XXXI V SOUTH AFRICA MEDAL. 



Cape Town in 1905 Sir George Darwin said, with reference to 

 variable-star work: 



" This is a branch of Astronomy to which much careful observation and skil- 

 ful analysis has been devoted ; and I am glad to mention that Alexander Roberts, 

 one of the most eminent of the astronomers who have considered the nature of 

 variable stars, is a resident in South Africa. " 



" In the Handbook ' Science in South Africa ' Sir David 



Gill says: 



" I know few instances of more successful devotion of small means and 

 limited opportunity to the attainment of great scientific ends than the work of 

 Dr. Roberts." 



" These terms of high appreciation will show that no more 

 suitable recipient can be found than Dr. Roberts for the award 

 of the South Africa Medal, and it is with considerable pleasure 

 that I urge upon the South African Association for the Advance- 

 ment of Science the great claims which a scientist of his character 

 and attainments has upon their consideration, especially as I feel 

 confident that the result will be a further stimulus to his efforts, 

 productive of valuable contributions to the astronomy of the 

 future." 



After the conclusion of the Presidential Address in the 

 Stevenson Hall of the Collegiate School, Port Elizabeth, the 

 President, Dr. A. Theiler, handed the South Africa medal and 

 award of £50 to Dr. Roberts. In doing so the President said : 



" Our medallist is one of the foremost astronomers of the 

 world, and in every sense but one of the word he is an amateur ; 

 astronomy is a science to which he devotes his time when the 

 daily duties of his office have been fulfilled. The sense of the 

 word ' amateur ' which I reserved is that sometimes the word 

 suggests a sort of intermittency of work, or that its standard, 

 although very good for a non-professional, is not of the highest 

 class. This reservation does not apply to our medallist, who I 

 fear has now and then deprived himself of the rest so necessary 

 for complete health. In his special branch, the study of variable 

 stars, he is indeed one of the facile princeps. His observations 

 extend over twenty-one years, in which time he has made 75,000 

 observations which involved nearly 2,000.000 light-determinations 

 with comparison stars, and all this with a meagre equipment of 

 instruments that less talented men might have despised. This 

 record alone would entitle Dr. Roberts to our consideration, 

 but he has done far more. Besides the capacity and patience to 

 make observations, he has had the capacity to reduce and the 

 genius to interpret them. His special line to which he has kept 

 with surprising but quite commendable fortitude, is that of the 

 variable stars, but even in this branch he has been a specialist in 

 the class of variable stars of the Algol type. 



"The constancy of the light of our own star (the Sun), 

 albeit it is supposed to vary some 1 or 2 per cent., and the con- 

 stancy of the light of nearly all the stars visible to the naked 

 eye, did not predispose the human mind to the idea of variable 



