subjects are among the most valuable sources of 

 solar spectroscopic data. . It was mainly to his foresight and organizing 

 ability that we owe the successful observations of the deflection of light by 

 the sun's gravitational field during the eclipse of 1919. 



The Davy Medal is awarded to Prof. Philippe Auguste Guye in recog- 

 nition of his work on optically active organic substances, on molecular 

 association and on atomic weights. 



In his early work on Organic Chemistry, Prof. Guye was led to investigate 

 the question whether a quantitative relationship exists between the molecular 

 rotations of optically active substances and their chemical constitution. 

 Although the answer proved to be in the negative, the attempt to establish 



