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few days of falling, and each night the upper crystals grow 
very much through the deposit of hoar frost. In the lower 
part of the valley, especially near the river, these arborescent 
crystals grow to be sometimes two inches long or even more, 
while on the sides of the hill they are but small. This test 
as to the amount of moisture in the air shows how much 
more healthy the higher positions must be. These crystals, 
however, grow on the surface, so that the smoke is no 
longer visible, but when a thaw comes then, in comparison 
to what it was twelve years ago, it may around the village 
be called black, though of course in comparison with that 
in a large English town we should have to call it white.* 
The Curverein, in their German answer to Mr. Symonds, 
replied that what he said about the smoke could not be true, 
as the snow crystals glittered, but as the English translation 
in the Pall Mall was very much modified on this point, it 
■would seem that a thaw in the meantime must have shown 
the writers the absolute incorrectness of what they had said.f 
# I should have been glad to have had some exact observations on the 
amount of smoke, but I did not see the importance of this until too late* 
I then wrote to my friend Professor F. Clowes, who kindly sent me 
weighed filter papers, but there has not been a favourable opportunity 
since. However, I sent Professor Clowes one of my larger used filter 
papers, and he removed the dirt, which will be almost all smoke to a 
weighed paper. I filled my tin, Feb. 20th, with 1300 grammes of snow } 
which must have fallen on the 19th, and when put into the tin looked 
quite clean. It was hung in my meteorological screen until the 23rd. The 
dirt thus removed, and weighed by Professor Clowes in the manner, 
mentioned: was 0'082 gramme. 
If I had taken this snow from an area three times the size of my tin, 
■which is an ample allowance, we should find that the amount of the dirt — 
mostly smoke — which falls in the large Curhaus garden, amounts in a 
few days to half a hundred weight. The position of the tin was nearly 
due south of the large chimney, which is situated 330 feet away. More 
exact observations on this point would be valuable. 
f Besides the observations mentioned, I have a few temperature 
measurements, made with the thermometer in the snow, or placed above 
it ; and further, I have a series, from various visitors, of about 3,000 
measurements of the blood temperature taken at fixed times, in order to 
study the physiological action of weather. These will take some time 
to work up, and will be dealt with in a separate communication. 
