150 DR. R. ANGUS SMITH ON A 



thesis I ventured to advance in a former paper — that 

 changes in solar activity, and consequently in the mag- 

 netic condition of the earth, produced corresponding 

 changes in the directions and velocities of the great cur- 

 rents of the atmosphere, and in the distribution of baro- 

 metric pressure, temperature, and rainfall. It is therefore 

 evidently very desirable to discuss observations made at 

 stations in various parts of the globe with reference to the 

 variations which take place in solar activity, and thus to 

 determine for each station the nature of the changes which 

 take place in the relations between the several meteoro- 

 logical elements during a solar-spot period. 



XVIII. On a peculiar Fog seen in Iceland, and on Vesicular 

 Vapour. By R. Angus Smith, Ph.D., F.R.S., &c. 



Read October 29th, 1872. 



One bright afternoon in July a party from Mr. Young's 

 yacht (the 'Nyanza') landed in Reikjavik and took tea 

 at a hospitable house in that capital. After tea we were 

 invited to go out and see the fashionable people on the 

 promenade. We saw few people ; but, as soon as we left 

 the house, a cloud came down a street from southwards, 

 and some one said "let us cross out of the way of the 

 dust." Dust was strange in such a place, where there 

 is gravel enough, but few particles on the ground so fine 

 as to be called dust. I looked more carefully, and, 

 finding the cloud moving very slowly on the ground, con- 

 cluded that it was smoke from a chimney, but smoke 



