346 
MEASURES OF HEAT. 
''April 7, Monday. For the last fortnight the ice 
has been perceptibly moist at the surface. The open 
crack near our brig to the south has now been closed 
for nearly a fortnight ; yet the snow which covers it 
is quite slushy. The trodden paths around our ship 
are in muddy pulp, adhering to the boots. All this 
can hardly be the direct influence of the sun upon the 
surface; for the thermometer seldom exceeds +16°, 
and is more generally below +10° at noonday. Yet 
this temperature has an evident influence upon the 
status of the ice, increasing its permeability, and per- 
mitting some changes analogous to thawing, but which 
I can not explain. May it be that the crystalline 
structure of the ice is undergoing some modification, 
that increases its capilarity, or develops an action like 
the endosmose and exosmose ! 
"It is a mere puzzle, of course, for we have not 
data enough to make it a question. Yet there is an- 
other like it that I can not help setting down. Can 
it be that our thermometers, so notorious in this Po- 
lar region for their imperfect coincidence with ' sensa- 
tions of cold,' are equally fallacious as measures of 
absolute increments or decrements of sensible caloric ? 
It will not do, I suppose, to admit such a supposition ; 
yet the marvels which come constantly before me 
may almost justify it. You know that I am no heat- 
maker. Well ! my winter trials, as you may imagine, 
have not increased my vital energies. Suppose me, 
then, as you knew me when I left New York. For 
the past week I have almost lived in the open air — 
genial, soft, bland, and to sensation just cool enough 
to be pleasantly tonic. I walk moderately, and am 
in comfortable, glowing warmth. I walk over the 
hummocks or ice floes, and am oppressed with per- 
