John Wesley.

A survey of the wisdom of God in the creation; or, A compendium of natural philosophy .. (Volume 3) online

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thing contributes to make the day agreeable. In other
countries, the scorching sun in summer, makes the day
unfit either for labour or amusement: and the rains are
no less troublesome, in the cooler parts .of the year*
But in this delightful climate, the su si rarely appears ;
for there is constantly a grey cheerful sky, just suflici-
ent to screen the sun, without obscuring Uie air. Thus
all parts of the day are proper for labour, 'while tLe

4



coolness produced elsewhere by rains, is here brought
about by fresh breezes, from the cooler regions.

This is chiefly owing to the Andes, which running not
far from, and nearly parallel with the shore, and rising
immensely higher than any other mountains in America,
form on their sides a prodigious tract of lanrj, where, ac-
cording to their different heights, all kinds 'of climates
may be found, at all seasons of the year. These moun-
tains intercept great part of the eastern winds, which
generally blow on the continent of America, cool that
part of the air which comes over their tops, and keep it
cool by the snows, with which they are always covered.
Thus by spreading the influence of their frozen crests,
to the neighbouring coasts and seas, they cause the tem-
perature and equability which constantly prevail there,
But when they leave these mountains, they experience
in a short time an entire change of climate, and iu two
or three days pass from the temperate air of Peru, to
the sultiy atmosphere of the West Indies.

The sparks which appear on striking fire with a flint
arid steel, are discovered by the microscope, to be so
many spherical balls of iron, detached by the blow from
the mass. They are then red hot. After they cool,
they are a sort of scoriae or dross.

2. Fire is generated chiefly, either by collecting the
sun-beams by a glass, or by rubbing hard bodies against
each other. Either way the subtle matter is collected
from all sides, aud put into a rapid circular motion.
This continues together, as long as it is supplied with
inflammable substances. The particles of these being
divided by the fire, are scattered hither and thither, and
the fire goes out unless fresh fuel be brought : as it does
if air be wanting. For as that subtle matter is dissipa-
ting continually, it soon fails, unless recruited from the
air. If water or dust be thrown upon fire, it is like-
wise quickly extinguished. For these interrupt that in-
ternal motion, which is essential to it.



83 .

That fuel cannot consume without air is clearly
proved by an easy experiment Let a strong, hollow
cylinder of iron be fitted with a firm screw at each end.
Inclose in this a piece of charcoal : then screw up both
ends, and place it in a strong fire. Let it stay there as
long as you will. Open it when cool, and the charcoal
is no way diminished. It is plain from this, that the
consumption of fuel depends on the rarefaction and agi-
tation of its parts by fresh air. And hence we have the
reason of the known method, of extinguishing fires by
smothering them.

3. The watry part of the fuel being rarefied by the
heat, ascends in the form of smoke, carrying with it
many of the lighter particles, which adhere as soot to
the chimney. The grosser and more compact, the con-
texture whereof the fire cannot wholly destroy, remain
arid constitute ashes, which are of consequence ex-
tremely porous, all that was combustible in it being con-
sumed.

To enlarge a little on this subject. Fire is a body,
and a body in motion. It is in motion ; for it expands
the air, which can no otherwise be done, than by com-
municating motion to it. And that it is a body appears
hence. Pure mercury inclosed in a phial, and kept in a
gentle heat for a year, is reduced into a solid. And its
weight is considerably increased, which can only spring
from the accession of fire.

Fire is the instrument of all the motion in the uni-
verse. Without it all bodies would become inrimove-
able. Men would harden into statues: and not only
water, but air cohere into a firm, rigid mass.

As it is in itself, it is termed elementary fire : joined
with other bodies it is called culinary. The minute par-
ticles of this, joining with those of the pure fire, consti-
tute what is termed flame. Pure fire, such as is collected
by a burning glass, yields no flame, smoke, or ashes. In
itself it is imperceptible, but is discovered by its effects.
The first of these is heat, which arises wholly from fire,
and the measure of heat is always as the measure of fire.
E 5



S4

The second is dilatation in all solid, and rarefaction m
all fluid bodies. So an iron rod, the more it. is heated,,
increases the more in ail its dimensions. And by the
same degrees that it cools, it contracts, till it shrink to*
its first magnitude. So gold, when fused, takes up more
space than it did before. And mercury ascends in a,
hollow tube over the fire, to above thirty times its for-
mer height. The same degree of heat rarefies fluids
sooner, and hi a greater degree than it does solids.
And the lighter the fluid, the more it is dilated. Thus
air, the lightest of all fluids, expands the most. The
third effect of fire is motion : for in dilating bodies, it
must needs move their parts. All motion springs
from it. Only take lire away, and all nature would
grow into one concrete, solid as gold, and hard as dia-
mond.

Pure fire needs no air to sustain it. Put calx of tin
into an exhausted receiver, and if you apply a burning
glass, the calx will be so vehemently dilated, as to break
the receiver into a thousand pieces.

All the effects of elementary fire may be increased.

1. By rubbing one body against another. And the
more iiard and solid the bodies are, the more heat is
produced. So sponges rubbed together acquire little
or no heat : but two pieces of iron, an intense heat,

2. By mixing certain bodies together. So steel-filings,
mixed with oil of cloves, or spirit of nitre, grow exceed-
ing hot ; yea, burst into a violent flame.

Yet it does not appear that any new fire is generated
in any of these ways. Friction does not create fire, but
only collect what was before dispersed. It is present
every where, in all bodies, in all space, at all times, and
that* in equal quantities. Go where you will, to the
highest mountain, or the deepest cavern, by" one or other
of these ways fire may be collected. Yea, there is no
place in the world, uhere the attrition of two sticks wiU
not make it sensible.

But in what manner soever fire is collected, if the
collecting cause cease, it disappears again, unless it be
supplied with fuel, and iheu it becomes culinary fire.



85

By fuel we mean whatever receives and retains fire, and
is consumed thereby. The only fuel in nature is oil or
sulphur, and bodies are only rue!, as containing oil.
Hence, 1. All vegetables net too moist or two dry, af-
ford fuel, particularly those which contain much oil, as
balsamic and resinous woods. 2. All vegetable and ani-
mal coals, being those parts which have exhaled their;
water and salt, and retained the oil alone inhering in the
earth. 3. All bituminous earth. 4. All mineral sulphur,
whether pure or joined with other things. 5- The fat
and dung of animals : and 6. Chymical oil and spirits.

On the removal of air, this lire goes out. Yet it
does not immediately bear the air, but repels it, and by
that means forms a kind of vault, which by it weight,
and the pressure of the incumbent air, confines the par-
ticles that would otherwise escape, and applies them to
the combustible matter. Hence the heavier the air, the
fiercer the fire ; which therefore is fiercest in still, cold
weather.

The fire in burning combustible matter, affords a shin-
ing fire or rlame, or both : and frequently too, smoke,
soot and ashes. Shining fire seems to be elementary
fire, so strongly attracted toward the particles of the
fuel, as to whirl, divide, attenuate them, and thus ren-
der them volatile, and just fit to be expelled. Flame
seems to be the most volatile part of the fuel, greatly
rarefied and heated red hot. Soot is a sort of coal con-
sisting of a thick sulpher, and an attenuated oil, with
earth and salt. Smoke is the earthy and watiy particles
of the fuel, so rarefied as to break through into the at-
mosphere. Ashes are the earth and salt, which the fire
leaves unchanged.

Fire increases the weight of some bodies. Thus if
antimony be placed under a burning glass, the great-
est part of it will seem to evaporate in fumes, and
yet if it is weighed, it will be found to have gained in
weight.

But beside the solar, there is a subterraneous fire.
The earth is only cold to the depth of forty or fifty feet.
Then it begins to grow warmer; and at a great depth it
6



86

is so hot as to destroy respiration. Hence we learn that
there is another source of fire, or as it were another sun
in the bosom of the earth.

Upon the application of fire to water, it boils : that
is, the particles of fire passing through the pores of the
vessel, strike on the lowest particles of the water, impel
them upwards, and render them lighter than before,
bolh by inflating them into little vesicles, and by break-
ing and separating their spherules. There will of conse-
quence be a constant flux of water, from the bottom of
the vessel to the top. And hence we see, why the
water is hot at the top, sooner than at the bottom.

Farther, the air contained in the interstices of the wa-
ter being dilated, and its spring increased by the heat,
it ascends through the water into the air, carrying with
it the contiguous particles of water; and by this means
much of the water will be heaved up, and let fall alter-
nately, as the air has no power to carry away into the
atmosphere more than that small part that rises in the
steam.

4. That this subtle matter is plentifully collected in
the bowels of the earth, appears from burning moun-
tains. It is observed, there is always in the neighbour-
hood of these, plenty of sulphur or bitumen, the stench
whereof spreads far and near, especially before any
great eruption. This feeds the fire, which may be
kindled by various means, so as to continue for nranj
centuries. jEtua and Vesuvius have burned for above
2000 years, and probably will till the end of time.



5. Mount $ltna is divided into three distinct regions,
called La llegione Culta, the fertile region ; La Regione
Sylvosa, the woody region ; and La llegione Deserta,
tlie barren region.

The three are as different, both iu climate and pro-
ductions, as the three zones of the earth : and perhaps
with equal propriety might have been stiled the torrid,
the temperate, and the frigid zone. The first region
surrounds the foot of the mountain, and constitutes the



87

most fertile country in the world on all sides of it, to
the extent of about fourteen or fifteen miles, where the
woody region begins. It is composed almost entirely
of lava, which, after a number of ages, is at last con-
verted into the most fertile of all soils.

Every eruption generally forms a new mountain. As
the great crater of ^Etna itself is raised to such an enor-
mous height above the lower regions of the mountain, it
is not possible that the internal fire raging for vent, even
round the base, and no doubt vastly below it, should be
carried to the height of twelve or thirteen thousand feet
to the summit of jEtna. It has therefore generally hap-
pened, that after shaking the mountain and its neigh-
bourhood for some time, it at last bursts open its side.
At first it only sends forth a thick, smoke and showers of
ashes, that lay waste the adjacent country: these are
soon -followed by red-hot stones, and rocks of a great
size, thrown to an immense height in the air. The fall
of these stones, together with the quantity of ashes dis-
charged at the same time, at last form one of these
spherical and conical mountains. Sometimes this pro-
cess is finished in the course of a few .days : sometimes
it lasts for months, which was the case in the eruption in
l66y. In that case the mountains formed are of a
great size, some of them are not less than seven or
eight miles roimd, and upwards of one thousand feet in
perpendicular height : others are not more than two or
three miles round, and three or four hundred feet high.

After the new mountain is formed, the lava generally
bursts put from its lower side; and bearing away every
thing before it, is for the most part terminated by the
sea. This is the common progress of an eruption ;
however, it sometimes happens, though rarely, that the
lava bursts at once from the side of the mountain, with-
out all these attending circumstances; and this is com-
monly the case with the eruption of Vesuvius, where the
elevation being so much smaller, the melted matter is
generally carried up into the crater of the mountain,
\vhicli then discharges showers of stones and ashes from
the mouth of the volcano, without forming any new



nioutitaui, but only adding considerably to the height of
the old one ; till at last tlie lava, rising near the summit,
bursts the side of the crater, and the eruption is declared.
This has been the case with two eruptions lately ; but
JBtna is upon a much larger scale, and one crater is not
enough to give vent to such oceans of liquid fire.

A Sicilian gentleman saw in an eruption of that
mountain, large rocks of fire discharged to the height of
some thousand feet, with a noise more terrible than that
of thunder. He measured from the time of their great-
est elevation, till they reached the ground, and found
they took twenty-one seconds to descend, which (the
spaces being as the squares of the times) amounting to
upwards of 7000 feet.

After contemplating these objects for some time, says
a late traveller, we set off, and soon after arrived at the
foot of the great crater of ^Etna. This is of an exact co-
nical figure, and rises equally on all sides. It is compo-
sed solely of ashes, and other burnt material dischar-
ed from the mouth of the volcano, which is in its cen-
tre. This conical mountain is of a very large size : its
circumference cannot be less than ten miles. Here we
took a second rest, as the greatest part of our fatigue
still remained. The mercury had fallen to 20 4|. We
found this mountain excessively steep ; and although it
had appeared black, yet it was likewise covered with
snow, but the surface (luckily for us) was spread over
with a pretty thick layer of ashes, thrown from the cra-
ter. Had it not been for this, we never should have
been able to get to the top.

The circumference of this zone or great circle on
JEtna is not less than seventy or eighty miles. It is
every where succeeded by the vineyards, orchards, and
corn-fields, that compose the Regione Culta, or the Fer-
tile Region. The last zone is much broader than the
others, and extends on all sides to the foot of the moun-
tain. Its whole circumference, is 1 83 miles.

The present crater of this immense volcano is a circle
of about three miles and a half in circumference. It
goes shelving down on each side, and forms a regular



89

Jibltow, like a vast amphitheatre. From many places of
this space, issue volumes of sulphureous smoke, which
being much heavier than the circumambient air, instead
of rising in it, as smoke generally does, immediately on
its getting oat of the crater, rolls down the side of the
mountain like a torrent, till coming to that part of the
atmosphere of the same specific gravity with itself, it
sliootd off horizontally ; and forms a large tract in the air,
according to the direction of the wind ; which happily
for us, carried it exactly to the side opposite to that where
we were placed. The crater is so hot that it is very
dangerous, if not impossible, to go down into it : besides
the smoke is very incommodious, and in many places
the surface is so soft, there have been instances of people
sinking down into it, and paying for their temerity with
their lives. Near the centre of the crater is the great
mouth of the volcano, that tremendous gulph so celebra-
ted in all ages. We beheld it with awe, and with horror,
and were not surprised that it had been considered as the
place of the damned. When we reflect on tile immensity
of its depth, the vast cells and caverns whence so many
lavas have issued ; the boiling of the matter, the shaking
of the mountain, the explosion of flaming rocks, we must
allow that the liveliest imagination hardly ever formed
an idea of hell more dreadful.

Kircher pretends to have measured it, and to have
found it four thousand French toises in height ; which
is more than any of the Andes are. The Italian mathe-
maticians are still more absurd. Some of them make
it eight miles, some six, and some four. Arnici, the
last, and I believe the best who has made this attempt,
reduces it to three miles, two hundred and sixty-four
paces ; but even this must be exceedingly erroneous, and
probably the perpendicular height of JEtna is little more
than two miles.

It is a curious consideration that this mountain should
re-unite every beauty and every horror; and in short,
all the inost opposite and dissimular objects ia nature.
Here you observe a gulf, that formerly threw out tor-
reats of fire, now covered with the most luxuriant vege*



90

tation ; and from an object of horror becomes one of de-
light. Here you gather the most delicious fruits, rising
from what was lately a black and barren rock. Here
the ground is covered with every flower ; and we wan-
der over these beauties, and contemplate this wilderness
of sweets without considering that hell and ail its ter-
rors are immediately under our feet, and thai but few
yards separate us from lakes of liquid fire and brimstone.

But our astonishment still increases, on casting our
eyes on the higher regions of the mountain. There we
behold in perpetual union, the two elements that are in
perpetual war ; an immense gulph of fire, for ever ex-
isting in the midst of snows, \\hich it has nor-po\ver to
melt ; and immense fields of snow and ice for ever sur-
rounding this gulph of fire, which they have not power
to extinguish.

The quantity of matter discharged from ./Etna, is sup
posed upon a moderate computation to exceed twenty
times the original bulk of the mountain. The greatest
part of Sicily seems covered with its eruptions. The
inhabitants of Catanea have found at the distance of se-
veral miles, streets and houses, sixty feet deep^ over-
whelmed by the lava or matter it has discharged : nay
the walls of these ve^y houses have been built of ma-
terials evidently thrown up by the mountain. The in-
ference is obvious : that the matter thus exploded can-
not belong to the mountain itself : otherwise it would
have been quickly consumed : it cannot be derived from
moderate depths ; since its amazing quantity evinces
that all the places near the bottom, must have long
since been exhausted : it niUat therefore be supplied from
the deeper region of the earth ; these undiscvered
tracts, where the deity performs his wonders in solitude.

An eruption of Mount /Etna, in 1669, was preceded
for eighteen days, with a dark, thick sky, thunder, light
rung, and frequent tremblings of the earth. The place
of eruption was twenty miles from the old mouth : the
matter of it was a stream of melted minerals, boil-
ing up and gushing out, as water does at the head of a
great river. Having run thus for more than a stoned



91

cast, the extremities began to crust, and turn into porous?
stones, resembling huge cakes of sea coal, full of a fierce
fire. These came roiling over one another, and where
any thing opposed, filled up the space and roiled over*
But they bore down any common building, and burnt
up all that was combustible. This inundation went on
about a furlong a day, for nineteen or twenty days. It
overwhelmed fourteen towns and villages. The noise
of the eruption was heard sixty miles.

On Sunday, March 9, 1755, about noon, Mount jEtna
began to east, from its mouth a great quantity of flame
and smoke, with a most horrible noise. At tour o'clock
the air became quite dark and covered with black clouds :
at six a shower of stones, each weighing about three
ounces, began to fall over all the city of Mascali and its
territories. This shower lasted till a quarter past seven;
and was succceeded all night by a shower of black sand.
On Monday morning at eight, there sprang from the
bottom of the mountain a river of scalding-hot water,
which in half a quarter of an honY, overflowed all the
rugged land that is near the foot of the hill, and sud-
denly going off, left the whole a large plain of sand.
The stones and sand which remain wherever this water
reached, differ in nothing from the stones and sand of
the sea, and have even the same saltness. After the
water was gone, there sprang from the same opening^
small stream of fire, which continued for four and twenty
hours. On Tuesday, about a mile below this opening,
there arose another stream of fire, which being in breadth
about four hundred feet, overflowed all the adjacent
country.

6. On the 3d of December, 1754, a stream of liquid
fire began to run down the side of Mount Vesuvius,
from an opening on the east-side. But it soon ceased
running from this orifice, and burst out from a much
larger one, about two hundred yards below it. After-
ward it burst out from a third orifice, and having ran some
space with great fury, the surface then began to cool
and incrust, as it ran over gently-declining ground, till it



92

came within about ten yards of the top of a steep deeli
A'ity. Here the fire collected, as in a reservoir, to sop-
ply a cascade, w hich rushed down from thence in a
channel of more than twenty feet wide, and about two <
huiid red yards in length, with a fall of at least fifty feet.
Alter this the stream was less rapid, but grew wider, and
spread several miles from its source. It now presented
a very different scene from what it afforded before.
The cascade (says an eye-witness) looks like melted gold,
and tears off large bodies of old lava (so they term the
incrustation) which float down the stream, till the in-
tenseness of the IK a; lifts them fioni the bottom. But
in the lower country, it divides iuto smaller streams,
running with less rapidity : and yet with such violence,
that it drives the strongest stone fences before it, and
lighting the trees like torches, affords a most extraordi-
nary, though dismal spectacle.

On December 23, 17^0, about two in the morning, a
violent shock of an earthquake was felt, near Mount
Vesuvius. Some time arter, some countrymen being at
work, four or five miles from it, perceived the ground
near them on a sudden heave and gape, like dough that
is rising. At the same time they observed smoke issuing
from the clefts. They immediately fled, till they thought
they were out of danger. And then looking back, saw
the water of a cistern, near which they had been at work,
spout out to a great height. This was succeeded by a
large discharge of fiery matter from the mouth of the
cistern, and from four other openings, attended with a
dreadful noise and explosion of burning stones, On a
sudden all the fiery streams united in one, flowed impe-
tuously down the mountain, and gliding quick as light-
ning, presently covered all|the adjacent lands. Mean-
time the whole mountain shook greatly, and a fixed pil-
lar of smoke issued out of the main aperture, which ri-
sing to a certain height, then dissolved into ashes, and
fell like rain all over the mountain. At the same time
an immense quantity of burning stones was thrown out*

The fiery stream continued running down the inouu-



93

tain the whole night bet ween the 23d and 24th. Houses,
gardens, and every thing in its way, were consumed.
And ashes were still thrown out, which lay deep on the
ground for several miles about, and reached as far as
the sea-coast.

On the 25th also there was an eruption of liquid fire,
with a shower of stones, and a huge noise. In several
parts this stream was fifty spans deep. The mountain
meantime continued to roar, and thick ashes fell like
rain over the whole country.

On the 26th both the mountain itself, and the hills
lately produced, sent forth stones and ashes ; the bellow-
ings were still heard, but with intermissions : and out of
the five apertures, two only continued to emit stones,
ashes, and fire.

On the 2?th only one fiery stream remained, and that
began to cool, and to loose its brightness, appearing
more dusky, like burning coals ready to go out. On the
28th the stream ran much slower, and no more burning



Online LibraryJohn WesleyA survey of the wisdom of God in the creation; or, A compendium of natural philosophy .. (Volume 3) → online text (page 8 of 24)