270 Annwersary Address by Sir A. Geikie. — [Nov. 30, 
Davy MEDAL. 
The Davy Medal has been assigned this year to Prof. Theodore W. Richards, 
as a mark of appreciation of the value of his work in the determination of 
the atomic weights of the elements. His researches on this subject have not 
been surpassed in comprehensiveness by those of any other chemist. He has 
himself determined the atomic weights of no less than 14 elements, and 
many other atomic weight determinations have been made under his direction 
and superintendence. The accuracy of the numbers obtained is certainly 
much higher than that which has been attained by any previous series of 
researches, and it is impossible to speak in too high terms of the ingenuity, 
the unremitting labour, and the masterly manipulation which Prof. Richards 
has brought to bear on his investigations. 
In addition to this work on atomic weights, Prof. Richards has made many 
important contributions to physical chemistry, and it is probably no 
exaggeration to say that he has done more to raise the standard of accuracy 
in physico-chemical work than any other living chemist. Theoretical 
contributions to this branch of science are comprised in a series of papers on 
“The Possible Significance of Changing Atomic Volume,” in which he 
suggests a relation between the energy of the atoms and their compressi- 
bilities. In order to test his hypothesis, he has made a long series of investi- 
gations on the compressibility of elements and compounds. He has 
determined this constant for nearly all the solid and liquid elements, and he 
has shown that the compressibility is a periodic function of the atomic 
weights. In electro-chemistry, Prof. Richards has made important deter- 
minations of the electro-chemical equivalent of silver, and he has supplied 
some of the most rigorous proofs of the universality of Faraday’s Law. 
DARWIN MEDAL. 
To Mr. Roland Trimen, who was for many years Curator of the South 
African Museum, in Cape Town, the Darwin Medal has been awarded. His 
official position, and the duties it involved, enabled him to do admirable work 
in African zoology. His name will always stand with those of Bates and 
Wallace in the establishment and illustration of the theory of mimicry. In 
addition to his researches on that subject, he has done admirable systematic 
work, his descriptions of insects, especially the Lepidoptera rhopalocera, being 
models of accuracy and literary style. He, furthermore, rendered the greatest 
assistance to Charles Darwin, especially in his work on orchids—assistance the 
high value of which is acknowledged in a long series of that great naturalist’s 
published letters. 
