142 
expands with heat like other substances. It is certain that, 
after a night’s hard frost, a surface of glare ice will be covered 
with a multitude of small cracks from the contraction ; and 
larger cracks will sometimes extend through the whole thickness, 
with a report almost like that of a cannon. I knew a case of 
a railway bridge, built on piles over a shallow lake, which was 
entirely destroyed by the alternate expansion and contraction of 
the ice with variations of temperature. With a spell of cold 
the ice would be split up with innumerable cracks, into which 
the water insinuated itself and froze. With warmer Weather the 
whole expanded, shoving} the ice up onthe shores. On a fresh 
contraction, the ice could not be withdrawn from the shores, but 
cracked again in preference. The consequence was, that there was 
-aconstant shoving from the middle of the lake towards both 
shores. The piles in the middle remained upright, but the nearer 
they were to each shore the more they were driven out of the 
perpendicular. The damage was great the first winter, but it 
was repaired. The next winter, by cutting up the ice with ice 
ploughs, and by making embankments from each shore, the 
damage was sought to be arrested; but every winter.it got 
worse, till the bridge had to be altogether abandoned ; and 
whilst the piles in the middle are still upright, those near each 
shore are now laid almost flat. It is to this constant motion 
in one direction, arising from alternate expansions and con- 
tractions, that I have always ina great measure attributed the 
downward progress of glaciers. 4 
** The true explanation of the prismatic structure appears to me 
to be the lines of air bubbles, which you yourself notice. These 
are visible in all ice before any thaw has commenced, and in the 
rocess of freezing they seem to be formed in vertical lines. 
When the thaw occurs, these lines of bubbles form the centres, 
as it were, from which it penetrates in every direction through 
the mass. ‘JOHN LANGTERS 
“© Ottawa, May 25” 
tna in Winter 
THE ascent of a high mountain always gives plenty of opportu- 
nities of observation and experiment, but that of the prince of 
the volcanoes of Europe, and at the same time one of the grandest 
of its mountains, must always be an undertaking of paramount 
interest to the student of the phenomena of Nature. 
We leave the edge of a plain with a semi-tropical luxuriance 
of vegetation (the great plain of Catania, where Ceres taught 
mankind husbandry, and where common belief states wheat to be 
indigenous), and pass through a country so rich in its profusion of 
orange, lemon, fig, and olive trees, so-called American aloes, 
prickly pears, vineyards, peach trees in full bloom,* &c., that 
it would remind us forcibly of Algiers, did not the irregular 
surface of the numerous lava currents (on which the prickly pear 
is cultivated extensively) and the lava-built walls and buildings 
around bring back Auvergne to our thoughts. 
Still higher above the sea level we find karouba trees, with 
umbrella pines and dwarfoaks in abundance ; fields of flax and of 
wheat (a foot high) and other signs of a more temperate 
climate ; nearer to Nicolosi (the village from which the ascent is 
made) in traversing the rugged lava current of 1536 we are struck 
by the peculiar appearance of the bushes of Etna broom which 
flourish on its surface. Even on the cones above Nicolosi up to 
a height of about 1,300 metres above the sea level, the vine is 
still cultivated and excellent wine produced. 
After supper and a short nap we start at 10 P.M. with a guide, 
mules, and a muleteer, and well provided with provisions and 
wraps (taking with us a few thermometers, &c.); and passing 
by the Monti Rossi, which were formed during the remarkable 
and well-described eruption of 1669, we traverse various lava 
currents and fields of cinders, and find ourselves at last in a 
straggling wood of stunted oak trees succeeded by one of Italian 
chestnuts, in which latter we come upon the Casa del Bosco (a 
solitary house, uninhabited in the winter) after a rather rough 
ride of nearly three hours. Here we rest for half an hour, warm 
ourselves at a wood fire which is soon made, and take our 
supper; then at 1.15 we start for our laborious ascent ; we come 
upon the snow in about an hour, and (having chosen a starlight 
night after a continuance of fine weather) find it dry and firm ; 
now the work begins; leaving the mules and their driver, 
we toil on slowly and steadily, not speaking for fear of 
wasting strength or getting out of breath, and after a long, 
stiff climb up a very steep surface of almost smooth snow, 
* March 4th. 
NATURE 
[Fune 23, 1870 
which scarcely gives a hold to one’s feet, we arrive at the 
Piana del Lago soon after 4 A.M. Here we have a com- 
parative respite, and march merrily up the slight ascent, with 
the black summit of the cone in front of us, and looking so close 
that we can hardly believe the guide who says that it will take us 
nearly two hours to get up to it. At about five o’clock we arrive 
at the Casa degli Inglesi, where travellers sleep in the summer, 
but which is now all but buried in snow. On we go (as we have 
no time to spare before sunrise), the guide pointing out where we 
might see the Torre del Filosofo were it not entirely covered, 
and in a quarter of an hour, after crossing several fields of thin, 
broken ice, and nearly falling into sundry uncomfortable-looking 
holes, which one doesn’t see until one has put one’s foot through 
the crust of ice and snow which conceals them, we reach the foot 
of the actual cone, and look up its steep sides with some dismay, 
knowing, as we do by manifold experience, that the ascent of a 
cone of loose cinders 300 metres high, and at an angle of 40°, is 
no joke; our work is made somewhat easier by the snow with 
which the base is covered ; but we soon get off this and hurry on 
to get to the top before the sun rises. Before we are half way up 
the cone we find the necessity of stopping to take breath so 
urgent, that we halt and look behind us at the inexpressibly 
magnificent colours in the sky ; this we have to do several times, 
and were it not for Pietro’s *‘ Avanti!” we should go to sleep as 
we walk ; besides which our legs have given way at the hip joints 
and seem no longer to belong to us ; perhaps also some of us may 
feel a sense of nausea, and those least used to such excursions 
doubtless have a sharp pain in the knee joints. By screwing up 
our courage, however, we get gradually higher, and soon the 
fumes of sulphurous acid that arise around us tell us that we 
can’t have much more to do. Five minutes more and we look 
down into the immense crater, and instantly turn round and see 
the sun rise above the horizon and light up the beautiful island 
at our feet. 
Our ascent has been a capital success; we have had a fine 
starlight night, firm snow, and a good guide; there is not too 
much vapour, &c., and the brisk north wind drives it away from 
us. We soon find out that although the soles of our boots are 
being burnt by the hot cinders, our right hands (which held the 
alpenstocks) are frozen, and during ten minutes we experience 
excruciating pain in them. After a hearty breakfast we look 
around us, and see that the heated state of the ground is 
due to the continual slow oxidation of the sulphur contained 
in the ashes or lying about on the surface, and not to any 
internal action of the volcano. Far down in the crater, where 
there is less sulphur, the surface is covered with snow, and at the 
very bottom of it is a huge plug of snow also. With some 
difficulty we make our way through the suffocating vapour to the 
highest point of the edge of the crater, and thence look down 
upon the marvellous scene. 
The effect is almost unique, from no other point, except perhaps 
the Peak of Teneriffe, has one so unbounded a view. We find 
ourselves at a height of nearly 11,000 feet above the sea level, 
with no other mountain of considerable height within the 
horizon at all: the ‘‘ garden of Europe” stretched out at our 
feet, beyond its borders the sea, on all sides extending far away 
into the dim distance, and confusing itself with the sky; to the 
north of us Calabria, the ‘‘toe” of Italy, bounded by mist and 
looking like an island ; we see yonder Monte St. Giuliano (the 
ancient Eryx), there the hills around Palermo ; to the north, the 
point of Milazzo, very plainly indeed; beyond it, the chain of 
the Lipari Islands, apparently raised up into the sky (a 
rather striking phenomenon) ; farther east, the island seems to 
touch Calabria, and there are the Straits of Messina ; here is 
Catania, from which we have come; there Syracuse, and in that 
direction Girgenti, the site of the famous Greek temples ; farther 
west Marsala with its vineyards. Allaround us, at the base of the 
mountain, we see the secondary cones, and look down into their 
craters, while the distant hills look like slight irregularities on 
the surface of the island, although some of them are so high as 
to be covered with snow. What with feasting our eyes on the 
grand view, looking down into the immense crater, the deepest 
and steepest that we have ever seen, and collecting specimens of 
the variously-coloured cinders, &c., around us, we have spent 
two hours on the summit: it is eight o’clock, and our guide 
warns us that the heat of the sun will fast melt the surface of the 
snow, and render the descent more difficult and more dangerous. 
We could not walk round the edge of the craters on account of the 
vast quantities of stifling vapour that arise from some parts of it, 
even if we wished to spend another hour in doing so, Taking 
