442 EF. Hungerford—Observations on Snow and Ice 
17th) the thermometer standing at 16° F.* This morning began with 1 Ib. and 
continued to increase the bah up to ze lbs. total=1693 Ibs. nieaexete Discon- 
tinued at 11°30 0 ‘edo the 19t Transformation into ice incomple he mass 
melted partly as ice but the lower portion of the cast from the rmpald ital more 
like snow. Notice that less than half the previous ealgut had been used. 
Here are four trials with the iron press, all purposely al 
and all but the last resulting in perfectly formed ice —the 
character in the last instance being developed in the upper Bor. 
tion of the mass, while the lower portion melted more like 
snow. This test of perfect and imperfect glaciation is worthy 
of notice. In no way is the true ice character better exhibited 
the union of the snow crystals is complete, the mass melts only 
at the surface, like lake ice, whereas if the conversion into ice 
is imperfect the mass, as the melting goes on, begins, after a 
time, to. disintegrate and betray a granular structure. Other 
tests such as whiteness and opacity or their opposites are less 
reliable. For, though the mass usually clears up under pro- 
longed pressure, the glaciation may be far advanced in a mass 
which retains much of the whiteness of snow. Nevertheless 
the usual result is a eletkits Sten ice of a grayish appearance 
highest pressure exerted is equal to 41 29 Ibs. to the square 
inch as against 1693 Le to the square inch in the fourth trial. 
In the first of the series the power was applied by hand and 
can not be certainly erent, erie as the final power applied i is 
described as “considerable, though by no means violent,” it was 
doubtless much less than 60 ey power. It would probably be 
safe to take it as equal to 45 lbs. fae would give an effective 
pressure of 3068 Ibs. to the squa 
n the first trial I ask the randee tuithibe to notice the man- 
ner in which the pressure was brought to bear. The screw, 
which had six threads to the inch, was turned only through a 
quarter circle at a time, and each quarter was made slowly, so 
* This was done in order to let the whole stand over ree without pressure and 
allow the temperature of the snow and press to ized, 
