2 
Proceedings of the Royal Society of Edinburgh. [Sess. 
an independent discoverer of the theory of natural selection, and was a 
conspicuous upholder of what he regarded as true Darwinism.” His 
books on the geographical distribution of animals have been a great 
stimulus to many a travelling naturalist. To the end he retained the 
keenest interest in all the problems of biology. He was elected an 
Honorary Fellow of our Society in 1910. 
Sir Robert S. Ball, LL.D., F.R.S., who died on 26th November 1913, 
was a distinguished mathematician and astronomer. His “ Treatise on the 
Theory of Screws ” is an extremely elegant mathematical treatment of 
the rotation of rigid bodies, and his elementary work on “ Experimental 
Mechanics ” gave a great impetus to the teaching of mechanics by means 
of apparatus and not simply in terms of mathematical formulae. 
He held in succession the Professorship of Astronomy in the University 
of Dublin and the Lowndean Professorship of Astronomy at Cambridge. 
He was much interested in stellar parallax, and while in charge of 
Dunsink Observatory gave much time to the observation of stars. For 
some years he was very active as a popular lecturer and writer of 
astronomical books. He was elected an Honorary Fellow of our Society 
in 1889. 
Sir David Gill, K.C.B., LL.D., F.R.S., was born in Aberdeen in June 1843, 
and was educated at Dollar Academy and at the University of Aberdeen. 
He was early attracted to the study of astronomy, and while still a young 
man carried out observations for finding the correct time at Aberdeen. As 
Superintendent of Lord Lindsay’s private observatory at Dunecht, 
David Gill organised an expedition to Mauritius to view the transit of 
Venus in 1874. The experience in this work suggested to him the 
utilising of observations of the minor planets and of Mars for the purpose 
of determining the solar parallax. In 1879 he was appointed Her Majesty’s 
astronomer at the Cape of Good Hope, and at once proceeded to observe 
several minor planets, from the observations of which he deduced the 
total distance of the sun to within one-tenth per cent. 
Sir David Gill took a leading part in advocating the advantages of 
photography for the cataloguing of stars, and also did valuable work in 
connection with geodetic surveys. He retired from the office of astronomer 
at the Cape in 1907. He was President of the British Association in 
1907-8, and of the Royal Astronomical Association from 1909 to 1911. 
He was elected an Honorary Fellow of our Society in 1892. After serious 
illness for some months he died on 26th January 1914. 
