687 
our power to scrutinise the operation as in some other cases, 
that here is what the chemist calls a 6 play of affinities' (?) 
in the elements of the higher atmosphere ; vapour parting 
with its whole electric charge and becoming water, and 
this water instantly concreting into small grains of ice, 
(why ?) which is quickly run together into large aggregates, 
in a manner which, though we may faintly conceive of 
the operation, we should in vain strive to imitate by any 
process we know. Those little opaque grains, like snow 
rolled up in pellets, which we see sprinkled on the ice 
in winter's mornings, having fallen in the night, are 
probably such concretes in the body of a cloud as by 
falling through a vaporous air in summer might collect 
ice enough upon them to make a regular hailstone, 
And we may admit the clear round balls, which do not, 
however, exceed a certain magnitude, to have been very 
large drops frozen aloft and increased by collecting ice from 
the air below. With respect to long icicles and pieces re- 
sembling fragments of a vast plate of ice formed aloft and then 
broken, we must here leave them among nature's wonders." 
The only difficulty in this case appears to be in the 
quantity of water to be frozen, for of the adequacy of a 
vacuum to freeze it there can be little doubt. But is there 
any difficulty in conceiving the gathering aloft such a 
quantity of water as will suffice for the formation of this 
ice? At Geneva, October 25, 1822, there fell thirty inches 
of rain in a day, and at Joyeuse, October 9, 1827, thirty- 
one inches in twenty-two hours. This amounts to 1.4 
inches an hour over the whole time, though beyond doubt 
the rainfall would be considerably in excess of this at 
times, and at other times much less. In London, two 
inches an hour have been observed during a thunder storm.* 
• The greatest storm which need be considered — such a storm as occurs in 
England only in the course of years — would be a fall of about two inches in the 
hour, or 44,789 gallons per acre. — Minutes of Information on Sewerage, 
General Board of Health, 1852, p. 60. 
