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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burnt to ashes. The ashes when taken up, left in the
hand a greasy, and stinking moisture. The bed received
no damage ; the clothes were raised on one side, as by
a person rising from it.

Doubtless the fire was kindled within her, by the
juices, and fermentations in the stomach, acting on the
many combustible matters, which abound in living
bodies, for the uses of life. These in sleep, by a full
respiration, are put into a stronger motion, and conse-
quently are more apt to take fire.

Borelli observes, that such accidents often happened
to great drinkers of wine and brandy. Such flames
would frequently rise in us, if the natural moisture did
not prevent.

Undoubtedly she was burnt standing ; hence her skull
was fallen between Ler legs, and the back part of her
head was damaged more than the fore part, partly be-
cause of her hair, partly because in the face, there were
many places, out of which the flames might pass.

An instance of the same kind, occurred at Christ
Church, in Hampshire, on June 26, 1613. One John
Hitchell, a carpenter of that parish, having ended his
day's work, came home, and went to rest, with his wife. ,
Her mother being frightened in her sleep, called to tU*rn
for help. None answering, she started up and waked her
daughter, who found her husband dead by her side. She
dragged him out of the bed into the street ; but the heat
G 4



ISO

then forced her to let him go. He lay burning thcrr for
three days. Not that there was any appearance of tire
outwardly, but only a smoke ascending from his carcass,
till it was burnt to ashes : except only a small part of;
his bones which were cast into a pit.

Grace Peit was a fisherman's wife, of the parish of St.
Clement's, in Ipswich, about sixty. She had a custom.
for several years of going down stairs every night, after
she was undrest, to smoke a pipe. Her daughter, who
lay with her, did not miss her till the morning, April 10 ?
1744> when going down stairs she found her mother's
body extended over the hearth, with her legs on the
deal floor, and appeared like a block of wood burning
vttih a glowing fire without flame. The neighbours,
coming in at her cries, found the trunk of the body in a.
manner burnt to ashes. It then appeared like a heap of
charcoal covered with white ashes : the head, arms, legs,
aad thighs were also much burnt. A child's clothes on
one side of her, and a paper skreen on the other, were
untouched. The deul floor also on which her legs lay
was neither singed nor discoloured.

?6. Almost as strange, though not attended with any
ill consequence, was the following incident In Novem-
ber, Mrs. Susanna Sewall, wife to Major Sewall, in New '
England, observed a strange flashing of sparks in all the
apparel she put off, which continued till Candlemas.?.
In the company of many persons she sent for several..
parts of her wearing apparel, aiid when they were,
slraken, sparks flew out, making a noise much like bay-
leaves thrown into the fire. One spark lit on Major
Sewall's thumb-nail, without any heat, and continued,
at least a minute, before it went out. They caused
Mrs. Sewall one (fay 10 put on her sister Diggers petti-.
caat ; and when she put it oil at Bight, it sparkled as her
to do,



27. There is no body but may be by fire converted ;
intogla^s; not excepting gold itself. And this is the
last effect, of fire : no art can carry the change of a,-
body any fsrtlier



As to the nature ancl properties of it. 1 . Common
glass is an artificial compound of salt with sand or
stones. 2. It is fusible by a strong tire, and when fused
is tenacious and coherent. 3. It does not waste in the
fire. 4. When melted it cleaves to iron. 5. When red
hot it is fashionable into any shape, and capable of being
blown into a hollowness, which no mineral is. 6. It is
frangible when thin, fryable when cold, and transparent'
whether hat or cold. 7. It is flexible, elastic, and dis-
soluble by cold. It can be cut only by emery or a
diamond. 8. It is not dissoluble by aquafortis, aqua
regia, or mercury. 9- Neither acids nor any thing else
extract colour, taste, or any sensible quality from it.
10. It looses nothing either of its substance or of its
weight, by the longest and most frequent use. 1 1. It is-
not capable of being calcined, neither of contracting rust*

But there is no property of glass more remarkable-
than its ductility, Glass-spinners draw threads of their
brittle matter, melting over a lamp, with far more ease
and expedition than common spinners do those of flax
or silk. These may be drawn fine as a hair, yea, as the
thread of a spider's w r r.b, so as to wave with every wind.
And the finer they are the more flexible. If the ends of
two such threads be knotted together, they may be drawn
and bent till the space in the middle of the knot does
not exceed the forty-eighth part of an inch in diameter*

Near the bay of Acra, in Palestine, runs a little river;
now called Kardanah, supposed to be the ancient Belus,
famous for its sand, much used in making glass, and
said to have given rise to the invention of it* The
Sidonians are reported to have made- this discovery
from the following accident*. Some travellers having
reared an hearth on the sand of this river with large
pieces of nitre, and set some fern on fire under a kettle,
in order to boil their victuals, perceived the sand and the
nitre to melt and incorporate with the fern-ashes, and
presently after run in a transparent stream, which
hardened as it cooled. From hence the hint of making
glass was taken, which was gradually, improved to its.
piesent use and beauty.



132

23. There are few phenomena relative to glass more-
hard to be accounted for, than that of the Bologna
bottle, so called because it was first discovered at ,
Bologna. If you let these bottles fall from some height
on a brick floor, they will not be broken ; tut drop into
them some hard body, and they will burst in pieces.. " I
took one of these," says Dr.. I. " which held near a pint,
and let it fall five feet and a half on a brick floor, and
it was not broken. I dropt into it a bit of flint, weighing
eleven grains, and immediately it burst in pieces.

" I dropt into another bottle a ball of lead, weighing
one hundred and forty grains, into a third a piece of
brass weighing three hundred grains,, and neither of
them was broken.

* c These glasses only differ from common phials in this,,
they have not cooled gradually in what is called the
nealing furnace, but are exposed to the open air as soon
as forn.'ed. They resist hard* blows from without. I
have given to some violent strokes with a mallet, and
they have not broke. They likewise do not break,
though several heavy bodies be dropt into them. I have
dropped into them, from the height of three feet, musket
balfs, and pieces of iron, brass, gold, without any effect;
but when I dropt into if, from the height of three inches,
a shiver of flint no bigger than a small pea, in about two
seconds the glass flew. Having tried the experiment on
several others with the same piece of flint, most pf theni
broke in the moment of the stroke, the rest one or two.
seconds after it.

" I let fall into several glasses a flint of half the size,,
and they flew in like manner. I let fall into one a flint
DO larger than a grain of sand, shook the glass, and set
it dowti. I did the sarnie with four ethers. In about half
an hour one of them flew, and the other four soon after,.
" 1 let fall into one a sapphire set in a ring : and though
the bottom of the glass was near an inch thick, the
sapphire passed through it as through a spider's web.-
The glass flew all ways, and the ring remained on the
tabk* just where it fell.

'< A bit of china, half a line thick ami two lines broad,
broke several glasses ; so. did a bit of glass of the same



133

size: so did diamonds also. And a very small piece of
tempered steel broke all the glasses into \vhich I
dropped it."

Some large hollow cups made at Worcester, of common
green glass, much larger than the others, and some of
them above three inches thick at the bottom, though
they were not affected by a musket-ball, dropt from the
height of near three feet, were instantly broken with a
shiver of flint, weighing but two grains.

There is something astonishing in the power of tele-
scopes to bring far distant objects near ; and of micro-
scopes, to render those clear and distinct, which are
quite invisible to the naked eye. And no less amazing
in another kind is the force of burning glasses. 1. A
piece of wood laid before a large burning glass, took
iire in an instant. 2. Water contained in an earthen
vessel boiled immediately, and in a short time quite
evaporated. 3. A mass of lead, three inches thick,
began to melt in a moment, and soon after ran in a con-
tinued thread. 4. A steel plate grew red hot almost in
an instant, and small holes were made through it.
5. Slate becomes black glass; tiles, yellow glass;
earthen pots, a darkish yellow glass. 6. A pumice
stone became white glass; earth, black glass; bones au
opake one.

But in the extremely hot weather at Paris, in 1705,
the rays of the sun, collected by a large glass, had scarce
any force, though the separate rays quite inflamed the
air. The reason of so surprising a thing seems to be,
that the heat raised from the earth's great sulphureous
exhalations, embarrassed, stopped, and in some degiee
absorbed the rays of the sun.

29. Equally strange are the phenomena of the glass-
drop. The make of this drop is as simple as its expla-
nation is difficult. They take up a small quantity of
melted glass on the top of an iron rod, and let it drop
into a pail of water. When it does not break in the
operation, it forms the glass-drop. This is of such
firmness, that it bears smart blows of a hammer, without
G '6



breaking. But if you break only >he tip of the small
end, the whole shatters into powder. This shattering is
attended with a loud report, and the povyder scatters alt
around. If the experiment be made in the air pump,
the drop bursts more impetuously, and the dust is finer
than when it bursts in the open air. This is a plain
matter of fact. I do not undertake to account for it.

Gunpowder is commonly supposed to have been in-
vented by Barthold Schwartz, about the year' 1380. ^
But Roger 'Bacon knew of it a hundred and fifty >ears^
before Schwartz was bora. For in iris treatise de Nul-
litate Magica, published at Oxford in 121 (i, are these-'
words. "You may raise thunder and lightning at
pleasure, by only taking sulphur, nitre, and charcoal,
which single have no effect, but mixed together 1 and
confined in a cldse place, cause a noise and. explosioa
greater than that of a clap of thunder."

The effect of gunpowder is owing to the spring of
fhe air, inclosed ia the grains and in the spaces between
them. All these springs arc dilated by the fire, and set
a playing at 6nce. The powder itself Only serves to'
light the fire, which puts the air in action.
, Aurum fulminans, a preparation- of gold, is far
stronger than gunpowder. A scruple of this acts more
forcibly than half a pound of that. A single grain laid
on a knife, and lighted at a candle, goes off with a
greater noise than a musket.

30. Air is that ckar, transparent, compressible fluid,
which is extended at least round the terraqueous globe,
fceing with us about 46,656,000,000 times more dense
and sluggish than ether, betwixt which and the air there
is a very great affinity or attractive force, which is a*
their density ; i. e. the air contiguous to the ether takes 17
in and concentrates the ether proportionally to its
greater density, by which it is rendered more springy
and active, with this difference, that the air by contact
and cohesion in the parts of bodies, becomes solid and
unelastic (but ether never); from whence again, by heat,
fire, or dissolution of |u"ts being separated, its elasticity



returns. This element has a near affinity or relation to >
water, because it eagerly takes up rarefied water iota
itself, as water again drinks up a portion of air within
its contact ; so that air and water, actuated by ether,
make the levers and wedges by which nature performs
all her changes in bodies. And it serves as the commort
medium of communication between us and all bodies.

The pressure of a column of air upon a square inch
only, is equal to fifteen pounds weight. That -upon the
surface of a human body generally amounts to at least-
thirteen tons weight : seeing all fluids press with an equal
force every way, upwards, downwards, sideways, and hi-
all directions.

" But how is it then that our bodies are not crushed -
in pieces 1" Our bodies, as well as all others, are filled
wit Ji air throughout : and the spring of the internal air
is equal to the pressure of that without. And when two
equal forces act in contrary directions, they entirely
destroy each other's effects: hence, if the ambient air
press? upon us, it is all one as if it did not* press at all.

The elasticity of the air is a counterbalance to its-
gravitation. And how necessary is it, that these should
balance each other ? Were the power of gravity to be
suspended for a moment, and that of elasticity to remain,
the atmosphere would instantly be dissipated througlj
the infinite regions of space. But while the weight of
the air and its elastic force are equal, they produce aa
equilibrium among the particles of air, in every part of
the atmosphere.

As the higher it is, the air is more and more expanded,.,
gravitation being less and less, sa the parts of the air in
the upper regions will be expanded, only not to infinity.
The air is generally invisible* And it is necessary it-
should be so. For as it is the medium through which
we see objects, if the parts of it were perceptible, it
would render the view of these objects far less perfect
and distinct. Hence a greatly magnifying telescope, as
it shews the body of air, makes the view ef other objects
more confused.

Yet in some cases you* may seem to see the air. In a
very hot summer's day, in an open part of .the country,.



136

place yourself on an eminence, nearly facing the sun.
Then, if there be a gentle wind, there will be a re-
flection of light from the body of the air in the vale
below. And you will see the undulations of waves of
air almost as perfectly as you may those of water,
agitated by a gentle wind. And yet in truth it is not
the air which you see, but the vapours that float therein.

One property of air is its weight or gravity. This
you will immediately feel if you lay your hand on the
mouth of a vessel, which is emptied of air. If you Jay
a square piece of glass on the orifice of an air pump,
when the air is drawn out, it will be broke to shivers
with a great noise. Or extract the air from between two
smoothly polished marbles, and close the edges with
wax, they will then be so strongly prest together, as not
easily to be separated. But we need no other proof of
it than the barometer : a glass tube, close at one end,
and filled with mercury ; immerge the other end in a
bason of the same fluid, and when it is erected, the mer-
cury in the tube will rise thirty inches above the surface
of that in the bason.

The changes then in the barometer are wholly owing
to the changes in the weight of the atmosphere. But
to what are these owing ? It seems chiefly to the
winds. For 1. These must alter the weight of the air
in any particular place, either by bringing together and
accumulating the air, which is the case when two winds
blow at the same time from opposite points ; or by
sweeping away part of the air, as when two winds blow
opposite ways from the same point ; or lastly, by cutting
tfrY the pressure of the atmosphere, which happens when
any wind blows briskly any way. 2. Cold nitrous par-
ticles load the atmosphere, and increase its weight.-

3, So do heavy, dry exhalations from the earth.

4. The air being- rendered heavier is more able to
support the vapours, which being intermixed with it,
make the weather fair and serene. When it is rendered
lighter by the contrary causes, it becomes unable to sup-
port the vapours, which then sink, gather into drops,
and fall in rain.



isr

With us the mercury is highest when the wind is north
or north-east, and so brings the cold condensed air of
the northern climates. In all northern countries the
mercury varies more than in the southern, the winds
being more frequent, strong, various, and opposite to
each other. Between the tropics it scarce varies at all, the
"winds being ; small*, and generally blowing the same way.

The pressure of the air is, coeteris paribus, as its
height. Carry the barometer to a higher place, where
the incumbent column of air is shorter, and a shorter
column of air is sustained : it being found to descend at
the rate of a quarter of an inch, for every hundred
feet of ascent.

Now air, as all other fluids, must press equally every
way* Hence it is, that soft bodies sustain their pressure,
without any change of figure, and brittle bodies without
breaking, though that pressure be equal to that of a
column of mercury, thirty inches high, or a column of
water of thirty feet. Nothing can keep these bodies un-
changed but the equable pressure on all sides, which re-
sists as much as it is resisted; And hence on removing
or lessening that pressure on one side, the effect of it is-
soon perceived on the other.

It is by means of its gravity, r. That the air closely
invests the earth with ail the bodies on it, and bends
them down : that it prevents the arterial vessels of
plants and animals from being too much distended by
the impetus of the circulating juices : and that it hinders
the blood from oozing out through the pores of their
containing vessels. Hence they who travel up high
mountains, the higher they ascend, are relaxed the more,
till, they fall into spitting of blood. 2. The mixture of
contiguous fluids is chiefly owing to this. Hence many
fluids which readily mix in the air, when that is removed,
remain separate. Q. It determines the action of one
body upon another. Thus it presses the particles of
fire against the fuel ; whereas upon removing the air,
the fire immediately goes out. So aqua regia ceases to
dissolve gold, if the air be taken away ; hence also on
the tops of high mountains, as on the Pike of Teneriffe,
the most acrid bodies, such as pepper, ginger, salt have



no sensible (aste, for want of a sufficient gravity m the
air to press their particles into the pores of the tongue.

Another property of air is elasticity. It yields to an
impression, by contracting its dimensions, and returns to
them on removing the impressive cause. This endeavours
to expand itself, every particle of air continually exerts
against an equal endeavour of the ambient particles.
Hence it is; that a bladder full of air will burst in aiv
exhausted receiver ; while one that befo?e seemed
empty, swells and appears to be full of air.

This power does not seem to have any bounds ; nor
ig it easy to be destroyed. Let air be expanded ever so
much, it still retains its spring; nor is* this sensibly di-
minished by any experiment which has yet been made*

There is no fixing any bounds to its condensation any
more than to its dilatation. It will dilate into a thousand
times its former space, \ea into 13,679 times; and all
this by its own expansive force, without any force of
fire. The air we breathe near the surface of the earth,
is comprest by its- own weight into at least the 13,()'7i)tli-
part of the space it would possess in vacuo. And if the-
same air be farther condensed by art, the space it will
take up when most dilated will be (according to Mr.-
Boyle) to that it possessed when most condensed, a&
550,000 to owe.

Jf while we increase the elasticity of air on one side
by compression, we iucrcase it on the other side by heat,
the force of both soon becomes irresistible; and a
French philosopher supposed that air thus confined and
expanding was sufficient for the explosion of a world.
In order to determine the elasticity of air, the wind-gun
has been invented, \\hicli is an instrument that com-
presses a large quantity of air into a tube in which there
is an ivory ball, and then gives the compressed elastic
air free power to act and drive the ball as directed.
The bail thus driven will pierce a thick board, and will
be iKs fatal at small distances as if driven with gun-
jpewder, I do not know whether ever the- force of this



139-

instrument has been assisted by heat ; certain T am, that
t;his, which could be very easily contrived by means of
phosphorus, or any other hot substance applied to the
barrel, would give such a force as I doubt whether gun-
powder itself could produce.

Every thing we see gives of its parts to the air, and;
has a little floating atmosphere of its own round it.
The rose is encompassed with a sphere of its own-
odorous particles ; while the nightshade infects the air
with scents of a more ungrateful nature. The perfume
of musk flies off in such abundance, that the quantity
remaining becomes sensibly lighter. A. thousand sub*
stances that escape all our senses we know to be there ;,
the powerful emanations of the loadstone, the effluvia of
electricity, the rays or light, and the insinuation of fire.
Such are the various substances through which we
move, and which we are constantly taking in at every
pore, and returning again with an imperceptible dis -
charge.

This great mixture of all earthly bodies is continually
operating upon itself; which, perhaps, may be the cause
of its unceasing motion ; but it operates still more
visibly upon such grosser substances as are exposed to
its influence ; for scarce any substance is found capable-
of resisting the corroding qualities of the air. The air,
say the chymists, is a chaos furnished with all kinds of
salts and menstniums ; and therefore it is, capable of
dissolving all kinds of bodies. It is well known that-
copper and iron are quickly eaten with rust ; and that
in the climates near the equator no art can keep them
clean. In those countries, instruments, knives and keys*,
though kept in the pocket, nevertheless are quickly en-
crusted ; and the great guns, v> ith every, precaution,
after some years, become useless. . Stones 'may be sup-
posed to be more easily soluble. The marble of which,
the noble monuments of Italian antiquity are composed,
although in one of the finest climates in the world,
nevertheless shew the impressions which have been made
upon them by the air. In many places they seem \vojfaa-.



140

eaten by time ; and in others they appear crumbling into*
dust. Gold alone seems to be exempted from this
general dissolution. It is never found to contract rust,
though exposed never so long : the reason is, that sea-
salt, which is the only menstruum of gold, is but very
little mixed with the air, being a very fixed body, and
not apt to volatilize. In the laboratories, however,
where the air is impregnated with it, gold is found to
rust, as well as other metals.

By its elasticity air insinuates into the pores of bodies,
carrying with it this faculty of expansion ; whence it
must necessarily put all the particles it is mixed with
into perpetual oscillations. And as its elasticity is never
the same for two moments together, there must be an
incessant dilatation and^contraetion in all bodies. To this
is owing all putrefaction and. fermentation, neither of
which will proceed in vacuo. And indeed all natural
corruption and alteration seem to depend hereon : so
that metals, particularly gold, are so durable, only by
being impervious to air. And yet it may be doubted
whether air itself be the true, original, universal, dis-
solvent ; or rather the ethereal fire, which is intimately
united with every particle of it ; and without which air
is effete and useless, neither able to feed flame, nor to
sustain animal life.

That there is some matter in the air much finer than
the air itself, appears from many considerations. In an
exhausted receiver something remains, which conveys the
heat near as readily as air. Now this must be a body,
and a body subtle enough to penetrate the pores of
glass. Doubtless then it penetrates the pores of all
other bodies, and consequently is diffused through the
universe. And this seems to be not only more subtle
than the air, but far more weighty and elastic. To the
weight of this may be owing the weight of the air, and
of all other bodies; to its elasticity, the elasticity of the
air, and of all other elastic bodies. This also may cause


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Online LibraryJohn WesleyA survey of the wisdom of God in the creation; or, A compendium of natural philosophy .. (Volume 3) → online text (page 12 of 24)