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Micrographia by Robert Hooke

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After I had almost compleated these Pictures and Observations (having had
divers of them ingraven, and was ready to send them to the Press) I was
inform'd, that the Ingenious Physitian _Dr. Henry Power_ had made several
_Microscopical_ Observations, which had I not afterwards, upon our
interchangably viewing each others Papers, found that they were for the
most part differing from mine, either in the Subject it self, or in the
particulars taken notice of; and that his design was only to print
Observations without Pictures, I had even then _suppressed_ what I had so
far proceeded in. But being further _excited_ by several of my Friends, in
complyance with their opinions, that it would not be unacceptable to
several inquisitive Men, and hoping also, that I should thereby discover
something New to the World, I have at length cast in my Mite, into the vast
Treasury of _A Philosophical History_. And it is my _hope_, as well as
_belief_, that these my _Labours_ will be no more comparable to the
_Productions_ of many other _Natural Philosophers_, who are now every where
busie about _greater_ things; then my _little Objects_ are to be compar'd
to the greater and more beautiful _Works of Nature_, A Flea, a Mite, a
Gnat, to an Horse, an Elephant, or a Lyon.


* * * * *


MICROGRAPHIA,

OR SOME

Physiological Descriptions

OF

MINUTE BODIES,

MADE BY

MAGNIFYING GLASSES;

WITH

OBSERVATIONS and INQUIRIES thereupon.

* * * * *


Observ. I. _Of the Point of a sharp small Needle._

As in _Geometry_, the most natural way of beginning is from a Mathematical
_point_; so is the same method in Observations and _Natural history_ the
most genuine, simple, and instructive. We must first endevour to make
_letters_, and draw _single_ strokes true, before we venture to write whole
_Sentences_, or to draw large _Pictures_. And in _Physical_ Enquiries, we
must endevour to follow Nature in the more _plain_ and _easie_ ways she
treads in the most _simple_ and _uncompounded bodies_, to trace her steps,
and be acquainted with her manner of walking there, before we venture our
selves into the multitude of _meanders_ she has in _bodies of a more
complicated_ nature; lest, being unable to distinguish and judge of our
way, we quickly lose both _Nature_ our Guide, and _our selves_ too, and are
left to wander in the _labyrinth_ of groundless opinions; wanting both
_judgment_, that _light_, and _experience_, that _clew_, which should
direct our proceedings.

We will begin these our Inquiries therefore with the Observations of Bodies
of the most _simple nature_ first, and so gradually proceed to those of a
more _compounded_ one. In prosecution of which method, we shall begin with
a _Physical point_; of which kind the _Point of a Needle_ is commonly
reckon'd for one; and is indeed, for the most part, made so sharp, that the
naked eye cannot distinguish any parts of it: It very easily pierces, and
makes its way through all kind of bodies softer then it self: But if view'd
with a very good _Microscope_, we may find that the _top_ of a Needle
(though as to the sense very _sharp_) appears a _broad_, _blunt,_ and very
_irregular_ end; not resembling a Cone, as is imagin'd, but onely a piece
of a tapering body, with a great part of the top remov'd, or deficient. The
Points of Pins are yet more blunt, and the Points of the most curious
Mathematical Instruments do very seldome arrive at so great a sharpness;
how much therefore can be built upon demonstrations made onely by the
productions of the Ruler and Compasses, he will be better able to consider
that shall but view those _points_ and _lines_ with a _Microscope_.

Now though this point be commonly accounted the sharpest (whence when we
would express the sharpness of a point the most _superlatively_, we say, As
sharp as a Needle) yet the _Microscope_ can afford us hundreds of Instances
of Points many thousand times sharper: such as those of the _hairs_, and
_bristles_, and _claws_ of multitudes of _Insects_; the _thorns_, or
_crooks_, or _hairs_ of _leaves_, and other small vegetables; nay, the ends
of the _stiriae_ or small _parallelipipeds_ of _Amianthus_, and _alumen
plumosum_; of many of which, though the Points are so sharp as not to be
visible, though view'd with a _Microscope_ (which magnifies the Object, in
bulk, above a million of times) yet I doubt not, but were we able
_practically_ to make _Microscopes_ according to the _theory_ of them, we
might find hills, and dales, and pores, and a sufficient bredth, or
expansion, to give all those parts elbow-room, even in the blunt top of the
very Point of any of these so very sharp bodies. For certainly the
_quantity_ or extension of any body may be _Divisible in infinitum_, though
perhaps not the _matter_.

But to proceed: The Image we have here exhibited in the first Figure[1],
was the top of a small and very sharp Needle, whose point _aa_ nevertheless
appear'd through the _Microscope_ above a quarter of an inch broad, not
round nor flat, but _irregular_ and _uneven_; so that it seem'd to have
been big enough to have afforded a hundred armed Mites room enough to be
rang'd by each other without endangering the breaking one anothers necks,
by being thrust off on either side. The surface of which, though appearing
to the naked eye very smooth, could not nevertheless hide a multitude of
holes and scratches and ruggednesses from being discover'd by the
_Microscope_ to invest it, several of which inequalities (as A, B, C,
seem'd _holes_ made by some small specks of _Rust_; and D some
_adventitious body_, that stuck very close to it) were _casual_. All the
rest that roughen the surface, were onely so many marks of the rudeness and
bungling of _Art_. So unaccurate is it, in all its productions, even in
those which seem most neat, that if examin'd with an organ more acute then
that by which they were made, the more we see of their _shape_, the less
appearance will there be of their _beauty_: whereas in the works of
_Nature_, the deepest Discoveries shew us the greatest Excellencies. An
evident Argument, that he that was the Author of all these things, was no
other then _Omnipotent_; being able to include as great a variety of parts
and contrivances in the yet smallest Discernable Point, as in those vaster
bodies (which comparatively are called also Points) such as the _Earth_,
_Sun_, or _Planets_. Nor need it seem strange that the Earth it self may be
by _Analogie_ call'd a Physical Point: For as its body, though now so near
us as to fill our eys and fancies with a sense of the vastness of it, may
by a little Distance, and some convenient _Diminishing_ Glasses, be made
vanish into a scarce visible Speck, or Point (as I have often try'd on the
_Moon_, and (when not too bright) on the _Sun_ it self.) So, could a
Mechanical contrivance succesfully answer our _Theory_, we might see the
least spot as big as the Earth it self; and Discover, as _Des Cartes_[2]
also conjectures, as great a variety of bodies in the _Moon_, or _Planets_,
as in the _Earth_.

But leaving these Discoveries to future Industries, we shall proceed to add
one Observation more of a _point_ commonly so call'd, that is, the mark of
a _full stop_, or _period_. And for this purpose I observed many both
_printed_ ones and _written_; and among multitudes I found _few_ of them
more _round_ or _regular_ then this which I have delineated in the third
figure of the second Scheme, but _very many_ abundantly _more disfigur'd_;
and for the most part if they seem'd equally round to the eye, I found
those points that had been made by a _Copper-plate,_ and Roll-press, to be
as misshapen as those which had been made with _Types_, the most curious
and smothly _engraven strokes_ and _points_, looking but as so many
_furrows_ and _holes_, and their _printed impressions_, but like _smutty
daubings_ on a matt or uneven floor with a blunt extinguisht brand or
stick's end. And as for _points_ made with a _pen_ they were much _more
ragged_ and _deformed_. Nay, having view'd certain pieces of exceeding
curious writing of the kind (one of which in the bredth of a _two-pence_
compris'd _the Lords prayer, the Apostles Creed, the ten Commandments, and
about half a dozen verses besides of the Bible_, whose _lines_ were _so
small_ and _near together_, that I was unable to _number_ them with my
_naked eye_,) a very ordinary _Microscope_, I had then about me, inabled me
to see that what the Writer of it had asserted was _true_, but withall
discover'd of what pitifull _bungling scribbles_ and _scrawls_ it was
compos'd, _Arabian_ and _China characters_ being almost as well shap'd, yet
thus much I must say for the Man, that it was for the most part _legible_
enough, though in some places there wanted a good _fantsy_ well _preposest_
to help one through. If this manner _of small writing_ were made _easie_
and _practicable_ (and I think I know such a one, but have never yet made
tryal of it, whereby one might be inabled to write _a great deale_ with
_much ease_, and _accurately_ enough in a very _little roome_) it might be
of very good use to convey _secret Intelligence_ without any danger of
_Discovery_ or _mistrusting_. But to come again to the point. The
_Irregularities_ of it are caused by three or four _coadjutors_, one of
which is, the _uneven surface_ of the _paper_, which at best appears no
smother then a very course piece of _shag'd cloth_, next the _irregularity
of the Type_ or _Ingraving_, and a third is the _rough Daubing_ of the
_Printing-Ink_ that lies upon the instrument that makes the impression, to
all which, add the _variation_ made by the Different _lights_ and
_shadows_, and you may have sufficient reason to guess that a _point_ may
appear much more _ugly_ then _this_, which I have here presented, which
though it appear'd through the _Microscope_ _gray_, like a great splatch of
_London_ dirt, about three inches over; yet to the _naked eye_ it was
_black_ and no bigger then that in the midst of the Circle A. And could I
have found Room in this Plate to have inserted an O you should have seen
that the _letters_ were not more distinct then the _points_ of Distinction,
nor a _drawn circle_ more exactly _so_, then we have now shown a _point_ to
be a _point_.

* * * * *


Observ. II. _Of the Edge of a Razor._

The sharpest _Edge_ hath the same kind of affinity to the sharpest _Point_
in Physicks, as a _line_ hath to a _point_ in Mathematicks; and therefore
the Treaty concerning this, may very properly be annexed to the former. A
Razor doth appear to be a Body of a very neat and curious aspect, till more
closely viewed by the _Microscope_, and there we may observe its very Edge
to be of all kind of shapes, except what it should be. For examining that
of a very sharp one, I could not find that any part of it had any thing of
sharpness in it; but it appeared a rough surface of a very considerable
bredth from side to side, the narrowest part not seeming thinner then the
back of a pretty thick Knife. Nor is't likely that it should appear any
otherwise, since as we just now shew'd that a _point_ appear'd a _circle_,
'tis rational a _line_ should be a _parallelogram_.

Now for the drawing this second Figure[3] (which represents a part of the
Edge about half a quarter of an inch long of a Razor well set) I so plac'd
it between the Object-glass & the light, that there appear'd a reflection
from the very Edge, represented by the white line abcdef. In which you may
perceive it to be somewhat sharper then elsewhere about d, to be indented
or pitted about b, to be broader and thicker about c, and unequal and
rugged about e, and pretty even between ab and ef. Nor was that part of the
Edge ghik so smooth as one would imagine so smooth bodies as a Hone and Oyl
should leave it; for besides those multitudes of scratches, which appear to
have raz'd the surface ghik, and to cross each other every way which are
not half of them exprest in the Figure, there were several great and deep
scratches, or furrows, such as gh and ik, which made the surface yet more
rugged, caus'd perhaps by some small Dust casually falling on the Hone, or
some harder or more flinty part of the Hone it self. The other part of the
Razor ll, which is polish'd on a grinding-stone, appear'd much rougher then
the other, looking almost like a plow'd field, with many parallels, ridges,
and furrows, and a cloddy, as 'twere, or an uneven surface: nor shall we
wonder at the roughnesses of those surfaces, since even in the most curious
wrought Glasses for _Microscopes_, and other Optical uses, I have, when the
Sun has shone well on them, discover'd their surface to be variously raz'd
or scratched, and to consist of an infinite of small broken surfaces, which
reflect the light of very various and differing colours. And indeed it
seems impossible by Art to cut the surface of any hard and brittle body
smooth, since _Putte_, or even the most curious _Powder_ that can be made
use of, to polish such a body, must consist of little hard rough particles,
and each of them must cut its way, and consequently leave some kind of
gutter or furrow behind it. And though Nature does seem to do it very
readily in all kinds of fluid bodies, yet perhaps future observators may
discover even these also rugged; it being very probable, as I elsewhere
shew, that fluid bodies are made up of small solid particles variously and
strongly mov'd, and may find reason to think there is scarce a surface _in
rerum natura_ perfectly smooth. The black spot mn, I ghess to be some small
speck of rust, for that I have oft observ'd to be the manner of the working
of Corrosive Juyces. To conclude, this Edge and piece of a Razor, if it had
been really such as it appear'd through the _Microscope_, would scarcely
have serv'd to cleave wood, much less to have cut off the hair of beards,
unless it were after the manner that _Lucian_ merrily relates _Charon_ to
have made use of, when with a Carpenters Axe he chop'd off the beard of a
sage Philosopher, whose gravity he very cautiously fear'd would indanger
the oversetting of his Wherry.

* * * * *


Observ. III. _Of fine Lawn, or Linnen Cloth._

This is another product of Art, A piece of the finest Lawn I was able to
get, so curious that the threads were scarce discernable by the naked eye,
and yet through an ordinary _Microscope_ you may perceive[4] what a goodly
piece of _coarse Matting_ it is; what proportionable cords each of its
threads are, being not unlike, both in shape and size, the bigger and
coarser kind of _single Rope-yarn_, wherewith they usually make _Cables_.
That which makes the Lawn so transparent, is by the _Microscope_, nay by
the naked eye, if attentively viewed, plainly enough evidenced to be the
multitude of square holes which are left between the threads, appearing to
have much more hole in respect of the intercurrent parts then is for the
most part left in a _lattice-window_, which it does a little resemble,
onely the crossing parts are round and not flat.

These threads that compose this fine contexture, though they are as small
as those that constitute the finer sorts of Silks, have notwithstanding
nothing of their glossie, pleasant, and lively reflection. Nay, I have been
informed both by the Inventor himself, and several other eye-witnesses,
that though the flax, out of which it is made, has been (by a singular art,
of that excellent Person, and Noble Vertuoso, M. _Charls Howard_, brother
to the _Duke of Norfolk_) so curiously dress'd and prepar'd, as to appear
both to the eye and the touch, full as _fine_ and as _glossie_, and to
receive all kinds of colours, as well as Sleave-Silk; yet when this Silken
Flax is twisted into threads, it quite loseth its former luster, and
becomes as plain and base a thread to look on, as one of the same bigness,
made of common Flax.

The reason of which odd _Phenomenon_ seems no other then this; that though
the curiously drest Flax has its parts so exceedingly small, as to
equallize, if not to be much smaller then the clew of the Silk-worm,
especially in thinness, yet the differences between the figures of the
constituting filaments are so great, and their substances so various, that
whereas those of the _Silk_ are _small_, _round_, _hard_, _transparent,_
and to their bigness proportionably _stiff_, so as each filament preserves
its proper _Figure_, and consequently its vivid _reflection_ intire, though
twisted into a thread, if not too hard; those of Flax are _flat_, _limber_,
_softer,_ and _less transparent_, and in twisting into a thread they joyn,
and lie so close together, as to lose their own, and destroy each others
particular reflections. There seems therefore three Particulars very
requisite to make the so drest Flax appear Silk also when spun into
threads. First, that the substance of it should be made more _clear_ and
_transparent_, Flax retaining in it a kind of opacating brown, or yellow;
and the parts of the whitest kind I have yet observ'd with the _Microscope_
appearing white, like flaw'd Horn or Glass, rather then clear, like clear
Horn or Glass. Next that, the filaments should each of them be _rounded_,
if that could be done, which yet is not so very necessary, if the first be
perform'd, and this third, which is, that each of the small filaments be
_stifned_; for though they be square, or flat, provided they be
_transparent_ and stiff, much the same appearances must necessarily follow.
Now, though I have not yet made trial, yet I doubt not, but that both these
proprieties may be also induc'd upon the Flax, and perhaps too by one and
the same Expedient, which some trials may quickly inform any ingenious
attempter of, who from the use and profit of such an Invention, may find
sufficient argument to be prompted to such Inquiries. As for the _tenacity_
of the substance of Flax, out of which the thread is made, it seems much
inferiour to that of Silk, the one being a _vegetable_, the other an
_animal_ substance. And whether it proceed from the better concoction, or
the more homogeneous constitution of _animal_ substances above those of
_vegetables_, I do not here determine; yet since I generally find, that
_vegetable_ substances do not equalize the _tenacity_ of _animal_, nor
these the _tenacity_ of some purified _mineral_ substances; I am very apt
to think, that the _tenacity_ of bodies does not proceed from the _hamous_,
or _hooked_ particles, as the _Epicureans_ and some modern _Philosophers_
have imagin'd; but from the more exact _congruity_ of the constituent
parts, which are contiguous to each other, and so bulky, as not to be
easily separated, or shatter'd, by any small pulls or concussion of heat.

* * * * *


Observ. IV. _Of fine waled Silk, or Taffety._

This[5] is the appearance of a piece of very fine Taffety-riband in the
bigger magnifying Glass, which you see exhibits it like a very convenient
substance to make Bed-matts, or Door-matts of, or to serve for Beehives,
Corn-scuttles, Chairs, or Corn-tubs, it being not unlike that kind of work,
wherewith in many parts in _England_, they make such Utensils of Straw, a
little wreathed, and bound together with thongs of Brambles. For in this
Contexture, each little filament, fiber, or clew of the Silk-worm, seem'd
about the bigness of an ordinary Straw, as appears by the little irregular
pieces, ab, cd, and ef; The _Warp_, or the thread that ran crossing the
Riband, appear'd like a single Rope of an Inch Diameter; but the _Woof_, or
the thread that ran the length of the Riband, appear'd not half so big.
Each Inch of six-peny-broad Riband appearing no less then a piece of
Matting Inch and half thick, and twelve foot square, a few yards of this,
would be enough to floor the long Gallery of the _Loure_ at _Paris_. But to
return to our piece of Riband: It affords us a not unpleasant object,
appearing like a bundle, or wreath, of very clear and transparent
_Cylinders_, if the Silk be white, and curiously ting'd; if it be colour'd,
each of those small horney _Cylinders_ affording in some place or other of
them, as vivid a reflection, as if it had been sent from a _Cylinder_ of
Glass or Horn. In-so-much, that the reflexions of Red, appear'd as if
coming from so many _Granates_, or _Rubies_. The loveliness of the colours
of Silks above those of hairy Stuffs, or Linnen, consisting, as I
else-where intimate, chiefly in the transparency, and vivid reflections
from the _Concave_, or inner surface of the _transparent Cylinder_, as are
also the colours of Precious Stones; for most of the reflections from each
of these _Cylinders_, come from the _Concave_ surface of the air, which is
as 'twere the foil that incompasses the _Cylinder_. The colours with which
each of these _Cylinders_ are ting'd, seem partly to be superficial, and
sticking to the out-sides of them; and partly, to be imbib'd, or sunck into
the substance of them: for Silk, seeming to be little else then a dried
thread of Glew, may be suppos'd to be very easily relaxt, and softened, by
being steeped in warm, nay in cold, if penetrant, juyces or liquors. And
thereby those tinctures, though they tinge perhaps but a small part of the
substance, yet being so highly impregnated with the colour, as to be almost
black with it, may leave an impression strong enough to exhibite the
desir'd colour. A pretty kinde of artificial Stuff I have seen, looking
almost like transparent Parchment, Horn, or Ising-glass, and perhaps some
such thing it may be made of, which being transparent, and of a glutinous
nature, and easily mollified by keeping in water, as I found upon trial,
had imbib'd, and did remain ting'd with a great variety of very vivid
colours, and to the naked eye, it look'd very like the substance of the
Silk. And I have often thought, that probably there might be a way found
out, to make an artificial glutinous composition, much resembling, if not
full as good, nay better, then that Excrement, or whatever other substance
it be out of which, the Silk-worm wire-draws his clew. If such a
composition were found, it were certainly an easie matter to find very
quick ways of drawing it out into small wires for use. I need not mention
the use of such an Invention, nor the benefit that is likely to accrue to
the finder, they being sufficiently obvious. This hint therefore, may, I
hope, give some Ingenious inquisitive Person an occasion of making some
trials, which if successfull, I have my aim, and I suppose he will have no
occasion to be displeas'd.

* * * * *


Observ. V. _Of watered Silks, or Stuffs._

There are but few _Artificial_ things that are worth observing with a
_Microscope_, and therefore I shall speak but briefly concerning them. For
the Productions of art are such rude mis-shapen things, that when view'd
with a _Microscope_, is little else observable, but their deformity. The
most curious Carvings appearing no better then those rude _Russian_ Images
we find mention'd in _Purchas_, where three notches at the end of a Stick,
stood for a face. And the most smooth and burnish'd surfaces appear most
rough and unpolisht: So that my first Reason why I shall add but a few
observations of them, is, their mis-shapen form; and the next, is their
uselessness. For why should we trouble our selves in the examination of
that form or shape (which is all we are able to reach with a _Microscope_)
which we know was design'd for no higher a use, then what we were able to
view with our naked eye? Why should we endeavour to discover mysteries in
that which has no such thing in it? And like _Rabbins_ find out
_Caballisms_, and _aenigmas_ in the Figure, and placing of Letters, where
no such thing lies hid: whereas in _natural_ forms there are some so small,
and so curious, and their design'd business so far remov'd beyond the reach
of our sight, that the more we magnify the object, the more excellencies
and mysteries do appear; And the more we discover the imperfections of our
senses; and the Omnipotency and Infinite perfections of the great Creatour.
I shall therefore onely add one or two Observations more _artificial_
things, and then come to the Treaty concerning such matters as are the
Productions of a more curious Workman. One of these, shall be that of a
piece of water'd Silk, represented in the second Figure of the third
_Scheme_,[6] as it appear'd through the least magnifying Glass. _AB_
signifying the long way of the Stuff, and _CD_ the broad way. This Stuff,
if the right side of it be looked upon, appears to the naked eye, all over
so waved, undulated, or grain'd, with a curious, though irregular variety
of brighter and darker parts, that it adds no small gracefulness to the
Gloss of it. It is so known a propriety, that it needs but little
explication, but it is observable, which perhaps everyone has not
considered, that those parts which appear the darker part of the wave, in
one position to the light, in another appears the lighter, and the
contrary; and by this means the undulations become transient, and in a
continual change, according as the position of the parts in respect of the
incident beams of light is varied. The reason of which odd _phaenomena_, to
one that has but diligently examin'd it even with his naked eye, will be
obvious enough. But he that observes it with a _Microscope_, may more
easily perceive what this _Proteus_ is, and how it comes to change its
shape. He may very easily perceive, that it proceeds onely from the variety
of the _Reflections_ of light, which is caus'd by the various _shape of the
Particles_, or little protuberant parts of the thread that compose the
surface; and that those parts of the waves that appear the brighter, throw
towards the eye a multitude of small reflections of light, whereas the
darker scarce afford any. The reason of which reflection, the _Microscope_
plainly discovers, as appears by the Figure. In which you may perceive,
that the brighter parts of the surface consist of an abundance of large and
strong reflections, denoted by a, a, a, a, a, &c. for the surfaces of those
threads that run the _long way_, are by the Mechanical process of watering,
_creas'd_ or _angled_ in another kind of posture then they were by the
weaving: for by the weaving they are onely _bent round_ the warping
threads; but by the watering, they are _bent with an angle, or elbow_, that
is in stead of lying, or being bent _round_ the threads, as in the third
Figure, a, a, a, a, a, are about b, b, b (b, b, b representing the ends, as
'twere, of the cross threads, they are bent about) they are creas'd on the
top of those threads, with an _angle_, as in the fourth Figure, and that
with all imaginable variety; so that, whereas before they reflected the
light onely from one point of the round surface, as about c, c, c, they now
when water'd, reflect the beams from more then half the whole surface, as
de, de, de, and in other postures they return no reflections at all from
those surfaces. Hence in one posture they compose the brighter parts of the
waves, in another the darker. And these reflections are also varied,
according as the particular parts are variously bent. The reason of which
creasing we shall next examine; and here we must fetch our information from
the Mechanism or manner of proceeding in this operation; which, as I have
been inform'd, is no other then this.

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