190 
THE MEDITERRANEAN NATURALIST 
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plation of past geological ages, reckoned by 'ail- 
lions of years, tlie fact that our earth is coeval 
with the sun in age — all these considerations tend 
to immeasurably expand our mental horizon, and 
thus to react in a way to broaden the mind. Geo- 
logy is also the complement of biology. As soon 
as one has mastered the rudiments of botany 
and zoology, and of the distribution of life forms 
in space, the range of his thoughts should be 
extended to take in the orderly succession of life 
in past ages, and the evolution of modern spe- 
cialized plants and animals from the earlier, gene- 
ralized types. 
The Sulphur Mines of Sicily. 
From the report to the State Department of Mr. 
Chas. Heath, U. S. Consul at Catania, Sicily, we 
learn that the mining and fusing of sulphur in 
Sicily are not carried on with the vigour and 
enterprise that the demand for this commodity 
might lead us to expect. 
The most primitive methods are still employed 
in the work owing to lack of enterprise, and 
the difficulty that is experienced in inducing capi- 
talists to invest their money in the industry. 
In the majority of mines, machinery is un- 
known, manual labour taking its place and giving 
employment to hundreds of women and children 
who carry the mineral on their heads in baskets 
from the mine to the surface. 
Four systems of melting sulphur are in vogue 
in Sicily — the Calcherone, the Sinopoli furnace, 
the steam process, and Gill’s furnace. On account 
of the small amount of capital required the first 
two are the most popular. 
The steam process, which consists of injecting 
dry steam through iron pipes filled with the 
mineral is the best method as the product ob- 
tained is better in quality and no fumes escape 
to destroy vegetation around. Gill’s process has 
been extensively tried, but as it requires skilled 
labour it has now fallen into disuse. 
Catania is the great centre for refining the sulphur; 
while Catania, Licata, and Girgenti are the prin- 
cipal shipping ports. 
The Relationship of the Structure of 
Rocks to the conditions of their 
Formation. 
By H. J. Johxstox La vis, m.d. 
Introduction — Two great questions of Yulcano- 
logy, of which our knowledge is still very limited, 
are in the first place the causes that bring al rut 
the wide range in force and character of volcanic 
activity; and, second! .. the difference in structure 
and composition of the resulting products. In the 
present Paper it is proposed to discuss a portion 
only of these very complex questions. 
Those who have lived in a .-till active volcanic 
region, and have gazed over the landmarks of 
former activity, and compared them with those 
at present in progress, cannot but be struck by 
the evidence afforded of .he enormous dispropor- 
tion in the exhibition of volcanic energy from one 
time to another. Before 1G31 the crater of Vesu- 
vius was clothed with trees, brushwood, and grass, 
where goats were pastured, while the only sign of 
igneous action was the presence of two small lakes 
of warm water occupying the bottom of that 
depression. The quietness e f the syh an seen a was 
only broken by the twitter of birds, the shepherd’s 
chant, or the wind-rustled leaves. Let us compare 
this state of placidity, or still more that in which 
no sign whatever existed oi the endogenous activity 
in the time of Spartacuu, with those gigantic, 
prehistoric eruptions which, tore away 1,000 metre-; 
or more of the mountain top, and hollowed out a 
cavity equal to a cone with a base -diameter of 
three kilometres and a height of 1400 to 1500 
metres. Even the Plinian eruption was an insig- 
nificant affair compared with its four predecessors. 
Between these two extremes in the vital activity 
of a volcano we have all stages of gradation. 
Yet the phenomena of Vesuvius bear the pro- 
portion of child’s play to a giant’s exploits, when 
we compare them with the catastrophe of Tom- 
boro, Krakat'oa, Cotopaxi, tlie Icelandic volcanoes, 
and many others. Meditating on these facts can 
hardly fail to awaken within us the inquiry as to 
the actuating cause of the variability in functions, 
if we may so call them, of a volcano. 
