444. FE. Hungerford—Observations on Snow and Ice 
sure brought to bear upon it by screws, the pressure will not 
remain constant. The prism will very slowly yield to the pres- 
sure, by what seems to be a molecular movement; and if the 
pressure is to be kept up, it becomes necessary to tighten the 
screws after a comparatively short time. I regret that the 
lateral expansion, which may be supposed to attend this longi- 
tudinal yielding, was not measured. That such a longitudinal 
yielding takes place is impressed upon my mind, as a constant 
experience, and I think there can be no mistake about it. 
Indeed I find attention called to it in my notes made on the 
under the pressure. Here in a firmly bound iron mould, there 
can be no lateral expansion, but the ice particles seem to 
e 
turn of the screw is comparative : 
Having thus established the main fact of the glaciation of 
snow of low temperature under pressure, we come to the discus- 
sion of the question whether, under the circumstances of these 
experiments, we are to suppose that glaciation is due to the 
production of water, or at least of moisture, under the pressure 
applied. 
or tbis purpose it will be necessary to combine with the 
observations above given, some earlier ones, made with wooden 
moulds, fitted with wooden plungers. It will be understood 
that trials next to be mentioned were of that kind. It is not 
of liquefaction. ; 
actual facts of observation, gathered from numerous efforts to 
The question of liquefaction at low ped pandas accordin 
is of, another 
er these larger 
t y an 
sufficient to account for liquefaction. In the outset suc 
