OF HARD AND SOFT, AND OF THE ATOMS THAT FLY IN
THE AIR.
_A._ Concerning this cover of the earth, made up of an infinite number
of parts of different natures, I had much ado to find any tolerable
method of enquiry. But I resolved at last to begin with the questions
concerning hard and soft, and what kind of motion it is that makes them
so. I know that in any pulsion of air, the parts of it go innumerable
and inexplicable ways; but I ask only if every point of it be moved?
_B._ No. If you mean a mathematical point, you know it is impossible.
For nothing is movable but body. But I suppose it divisible, as all
other bodies, into parts divisible. For no substance can be divided into
nothings.
_A._ Why may not that substance within our bodies, which are called
animal spirits, be another kind of body, and more subtile than the
common air?
_B._ I know not why, no more than you or any man else knows why it is
not very air, though purer perhaps than the common air, as being
strained through the blood into the brain and nerves. But howsoever that
be, there is no doubt, but the least parts of the common air,
respectively to the whole, will easilier pierce, with equal motion, the
body that resisteth them, than the least parts of water. For it is by
motion only that any mutation is made in any thing; and all things
standing as they did, will appear as they did. And that which changeth
soft into hard, must be such as makes the parts not easily to be moved
without being moved all together; which cannot be done but by some
motion compounded. And we call hard, that whereof no part can be put out
of order without disordering all the rest; which is not easily done.
_A._ How water and air beaten into extreme small bubbles is hardened
into ice, you have told me already, and I understand it. But how a soft
homogeneous body, as air or water, should be so hardened, I cannot
imagine.
_B._ There is no hard body that hath not also some degree of gravity;
and consequently, being loose, there must be some efficient cause, that
is, some motion, when it is severed from the earth, to bring the same to
it again. And seeing this compounded motion gives to the air and water
an endeavour from the earth, the motion which must hinder it, must be in
a way contrary to the compounded motion of the earth. For whatsoever,
having been asunder, comes together again, must come contrary ways, as
those that follow one another go the same way, though both move upon the
same line.
_A._ What experiment have you seen to this purpose?
_B._ I have seen a drop of glass like that of the second figure, newly
taken out of the furnace, and hanging at the end of an iron rod, and yet
fluid, and let fall into the water and hardened. The club-end of it A A
coming first to the water, the tail B C following it. It is proved
before, that the motion that makes it is a compounded motion, and gives
an endeavour outward to every part of it; and that the motion which
maketh cold, is such as shaving the body in every point of contact, and
turning it, gives them all an endeavour inward. Such is this motion made
by the sinking of the hot and fluid glass into the water. It is
therefore manifest that the motion which hardeneth a soft body, must in
every point of contact be in the contrary way to that which makes a hard
body soft. And farther, that slender tail B C shall be made much more
hard than common glass. For towards the upper end, in C, you cannot
easily break it, as small as it is. And when you have broken it, the
whole body will fall into dust, as it must do, seeing the bending is so
difficult. For all the parts are bent with such force, that upon the
breaking at D, by their sudden restitution to their liberty, they will
break together. And the cause why the tail B C, being so slender,
becomes so hard, is, that all the endeavour in the great part A B, is
propagated to the small part B C, in the same manner as the force of the
sun-beams is derived almost to a point by a burning-glass. But the cause
why, when it is broken in D, it breaks also in so many other places, is,
that the endeavour in all the other parts, which is called the spring,
unbends it; from whence a motion is caused the contrary way, and that
motion continued bends it more the other way and breaks it, as a bow
over-bent is broken into shivers by a sudden breaking of the string.
_A._ I conceive now how a body which having been hard and softened
again, may be rehardened; but how a fluid and mere homogeneous body, as
air or water, may be so, I see not yet. For the hardening of water is
making a hard body of two fluids, whereof one, which is the water, hath
some tenacity; and so a man may make a bladder hard with blowing into
it.
_B._ As for mere air, which hath no natural motion of itself, but is
moved only by other bodies of a greater consistence, I think it
impossible to be hardened. For the parts of it so easily change places,
that they can never be fixed by any motion. No more I think can water,
which though somewhat less fluid, is with an insensible force very
easily broken.
_A._ It is the opinion of many learned men, that ice, in long time, will
be turned into crystal; and they allege experience for it. For they say
that crystal is found hanging on high rocks in the Alps, like icicles on
the eaves of a house; and why may not that have formerly been ice, and
in many years have lost the power of being reduced?
_B._ If that were so, it would still be ice, though also crystal: which
cannot be, because crystal is heavier than water, and therefore much
heavier than ice.
_A._ Is there then no transubstantiation of bodies but by mixture?
_B._ Mixture is no transubstantiation.
_A._ Have you never seen a stone that seemed to have been formerly wood,
and some like shells, and some like serpents, and others like other
things?
_B._ Yes. I have seen such things, and particularly I saw at Rome, in a
stone-cutter’s workhouse, a billet of wood, as I thought it, partly
covered with bark, and partly with the grain bare, as long as a man’s
arm, and as thick as the calf of a man’s leg; which handling I found
extreme heavy, and saw a small part of it which was polished, and had a
very fine gloss, and thought it a substance between stone and metal, but
nearest to stone. I have seen also a kind of slate painted naturally
with forest-work. And I have seen in the hands of a chemist of my
acquaintance at Paris, a broken glass, part of a retort, in which had
been the rosin of turpentine, wherein though there were left no rosin,
yet there appeared in the piece of glass many trees; and plants in the
ground about them, such as grow in woods; and better designed than they
could be done by any painter; and continued so for a long time. These be
great wonders of nature, but I will not undertake to show their causes.
But yet this is most certain, that nothing can make a hard body of a
soft, but by some motion of its parts. For the parts of the hardest body
in the world can be no closer together than to touch; and so close are
the parts of air and water, and consequently they should be equally
hard, if their smallest parts had not different natural motions.
Therefore if you ask me the causes of these effects, I answer, they are
different motions. But if you expect from me how and by what motions, I
shall fail you. For there is no kind of substance in the world now, that
was not at the first creation, when the Creator gave to all things what
natural and special motion he thought good. And as he made some bodies
wondrous great, so he made others wondrous little. For all his works are
wondrous. Man can but guess, nor guess farther, than he hath knowledge
of the variety of motion. I am therefore of opinion, that whatsoever
perfectly homogeneous is hard, consisteth of the smallest parts, or, as
some call them, atoms, that were made hard in the beginning, and
consequently by an eternal cause; and that the hardness of the whole
body is caused only by the contact of the parts by pressure.
_A._ What motion is it that maketh a hard body to melt?
_B._ The same compounded motion that heats, namely, that of fire, if it
be strong enough. For all motion compounded is an endeavour to
dissipate, as I have said before, the parts of the body to be moved by
it. If therefore hardness consist only in the pressing contact of the
least parts, this motion will make the same parts slide off from one
another, and the whole to take such a figure as the weight of the parts
shall dispose them to, as in lead, iron, gold, and other things melted
with heat. But if the small parts have such figures as they cannot
exactly touch, but must leave spaces between them filled with air or
other fluids, then this motion of the fire, will dissipate those parts
some one way, some another, the hard part still hard; as in the burning
of wood or stone into ashes or lime. For this motion is that which
maketh fermentation, scattering dissimilar parts, and congregating
similar.
_A._ Why do some hard bodies resist breaking more one way than another?
_B._ The bodies that do so, are for the most part wood, and receive that
quality from their generation. For the heat of the sun in the
spring-time draweth up the moisture at the root, and together with it
the small parts of the earth, and twisteth it into a small twig, by its
motion upwards, to some length, but to very little other dimensions, and
so leaves it to dry till the spring following; and then does the same to
that, and to every small part round about it; so that upward the
strength is doubled, and the next year trebled, &c. And these are called
the grain of the wood, and but touch one another, like sticks with
little or no binding, and therefore can hardly be broken across the
grain, but easily all-along it. Also some other hard bodies have this
quality of being more fragile one way than another, as we see in
quarrels of a glass window, that are aptest many times to break in some
crooked line. The cause of this may be, that when the glass, hot from
the furnace, is poured out upon a plain, any small stones in or under it
will break the stream of it into divers lines, and not only weaken it,
but also cause it falsely to represent the object you look on through
it.
_A._ What is the cause why a bow of wood or steel, or other very hard
body, being bent, but not broken, will recover its former degree of
straightness?
_B._ I have told you already, how the smallest parts of a hard body have
every one, by the generation of hardness, a circular, or other
compounded motion; such motion is that of the smallest parts of the bow.
Which circles in the bending you press into narrower figures, as a
circle into an ellipsis, and an ellipsis into a narrower but longer
ellipsis with violence; which turns their natural motion against the
outward parts of the bow so bent, and is an endeavour to stretch the bow
into its former posture. Therefore if the impediment be removed, the bow
must needs recover its former figure.
_A._ It is manifest; and the cause can be no other but that, except the
bow have sense.
_B._ And though the bow had sense, and appetite to boot, the cause will
be still the same.
_A._ Do you think air and water to be pure and homogeneous bodies?
_B._ Yes, and many bodies both hard and heavy to be so too, and many
liquors also besides water.
_A._ Why then do men say they find one air healthy, another infectious?
_B._ Not because the nature of the air varies, but because there are in
the air, drawn, or rather, beaten up by the sun, many little bodies,
whereof some have such motion as is healthful, others such as is hurtful
to the life of man. For the sun, as you see in the generation of plants,
can fetch up earth as well as water: and from the driest ground any kind
of body that lieth loose, so it be small enough, rather than admit any
emptiness. By some of these small bodies it is that we live; which being
taken in with our breath, pass into our blood, and cause it, by their
compounded motion, to circulate through the veins and arteries; which
the blood of itself, being a heavy body, without it cannot do. What kind
of substance these atoms are, I cannot tell. Some suppose them to be
nitre. As for those infectious creatures in the air, whereof so many die
in the plague, I have heard that Monsieur Des Cartes, a very ingenious
man, was of opinion, that they were little flies. But what grounds he
had for it, I know not, though there be many experiments that invite me
to believe it. For first, we know that the air is never universally
infected over a whole country, but only in or near to some populous
town. And therefore the cause must also be partly ascribed to the
multitude thronged together, and constrained to carry their excrements
into the fields round about and near to their habitation, which in time
fermenting breed worms, which commonly in a month or little more,
naturally become flies; and though engendered at one town, may fly to
another. Secondly, in the beginning of a plague, those that dwell in the
suburbs, that is to say, nearest to this corruption, are the poorest of
the people, that are nourished for the most part with the roots and
herbs which grow in that corrupted dirt; so that the same filth makes
both the blood of poor people, and the substance of the fly. And it is
said by Aristotle, that everything is nourished by the matter whereof it
is generated. Thirdly, when a town is infected, the gentlemen, and those
that live on wholsomest food, scarce one of five hundred die of the
plague. It seems therefore, whatsoever creatures they be that invade us
from the air, they can discern their proper nourishment, and do not
enter into the mouth and nostrils with the breath of every man alike, as
they would do if they were inanimate. Fourthly, a man may carry the
infection with him a great way into the country in his clothes, and
infect a village. Shall another man there draw the infection from the
clothes only by his breath? Or from the hangings of a chamber wherein a
man hath died? It is impossible. Therefore whatsoever killing thing is
in the clothes or hangings, it must rise and go into his mouth or
nostrils before it can do him hurt. It must therefore be a fly, whereof
great numbers get into the blood, and there feeding and breeding worms,
obstruct the circulation of blood, and kill the man.
_A._ I would we knew the palate of those little animals; we might
perhaps find some medicine to fright them from mingling with our breath.
But what is that which kills men that lie asleep too near a
charcoal-fire? Is it another kind of fly? Or is charcoal venomous?
_B._ It is neither fly nor venom, but the effect of a flameless glowing
fire, which dissipates those atoms that maintain the circulation of the
blood; so that for want of it, by degrees they faint, and being asleep
cannot remove, but in short time, there sleeping die; as is evident by
this, that being brought into the open air, without other help, they
recover.
_A._ It is very likely. The next thing I would be informed of, is the
nature of gravity. But for that, if you please, we will take another
day.
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