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Report on Atmospheric Dust. By John Aitken, LL.D., F.R.S. 



In 1889 the Scottish Meteorological Society decided on making observations on the 

 ■dust in the atmosphere at their Observatory on Ben Nevis. Having prepared the plans 

 for the apparatus to be used for counting the dust particles, I visited the Observatory 

 on the 1st of August of that year, and, after consulting with Mr Omond, decided that 





Fig. 1.— Dust-Counter. 



the tower of the Observatory was the best place for fitting up the instrument. The 

 apparatus was afterwards made by White of Glasgow, and fitted up in the Observatory 

 on 5th June 1890. 



Fig. 1 is a photograph of the apparatus taken before it left the low level. A is a 

 receiver in which the air is tested in the usual manner by moistening and expanding it, 



