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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 _ænigmâs_ 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 _phænomena_, 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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They double all the Stuff that is to be water’d, that is, they crease it just through the middle of it, the whole length of the piece, leaving the right side of the Stuff inward, and placing the two edges, or silvages just upon one another, and, as near as they can, place the wale so in the doubling of it, that the wale of the one side may lie very near parallel, or even with the wale of the other; for the nearer that posture they lie, the greater will the watering appear; and the more obliquely, or across to each other they lie, the smaller are the waves. Their way for folding it for a great wale is thus: they take a Pin, and begin at one side of the piece in any wale, and so moving it towards the other side, thereby direct their hands to the opposite ends of the wale, and then, as near as they can, place the two opposite ends of the same wale together, and so double, or fold the whole piece, repeating this enquiry with a Pin at every yard or two’s distance through the whole length; then they sprinkle it with water, and fold it the long-ways, placing between every fold a piece of Pastboard, by which means all the wrong side of the water’d Stuff becomes flat, and with little wales, and the wales on the other side become the more protuberant; whence the creasings or angular bendings of the wales become the more perspicuous. Having folded it in this manner, they place it with an interjacent Pastboard into an hot Press, where it is kept very violently prest, till it be dry and stiff; by which means, the wales of either contiguous sides leave their own impressions upon each other, as is very manifest by the second Figure, where ’tis obvious enough, that the wale of the piece ABCD runs parallel between the pricked lines ef, ef, ef, and as manifest to discern the impressions upon these wales, left by those that were prest upon them, which lying not exactly parallel with them, but a little athwart them, as is denoted by the lines of, oooo, gh, gh, gh, between which the other wales did lie parallel; they are so variously, and irregularly creas’d that being put into that shape when wet, and kept so till they be drie, they so let each others threads, that the Moldings remain almost as long as the Stuff lasts.

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Hence it may appear to any one that attentively considers the Figure, why the parts of the wale a, a, a, a, a, a, should appear bright; and why the parts b, b, b, b, b, b, b, should appear shadowed, or dark; why some, as d, d, d, d, d, d, should appear partly light, and partly dark: the varieties of which reflections and shadows are the only cause of the appearance of watering in Silks, or any other kind of Stuffs.

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From the variety of reflection, may also be deduc’d the cause why a small breez or gale of wind ruffling the surface of a smooth water, makes it appear black; as also, on the other side, why the smoothing or burnishing the surface of whitened Silver makes it look black; and multitudes of other phænomena might hereby be solv’d, which are too many to be here insisted on.

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* * * * *

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Observ. VI. _Of Small Glass Canes._

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That I might be satisfi’d, whether it were not possible to make an _Artificial_ pore as _small_ as any _Natural_ I had yet found, I made several attempts with small _glass pipes_, melted in the flame of a Lamp, and then very _suddenly_ drawn out into a great length. And, by _that means_, without much difficulty, I was able to draw some almost as small as a _Cobweb_, which yet, with the _Microscope_, I could plainly perceive[7] to be _perforated_, both by looking on the _ends_ of it, and by looking on it _against the light_ which was much the _easier way_ to determine whether it were solid or perforated; for, taking a small pipe of glass, and closing one end of it, then filling it _half full_ of water, and holding it _against the light_, I could, by this means, very easily find what was the _differing aspect_ of a _solid_ and a _perforated_ piece of glass; and so easily distinguish, without seeing either end, whether any _Cylinder_ of glass I look’d on, were a _solid stick_, or a _hollow cane_. And by this means, I could also presently judge of any small _filament_ of glass, whether it were _hollow_ or _not_, which would have been exceeding tedious to examine by looking on the end. And many such like ways I was fain to make use of, in the examining of divers other particulars related in this Book, which would have been no easie task to have determined meerly by the more common way of looking on, or viewing the Object. For, if we consider first, the very _faint light_ wherewith the object is enlightened, whence many particles appear _opacous_, which when more enlightned, appear very _transparent_, so that I was fain to _determine_ its _transparency_ by one glass, and its _texture_ by another. Next, the _unmanageableness_ of most _Objects_, by reason of their _smalness_, 3. The _difficulty of finding_ the desired point, and of _placing_ it so, as to reflect the _light conveniently_ for the Inquiry. Lastly, ones being able to view it but with _one eye_ at once, they will appear no small _obstructions_, nor are they easily _remov’d_ without many _contrivances_. But to proceed, I could not find that water, or some _deeply ting’d_ liquors would in small ones rise so high as one would expect; and the _highest_ I have found it yet rise in any of the pipes I have try’d, was to 21 _inches_ above the level of the water in the vessel: for though I found that in the small pipes it would _nimbly enter_ at first, and run about 6 or 7 _inches_ upwards; yet I found it then to move upwards _so slow_, that I have not yet had the _patience_ to observe it above that height of 21 _inches_ (and that was in a pretty _large Pipe_, in comparison of those I formerly mentioned; for I could observe the _progress_ of a _very deep ting’d liquor_ in it with my _naked eye_, without much trouble; whereas many of the _other pipes_ were so _very small_, that unless in a _convenient posture_ to the light, I could not perceive _them_:) But ’tis very probable, that a greater _patience_ and _assiduity_ may discover the liquors to _rise_, at least to remain _suspended_, at heights that I should be loath now even to _ghess_ at, if at least there be any _proportion_ kept between the height of the ascending liquor, and the _bigness of the holes_ of the pipes.

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_AN ATTEMPT FOR THE EXPLICATION OF THIS EXPERIMENT._

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My Conjecture, _That the unequal height of the surfaces of the water, proceeded from the greater pressure made upon the water by the Air without the Pipes_ ABC, _then by that within them_[8]; I shall endeavour to confirm from the truth of the two following _Propositions_:

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The first of which is, _That an unequal pressure of the incumbent Air, will cause an unequal height in the water’s Surfaces_.

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And the second is, _That in this experiment there is such an unequal pressure_.

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That the first is true, the following _Experiment_ will evince. For if you take any Vessel so contrived, as that you can at pleasure either _increase_ or _diminish_ the _pressure_ of the Air upon this or that part of the _Superficies_ of the _water_, the _equality_ of the height of those parts will presently be _lost_; and that part of the _Superficies_ that sustains the _greater pressure_, will be _inferior_ to that which undergoes the _less_. A fit Vessel for this purpose, will be an inverted Glass _Syphon_, such an one as is described in the _Sixth Figure_. For if into it you put Water enough to fill it as high as _AB_, and gently blow in at _D_, you shall _depress_ the Superficies _B_, and thereby _raise_ the opposite Superficies _A_ to a _considerable height_, and by gently _sucking_ you may produce clean _contrary_ effects.

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Next, That there is such an _unequal pressure_, I shall prove from this, _That there is a much greater incongruity of Air to Glass, and some other Bodies, then there is of Water to the same_.

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By _Congruity, I mean a property of a fluid Body, whereby any part of it is readily united with any other part, either of itself, or of any other Similar, fluid, or solid body: And by Incongruity a property of a fluid, by which it is hindred from uniting with any dissimilar, fluid, or solid Body._

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This last property, any one that hath been observingly conversant about fluid Bodies, cannot be ignorant of. For (not now to mention several _Chymical Spirits_ and _Oyls_, which will _very hardly_, if at _all_, be brought to _mix_ with one another; insomuch that there may be found some 8 or 9, or more, several distinct Liquors, which _swimming_ one upon another, will not presently _mix_) we need seek no further for Examples of this kind in _fluids_, then to observe the _drops of rain_ falling through the _air_ and the _bubbles of air_ which are by any means conveyed under the surface of the _water_; or a drop of common _Sallet-Oyl_ swimming upon water. In all which, and many more examples of this kind that might be enumerated, the _incongruity_ of two _fluids_ is easily discernable. And as for the _Congruity_ or _Incongruity_ of Liquids, with several kinds of _firm_ Bodies, they have long since been taken notice of, and called by the Names of _Driness_ and _Moisture_ (though these two names are not comprehensive enough, being commonly used to signifie only the adhering or not adhering of _water_ to some other _solid Bodies_) of this kind we may observe that _water_ will more readily _wet some woods_ then _others_; and that _water_, let fall upon a _Feather_, the whiter side of a _Colwort_, and some other leaves, or upon almost any _dusty_, _unctuous_, or _resinous_ superficies, will not _at all adhere_ to them, but easily _tumble off_ from them, like a solid _Bowl_; whereas, if dropt upon _Linnen_, _Paper_, _Clay_, _green Wood_, &c. it will not be taken off, without leaving some part of it behind _adhering_ to them. So _Quick-silver_, which will very _hardly_ be brought to _stick_ to any _vegetable body_, will _readily adhere_ to, and _mingle_ with, several clean _metalline bodies_.

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And that we may the better finde what the _cause_ of _Congruity_ and _Incongruity_ in bodies is, it will be requisite to consider, First, what is the _cause_ of _fluidness_; And this, _I conceive_, to be nothing else but a certain _pulse_ or _shake_ of _heat_; for Heat being nothing else but a very _brisk_ and _vehement agitation_ of the parts of a body (as I have elswhere made _probable_) the parts of a body are thereby made so _loose_ from one another, that they easily _move any way_, and become _fluid_. That I may explain this a little by a gross Similitude, let us suppose a dish of sand set upon some body that is very much _agitated_, and shaken with some _quick_ and _strong vibrating motion_, as on a _Milstone_ turn’d round upon the under stone very violently whilst it is empty; or on a very stiff _Drum_-head, which is vehemently or very nimbly beaten with the Drumsticks. By this means, the sand in the dish, which before lay like a _dull_ and unactive body, becomes a perfect _fluid_; and ye can no sooner make a _hole_ in it with your finger, but it is immediately _filled up again_, and the upper surface of it _levell’d_. Nor can you _bury_ a _light body_, as a piece of Cork under it, but it presently _emerges_ or _swims_ as ’twere on the top; nor can you lay a _heavier_ on the top of it, as a piece of Lead, but it is immediately _buried_ in Sand, and (as ’twere) sinks to the bottom. Nor can you make a _hole_ in the side of the Dish, but the sand shall _run out_ of it to a _level_, not an _obvious property_ of a fluid body, as such, but this dos _imitate_; and all this meerly caused by the vehement _agitation_ of the conteining vessel; for by this means, _each_ sand becomes to have a _vibrative_ or _dancing_ motion, so as no other heavier body can _rest_ on it, unless _sustein’d_ by some other on either side: Nor will it suffer any Body to be _beneath_ it, unless it be a _heavier_ then it self. Another Instance of the strange _loosening_ nature of a violent jarring Motion, or a strong and nimble vibrative one, we may have from a piece of _iron_ grated on very strongly with a _file_: for if into that a pin _screw’d_ so firm and hard, that though it has a convenient head to it, yet it can by no means be _unscrew’d_ by the fingers; if, I say, you attempt to unscrew this whilst _grated on by the file_, it will be found to undoe and turn very _easily_. The first of these Examples manifests, how a body actually _divided_ into small parts, becomes a _fluid_. And the latter manifests by what means the agitation of heat so easily _loosens_ and _unties_ the parts of _solid_ and _firm_ bodies. Nor need we suppose heat to be any thing else, besides such a motion; for supposing we could _Mechanically_ produce such a one _quick_ and _strong_ enough, we need not spend _fuel_ to _melt_ a body. Now, that I do not speak this altogether groundless, I must refer the Reader to the Observations I have made upon the shining sparks of Steel, for there he shall find that _the same_ effects are produced upon small chips or parcels of Steel by the _flame_, and by _a quick and violent motion_; and if the body of _steel_ may be thus melted (as I there shew it may) I think we have little reason to doubt that almost _any other_ may not also. Every Smith can inform one how quickly both his _File_ and the _Iron_ grows _hot_ with _filing_, and if you _rub_ almost any two _hard_ bodies together, they will do the same: And we know, that a sufficient degree of heat causes _fluidity_, in some bodies much sooner, and in others later; that is, the parts of the body of some are so _loose_ from one another, and so _unapt to cohere_, and so _minute_ and _little_, that a very _small_ degree of agitation keeps them always in the _state of fluidity_. Of this kind, I suppose, the _Æther_, that is the _medium_ or _fluid_ body, in which all other bodies do as it were swim and move; and particularly, the _Air_, which seems nothing else but a kind of _tincture_ or _solution_ of terrestrial and aqueous particles _dissolv’d_ into it, and agitated by it, just as the _tincture_ of _Cocheneel_ is nothing but some finer _dissoluble_ parts of that Concrete lick’d up or _dissolv’d_ by the _fluid_ water. And from this Notion of it, we may easily give a more Intelligible reason how the Air becomes so capable of _Rarefaction_ and _Condensation_. For, as in _tinctures_, one grain of some _strongly tinging_ substance may _sensibly_ colour some _hundred thousand_ grains of _appropriated_ Liquors, so as every _drop_ of it has its proportionate share, and be sensibly ting’d, as I have try’d both with _Logwood_ and _Cocheneel_: And as some few grains of _Salt_ is able to infect as great a quantity, as may be found by _præcipitations_, though not so easily by the _sight_ or _taste_; so the _Air_, which seems to be but as ’twere a _tincture_ or _saline substance, dissolv’d and agitated by the fluid and agil Æther_, may disperse and _expand_ it self into a _vast space_, if it have room enough, and infect, as it were, every part of that space. But, as on the other side, if there be but some _few grains_ of the liquor, it may _extract all_ the colour of the tinging substance, and may _dissolve_ all the Salt, and thereby become _much more impregnated_ with those substances, so may _all_ the air that sufficed in a _rarify’d state_ to fill some _hundred thousand_ spaces of Æther, be compris’d in only _one_, but in a position proportionable _dense_. And though we have not yet found out such _strainers_ for Tinctures and Salts as we have for the Air, being yet unable to _separate_ them from their dissolving liquors by any kind of _filtre_, without _præcipitation_, as we are able to _separate_ the Air from the Æther by _Glass_, and several other bodies. And though we are yet unable and ignorant of the ways of _præcipitating_ Air out of the Æther as we can Tinctures, and Salts out of several _dissolvents_; yet neither of these seeming _impossible_ from the nature of the things, nor so _improbable_ but that some happy future industry may find out ways to effect them; nay, further, since we find that Nature _does really perform_ (though by what means we are not certain) both these actions, namely, by _præcipitating_ the Air in Rain and Dews, and by supplying the Streams and Rivers of the World with fresh water, _strain’d_ through secret subterraneous Caverns: And since, that in very many other _proprieties_ they do so exactly _seem_ of the _same nature_; till further observations or tryals do inform us of the _contrary_, we may _safely enough conclude_ them of the _same kind_. For it seldom happens that any two natures have so many properties _coincident_ or the _same_, as I have observ’d Solutions and Air to have, and to be _different_ in the rest. And therefore I think it neither _impossible_, _irrational_, nay nor _difficult_ to be able to _predict_ what is _likely_ to happen in other particulars also, besides those which _Observation_ or _Experiment_ have declared thus or thus; especially, if the _circumstances_ that do often very much conduce to the variation of the effects be duly _weigh’d_ and _consider’d_. And indeed, were there not a _probability_ of this, our _inquiries_ would be _endless_, our _tryals vain_, and our greatest _inventions_ would be nothing but the meer _products_ of _chance_, and not of _Reason_; and, like _Mariners_ in an Ocean, destitute both of a _Compass_ and the sight of the _Celestial guides_, we might indeed, _by chance_, Steer _directly_ towards our desired Port, but ’tis _a thousand to one_ but we _miss_ our aim. But to proceed, we may hence also give a plain reason, how the Air comes to be _darkned_ by _clouds_, &c. which are nothing but a kind of _precipitation_, and how those _precipitations_ fall down in _Showrs_. Hence also could I very easily, and I think truly, deduce the cause of the curious _sixangular figures_ of Snow, and the appearances of _Haloes, &c._ and the sudden _thickning_ of the Sky with Clouds, and the _vanishing_ and _disappearing_ of those Clouds again; for all these things may be very easily _imitated_ in a _glass of liquor_, with some slight _Chymical preparations_ as I have often try’d, and may somewhere else more largely relate, but have not now time to set them down. But to proceed, there are other bodies that consist of particles more _Gross_, and of a more _apt_ figure for _cohesion_, and this requires _somewhat greater_ agitation; such, I suppose ☿, _fermented vinous_ _Spirits_, several _Chymical Oils_, which are much of kin to those Spirits, &c. Others yet require a _greater_, as _water_, and so others _much greater_, for almost infinite degrees: For, I suppose there are very _few_ bodies in the world that may not be made _aliquatenus_ fluid, by _some_ or _other_ degree of agitation or heat.
