784 
Proceedings of the Boyal Society 
Monday , '7th June 1886. 
The Hon. LORD MACLAREN, Vice-President, 
in the Chair. 
The Keith Prize for 1883-85 was presented to John Aitken, Esq., 
Darroch, for his paper “ On the Formation of Small Clear Spaces in 
Dusty Air,” and for previous papers on Atmospheric Phenomena, 
after the following statement by Mr Buchan : — 
One of the earliest of Mr Aitken’s communications to the Society, 
and certainly one of the most valuable, is that on “ Dust, Fogs, and 
Clouds,” in vol. xxx. of our Transactions. The discovery that a 
solid nucleus is necessary for the condensation of water-vapour is 
one of the most important contributions, alike to pure and to applied 
science, which has been made in recent years. Mr Aitken made the 
discovery independently ; but he had been to a certain extent anti- 
cipated by Coulier, who, however, by a strange want of judgment, 
withdrew his statements not long after they had been published. 
The paper referred to, in intimating the award of the prize, “ On the 
Formation of Small Clear Spaces in Dusty Air,” is in continuation 
of the same subject. 
The more important of his other contributions to Meteorology are 
his papers “ On Thermometer Screens,” read in June 1884. Owing 
to the extreme difficulty of making observations of the true tem- 
perature of the air at any given instant, meteorologists have 
contented themselves with uniformity in the methods of observing. 
In this paper Mr Aitken has, by the novel appliances for observa- 
tion introduced by him, made a distinct advance towards making 
observations of atmospheric temperature more approximately correct 
than those hitherto made; and, it may be added, that the ultimate 
solution of the problem is likely to be reached on the lines he has 
thus indicated. 
The Makdougall-Brisbane Prize for 1882-84 was presented to 
Edward Sang, Esq., LL.D., for his communication “On the Need 
for Decimal Subdivisions in Astronomy and Navigation, and on 
