 Section 1 of Micrographia. By the Council of the Royal Society of London for Improving of Natural Knowledge, ordered that the book written by Robert Hooke, M.A., fellow of this society, entitled Micrographia, or Some Physiological Descriptions of Minute Bodies Made by Magnifying Glasses with Observations and Inquiries Thereupon, be printed by John Martin and James Allistery, printers to the SED Society, November 23, 1664, Bruncker, P.R.S., Micrographia, or Some Physiological Descriptions of Minute Bodies Made by Magnifying Glasses with Observations and Inquiries Thereupon, by R. Hooke, fellow of the Royal Society, Non-Posese Oculo-Quantum Contenderae Linkus, Non-Tamen in Kierdkoe Contemnus Lipus Inungui, Choratius Epistolarum Libropremus, London, printed by John Martin and James Allistery, printers to the Royal Society and are to be sold at their shop at the Bell and St. Paul's Churchyard, 1665. To the King. Sir, I do hear most humbly lay this small present at your Majesty's Royal Feet, and though it comes accompanied with two disadvantages, the meanness of the author and of the subject, yet in both I am encouraged by the greatness of your mercy and your knowledge, by the one I am taught that you can forgive the most presumptuous offenders, and by the other that you will not esteem the least work of nature or art unworthy your observation. Amidst the many felicities that have accompanied your Majesty's happy restoration in government, it is none of the least considerable that philosophy and experimental learning have prospered under your royal patronage. And as the calm prosperity of your reign has given us the leisure to follow these studies of quiet and retirement, so it is just that the fruits of them should, by way of acknowledgment, be returned to your Majesty. There are, sir, several other of your subjects of your royal society now busy about nobler matters, the improvement of manufacturers in agriculture, the increase of commerce, the advantage of navigation, in all which they are assisted by your Majesty's encouragement and example. Amidst all those greater designs I here presume to bring in that which is more proportional to the smallness of my abilities, and to offer some of the least of all visible things to that mighty King that has established an empire over the best of all invisible things of this world, the minds of men. Your Majesty's most humble and most obedient subject and servant, Robert Hooke. To the royal society. After my address to our great founder and patron I could not but think myself obliged in consideration of those many engagements you have laid upon me, to offer these, my poor labours to this most illustrious assembly. You have been pleased formally to accept of these rude drafts, I have since added to them some descriptions and some conjectures of my own. And therefore, together with your acceptance I must also beg your pardon. The rules you have prescribed yourselves in your philosophical progress do seem the best that have ever yet been practised, and particularly that of avoiding dogmatising and the espousal of any hypothesis not sufficiently grounded and confirmed by experiments. This way seems the most excellent, and may preserve both philosophy and natural history from its former corruptions. In saying which I may seem to condemn my own course in this treatise, in which there may perhaps be some expressions which may seem more positive than your prescriptions will permit. And though I desire to have them understood only as conjectures and queries, which your method does not altogether disallow, yet if even in those I have exceeded, to his fit that I should declare that it was not done by your directions, for it is most unreasonable that you should undergo the imputation of the faults of my conjectures, seeing you can receive so small advantage of reputation by the slight observations of your most humble and most faithful servant, Robert Hooke. CHAPTER II It is the great prerogative of mankind above other creatures that we are not only able to behold the works of nature, or barely to sustain our lives by them, but we have also the power of considering, comparing, altering, assisting, and improving them to various uses. And as this is the peculiar privilege of human nature in general, so it is capable of being so far advanced by the helps of art and experience, as to make some men excel others in their observations and deductions almost as much as they do beasts. By the addition of such artificial instruments and methods there may be in some manner a reparation made for the mischiefs and imperfection mankind is drawn upon itself, by negligence and intemperance, and a willful and superstitious deserting the prescripts and rules of nature, whereby every man, both from a derived corruption innate and born with him, and from his inbreeding and converse with men, is very subject to slip into all sorts of errors. The only way which now remains for us to recover some degree of those former perfections seems to be by rectifying the operations of the sense, the memory, and reason, since upon the evidence, the strength, the integrity, and the right correspondence of all these, all the light, by which our actions are to be guided is to be renewed, and all our command over things is to be established. It is therefore most worthy of our consideration to recollect their several defects, so that we may the better understand how to supply them, and by what assistances we may enlarge their power and secure them in performing their particular duties. As for the actions of our senses we cannot but observe them to be in many particulars much outdone by those of other creatures, and when at best to be far short of the perfection they seem capable of. And these infirmities of the senses arise from a double cause, either from the disproportion of the object to the organ, whereby an infinite number of things can never enter into them, or else from error in the perception, that many things which come within their reach are not received in a right manner. The like frailties are to be found in the memory. We often let many things slip away from us which deserve to be retained, and of those which we treasure up a great part is either frivolous or false, and if good, and substantial, either in tractive time obliterated or at best so overwhelmed and buried under more fraughty notions that when there is need of them they are in vain sought for. The two main foundations being so deceivable it is no wonder that all the succeeding works which we build upon them of arguing, concluding, defining, judging, and all the other degrees of reason are liable to the same imperfection. Being at best either vain or uncertain, so that the errors of the understanding are answerable to the two other, being defective both in the quantity and goodness of its knowledge, for the limits to which our thoughts are confined or small in respect of the vast extent of nature itself. Some parts of it are too large to be comprehended and some too little to be perceived. And from thence it must follow that not having a full sensation of the object we must be very lame and imperfect in our conceptions about it, and in all the proportions which we build upon it. Hence we often take the shadow of things for the substance, small appearances for good similitudes, similitudes for definitions, and even many of those which we think to be the most solid definitions, are rather expressions of our own misguided apprehensions than of the true nature of the things themselves. The effects of these imperfections manifested in different ways according to the temper and disposition of the several minds of men. Some they inclined to gross ignorance and stupidity and others to a presumptuous imposing on other men's opinions, and a confident dogmatizing on matters whereof there is no assurance to be given. Thus all the uncertainty and mistakes of human actions proceed either from the narrowness and wandering of our senses, from the slipperiness or delusion of our memory, from the confinement or rashness of our understanding, so that tis no wonder that our power over natural causes and effects is so slowly improved, seeing we are not only to contend with the obscurity and difficulty of the things whereon we work and think, but even the forces of our own minds conspire to betray us. These being the dangers in the process of human reason, the remedies of them all can only proceed from the real, the mechanical, the experimental philosophy, which has this advantage over the philosophy of discourse and disputation, that whereas that chiefly aims at the subtlety of its deductions and conclusions without much regard to the first groundwork, which ought to be well laid on the sense and memory, so this intends the right ordering of them all, and the making them serviceable to each other. The first thing to be undertaken in this weighty work is a watchfulness over the failings and an enlargement of the dominion of the senses, to which end it is requisite, first, that there should be a scrupulous choice and a strict examination of the reality, constancy, and certainty of particulars that we admit. This is the first rise whereon truth is to begin, and here the most severe and most impartial diligence must be employed. The storing up of all without any regard to evidence or use will only tend to darkness and confusion. We must not therefore esteem the riches of our philosophical treasure by the number only, but chiefly by the weight. The most vulgar instances are not to be neglected, but above all the most instructive are to be entertained. The footsteps of nature are to be traced, not only in her ordinary course, but when she seems to be put to her shifts, to make many doublings and turnings and to use some kind of art in endeavoring to avoid our discovery. The next care to be taken in respect of the senses is a supplying of their infirmities with instruments, and, as it were, the adding of artificial organs to the natural. This in one of them has been of late years accomplished with prodigious benefit to all sorts of useful knowledge, by the invention of optical glasses. By the means of telescopes there is nothing so far distant but may be represented to our view, and by the help of microscopes there is nothing so small as to escape our inquiry. Hence there is a new visible world, discovered to the understanding. By this means the heavens are opened and a vast number of new stars and new motions and new productions appear in them, to which all the ancient astronomers were utterly strangers. By this the earth itself, which lies so near us, under our feet, shows quite a new thing to us and in every little particle of its matter, we now behold almost as great a variety of creatures as we were able before to reckon up in the whole universe itself. It seems not improbable, but that by these helps the subtlety of the composition of bodies, the structures of their parts, the various textures of their matter, the instruments and manner of their inward motions, and all the other possible appearances of things may come to be more fully discovered, all which the ancient parapetetics were content to comprehend in too general and unless further explained useless words of matter and form. From whence there may arise many admirable advantages towards the increase of the operative, and the mechanic knowledge to which this age seems so much inclined because we may perhaps be unable to discern all the secret workings of nature almost in the same manner as we do those that are the production of art and are managed by wheels and engines and springs that were devised by human wit. In this kind I here present to the world my imperfect endeavors, which though they shall prove no other way considerable, yet I hope they may be in some measure useful to the main design of a reformation and philosophy, if it be only by showing that there is not so much required towards it any strength of imagination or exactness of method or depth of contemplation, though the addition of these where they can be had must needs produce a much more perfect composure, as a sincere hand and a faithful eye to examine and to record the things themselves as they appear. And I beg my reader to let me take the boldness to assure him that in this present condition of knowledge a man so qualified as I have endeavored to be only with resolution and integrity and plain intentions of employing his senses aright may venture to compare the reality and the usefulness of his services towards the true philosophy with those of other men that are of much stronger and more acute speculations that shall not make use of the same method by the senses. The truth is the science of nature has been already too long made only a work of the brain and the fancy. It is now high time that it should return to the plainness and soundness of observations on material and obvious things. It is set of great empires that the best way to preserve them from decay is to bring them back to the first principles and arts on which they did begin. The same is undoubtedly true in philosophy that by wandering far away into invisible notions has almost quite destroyed itself, and it can never be recovered or continued but by returning into the same sensible paths in which it did at first proceed. If therefore the reader expects from me any infallible deductions or certainty of axioms I am to say for myself that these stronger works of wit and imagination are above my weak abilities. Or if they had not been so I would not have made use of them in this present subject before me. Whenever he finds that I have ventured at any small conjectures, at the causes of the things that I have observed, I beseech him to look upon them only as doubtful problems and uncertain guesses, and not as unquestionable conclusions or matters of unconfutable science. I have produced nothing here with intent to bind his understanding to an implicit consent. I am so far from that that I desire him not absolutely to rely upon these observations of my eyes if he finds them contradicted by the future ocular experiments of other and impartial discoverers. As for my part, I have obtained my end if these my small labours shall be thought fit to take up some place in the large stock of natural observations which so many hands are busy in providing. If I have contributed the meanest foundations whereon others may raise noble or superstructures I am abundantly satisfied, and all my ambition is that I may serve to the great philosophers of this age as the makers and the grinders of my glasses did to me, that I may prepare and furnish them with some materials, which they may afterwards order and manage with better skill and to far greater advantage. The next remedies in this universal cure of the mind are to be applied to the memory, and they are to consist of such directions as may inform us what things are best to be stored up for our purpose, and which is the best way of so disposing them, that they may not only be kept in safety but ready and convenient to be at any time produced for use, as occasions shall require. But I will not here present myself in what I may say in another discourse, wherein I shall make an attempt to propose some considerations of the manner of compiling a natural and artificial history, and of so ranging and registering its particulars into philosophical tables, as may make them most useful for the raising of axioms and theories. The last indeed is the most hazardous enterprise, and yet the most necessary. And that is to take such care that the judgment and the reason of man, which is the third faculty to be repaired and improved, should receive such assistance as to avoid the dangers to which it is by nature most subject. The imperfections which I have already mentioned, to which it is liable, do either belong to the extent or the goodness of its knowledge. And here the difficulty is the greater. Least that which may be thought a remedy, for the one should prove destructive to the other, least by seeking to enlarge our knowledge, we should render it weak and uncertain, and least by being too scrupulous and exact about every circumstance of it we should confine and straighten it too much. In both these the middle ways are to be taken. Nothing is to be omitted in yet everything to pass a mature deliberation. No intelligence from men of all professions and quarters of the world to be slided, and yet all to be so severely examined that there remain no room for doubt or instability. Much rigor in admitting, much strictness in comparing, and above all much slowness in debating and shyness in determining, is to be practiced. The understanding is to order all the inferior services of the lower faculties. But yet it is to do this only as a lawful master and not a tyrant. It must not encroach upon their offices nor take upon itself the employments which belong to either of them. It must watch the irregularities of the senses, but it must not go before them or prevent their information. It must examine, range, and dispose of the bank which it laid up in the memory. But it must be sure to make distinction between the sober and well-collected heap, and the extravagant ideas and mistaken images which there it may sometimes light upon. So many are the lengths upon which the true philosophy depends, of which if any one be loose or weak the whole chain is in danger of being dissolved. It is to begin with the hands and eyes, and to proceed on through the memory to be continued by the reason, nor is it to stop there but to come about to the hands and eyes again. And so by a continual passage round from one faculty to another it is to be maintained in life and strength. As much as the body of man is by the circulation of the blood through the several parts of the body, the arms, the feet, the lungs, the heart, and the head. If once this method were followed with diligence and attention there is nothing that lies within the power of human wit, or which is far more effectual of human industry, which we might not compass. We might not only hope for inventions to equalize those of Copernicus, Galileo, Gilbert, Harvey, and of others whose names are almost lost, that were the inventors of gunpowder, the Siemens compass, printing, etching, graving, microscopes, et cetera, but multitudes that may far exceed them, for even those discoveries seem to have been the products of some such method though but imperfect. What may not be therefore expected from it if thoroughly prosecuted, talking and contention of arguments would soon be turned into labours. All the fine dreams of opinions and universal metaphysical natures, which the luxury of subtle brains has devised, would quickly vanish and give place to solid histories, experiments, and works, and, as at first, mankind fell by tasting of the forbidden tree of knowledge, so we, their posterity, may be in part restored by the same way, not only by beholding and contemplating, but by tasting, too, those fruits of natural knowledge that were never yet forbidden. From hence the world may be assisted with variety of inventions. New matters for sciences may be collected, the old improved and their rust rubbed away, and as it is by the benefit of the senses that we receive all our skill in the works of nature, so they also may be wonderfully benefited by it and may be guided to an easier and more exact performance of their offices. It is not unlikely, but that we may find out wherein our senses are deficient, and as easily find ways of repairing them. The endeavours of skillful men have been most conversant about the assistance of the eye, and many noble productions have followed upon it, and from hence we may conclude that there is a way opened for advancing the operations not only of all the other senses, but even of the eye itself. That which has been already done ought not to content us, but rather to encourage us to proceed further, and to attempt greater things in the same and different ways. It is not unlikely but that there may be yet invented several other helps for the eye, at much exceeding those already found, as those do the bare eye, such as by which we may perhaps be able to discover living creatures in the moon or other planets, the figures of the compounding particles of matter, and the particular schematisms and textures of bodies. And as glasses have highly promoted our seeing, so tis not improbable but that there may be found many mechanical inventions to improve our other senses, of hearing, smelling, tasting, touching. Tis not impossible to hear a whisper of Furlong's distance at having been already done, and perhaps the nature of the thing would not make it more impossible, though that Furlong should be ten times multiplied. And though some famous authors have affirmed it impossible to hear through the thinnest plate of Muscovy glass, yet I know a way by which tis easy enough to hear one speak through a wall a yard thick. It has not been yet thoroughly examined how far Otakustakans may be improved, nor what other ways there may be of quickening our hearing or conveying sound through other bodies than the air, for that that is not the only medium I can assure the reader, that I have by help of a distended wire propagated the sound to a very considerable distance in an instant, or with his seeming quick emotion as that of light, at least incomparably swifter than that which at the same time was propagated through the air. And this not only in a straight line or direct but in one bended in many angles. Nor are the other three so perfect, but the diligence attention and many mechanical contrivances may also highly improve them. For since the sense of smelling seems to be made by the swift passage of the air, impregnated with the steams and effluvia of several odorous bodies, through the grisly meanders of the nose whose surfaces are covered with a very sensible nerve, and moistened by a transudation from the processes, maximallaries of the brain and some adjoining glandules and by the moist steam of the lungs, with a liquor convenient for the reception of those effluvia, and by the adhesion and mixing of those steams with that liquor, and thereby affecting the nerve or perhaps by insinuating themselves into the juices of the brain. After the same manner, as I have in the following observations intimated, the parts of salt pass through the skins of effs and frogs. Since, I say, smelling seems to be made by some such way, it is not improbable but that some contrivance for making a great quantity of air pass through the nose might at much promote the sense of smelling, as the anyways hindering that passage does dull and destroy it. Several trials I have made both of hindering and promoting this sense, and have succeeded in some according to expectation, and indeed to me it seems capable of being improved for the judging of the constitutions of many bodies. Perhaps we may thereby also judge, as other creatures seem to do, what is wholesome, what poison, and in a word what are the specific properties of bodies. There may be also some other mechanical ways found out of sensibly perceiving the effluvia of bodies, several instances of which were it here proper I could give of mineral streams and exhalations, and it seems not impossible but that by some such ways improve may be discovered, what minerals lie buried under the earth without the trouble to dig for them. Some things to confirm this conjecture may be found in agricola and other writers of minerals speaking of the vegetables that are apt to thrive or pine in these streams. But there also these steams which seem to issue out of the earth and mix with the air, and so to precipitate some aqueous exhalations wherewith tis impregnated, may not be by some way detected before they produce the effect, seems hard to determine. Yet something of this kind I am able to discover by an instrument I can drive to show all the minute variations in the pressure of the air, by which I constantly find that before enduring the time of rainy weather the pressure of the air is less, and in dry weather but especially when an eastern wind which having passed over vast tracts of land is heavy with earthy particles, blows, it is much more though these changes are varied according to very odd laws. The instrument is this. I prepare a pretty capacious bolt head AB with a small stem about two foot and a half long DC. Upon the end of this, D, I put on a small bended glass, or brazen siphon, D, E, F, open at D, E and F, but to be closed with cement at F and E as occasion serves, whose stem F should be about six or eight inches long, but the bore of it not above half an inch diameter and very even. These I fix very strongly together by the help of very hard cement and then fit the whole glass ABC D, E, F into a long board or frame in such manner that almost half the head AB may lie buried in a concave hemisphere cut into the board RS. Then I place it so on the board RS, as is expressed in the first figure of the first scheme, and fix it very firm and steady in that posture so as that the weight of the mercury that is afterwards to be put into it may not in the least shake or stir it, then drawing a line XY on the frame RT so that it may divide the ball into two equal parts or that it may pass as tour through the center of the ball. I begin from that and divide all the rest of the board towards UT into inches and the inches between the 25 and the end E, which need not be above two or three and 30 inches distant from the line XY. I subdivide into decimals. Then stopping the end F with soft cement or soft wax, I invert the frame placing the head downwards and the orifice E upwards and by it with a small funnel I fill the whole glass with quicksilver. Then by stopping the small orifice E with my finger, I oftentimes erect and invert the whole glass and frame, and thereby free the quicksilver and glass from all the bubbles or parcels of lurking air then, inverting it as before, I fill it top full with clear and well strained quicksilver, and having made ready a small ball of pretty hard cement by heat made very soft, I press it into the whole E and thereby stop it very fast, and to secure the cement from flying out afterwards I bind over to piece of leather that is spread over in the inside with cement and wound about it while the cement is hot. Having thus softened it, I gently erect again the glass after this manner. I first let the frame down edge ways till the edge R.V. touch the floor or lie horizontal. And then in that edging posture raise the end R.S. This I do that if there chance to be any air hidden in the small pipe E it may ascend into the pipe F and not into the pipe D.C. Having thus erected it and hung it by the whole Q or fixed it perpendicularly by any other means, I open the end F and by a small siphon I draw out the mercury so long till I find the surface of it A.B. in the head to touch exactly the line X.Y. At which time I immediately take away the siphon and if by chance it be run somewhat below the line X.Y. by pouring in gently a little mercury at F, I raise it again to its desired height. By this contrivance I make all the sensible rising and falling of the mercury to be visible in the surface of the mercury in the pipe F and scarce any in the head A.B. But because there really is some small change of the upper surface also, I find by several observations how much it rises in the ball and falls in the pipe F to make the distance between the two surfaces an inch greater than it was before. And the measure that it falls in the pipe is the length of the inch by which I am to mark the parts of the tube F or the board on which it lies into inches and decimals. Having thus justened and divided it, I have a large wheel MNOP whose outmost limb is divided into 200 equal parts. This by certain small pillars is fixed on the frame RT in the manner expressed in the figure. In the middle of this on the backside in a convenient frame is placed a small cylinder whose circumference is equal to twice the length of one of those divisions which I find answers to an inch of ascent or descent of mercury. This cylinder I is movable on a very small needle on the end of which is fixed a very light index KL all which are so poised on the axis or needle that no part is heavier than another. Then about this cylinder is wound a small clue of silk with two small steel bullets at each end of it GH. One of these which is somewhat the heavier ought to be so big as freely to move to and fro in the pipe F by means of which contrivance every the least variable of the height of the mercury will be made exceedingly visible by the motion to and fro of the small index KL. But this is but one way of discovering the effluvia of the earth mixed with the air. There may be perhaps many others. Witness the Hygroscope. An instrument whereby the watery steams volatile in the air are discerned, which the nose itself is not able to find. This I have described in the following tract in the description of the beard of a wild oat. Others there are may be discovered both by the nose and by other ways also. Thus the smoke of burning wood is smelt, seen, and sufficiently felt by the eyes. The fumes of burning brimstone are smelt and discovered also by the destroying the colors of bodies as by the whitening of a red rose. And who knows but that the industry of man following this method may find out ways of improving this sense to as yet a great degree of perfection as it is in any animal and perhaps yet higher. Tis not improbable also but that our taste may be very much improved either by preparing our taste for the body as after eating bitter things wine or other vina-slickers are more sensibly tasted, or else by preparing bodies for our taste as the dissolving of metals with acid liquors makes them tasteable, which were before altogether insipid. Thus lead becomes sweeter than sugar and silver more bitter than gall, copper and iron of most loathsome tastes. And indeed the business of this sense being to discover the presence of dissolved bodies and liquors put on the tongue, or in general to discover that a fluid body has some solid body dissolved in it and what they are. Whatever contrivances makes this discovery improves this sense. In this kind the mixtures of chemical liquors afford many instances as the sweet vinegar that is impregnated with lead may be discovered to be so by the effusion of a little of an alkalazade solution. The bitter liquor of aquafortis and silver may be discovered to be charged with that metal by laying it in some plates of copper. Tis not improbable also but there may be multitudes of other ways of discovering the parts of dissolved or dissoluble in liquors. And what is this discovery but a kind of secondary tasting? Tis not improbable also but that the sense of feeling may be highly improved, for that being a sense that judges of the more gross and robust motions of the particles of bodies seems capable of being improved and assisted in very many ways. Thus for the distinguishing of heat and cold the weather glass and thermometer which I have described in this following treatise to exceedingly perfect it, by each of which the least variations of heat or cold which the most acute sense is not able to distinguish are manifested. This is often times further promoted also by the help of burning glasses and the like which collect and unite the radiating heat. Thus the roughness and smoothness of a body is made much more sensible by the help of a microscope than by the most tender and delicate hand. Perhaps a physician might by several other tangible properties discover the constitution of a body as well as by the pulse. I do but instance in these to show what possibility there may be of finding others and what probability and hopes there were of finding them, if this method were followed. For the offices of the five senses being to detect either the subtle and curious motions propagated through all pellucid or perfectly homogeneous bodies, or the more gross and vibrative pulse communicated through the air and all other convenient mediums, whether fluid or solid, or the effluvia of bodies dissolved in the air, or the particles of bodies dissolved or dissolvable in liquors, or the more quick and violent shaking motion of heat in all or any of these, whatsoever does any ways promote any of these kinds of criteria does afford a way of improving with some one sense. And what a multitude of these would a diligent man meet with in his inquiries. And this for the helping and promoting the sensitive faculty only. Next as for the memory or retentive faculty we may be sufficiently instructed from the written histories of civil actions. What great assistance may be afforded the memory in the committing to writing things observable in natural operations? If a physician be therefore accounted the more able in his faculty because he has had long experience in practice, the remembrance of which, though perhaps very imperfect, does regulate all his after-actions, what ought to be thought of that man that is not only a perfect register of his own experience, but it grown old with the experience of many hundreds of years and many thousands of men. And though of late men beginning to be sensible of this convenience have here and there registered and printed some few centuries, yet for the most part they are set down very lamely and imperfectly, and I fear many times not so truly. They seeming several of them to be designed more for ostentation than public use. For not to an instance that they do for the most part omit those experience they have made wherein their patience have miscarried, it is very easy to be perceived that they do all along hyperbolically extol their own prescriptions and vilify those of others. Notwithstanding all which these kinds of histories are generally esteemed useful even to the ableist physician. What may not be expected from the rational or deductive faculty that is furnished with such materials and those so readily adapted and ranged for use that in a moment, as twer, thousands of instances serving for the illustration, determination, or invention of almost any inquiry may be represented even to the side. How near the nature of axioms must all those propositions be which are examined before so many witnesses? And how difficult will it be for any though never so subtle an error in philosophy to escape from being discovered after it has endured the touch and so many other trials? What kind of mechanical way and physical invention also is there required, that might not, this way, be found out? The invention of a way to find the longitude of places is easily performed, and that to as great perfection as is desired or to at great anacuretness as the latitude of places can be found at sea, and perhaps yet also to a greater certainty than that has been hitherto found, as I shall very speedily freely manifest to the world. The way of flying in the air seems principally unpracticable by reason of the want of strength in human muscles. If therefore that could be supplied it were, I think, easy to make twenty contrivances to perform the offices of wings. What attempts also I have made for the supplying of that defect and my successes therein which I think are wholly new and not inconsiderable, I shall in another place relate. It is not unlikely also but that the chemists, if they follow this method, might find out they're so much sought after for alcoholist. What a universal minstrum, which dissolves all sorts of sulfurous bodies I have discovered, which hath not been before taking notice of, as such, I have shown in the sixteenth observation. What a prodigious variety of inventions and anatomy has this latter age afforded, even in our own bodies in the very heart by which we live and the brain which is the seat of our knowledge of other things. Witness all the excellent works of Piquet, Bartholenus, Bilius, and many others, and at home of Dr. Harvey, Dr. Int, Dr. Willis, Dr. Glyson. In celestial observations we have far exceeded all the ancients even the Chaldeans and Egyptians themselves whose vast plains, high towers, and clear air did not give them so great advantages over us as have over them by our glasses, by the help of which they have been very much outdone by the famous Galileo, Helvelius, Zulicum, and our own countrymen Mr. Rook, Dr. Wren, and the great ornament of our church and nation, the Lord Bishop of Exeter. And to say no more in aerial discoveries there has been a wonderful progress made by the noble engine of the most illustrious Mr. Boyle, whom it becomes me to mention with all honour not only as my particular patron, but as the patron of philosophy itself, which he every day increases by his labours and adorns by his example. The good success of all these great men and many others in the now seeming great obviousness of most of their endiver's other inventions which were from the beginning of the world have been as tore traudon. And not yet minded till the last inquisitive ages, an argument that there may be yet behind multitudes of the like, puts me in mind to recommend such studies and the prosecution of them by such methods to the gentlemen of our nation whose leisure makes them fit to undertake, and the plenty of their fortunes to accomplish extraordinary things in this way. And I do not only propose this kind of experimental philosophy as matter of high rapture and delight of the mind, but even as a material insensible pleasure. So vast is the variety of objects which will come under their inflections, so many different ways there are of handling them, so great is the satisfaction of finding out new things, that I dare compare the contentment which they will enjoy not only to that of contemplation, but even to that which most men prefer of the very senses themselves. And if they will please to take any encouragement from so mean and so imperfect endeavors as mine upon my own experience, I can assure them without arrogance that there has not been any inquiry or problem in mechanics that I have hitherto propounded to myself, but by a certain method, which I may on some other opportunity explain. I have been able presently to examine the possibility of it, and if so, as easy to excogitate diver's ways of performing it. And indeed it is possible to do as much by this method in mechanics as by algebra can be performed in geometry. Nor can I at all doubt but that the same method is as applicable to physical inquiries and is likely to find in reapthence a plentiful crop of inventions, and indeed there seems to be no subject so barren but may with this good husbandry be highly improved. CHAPTER II Toward the prosecution of this method in physical inquiries I have herein their gleaned-depth and handful of observations in the collection of most of which I made use of microscopes and some other glasses and instruments that improve the sense. Which way I have herein taken, not that there are not multitudes of useful and pleasant observables, yet uncollected, obvious enough without the helps of art, but only to promote the use of mechanical helps for the senses, both in the surveying the already visible world and for the discovery of many others hitherto unknown, and to make us with the great conqueror to be affected that we have not yet overcome one world when there are so many others to be discovered. Every considerable improvement of telescopes or microscopes producing new worlds and terra incognitas to our view. The glasses I used were of our English make, but though very good of the kind yet far short of what might be expected could we once find a way of making glasses elliptical or of some more true shape. For though both microscopes and telescopes as they now are will magnify an object about a thousand times bigger than it appears to the naked eye, yet the apertures of the object glasses are so very small that very few rays are admitted, and even of those few there are so many false that the object appears dark and indistinct. And indeed these inconveniences are such as seem inseparable from spherical glasses, even when most exactly made. But the way we hitherto made use of for that purpose is so imperfect that there may be perhaps ten wrought before one be made tolerably good, and most of those ten perhaps every one differing in goodness one from another, which is an argument that the way hitherto used is at least very uncertain. So that these glasses have a double defect, the one that very few of them are exactly true wrought, the other that even of those that are best among them none will admit a sufficient number of rays to magnify the object beyond a determinate bigness, against which inconveniences the only remedies I hitherto met with are these. First for microscopes, where the object we view is near and within our power, the best way of making it appear bright in the glass is to cast a great quantity of light on it by means of convex glasses, for thereby though the aperture be very small, yet there will throng in through it such multitudes that an object will by this means endure to be magnified as much again as it would be without it. The way for doing which is this. I make choice of some room that has only one window open to the south, and at about three or four foot distance from this window on a table I place my microscope, and then so place either a round globe of water or a very deep, clear, plano-convex glass whose convex side is turned towards the window, that there is a great quantity of rays collected and thrown upon the object, or if the sunshine I place a small piece of oily paper very near the object between that and the light, then with a good large burning glass I so collect and throw the rays on the paper that there may be a very great quantity of light pass through it to the object, yet I so proportion that light that it may not send or burn the paper, instead of which paper there may be made use of a small piece of looking glass plate, one of whose sides is made rough by being rubbed on a flat tool with very fine sand. This will, if the heat be leisurely cast on it, endure a much greater degree of heat and consequently very much augment a convenient light. By all which means the light of the sun or of a window may be so cast on an object as to make it twice as light as it would otherwise be without it, and that without any again convenience of glaring which the immediate light of the sun is very apt to create in most objects, for by this means the light is so equally diffused that all parts are alike enlightened, but when the immediate light of the sun falls on it the reflections from some few parts are so vivid that they drown the appearance of all the other, and are themselves also by reason of the inequality of light in distinct and appear only radiant spots. But because the light of the sun and also that of a window is in continual variation, and so many objects cannot be viewed long enough by them to be thoroughly examined, besides that often times the weather is so dark and cloudy that for many days together nothing can be viewed, and because also there are many objects to be met with in the night which cannot so conveniently be kept perhaps till the day. Therefore to procure and cast a sufficient quantity of light on an object in the night I thought of and often used this expedient. I procured me a small pedestal, such as is described in the fifth figure of the first scheme on the small pillar AB of which were two movable arms, CD, which by means of the screws EF I could fix in any part of the pillar. On the undermost of these I placed a pretty large globe of glass G, filled with exceedingly clear brine, stopped, inverted and fixed in the manner visible in the figure. Out of the side of which arm proceeded another arm H, with many joints, to the end of which was fastened a deep, plain convex glass I, which by means of this arm could be moved to and fro and fixed in any posture. On the upper arm was placed a small lamp K, which could be to moved upon the end of the arm as to be set in a fixed posture to give light through the ball. By means of this instrument duly placed, as is expressed in the figure, with the small flame of a lamp may be cast as great and convenient a light on the object as it will well endure, and being always constant and to be had at any time I found most proper for drawing the representations of those small objects I had occasion to observe. None of all which ways, though much beyond any other hitherto made use of by any I know, do afford a sufficient help, but after a certain degree of magnifying they leave us again in the large. Hence it were very desirable that some way were thought of for making the object glass of such a figure as would conveniently bear a large aperture, as for telescopes. The only improvement they seem capable of is the increasing of their length, for the object being remote there is no thought of giving it a greater light than it has, and therefore to augment the aperture the glass must be ground of a very large sphere, for by that means the longer the glass be the bigger aperture will it bear, if the glasses be of an equal goodness in their kind. Therefore a six will endure a much larger aperture than a three foot glass, and a sixty foot glass will proportionally bear a greater aperture than a thirty, and will as much excel it also as a six foot does a three foot, as I have experimentally observed in one of that length made by Mr. Richard Reeves here at London, which will bear an aperture above three inches over and yet make the object proportionally big and distinct, whereas there are very few thirty foot glasses that will endure an aperture of more than two inches over, so that for telescopes supposing we had a very ready way of making their object glasses of exactly spherical surfaces we might by increasing the length of the glass magnify the object to any assignable bigness, and for performing both these I cannot imagine any way more easy and more exact than by this following engine by means of which any glasses of what length so ever may be speedily made. It seems the most easy because with one and the same tool may be with care ground and object glass of any length or breadth requisite, and that with very little or no trouble in fitting the engine and without much skill in the grinder. It seems to be the most exact for to the very last stroke the glass does regulate and rectify the tool to its exact figure, and the longer or more the tool and glass are wrought together the more exact will both of them be of the desired figure. Further the motions of the glass and tool do so cross each other that there is not one point of either surface, but is thousands of cross motions thwarting it, so that there can be no kind of rings or gutters made either in the tool or glass. The contrivance of the engine is only to make the ends of two large mandrels so to move that the centers of them may be at any convenient distance asunder, and that the axis of the mandrels lying both in the same plane produced may meet each other in any assignable angle, both which requisites may be very well performed by the engine described in the third figure of the first scheme, where A.B. signifies the beam of a lath fixed perpendicularly or horizontally C.D., the two poppet heads fixed at about two foot distance, E.F. an iron mandrel whose tapering neck F. runs in an adapted tapering brass collar, the other end E runs on the point of a screw G, and a convenient place of this is fastened H, a pulley wheel, and into the end of it that comes through the poppet head C is screwed a ring of a hollow cylinder K, or some other conveniently shaped tool of what wideness shall be thought most proper for the size of glasses about which it is to be employed. As for object glasses between twelve foot and a hundred foot long, the ring may be about six inches over or indeed somewhat more for those longer glasses. It would be convenient also and not very chargeable to have four or five several tools, as one for all glasses between an inch and a foot, one for all glasses between a foot and ten foot long, and another for all between ten and a hundred, a fourth for all between a hundred and a thousand foot long, and if curiosity shall ever proceed so far, one for all lengths between a thousand and ten thousand foot long. For indeed the principle is such that supposing the mandrels well made and of a good length and supposing great care be used in working and polishing them, I see no reason but that a glass of a thousand, nay of ten thousand foot long, may be as well made as one of ten. For the reason is the same, supposing the mandrels and tools be made sufficiently strong, so that they cannot bend, and supposing the glass out of which they are wrought to be capable of so great irregularity in its parts as to refraction, this hollow cylinder K is to contain the sand, and by being drove round very quick to and fro by means of a small wheel, which may be moved with one's foot, serves to grind the glass. The other mandrel is shaped like this, but it has an even neck instead of a taper one and runs in a collar that by the help of a screw and a joint made like M in the figure, it can still be adjusted to the wearing or wasting neck. Into the end of this mandrel is screwed a chalk, N, on which with cement or glue is fashioned the piece of glass Q that is to be formed. The middle of which glass is to be placed just on the edge of the ring, and the lath O.P. is to be set and fixed by means of certain pieces and screws the manner whereof will be sufficiently evidenced by the figure, in such an angle as is requisite to the forming of such a sphere as the glass is designed to be of. The geometrical ground of which, being sufficiently plain though not heated before, I shall for brevity's sake pass over. This last mandrel to be made by means of the former or some other wheel to run round very swift also by which two cross motions the glass cannot choose if care be used, but be wrought into a most exactly spherical surface. But because we are certain from the laws of refraction, which I have experimentally found to be so by an instrument I shall presently describe, that the lines of the angles of incidence are proportionate to the lines of the angles of refraction. Therefore if glasses could be made of those kind of figures or some other, such as the most incomparable Descartes has invented and demonstrated in his philosophical and mathematical works, we might hope for a much greater perfection of optics than can be rationally expected from spherical ones. For though Citeris paribus, we find that the larger the telescope object glasses are in the shorter those of the microscope, the better they magnify, yet both of them, besides such determinant dimensions are by certain inconveniences rendered unuseful. For it will be exceedingly difficult to make and manage a tube above an hundred foot long, and it will be as difficult to enlighten an object less than an hundred part of an inch distant from the object glass. I have not as yet made any attempts of that kind, though I know two or three ways which, as far as I have yet considered, seem very probable and may invite me to make a trial as soon as I have an opportunity, of which I may hear after perhaps a point the world. In the interim I shall describe the instrument I even now mention by which the refraction of all kinds of liquors may be most exactly measured. Thereby, to give the curious an opportunity of making what further trials of that kind they shall think requisite to any of their intended trials, and to let them see that the laws of refraction are not only notional. The instrument consisted of five rulers or long pieces placed together after the manner expressed in the second figure of the first scheme, where A.B. denotes a straight piece of wood about six foot and two inches long, about three inches over, and an inch and a half thick on the backside of which was hung a small plummet by a line stretched from top to bottom, by which this piece was set exactly upright, and so very firmly fixed, and in the middle of this was made a hole or center into which one end of a hollow cylindrical brass box C.C., fashioned as I shall by and by describe, was placed, and could very easily and truly be moved to and fro. The other end of this box being put into and moving in a hole made in a small arm D.D. Into this box was fastened the long ruler E.F., about three foot and three or four inches long, and at three foot from the above mentioned center's P.P. was a hole E, cut through and crossed with two small threads and at the end of it was fixed a small side G, and on the backside of it was fixed a small arm H, with a screw to fix it in any place on the ruler L.M. This ruler L.M. was moved on the center B, which was exactly three foot distance from the middle center, P, and a line drawn through the middle of it L.M. was divided by a line of cords into some sixty degrees, and each degree was subdivided into minutes, so that putting the cross of the threads in E upon any part of this divided line I presently knew what angle the two rules A.B. and E.F. made with each other, and by turning the screw in H I could fix them in any position. The other ruler also R.S. was made much after the same manner only it was not fixed to the hollow cylindrical box, but by means of two small brass arms or ears it moved on the center's of it. This also by means of the cross threads in the whole S, and by a screw in K, could be fastened on any division of another line of cords of the same radius drawn on N.O., and so by that means the angle made by the two rulers A.B. and R.S. was also known. The brass box C.C. in the middle was shaped very much like the figure X. That is, it was a cylindrical box stopped close at either end, off of which apart both of the sides and bottoms was cut out, so that the box, when the pipe and that was joined to it, would contain the water when filled half full, and would likewise, without running over, endure to be inclined to an angle equal to that of the greatest refraction of water, and no more, without running over. The ruler E.F. was fixed very fast to the pipe V, so that the pipe V directed the length of the ruler E.F. and the box and ruler were moved on the pin T.T., so as to make any desirable angle with the ruler A.B. The bottom of this pipe V was stopped with a small piece of exactly plain glass, which was placed exactly perpendicular to the line of direction, or axis of the ruler E.F. The pins, also T.T., were drilled with small holes through the axis, and through those holes was stretched and fastened a small wire. There was likewise a small pipe of tin loosely put on upon the end of V, and reaching down to the side of G, the use of which was only to keep any false rays of light from passing through the bottom of V, and only admitting such to pass as pierced through the site G. All things being placed together in the manner described in the figure. That is, the ruler A.B. being fixed perpendicular, I filled the box C.C. with water, or any other liquor, whose refraction I intended to try till the wire passing through the middle of it were just covered. Then I moved and fixed the ruler F.E. at any assignable angle and placed the flame of a candle just against the site G, and looking through the site I moved the ruler R.S. to info till I perceived the light passing through G to be covered, as to were, or divided by the dark wire passing through P.P. Then turning the screw in K I fixed it in that posture, and through the whole S I observed what degree and part of it was cut by the cross threads in S. And this gave me the angle of inclination. A.P.S. answering to the angle of refraction B.P.E. For the surface of the liquor in the box will be always horizontal and consequently A.B. will be a perpendicular to it. The angle therefore A.P.S. will measure, or be the angle of inclination in the liquor. Next E.P.B. must be the angle of refraction. For the ray that passes through the site G passes also perpendicularly through the glass diaphragm at F. And consequently also perpendicularly through the lower surface of the liquor contiguous to the glass, and therefore suffers no refraction till it meet with the horizontal surface of the liquor in C.C., which is determined by the two angles. By means of this instrument I can with little trouble in a very small quantity of any liquor examine most accurately the refraction of it not only for one inclination but for all. And thereby I am enabled to make very accurate tables several of which I have also experimentally made, and find that oil of turpentine is a much greater refraction than spirit of wine though it be lighter, and that spirit of wine has a greater refraction than water though it be lighter also. But the salt water also has a greater refraction than fresh though it be heavier, but alum water has a less refraction than common water though heavier also. So that it seems as to the refraction made in a liquor the specific gravity is of no efficacy. By this I have also found that look what proportion the sign of the angle of the one inclination has to the sign of the angle of refraction, correspondent to it the same proportion have all the signs of other inclinations to the signs of their appropriate refractions. My way for measuring how much a glass magnifies an object placed at a convenient distance from my eye is this. Having rectified the microscope to see the desired object through it very distinctly, at the same time that I look upon the object through the glass with one eye, I look upon other objects at the same distance with my other bare eye, by which means I am able by the help of a ruler divided into inches and small parts, and laid on the pedestal of the microscope to cast as it were the magnified appearance of the object upon the ruler, and thereby exactly to measure the diameter it appears of through the glass, which being compared with the diameter it appears of to the naked eye, will easily afford the quantity of its magnifying. The microscope which for the most part I made use of was shaped much like that in the sixth figure of the first scheme, the tube being for the most part not above six or seven inches long, though by reason it had four drawers it could very much be lengthened as occasion required. This was contrived with three glasses, a small object glass at A, a thinner eye glass about B, and a very deep one about C. This I made use of only when I had occasion to see much of an object at once, the middle glass conveying a very great company of radiating pencils, which would go another way and throwing them upon the deep eye glass. But whenever I had occasion to examine the small parts of a body more accurately, I took out the middle glass and only made use of one eye glass with the object glass, for always the fewer the refractions are, the more bright and clear the object appears. And therefore, tis not to be doubted, but could we make a microscope to have only one refraction? It would, kiterus paribus, far excel any other that had a greater number. And hence it is that if you take a very clear piece of a broken venous glass, and in a lamp draw it out into very small hairs or threads, then holding the ends of these threads in the flame till they melt and run into a small round globule or drop, which will hang at the end of the thread. And if further you stick several of these upon the end of a stick with a little ceiling wax, so as that the threads stand upwards, and then on a whetstone first grind off a good part of them, and afterward on a smooth metal plate with a little triply, rub them till they come to be very smooth. If one of these be fixed with a little soft wax against a small needle-hole, pricked through a thin plate of brass, lead, pewter, or any other metal, and an object placed very near be looked at through it, it will both magnify and make some objects more distinct than any of the great microscopes. But because these, though exceeding easy made, are yet very troublesome to be used, because of their smallness and the nearness of the object, therefore to prevent both these and yet have only two refractions, I provided me a tube of brass. Shaped much like that in the fourth figure of the first scheme. Into the smaller end of this I fixed with wax a good plain-o-convex object glass. With the convex side towards the object and into the bigger end I fixed also with wax a pretty large plain-o-convex glass. With the convex side towards my eye. Then by means of the small hole by the side I filled the intermediate space between these two glasses with very clear water, and with a screw stopped it in. And then putting on a cell for the eye I could perceive an object more bright than I could when the intermediate space was only filled with air. But this for other inconveniences I made but little use of. My way of fixing both the glass and object to the pedestal most conveniently was thus. Upon one side of a round pedestal AB in the sixth figure of the first scheme, was fixed a small pillar CC. On this was fitted a small iron arm D, which could be moved up and down and fixed in any part of the pillar by means of a small screw E. On the end of this arm was a small ball fitted into a kind of socket F, made in the side of the brass ring G, through which the small end of the tube was screwed by means of which contrivance I could place and fix the tube in what posture I desired. Which for many observations was exceeding necessary. An adjustment most exactly to any object. For placing the object I made this contrivance. Upon the end of a small brass link or staple HH I so fastened a round plate II that it might be turned round upon its center K, and going pretty stiff would stand fixed in any posture it was set. On the side of this was fixed a small pillar P about three quarters of an inch high, and through the top of this was thrust a small iron pin M, whose top just stood over the center of the plate. On this top I fixed a small object, and by means of these contrivances I was able to turn it into all kinds of positions, both to my eye and the light. For by moving round the small plate on its center could move it one way, and by turning the pin M I could move it another way, and this without stirring the glass at all or at least but very little. The plate likewise I could move too in fro to any part of the pedestal, which in many cases was very convenient, and fix it also in any position by means of a nut N which was screwed on upon the lower part of the pillar C, C. All the other contrivances are obvious enough from the draft and will need no description. Now though this were the instrument I made most use of, yet I have made several other trials with other kinds of microscopes, which both for matter and form were very different from common spherical glasses. I have made a microscope with one piece of glass, both whose surfaces were planes. I have made another only with a plain Oconque without any kind of reflection, divers also by means of reflection. I have made others of water, gums, rosins, salts, arsenic, oils, and with divers other mixtures of watery and oily liquors. And indeed the subject is capable of a great variety, but I find generally none more useful than that which is made with two glasses such as I have already described. What the things are I observed the following descriptions will manifest. In brief they were either exceeding small bodies or exceeding small pores or exceeding small motions, some of each of which the reader will find in the following notes, and such as I presume, many of them at least, will be new and perhaps not less strange. Some specimen of each of which heads the reader will find in the subsequent delineations and indeed of some more than I was willing there should be, which was occasioned by my first intentions to print a much greater number than I have since found time to complete. Of such therefore as I had I selected only some few of every head, which for some particular seem most observable, rejecting the rest is superfluous to the present design. What each of the delineated subjects are the following descriptions annexed to each will inform, of which I shall hear only once for all add that in divers of them the gravers have pretty well followed my directions and drafts, and that in making of them I endeavored, as far as I was able, first to discover the true appearance, and next to make a plain representation of it. This I mention the rather because of these kind of objects there is much more difficulty to discover the true shape than of those visible to the naked eye, the same objects seeming quite differing in one position to the light from what it really is, and may be discovered in another. And therefore I never began to make any draft before by many examinations in several lights, and in several positions to those lights I had discovered the true form. For it is exceeding difficult in some objects to distinguish between a prominency and a depression, between a shadow and a black stain, or a reflection and a whiteness in the color. Besides the transparency of most objects renders them yet much more difficult than if they were opacious. The eyes of a fly in one kind of light appear almost like a lattice, drilled through with abundance of small holes, which probably may be the reason why the ingenious Dr. Power seems to suppose them such. In the sunshine they look like a surface covered with golden nails, in another posture like a surface covered with pyramids, in another with cones, and in other postures of quite other shapes. That which exhibits the best is the light collected on the object by those means I have already described. And this was undertaken in prosecution of the design which the Royal Society has proposed to itself. For the members of the Assembly, having before their eyes so many fatal instances of the errors and falsehoods in which the greatest part of mankind is so long wandered, because they relied upon the strength of human reason alone, have begun anew to correct all hypotheses by sense as seamen do their dead reckonings by celestial observations. And to this purpose it has been their principal endeavour to enlarge and strengthen the senses by medicine, and by such outward instruments as are proper for their particular works. By this means they find some reason to suspect that those efforts of bodies which have been commonly attributed to qualities, and those confessed to be a cult, are performed by the small machines of nature which are not to be discerned without these helps, seeming the mere products of motion, figure and magnitude, and that the natural textures which some call the plastic faculty may be made in looms which a greater perfection of optics may make discernable by these glasses. So as now they are no more puzzled about them than the vulgar are to conceive how tapestry or flowered stuffs are woven. In the ends of all these inquiries they intend to be the pleasure of contemplative minds, but above all the ease and dispatch of the labours of men's hands. They do indeed neglect no opportunity to bring all the rare things of remote countries within the compass of their knowledge and practice, but they still acknowledge their most useful information to arise from common things, and from diversifying their most ordinary operations upon them. They do not wholly reject experiments of mere light and theory, but they principally aim at such, whose applications will improve and facilitate the present way of manual arts. And though some men who are perhaps taken up about less honorable employments are pleased to censure their proceedings, yet they can show more fruits of their first three years wherein they have assembled than any other society in Europe can for a much larger space of time. Tis true such undertakings as theirs do commonly meet with small encouragement, because men are generally rather taken with the plausible and discursive than the real and the solid part of philosophy. Yet by the good fortune of their institution in an age of all others, the most inquisitive, they have been assisted by the contribution and presence of very many of the chief nobility and gentry, and others who are some of the most considerable in their several professions. But that that yet farther convinces me of the real esteem that the more serious part of men have of this society is that several merchants, men who act in earnest, whose object is mayum and tuum, that great rudder of human affairs, have adventured considerable sums of money to put in practice what some of our members have contrived, and have continued steadfast in their good opinions of such endeavours when not one of a hundred of the vulgar have believed their undertakings reasonable. And it is also fit to be added that they have one advantage peculiar to themselves, that very many of their number are men of converse and traffic, which is a good omen, that their attempts will bring philosophy from words to actions seeing the men of business have had so great a share in their first foundation. And of this kind I ought not to conceal one particular generosity which more nearly concerns myself. It is the munificence of Sir John Cutler in endowing a lecture for the promotion of mechanic arts to be governed and directed by this society. This bounty I mention for the honourableness of the thing itself, and for the expectation which I have of the efficacy of the example. For it cannot now be objected to them that their designs will be esteemed frivolous in vain when they have such a real testimony of the approbation of a man that is such an imminent ornament of this renowned city. And one who, by the variety and the happy success of his negotiations, has given evident proofs that he is not easy to be deceived. This gentleman has well observed that the arts of life have been too long imprisoned in the dark shops of mechanics themselves, and they are hindered from growth, either by ignorance or self-interest, and he has bravely freed them from these inconveniences. He had not only obliged tradesmen but trade itself. He has done a work that is worthy of London and has taught the chief city of commerce in the world the right way how commerce is to be improved. We have already seen many other great signs of liberality in a large mind from the same hand, for by his diligence about the corporation for the poor, by his honourable subscription for the rebuilding of St. Paul's, by his cheerful disbursement for the replanting of Ireland, and by many other such public works, he has shown by what means he endeavours to establish his memory. And now by this last gift he has done that which became one of the wisest citizens of our nation to accomplish. Seeing one of the wisest of our statesmen, the Lord Veralam, first propounded it. But to return to my subject from a digression which I hope my reader will pardon me, seeing the example is so rare that I can make no more such digressions. If these my first labour shall be any ways useful to inquiring men, I must attribute the encouragement and promotion of them to a very reverent and learned person, of whom this ought injustice to be said. That there is scarce any one invention which this nation has produced in our age, but it has some way or other been set forward by his assistance. My reader, I believe, will quickly guess that it is Dr. Wilkins that I mean. He is indeed a man born for the good of mankind and for the honour of his country. In the sweetness of whose behaviour, in the calmness of his mind and the unbounded goodness of his heart, we have an evident instance what the true and the primitive unpassionate religion was before it was soured by particular faction. In a word his zeal has been so constant and effectual in advancing all good and profitable arts, that as one of the ancient Romans said of Scipio, that he thank God that he was a Roman because where er Scipio had been born there had been the seat of an empire of the world. So I may thank God that Dr. Wilkins was an Englishman, for wherever he had lived there had been the chief seat of generous knowledge and true philosophy. To the truth of this there are so many worthy men living that will subscribe that I am confident what I have here said will not be looked upon by any ingenious reader as a pangyric, but only as a real testimony. By the advice of this excellent man I first set upon this enterprise yet still came to it with much reluctancy, because I was to follow the footsteps of so imminent a person as Dr. Wren, who was the first that attempted anything of this nature, whose original drafts do now make one of the ornaments of that great collection of rarities in the King's Closet. This honour which his first beginnings of this kind have received to be admitted into the most famous place of the world did not so much encourage as the hazard of coming after Dr. Wren did affright me. For of him I must affirm that since the time of Archimedes their scarce ever met in one man in so great a perfection such a mechanical hand and so philosophical a mind. But at last being assured both by Dr. Wilkins and Dr. Wren himself that he had given over his intention of prosecuting it and not finding that there was any else designed the pursuing of it, I set upon this undertaking and was not a little encouraged to proceed with it by the honour the Royal Society was pleased to favour me with in approving of those drafts which from time to time as I had an opportunity of describing I presented to them and particularly by the incitements of divers of those noble and excellent persons of it which were my more special friends who were not less urgent with me for the publishing than for the prosecution of them. After I had almost completed these pictures and observations having had divers of them engraving and was ready to send them to the press I was informed that the ingenious physician Dr. Henry Power had made several microscopic observations which had I not afterwards upon our interchangeably viewing each other's papers found that they were for the most part differing from mine either in the subject itself 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 compliance with their opinions that it would not be unacceptable to several inquisitive men in hoping also that I should thereby discover something new to the world I haven't length cast in my might into the vast treasury of a philosophical history. And it is my hope as well as belief that these my labors will be no more comparable to the production of many other natural philosophers who are now everywhere busy about greater things than my little objects are to be compared to the greater and more beautiful works of nature a flea, a mite, a gnat, to a horse, an elephant, or a lion. End of section two, recording by Philip Gould. Section four of Micrographia. This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. Recording by Avae in January 2018. Micrographia by Robert Hook. Section four, observation one 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 endeavour to make letters and draw single strokes true before we venture to write whole sentences or to draw large pictures. And in physical inquiries, we must endeavour to follow nature in the more plain and easy ways she trades in the most simple and uncompounded bodies, to trace her steps and be acquainted with her manner of walking there, before we venture ourselves 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 ourselves too, and are left to wander in the labyrinth of groundless opinions, wanting both judgment, that light, and experience, that claw, which should direct our proceedings. We will begin these 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 reckoned for one, and is indeed, for the most part, made so sharp that a naked eye cannot distinguish any parts of it. It very easily pierces and makes its way through all kind of bodies softer than itself. But, if viewed 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 imagined, but only a piece of a tapering body, with a great part of the top removed or deficient. The points of pins are yet more blunt, and the points of the most curious mathematical instruments do very seldom arrive at so great a sharpness. How much, therefore, can be built upon demonstrations made only 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 styriae or small parallelly pipettes of amianthus and aluminum plumosum, of many of which, though the points are so sharp as not to be visible, though viewed with a microscope, which magnifies the object in bulk above a million of times, yet add out not, but where we are able practically to make microscopes according to the theory of them, we might find hills and dales and pores and a sufficient breadth 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 was the top of a small and very sharp needle, whose point AA nevertheless appeared through the microscope above a quarter of an inch broad, not round nor flat, but irregular and uneven, so that it seemed to have been big enough to have afforded a hundred armed mites, room enough to be ranged by each other without endangering the breaking one another's 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 discovered by the microscope to invest it, several of which inequalities, as A, B, C seemed holes made by some small specks of rust, and D, some adventitious body that struck very close to it, were casual. All the rest that roughened the surface were only so many marks of the rudeness and bungling of art. So inaccurate it is in all its productions, even in those which seem most neat, that if examined with an organ more acute than 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 show us the greatest excellencies. An evident argument that he that was the author of all these things was no other than omnipotent, being able to include as great a variety of parts and contrivances in the yet smallest discernible 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 itself may be by analogy called a physical point, for as its body, though not so near us as to fill our eyes and fancies with the 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 tried on the moon and were not too bright on the sun itself. So could a mechanical contrivance successfully answer our theory, we might see the least spot as big as the earth itself and discover, as Descartes 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 cold, 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 than this which I have delineated in the third figure of the second scheme, but very many abundantly more disfigured, and for the most part, if they seemed 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 smoothly engraven strokes and points, looking but as so many furrows and holes, and their printed impressions, but like smutty dobbings on a matte or uneven floor with a blunt extinguished brand or a stick's end. And as for points made with a pen, they were much more ragged and deformed. Nay, having viewed certain pieces of exceeding curious writing of the kind, one of which, and a breadth of two pens comprised the Lord's Prayer, the Apostle's 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, enabled me to see that what the writer of it had asserted was true, but with all discovered of what pitiful bungling scribbles and scrolls it was comprised, Arabian and China characters being almost as well shaped, 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 fancy well preposest to help one through. If this manner of small writing were made easy and practicable, and I think I know such a one, but have never yet made trial of it, whereby one might be enabled to write a great deal with much ease and accurately enough in a very little room, it might be a 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 co-educers, one of which is the uneven surface of the paper, which at best appears no smoother than a very coarse piece of shagged cloth. Next the irregularity of the type or engraving, and a third is the rough dobbing 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 than this, which I have here presented, which though it appeared through the microscope gray, like a great splash of London dirt about three inches over, yet to the naked eye it was black and no bigger than 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 than the points of distinction, nor a drawn circle more exactly so, then we have now shown a point to be a point. End of Section 4. Section 5 of Micrographia. This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer please visit LibriVox.org. Recording by Abahi in January 2018. Micrographia by Robert Hook. Section 5. Observation 2 of the edge of a razor. The sharpest edge has the same kind of affinity to the sharpest point in physics as a line has to a point in mathematics, 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 anything of sharpness in it, but it appeared a rough surface of a very considerable breadth from side to side, the narrowest part not seeming thinner than the back of a pretty thick knife. Nor is it likely that it should appear any otherwise, since as we just now showed that a point appeared a circle, its rational a line should be a parallelogram. Now for the drawing, this second figure, which represents a part of the edge about half a quarter of an inch long of a razor well set, I so placed it between the object glass and the light that there appeared a reflection from the very edge, represented by the white line ABCDEF, in which you may perceive it to be somewhat sharper than 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 G-H-I-K, so smooth as one would imagine so smooth bodies as a horn and oil should leave it. For besides those multitudes of scratches, which appear to have raised to surface G-H-I-K, and to cross each other every way which are not half of them expressed in the figure, there were several great and deep scratches or furrows, such as G-H and I-K, which made the surface yet more rugged, caused perhaps by some small dust casually falling on the horn or some harder or more flinty part of the horn itself. The other part of the razor, L-L, which is polished on a grinding stone, appeared much rougher than the other, looking almost like a plowed field, with many parallels, ridges and furrows, and a cloudy, as it were, 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 shown well on them, discovered their surface to be variously raised or scratched, and to consist of an infinite of small broken surfaces which reflect the light of very various and differing colors. And indeed it seems impossible by art to cut the surface of any hard and brittle body smooth, since putt 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 cutter or furrow behind it. And though nature does seem to do it very readily in all kinds of fluid bodies, yet perhaps future observers may discover even these also rugged. It being very probable, as I elsewhere show, that fluid bodies are made up of small solid particles, variously and strongly moved, and may find reason to think that there is scarce surface in the rare umnatura perfectly smooth. The black spot MN, I guess to be some small speck of rust, for that I have often observed to be the manner of the working of corrosive juices. To conclude, this edge and piece of a razor, if it had been really such as it appeared through the microscope, would scarcely have served to cleave wood, much less to have cut off the hair of beards, unless it were after the manner that Lucien merely relates Charon to have made use of, when with a carpenters axe he chopped off the beard of a sage philosopher, whose gravity he very cautiously feared would endanger the over-setting of his wary. Micrographia by Robert Hooke, Section 6 Observation 3 of Fine Lawn or Linencloth This is another product of art. A piece of the finest lawn I was able to get so curious that the threads were scarce discernible by the naked eye, and yet through an ordinary microscope you may perceive what a goodly place of course metting it is. What proportionable cords each of the 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, nigh, by the naked eye, if it tentatively viewed, plainly enough evident to be the multitude of square holes which are left between the threads. Appearing to have much more holes in respect to the intercurrent parts, then, is for the most part left in the lettuce window, which it does a little resemble, only the crossing parts around and not flat. These threads that compose the fine texture, though they are small as those that constitute the finer sorts of silks, have nonewithstanding nothing of their glossy, pleasant and lively reflection. Nay, I have been informed both by the inventor himself and several other eyewitnesses that though the flex, out of which is made, has been by a singular art of that excellent person and noble virtuoso, Mr. Charles Howard, brother to the Duke of Norfolk, so curiously dressed and prepared, as to appear both to the eye and the touch, full as fine and as glossy, and to receive all kinds of colors, as well as sleeve silk, yet when the silken flex is twisted into threads, it quite loothes its former luster and becomes as plain and bathed a thread to look on as one of the same bigness made of common flex, the reason of which odd phenomenon seems no other than this. Though the curiously dressed flex has its part so exceedingly small as to equalize, if not to be much smaller than the clue of the silkworm, especially in thinness, yet the differences between the figures of the constituting filaments are so great and their substance so various that where as those of the silk are small, round, hard, transparent, and to the bigness proportionally stiff. So as each filament preserve its proper figure, and consequently its vivid reflection entire, though twisted into a thread, if not too hard, those of flecks are flat, limber, softer, and less transparent, and the twisting into a thread they join and lie so close together as to lose their own and destroy each other's particular reflections. There seems, therefore, three particular very requisite to make the so dressed flecks appear silk also wins one into threads. First, that the substance of it should be made more clear and transparent, flecks retaining it in a kind of a pasting brown or yellow, and the parts of the whitest kind I have yet observed with a microscope appearing white, like flot horn or glass, rather than like clear horn or glass. Next, that the filaments should each of them be rounded that could be done, which yet is not so very necessary if the first be performed, the third, which is that each of the small filaments be stipend, for though they be square or flat, provided they be transparent and stiff, much the same appearances must necessary follow. Now, though I have not yet made trial, yet I doubt not, but that both these properties may be also induced upon the flecks, and perhaps two by one and the same expedient. Which some trials may quickly inform any ingenious attemper of, who from the use and profit as such an invention may find sufficient argument to be prompted to such increase, as for a tendency of the substance of flecks, out of which the threat is made, it seems much inferior to that one of silk. The one being a vegetable, the other an animal substance, and rather it proceed from the better concoction, or the more homogeneous constitution of animal substances above those of vegetables. I do not hear detail mine, since I generally find that vegetable substances do not equalize the tendency of animal, nor these the tendency of some purified mineral substances. I am very apt to think that the tendency of bodies does not proceed from the or hoped particles as the epicureans and some modern philosophers have imagined, 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 shattered by any small poles or concussions of heat. End of Section 6. Section 7 of Micrographia. This is the LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. Micrographia by Robert Hooke. Section 7. Observation 4 of Fine Walled Silk or Taffetti. This is the appearance of a piece of very fine taffetti ribbon in the bigger magnifying glass, which you see exhibit it like a very convenient substance to make bed mats or door mats of, or to serve for beehives, corn scuttles, chairs or corn tops. It being not unlike that kind of work, where with in many parts of England they make such utensils of straw a little wet and bound together with thongs of brambles. For in this contexture, each little filament, fiber or glue of the silk worm seemed about the bigness of an ordinary straw as it appears by the little irregular pieces A, B, C, D and EF. The rob or the thread that ran across the ribbon appeared like a single rope of an inch diameter, but the woof or the thread that ran at the length of the ribbon appeared not half so big. Each inch of six penny brown ribbon appeared no less than a piece of matting inch and a half thick and twelve foot square. A few yards of this would be enough to floor the long gallery of the lure at Paris. But to return to our piece of ribbon, it affords us a not unpleasant object appearing like a bundle or weft of very clear and transparent cylinders. If the silk be white and curiously tinked, if it be colored, each of those small horny cylinders affording in some place or another of them as vivid a reflection as if it had been sent from a cylinder of glass or horn. In so much that the reflections of red appeared as if coming from so many granades or rubies. The loveliness of the colors of silk above those of Harry's stuff or linen consisting else I elsewhere intimate, chiefly in the transparency and vivid reflections from the concave or inner surface of the transparent cylinder as are also the colors of precious stones. For most of the reflections from each of these cylinders come from the concave surface of the air, which is as square the foil that encompasses the cylinder. The colors with which each of these cylinders are tinked seem partly to be superficial and sticking to the outsides of them and partly to be imbibed or sunk into the substance of them. For silk, seeming to be little else than a dried thread of glue, may be supposed to be very easily relaxed and softened by being steeped in warm, nay cold if penetrant, juices or liquors. And thereby those tincture, though they tink perhaps but a small part of the substance, yet being so highly impregnated with the color as almost to be black with it, may leave an impression strong enough to exhibit the desired color. A pretty kind of artificial stuff I have seen looking almost like transparent parchment horn or isling glass and perhaps some such thing may be made of, which being transparent and of a glutinous nature and easily modified by keeping in water as I found upon trial, had imbibed and did remain tinked with a great variety of very vivid colors and to the naked eye it looked very like the substance of the silk. And I have often thought that probably there might be a way found out to make artificial glutinous composition much resembling if not full as good, nay better than the excrement or whatever other substance it be out of which the silkworm wire draws this glue. If such a composition were found, it was certainly an easy 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 and they being sufficiently obvious, this hint therefore may, I hope, give some ingenious inquisitive person an occasion of making some trials, which is successful, I have my aim and suppose he will have no occasion to be displeased. End of section seven. Section eight of micrographia. This is a LibriVox recording. A LibriVox recordings are in the public domain for more information or to volunteer. Please visit LibriVox.org recording by Dion Giants, Salt Lake City, Utah. Micrographia by Robert Hook. Section eight. Observation five 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, misshapen things that when viewed with a microscope is little else observable but their deformity. The most curious carvings appearing no better than those rude Russian images we find mentioned in purchase where three notches at the end of a stick stood for a face. And the most smooth and burnished surfaces appear most rough and unpolished so that my first reason why I shall add but a few observations of them is their misshapen form and the next is their uselessness for why should we trouble ourselves in the examination of that form or shape which is all we are able to reach with a microscope which we know was designed for no higher a use than what we were able to view with our naked eye. Why should we endeavor to discover mysteries in that which has no such thing in it and like rabbits find out cobalasms and enigmas 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 designed business so far removed 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 Creator I shall therefore only 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 watered silk represented in the second figure of the third scheme as it appeared through the least magnifying glass a b signifying the long way of the stuff and c d broadway this stuff if the right side of it be looked upon appears to the naked eye all over so waved undulated or grained with a curious though irregular variety of brighter and darker parts that it adds no small gracefulness to the glass 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 phenomena to one that has but diligently examined it even with his naked eye will be obvious enough but he that observes it with a microscope may more easily perceive what this proteas is and how it comes to change its shape he may very easily perceive that it proceeds only from the variety of the reflections of light which is caused 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 etc for the surfaces of those threads that run the long way are by the mechanical process of watering creased or angled in another kind of posture than when they were by the weaving for by the weaving they are only bent round the warping threads but by the watering they are bent with an angle or elbow that is instead 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 tour of the cross threads they are bent about they are creased 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 only from one point of the round surface as about c c c they now when watered reflect the beams from more than half the whole surface as d e d e d e 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 informed is no other than this they double all the stuff that is to be watered 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 salvages just upon one another and as near as they can place the whale so in the doubling of it that the whale of the one side may lie very near parallel or even with the whale 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 whale is thus they take a pin and begin at one side of the piece in any whale and so moving it towards the other side thereby directing their hands to the opposite ends of the whale and then as near as they can place the two opposite ends of the same whale together and so double or fold the whole piece repeating this inquiry with a pin at every yard or twos distance through the whole length then they sprinkle it with water and fold it the long ways placing between every fold a piece of pasteboard by which means all the wrong side of the watered stuff becomes flat and with little whales and the whales on the other side become the more protuberant whence the creasing or angular bendings of the whales become the more perspicuous having folded it in this manner they place it with an interjacent pasteboard into and hot press where it is kept very violently pressed till it be dry and stiff by which means the whales of either contiguous sides leave their own impressions upon each other as is very manifest by the second figure where it is obvious enough that the whale of the piece a b c d runs parallel between the pricked lines e f e f e f and as manifest to discern the impressions upon these whales left by those that were pressed upon them which lying not exactly parallel with them but a little a thwart them as is denoted by the lines of o o o o g h g h g h between which the other whales did lie parallel they are so variously and irregularly creased that being put into that shape when wet and kept so till they be dry they so let each other's threads that the moldings remain almost as long as the stuff lasts hence it may appear to anyone that attentively considers the figure why the parts of the whale 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 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 from the variety of reflection may also be deduced the cause why a small breeze 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 phenomena might hereby be solved which are too many to be here insisted on and a section 8