86 
in 1822 figured about one hundred forms from the Arctic 
Kegions, and Glaisher in 1844 gave some very elaborate 
drawings in the Journal of the Microscopical Society. The 
figures from both these two last sources have been very 
largely copied for various text books and scientific works, 
and are probably familiar to most present. 
These figures are made up of angular lines, which seems 
quite natural for crystalline forms. Some such ice crystals^ 
which I observed and figured from Davos in Switzerland, 
show a variety of curved lines, the cause of which I found 
for some time enigmatical, but the explanation is so ex- 
tremely simple that I feel surprise that it did not at once 
present itself to me, and the explanation I believe shows 
that such observations may have a scientific utility. 
It is not often in England that there are favourable op- 
portunities for observation, as the temperature seldom is 
much below freezing. Frequently in the Swiss mountainous 
districts when a very low temperature obtains there are a 
great number of the ice crystals just mentioned floating in 
the air. These are usually the most beautiful and regular, 
and are the most readily examined. The illumination I 
used was Wenham’s Parabolic Keflector. 
The lines which I wish to bring 
before your notice are the curved 
internal ones, especially such as 
the meander line in fig. G. This 
crystal I carefulty watched during 
the process of melting. First the 
external arms melted down as far 
as this meander line; next the 
crystal melted down to the straight 
sided hexagon; this then melted 
further, leaving a crystal with the 
shape of the next Interior lines. When we see it taken to 
pieces we may judge that it was built up in somewhat 
* Klimatologisclie Notizen ii. d. Winter im Hocligebirge von Arthur Wm. 
Waters, Basel, 1871. 
FIG. G. 
