* 
Hartitty—On Haze, Dry Fog, and Hail. 509 
across the St. George’s Channel, but at a great elevation. If 
the air-current amounts to a breeze, the dust is dispersed through 
a vast volume of air, and is not visible, and perhaps not otherwise 
capable of detection. 
Taking these facts into consideration in connexion with what 
was observed inthe South Wales district, the conclusion becomes 
inevitable that the haze was caused by dust originating with 
fume, which ascended during a period of anticyclone from one of 
the manufacturing centres of either South Wales, South Stafford- 
shire, or possibly the pottery district of North Staffordshire. 
Travelling slowly over St. George’s Channel at an altitude of 
10,000 to 15,000 feet, it may readily be understood that aqueous 
vapour could condense upon it and be precipitated as rain, snow, 
or hail. Metallurgical operations in the district around Swansea 
comprise lead and copper smelting; in the potteries lead oxide 
and alkalies volatilise from the kilns; in iron districts fume arises 
from Bessemer steel and ferromanganese works. A. very reason- 
able explanation of the composition and origin of the nuclei of 
these hail-stones is afforded by these facts. It seems worth while 
to prosecute this inquiry somewhat further by examining dust 
collected from the neighbourhood of manufacturing towns, and 
afterwards in places far remote from them. I believe that from 
the spectrographic analysis of such dust it could be, in most 
cases, easily identified and traced to its source. 
