498 Proceedings of the Poyal Society of Edinburgh. [Sess. 
numbers thus represents only the sun-formed nuclei brought by other than 
N.W. winds. 
It will be noticed that the Kingairloch number is only about 2 per cent, 
higher than the inland number when the air is fairly humid, and that the 
difference increases with the dryness, being 11 per cent, at wet-bulb depres- 
sions between 4° and 7 C , and is 26 per cent, higher when the air is very dry, 
Table III. 
Place. 
Values of C at the different Wet-bulb 
Depressions. 
2° to 4°. 
4° to 7°. 
7° and over. 
Kingairloch, 1892-93 . 
77,525 
111,300 
157,730 
Kigi Kulm and Alford . 
75,325 
99,791 
124,566 
Difference 
2,200 
11,509 
33,164 
Per cent. . 
3 
11 
26 
a result easily explained by the state of the weather under the different con- 
ditions. High humidities will generally be accompanied by much cloud, 
while with low humidities the sunshine will generally be plentiful and so 
produce more nuclei. It is evident from Table III. that the Kingairloch 
observations give too high a figure for the number of particles required to 
produce a complete haze, especially when the air is dry, being in error to as 
much as 26 per cent. 
I feel that an apology is due for presenting this paper. The subject is 
an uninteresting one to most people, and I have to admit that its presenta- 
tion is badly focussed and gives but a hazy impression. If it had not 
been for the discovery of the origin of the sun-formed nuclei at Kingairloch, 
the work would not have been done. Perhaps the difficulty of experiment- 
ing on a subject in which such extremely small quantities of matter produce 
such marked effects, and the varied nature of the contents of the paper, 
may be some excuse for these defects. 
( Issued separately July 6, 1911.) 
