180 Proceedings of the Royal Society of Edinburgh. [Sess. 
and Proceedings his most important work is published, Dr Aitken spared 
no pains in bringing before his audience the very experiments he had 
devised in following out his ideas. Thus he imitated on a large experi- 
mental scale the production of cyclones and the manner of their trend over 
the earth’s surface.* Whether, in view of the new information we have in 
regard to the vertical distribution of temperature in cyclonic and anti- 
cyclonic distributions, Aitken’s own views as to the genesis and maintenance 
of cyclones will continue to meet with acceptance, it is perhaps too soon to 
give a judgment. He himself believed that apparent discrepancies could be 
explained, and his latest paper on this subject, published in the Proceedings 
of the Royal Society of London, discusses many of the physical relations in 
an interesting and profound way. In this kind of work, however, he was 
handicapped from lack of mathematical equipment. 
With a mind keenly alive to all problems of a meteorological character. 
John Aitken entered in 1884 upon a long series of experiments on the 
measurement of air temperatures. In the majority of our meteorological 
stations the thermometers are placed within what is known as the Stevenson 
screen. This form of screen was long ago found to be quite unsuitable for 
hot climates, and in India the thermometers are placed under a broad shed 
through which the air courses freely. Aitken soon satisfied himself that 
in this country also the temperature given by thermometers hung within 
the Stevenson screen read several degrees too high when the day was fine 
and sunny. After many experiments on various forms of screen, he finally 
devised a form free from the defects of the Stevenson screen, and incidentally 
made many other interesting and important observations on temperatures 
of air and soil and solar radiation. At his death on November 14, 1919, 
he left in manuscript what might be called his matured views after 
thirty years of experimenting, wherein he lamented that meteorologists 
still continued to use a demonstrably inefficient method of screening the 
thermometer from the effects of radiation, direct and indirect. This paper 
has been published in the Proceedings of the Royal Society of Edinburgh, 
and it may well be regarded in the light of a scientific legacy from a great 
natural philosopher. 
The bulk of his estate Dr Aitken left in the hands of trustees to use 
(1) for the benefit of the poor of Falkirk; (2)^to establish a temperance 
public-house in Falkirk. He also left a fund of £1000 to the Council of 
the Royal Society of Edinburgh to meet the cost of publication of a 
collected edition of his more important papers. This is now being prepared. 
* See <c Notes on the Dynamics of Cyclones and Anticyclones,” Trans. Roy. Soc. Edin., 
xl, 1900 ; also Proc. Roy. Soc. Edin., xxxvi, 1916. 
