ESSAYS of NATURAL EXPERIMENTS Made in the Academy Del Cimento Under the Protection of the most seren Prince Leopold of Tuscany Englished by Ric. Waller S.R.S.  
LONDON Printed for Benj: Alsop at the Angel & Bible in the Poultry. 1684.    

ESSAYS O F Natural Experiments Made in the ACADEMY DEL CIMENTO, Under the Protection of the Most SERENE PRINCE LEOPOLD of TUSCANY.  
Written in Italian by the Secretary of that ACADEMY.  
Englished by RICHARD WALLER, Fellow of the Royal Society.  
LONDON, Printed for Benjamin Alsop at the Angel and Bible in the Poultry, over-against the Church. 1634.   

To Sir John Hoskyns Knight and Baronet, Precedent of the Royal Society, etc.  
SIR,  
AS your Commands gave the first being to this Attempt, so 'tis but Justice to offer it to yourself; and 'twas but necessary to crave so advantageous a Protection, to defend it against the Difficulties, things of this Nature meet with, in this Censorious Age.  
I shall wave, as less grateful to you, a large Description of the Happiness the Royal Society enjoys under such a Precedent, whose perspicacious Judgement is actuated by a true desire of promoting real Knowledge; and shall rather give some account of the Work itself: It was presented in a Public Meeting of the Royal Society, March 12. 166 ⅞ by Sig r. Lorenzo Magalotti, and Sig r. Paulo Falconieri, from the Most Serene Prince Leopold, Brother to Ferdinand the Second, Great Duke of Tuscany; and has ever since lain in our Library expecting a more skilful Pen, to perform what I have here aimed at. The Experiments are many, and curious, made under the favour of that Prince, by the Members of the Academy Del Cimento, men of great ingenuity; and related with much sincerity by the Secretary of that Academy; which Society (I hear) is now scattered, and the Hopes of those Benefits the Learned World might justly expect from them, frustrated. Many indeed of these Experiments have been made, and shown in several Meetings of the Royal Society (before, and since the Publication of this in the Italian, in the Year 1667) by the Honourable Robert boil, Esq and other worthy Members thereof; but for all this, I hope it may not prove unacceptable to find the Ingenious in other Parts of the World, have not thought their time misspent in these Endeavours, what contrary Sentiments soever some may have; nor will the agreement between the success of Experiments made there, and what has been attempted here (often with a differing Apparatus) be less pleasing▪ very many, I dare undertake, are New to most Persons, except yourself, and upon that account will prove more diverting. I need not add the great Expense of Care, and Charge, and Fatigues of the Academy in this Work; nor the scarcity of this Piece in the Original, no small Motive to this Undertaking (that it might be obtained with more Ease, and at a cheaper Rate;) which how performed, I submit to yourself, and the worthy Members of the most Illustrious Royal Society; begging Pardon for this Presumption; desiring only to subscribe myself,  
SIR, Your most humble Servant, Richard Waller.   

To the Most SERENE Ferdinand II. GRAND DUKE of TUSCANY.  
Most SERENE PRINCE,  
THE Publishing of these First Essays of Natural Experiments, which for many Years have been made in our Academy, under the Protection, and with the Indefatigable Assistance of the most Serene Prince Leopold your Highness' Brother, will prove the happy occasion of giving fresh Testimonies (of your Highness' great Liberality) to all those parts of the World where Virtue is adorned with its deserved Lustre; and will create a new sense of Gratitude and Respect in all true Lovers of the more curious Arts, and Nobler Sciences. Especially we ought to frame our thoughts to a more humble Acknowledgement, as we are more nearly concerned and warmed by the cherishing Rays, and invigorating Influence of your Highness' bounty. Which with the favour of your Patronage, the encouraging invitation of your Mind, and proper Genius that way; but above all, with the Honour of your Presence, sometimes stooping to our Academy, sometimes commanding us to your Royal Apartments, has bestowed upon it an Immortal Name; Kindled Active Desires in our Breasts, and given an happy increase to our Studies. These considerations easily demonstrate, with what duty we are engaged to Consecrate the first Fruits of our Labours to your Highness' most Illustrious Name; since nothing can proceed from us, wherein you can have a greater share, and by consequence more due to you; nor any thing that may make fairer approaches to merit the happy Fate of your generous Acceptance. 'Tis certain, that through the Excess of so large and signal Favours, we can be sensible of no greater Resentments than to find ourselves so much obliged to your Highness: not that we refuse to bear the Weight of so endearing and inestimable an Obligation; but only because we would wish to be able to offer something not purely your own; whence we might at least flatter ourselves, That we had made some small return which your Highness might impute in some degree to our choice, and not wholly redewable to your Highness' Self, or Necessity· But we must rest satisfied with the bare desire of so just and deserved a Passion; since these new Philosophical Speculations are so deeply Radicated in your Highness' Protection, that not only what is now produced by our Academy, but what ever shall be brought to Maturity in the most Famous Schools of Europe, or After Ages raise up, shall be likewise due to your Highness, as the gift of your Beneficence: since as long as the Sun, Planets, and Stars retain their glory, and Heaven endures, there will remain a glorious Memory of one that contributes so much with his auspicious Influence to such new and strange Discoveries; opening an unbeaten Path for the least fallacious Method of search after Truth. Yet in so great a scarcity of Tributes, some little thing presents itself to manifest our grateful observance; which is the only joy wherewith we support our Deficiency, while all redounds in more resplendent Glory to your Highness, who having already acted your full Proportion of what ever new, good, and great, is at any time to be found in the Repository of Sciences, has enervated and discouraged all thoughts of emulation in others. This, and this alone are we able to lay at your Highness' Feet, whose continual Protection we crave with Respect and Reverence, begging from Heaven the height of Prosperity and Grandeur to your Highness.  
Your most Serene Highness' Most humble Servants Of the Academy Del Cimento. Il Saggiato Segretario. Florence July 14 th'. 1667.   

THE PREFACE TO THE READER.  
AMong all the Creatures of Divine Wisdom, the Birthright doubtless belongs to the Idea of Truth, which the Eternal Artificer so exactly followed in the Universal Fabric of Nature, That no Being was made with the least irregular Bias of falsehood: But Man afterwards, (in the Contemplation of so high and perfect a Structure, through an extravagant desire of Comprehending the admirable Design, and finding out all the Measures and Proportions of so Beautiful an Order) when he aims to penetrate too deep into the Truth, frames to himself an indefinite number of falsities, which proceeds from no other cause but his Ambition to take those Wings Nature never designed (perchance fearing to be some time or other discovered by him unwillingly in the preparation of her greater Works;) yet upon these he begins to raise himself, and though charged with the weight of a Material Body, stretches forth these Pinions to soar higher than the Scale of Sense leads, and fixes himself upon that Light, whose Rays, too powerful for his Eyes dazzle, and blind him. Thus we see from Man's Rashness, the first Seeds of false Notions came; from which yet it happens, not that the bright Splendour of God's Excellent Creatures is at all shaded, or by their Commerce with them in the least vitiated: since all these Imperfections are to be Attributed to Man's Ignorance, vitiated whence they had their Beginnings; when improperly applying the Causes to the Effects, he takes not from either the verity of their Being's, but only delineates in his own mind a false Conception of their Relation to each other, and agreement; not that the sovereign Beneficence of God when he Creates our Souls, denies them to pry, as we may say for a Moment into the Immense Treasure of his Eternal Wisdom; adorning them as with the most precious Jewels, with some first Sparks of Truth, sufficiently evident from their retaining Notions not to be acquired here, whence we must conclude, They received them from some other Place.  
But it happens through our Misfortune, that these rare Gems, as they are but loofly set in the Mind, yet too tender when she first falls into her Earthly Habitation, and wraps herself in this Clay; so for a time they fall out of their Collets, are sullied, and worth nothing till by assiduous and careful Study, they are again reset in their proper places. This is what the Mind attempts in the search of Nature; wherefore we must Confess, we have no better means than Geometry, which at first Essay hits the Truth, and frees at once from all doubts, and wearying Researches. And indeed she leads into the way of Philosophical Speculations, but at last leaves us; not that Geometry has not a large Field to expatiate in, and Travels not over all Nature's Works; as they all submit to those Mathematic Laws, by which the Eternal Decree freely Rules, and Commands them; but because we hitherto are unable to follow her in so long, and wide a Path only a few steps. Now where we may not trust ourselves to go farther, we can rely on nothing with greater Assurance than the faith of Experience, which (like one that having several loose and scattered Gems, endeavours to fix each in its proper Collet) by Adapting the Effects to the Causes; and again the Causes to the Effects if not at first Essay, as Geometry yet at last succeeds so happily, 
Provando. e Riprovand●.  that by frequent Trying, and Rejecting, she hits the Mark. We ought then to proceed with much Circumspection, lest too great a reliance and trust in Experience, turn us out of the way, and impose upon us; since it sometimes falls out, that before the clear Truth appears to us, when the first more open Veils of Deceit are taken off, we discover some cheating Appearances that indeed have some likeness, and Resemblance of Truth: and these are the imperfect Lineaments that are seen through the last cover that more nearly veil the lovely face of Truth; through the fine Web whereof she sometimes seems so plain and lively, that some might conclude, She was Nakedly Discovered.  
Here than we ought to carry ourselves as Master-workmen, to discern between Truth and Error, and the utmost perspicacy of Judgement is but requisite, to see well what really is, from what is not; And to be the better able to perform this Task, doubtless 'tis necessary to have at some time or other seen Truth unvailed; an Advantage they only have; who have had some taste of the studies of Geometry.  
Nor is it of less use to search among Experiments already made, than to attempt New ones, if haply any may be found, that have at all disguised the simple Face of Truth: wherefore 'tis aimed at in our Academy, besides what has been Invented by us, to try also (either for Curiosity, or as we light upon them by chance) those things which have been already done, or wrote off by others: observing too well, That under this Name of Experiments, frequent Errors have crept in, and been entertained.  
This was the first Motive to the perspicacious and indefatigable Mind of the most Serene Prince Leopold of Tuscany; who in the Recess of those daily Negotiations, and solicitous Cares that attend his High Quality, diverted into the rough Path of the Noblest Sciences. But his Highness' discerning Judgement easily foreseeing that the Reputation of great Authors proves too often hurtful to the Studious, who through too much Confidence, and Veneration of their Names, fear to call in question what is delivered upon their Authority; wherefore he judges it an Undertaking worthy of his great Mind to confront with the most Accurate, and sensible Experiments, the force of their Assertions, and with the due rejection of Errors, and Embracing of Realities, to make so desirable, and inestimable a Present to those that earnestly wish for the discovery of Truth. These prudent Instructions of our most Serene Patron, received with due Reverence and Respect by our Academy, has not moved us to be indiscreet Censurers of the Learned Pains of others, nor made us bold Obtruders of our own Sentiments for Truths, and discoveries of Abuses: but it is our Principal Intent to incite others also to repeat with the greatest severity, and niceness, the same Experiments; as we have now adventured to do with those of any other Person: Tho in Publishing these first Essays, we have, what we could abstained therefrom, that we might by this due respect, gain upon the Adversary to believe the sincerity of our Impartial, and Respectful Thoughts. And to the full completing of so generous and useful an Undertaking, we desire only a free Correspondence with those several Societies that are dispersed throughout the more Illustrious, and Noted Parts of Europe: That with the same design of attaining such high Ends, so profitable a Commerce being in all parts round about promoted, we may all go on with equal freedom, enquiring as much as possible, and participating of the Truth: and for our parts, we will concur to this Work with the greatest simplicity, and ingenuity; whereof 'tis no small Argument, That when we have related the Experiments of others, we have still mentioned the Author's Name, when known to us; and that we have often freely confessed, that supposition concerning some Experiments, which when put in practice we were never so successful as to bring to Perfection. But above all, to prove clearly the unfeigned sincerity of our Proceedure, let that Freedom suffice, wherewith we have still communicated the Essays and Experiments themselves to any that, Travelling by our Country, showed any desire, or relish of such Sciences, moved either by a gentile Humour, Esteem of Learning, or Spur of Curiosity; and that from the first time our Academy was Founded in the Year 1657, when the greatest part, if not all the Experiments were invented, whereof these Essays are now Published. If it shall happen, that among them there shall be any found, thought of before, or after the time they were made here by other Persons, and made Public, let us not be blamed for it, since we could neither know, nor see all things; so that no man ought to wonder at the lucky Accord of our Minds, and Inventions with other men's; nor indeed will we, if we find those of other Men agree with ours.  
Lastly, We are unwilling any should imagine, That we pretend in this Publication, a Perfect Work; or in the least, an Exact Module of a large Experimental History; conscious to ourselves, that more Time, and greater Abilities are necessary to so vast a Design; as may be seen by the very Title we have prefixed, only of Essays, which we had never put forth, had we not been much urged thereto by Persons Meriting from us, by their dear importunities, the Sacrifice of a Blush, for exposing such imperfect Embrio's.  
And now we will close all with a Protestation, That we never desire to entertain Controversy with any, or engage in any Nice Disputation, or heat of Contradiction; and if sometimes, as a Transition from one Experiment to another, or upon what occasion soever, there shall be inserted any hints of Speculation, we Request they may be taken always for the thoughts, and particular sense of some one of the Members, but not imputed to the whole Academy, whose sole Design is to make Experiments, and Relate them. For such was our first Proposal, and the Intent of that great Personage, who with his Particular Protection, and far-reaching Judgement, caused us to take that Method; to which Sage, and Prudent Advice we have still punctually, and regularly conformed.   

THE CONTENTS.  

THe Description of some Instruments to discover the alteration of the Air. page 1  
The Description of Instruments to measure time 10  
Experiments appertaining to the Natural Pressure of the Air 13  
That the Pressure of the Air sustains the Quicksilver in the Tube 14 

Mr. Roberval's Exper. of the Airs Pressure repeated 17  
Experiments against the Airs Pressure Answered 19  
Whether the Air gravitates, and of its Expansion 22  
When the Pressure is taken off, that the Mercury falls, with other Experiments relating thereto 24 etc.  
The Efficacy of another Fluid joined to the Airs Pressure 30  
Several Experiments about the Airs Pressure to 34    
The Description of Instruments, showing the Alterations happening in the State of the Natural Compression of the Air 35  
Various Experiments made in Vacuo 40 

Of the Spherical Figure of small Drops in Vacuo ib.  
Of Heat and Cold applied outwardly to the Vacuum 41  
Whether the Air Reflects the second Image visible in a Lens 42  
Of Amber in Vacuo 43  
Of the Effluvia of Fire in Vacuo 46  
Of the Motion of Smoke in Vacuo 48  
Of Sounds in Vacuo 50  
Of the Magnet in Vacuo 53  
Of hollow Canes in Vacuo ib.  
Of the boiling of Water in Vacuo. 57  
Of Snow in Vacuo 58  
Of the Dissolution of Pearl and Coral in Vacuo. 59  
Of several Animals included in Vacuo 61 etc.  
Of Bladders of small Fish in Vacuo 66    
Experiments of Artificial Freezing 69 

Of the Dilatation of Water in Freezing 71  
Of the Measure of the force of Rarifaction in freezing Water 77  
To measure the utmost Expansion in freezing Water 79  
Of the Procedure of Artificial Freezing 77    
Tables of several Fluids' Freezing. 83 etc.  
Experiments of Natural Freezing 95 

Of Common Water in Air ib.  
Of the same in Vacuo. 98  
Of stilled Water 99  
Of Sea Water ib.  
Of the Power of Sal Armoniac, etc. in Freezing 100  
Of the Metals that keep Ice best 101  
Of Freezing a pieee of Ice to a Table ib.  
Of Freezing the Dew upon the outsides of Glasses 102  
Of Reflected Cold 103    
Experiments about the alteration of the size of Vessels, etc. by heat & cold, 104 

That the Vessel altars before the Liquor contained 105  
Of the Alteration of a Brass Ring by heating in the fire 107  
Of Bodies dilated by imbibing Moisture 108  
Of the Dilating and Contracting of Glass by heat and cold 109  
Of the same in Tinn 110  
In Brass Wires 111  
The same proved by a different Observable 112  
That a Vessel also may be distended by Weight 113    
Experiments about the Compression of Water 114 etc.  
Experiments against positive Levity. 118  
Experiments Magnetical 123 

About Diverting the Passage of the Magnetic Virtue 124  
About the Magnetic Virtue passing through divers Fluids' 125  
About the Placing the Magnetic in respect of the Poles of the Earth 127    
Experiments touching Amber and other Electic Bodies 128  
Experiments about altering the Colours of several Fluids' 133 

Of Altering Water ib.  
Of Altering Wine 135  
Of Altering a Tincture of Red Roses ib.  
Of Altering a Tincture of Saffron 136  
Of Altering Green's ib.  
Of Altering Violet Colours 137    
Experiments about the Motions of Sounds 138 

Of Sounds passing equal spaces in equal times ib.  
Of contrary and favouring Winds 140  
Of the Equability of Motion in Sounds ib.    
Experiments about Bodies Projected 143 

Of Horizontal Shot from the top of a Tower ib.  
Of Perpendicular Shot 144  
Motion impressed, not altered by a new direction 145    
Miscellaneous Experiments 147 

Of the absolute weight of Air to Water ib.  
Of Heat and Cold  
Of a Wire seeming lighter Hot than Cold 149  
Of the force of Heat in Rarifaction 150  
Of Antiperistasis 151  
Whether Cold be caused by the intrusion of Frigorific Atoms 152  
Of Ebullitions by Salts, etc. 153  
Whether Glass be Penetrable by Odours 155  
Whether Glass be Penetrable by Humidity 156    
Experiments of Light 

Of the instantaneous Motion of Light 157  
Of Firing Bodies with a Burning Glass 158  
Of Bodies affording Light ib.    
Experiments about the digestion of some Animals 160    


Tab. 1. p. 1.   
THE DESCRIPTIONS OF SOME Instruments To discover the Alterations of the AIR, Caused by HEAT and COLD.  
IT is most useful, and indeed a necessary thing in the making of Natural Experiments, to be truly informed of all the Alterations the Air is incident to; for since it receives into itself, and as it were, embraces all things, leaning on them with its whole weight from a vast height, they must needs all bend under this Pressure; and as this violence which they suffer, is more or less, so are they more imprisoned or enlarged. Thus the Mercurial Standard either rises or falls, at the different height of the Atmosphere, or as some think, correspondent to the various Temperaments which the Air receives from the Sun, or from the Shade, from the Heat, or from the Cold, when open, and free, or when shaded and oppressed with Clouds, when it either rarefies, or condenses itself, and so gravitates more or less upon the Stagnant Mercury, by which, with different Pressures, it forces it higher or lower into the immersed Cane. It is therefore requisite (as well for that Experiment which we shall amply Treat of in the first place, as for others, which in the sequel of this Discourse we shall handle) to be provided with such Instruments that we may be able to assure ourselves, what is the true Measure, not only of the greatest changes of the Air; but if it be possible, the niceties of the smallest variation. We will therefore in the first place, describe those which have been serviceable to us, though they may have been already dispersed hence to several parts of Europe, so that they will want the pleasing dress of Novelty to recommend them: nevertheless, they will not be unacceptable to those that desire a more nice and particular Information (if not of their use, which is easily comprehended, yet) of the way and Artifice of making them.  

The First Instrument  
To measure the degrees of Heat and Cold in the Air.  

Tab. 1. Fig. 1.  LEt the First Instrument be that represented by Fig. 1. which may serve, (as likewise several others) to show the changes of the Air, in reference to Heat and Cold, and is commonly called a Thermometer: 'tis made of Cristalglass, after this manner. The Artificer by blowing with his own Mouth (instead of Bellows) through a Glass-Pipe upon the flame of a Lamp, forces it in one continued Stream, or several, at pleasure, from one place to another, where it is requisite; and by this means, shapes most curious, and admirable Works of Glass. Such an Artificer we call a Lamp blower. Let him then make the Ball of this Instrument of such a Capacity, and join thereto a Cane of such a bore, that by filling it to a certain mark in the Neck with Spirit of Wine, the simple cold of Snow or Ice Externally Applied, may not be able to condense it below the 20 deg. of the Cane; nor on the contrary, the greatest vigour of the Sun's Rays at Midsummer, to Rarify it above 80 deg. which Instrument may be thus filled, viz. by heating the Ball very hot, and suddenly plunging the open end of the Cane in the Spirit of Wine, which will gradually mount up, being sucked in as the Vessel Cools. But because 'tis hard, if not altogether impossible to evacuate the Ball of all the Air by Rarefaction; and the Ball will want so much of being filled as there was Air left in it; we may thus quite fill it with a Glass Funnel, having a very slender shank, which may easily be made when the Glass is red hot, and ready to run; for than it may be drawn into exceeding small hollow Threads, as is well known to those that work in Glass. Put the small shank of this Funnel into the Cane to be filled, and by forcing the Spirit of Wine through the Funnel with ones Breath, or sucking it back again when there is too much; you may fill the Instrument up to what mark in the Neck you please. The next thing is to divide the Neck of the Instrument or Tube into Degrees exactly; therefore first, divide the whole Tube into Ten equal Parts with Compasses, marking each of them with a knob of white Enamel, 
Smalto Bianco. Smalto Nero.  and you may mark the intermediate Divisions with green Glass, or black Enamel: these lesser Divisions are best made by the Eye, which Practice will render easy. This done, and with the proof of Sun and Ice, the proportion of the Spirit of Wine found; the Mouth of the Tube must be closed with Hermes Seal at the flame of a Lamp, and the Thermometer is finished.  
We rather make use of Spirits, than simple Spring Water for these Instruments; because, first 'tis colder, (i. e.) sooner sensible of the least change of Heat and Cold, and by reason of its extreme lightness, it more readily contracts itself, quickly falling or rising. Secondly, Simple Water, how pure and clear soever, yet in a little time le's fall some Sediment, or Dregs, which sticking to the sides of the Vessel, at last clouds its Transparency: whereas the highest rectified Spirit of Wine, or the like burning Spirits, always keep Pellucid, nor ever abate of their first Beauty. And since it is so clear and Cristaline, that at first view 'tis hard to discern the bounds between it, and the void space of the Neck of the Vessel; we sometimes used to tinge it with the Infusion of Kermes, or Sanguis Draconis; But when we observed, that how light and Refined soever the Tincture was, yet in time something still adhered to the sides of the Glass, and augmented rather then lessened the Difficulty, we at last wholly omitted the use of coloured Liquors; the other being discernible with a little straining the Eyes. We might here add many other Works and Curiosities touching Lamp working; but as 'tis very difficult to Design, and draw things of this Nature upon Paper; so 'tis altogether impossible to make them intelligible in Writing: wherefore our Operator ought to be pretty well instructed before, and his Art will improve with frequent Practice.   

The Second Instrument,  
For the same use.  

Tab. 1. Fig. 2.  THis is but a Copy of the former, in little; there being no other difference between them, but in the length of the Stages the liquor has to run: that being double the length of this; that being divided into 100 deg. this but 50. that at the greatest Cold of our Winter subsiding to 17 or 16 deg. this usually to 12, or 11; and at a great extremity of Cold one year, to 8 deg. and this to 6 deg. And on the contrary, the first being exposed to the greatest Rage and Heat of the Midday Sun in our Climate, does not rise above 80 deg. When the Second at the same time exceeds little, or not at all 40 deg. The Rule of making these, so as they shall keep such a correspondence, is only obtained by Practice, teaching how to proportionate the Ball to the Cane, and so to adjust the Quantity of Liquor, as they shall not vary in their Motions.   

The Third Thermometer.  
THe Third is also a Copy of the First, but much larger, whence it is more sensible, and swifter near four times; its length is 300 deg. made like the other Two, but as was said before we can lay down no certain Rule to make it Practise, and often Trials being the only way to effect it, by increasing, and diminishing the size of the Ball, or the bore of the Cane, or the quality of the Liquor, till at length it hits right: And a famous Man in this Art, who served the most Serene Grand Duke, used to say, He could make Two or Three, or as many as you desired, of 50 deg. which being encompassed with the same Ambient, should all agree: but that the case was otherwise in those of 100 deg. especially of 300 deg. the smallest Inequality and Error committed, in making one with a large Ball, and small Neck, being very easy to be discovered: so that they will show great Disagreement and inequality when compared together.   

The Fourth Thermometer.  

Tab. 1. Fig. 3.  THis Fourth Instrument has a Spiral Canale, yet differs not much from the former; indeed it comes not near the same Scale of Proportion, it being impossible to draw so very long a Neck equal, and of the same size and bore throughout the whole length; because there is a necessity to pass and repass it often over the flame to bend it; whence it cannot be avoided when the Metal is softened by the flame, but the Cane will be straitened and contracted in some places, and in others relaxed and swelled.  
Blow then a Globe of a great Capacity, with a very long slender Neck, and coil it round as in the Fig. each turn being close to the other, and rising but with a small Angle, that the whole Height may be as little as possible, and so less subject to be broken to pieces; then let it have at the top another less Ball hollow, and sealed at the Flame, to be a receptacle for the Air in the Cane to retreat to, from the pressure of the Water in raising itself, lest for want of room, and being every way closed, it resists the ascent of the Water, and so crack the Vessel; after this manner may be had a very ticklish Thermometer: and as I may say, of so exquisite a sense, that the least flame of a Candle, in an instant shall be able to make the contained Spirit of Wine move swiftly: which Effect will be so much more conspicuous, as the Ball is larger, which may be made very Capacious at pleasure, without being tied to any Rule: This Instrument being made rather for fancy and curiosity to see the Liquor run the Decimals of Degrees by the only impulse of a warm breath, etc. than for any accurate Deduction, or Infallible Proportion of Heat, and Cold to be learned thereby.   

The Fifth Thermometer.  

Tab. 1. Fig. 4.  THis is more slow and lazy than any of the former, which immediately answer to the least change of the Air; but this is not so nice to move upon a small alteration; yet since 'tis made use of in divers Parts of Italy, and other places, we will not omit to say something briefly of its make.  
To make it, you must fill a glass Vessel with Rectified Spirits of Wine, and immersing a Thermometer of 100 deg. therein, place it in Snow or Ice to cool it; you must also put into the same Liquor many little glass bubbles blown, and Hermetically Sealed at a Lamp; these by reason of the Air contained in them, will keep themselves floating upon the Surface of the Water; and if by chance any one being a little heavier in Specie than Water, shall sink to the bottom; take it out, and upon a plate of Lead, with fine Emeril grind off so much of the end as will make it light enough to swim. Then the Vessel being taken out of the Ice, carry it into a Room where the Air is well heated by a Fire, that the Liquor which before was very cold, may receive equally on all sides the temperament of Heat. So by little and little, as the Liquor grows warmer, and by Rarefaction lighter, the Balls (which at a more intense degree of Cold kept just upon the Surface) shall begin to dive toward the bottom, and at the same time the Spirit of Wine in the Thermometer shall creep up. That Bubble or Ball thereof which sinks when the Thermometer is at 20 deg. shall be reckoned the first, that is, the heaviest, because it descended when the Water was yet very cold, and little, or not at all altered. That which sinks when the Thermometer is at 30. deg. may be accounted the Second, at 40°. the Third, at 50°. the Fourth, at 60°. the Fifth, at 70°. the Sixth, and Last, or Lightest; whence it appears, that the Bubbles make a Scale of equal Differences; that is, from 10°. to 10 deg. as likewise, whence this Instrument is more gross than the rest, in that it shows by the rising and falling of the Bubbles, the alteration of the Air; but to every 10 th'. Degree of that Thermometer which is divided into 100°. and to about every 4 th'. or 5 th'. of that of 50 deg. and to every 40°. of that of 300°. Let these Bubbles so tried and chosen (And it would do well, if they were of coloured Glass, to be the more discernible in the midst of the Liquor) be enclosed in a large Cane of Glass filled with Spirit of Wine, but not quite to the top, leaving some space for the Liquor to rarefie, when the heat of the Season shall require it; and then seal it Hermetically. If the heat of the Room is not sufficient to make the Thermometer rise to 60, it may be helped, by putting the Vessel in a Bath of warm water, increasing the heat by gradual pouring in boiling Water, if needful; and so the Spirit of Wine contained therein will not be more heated in one part than another, but take its temperature as gently and equally as possible.   

The Description of an Instrument to discover the difference of Moisture in the Air.  
HAving already treated of those Instruments which serve to show the Alterations happening to the Air from Heat and Cold; we come next to Describe another, useful to discover the Changes which the Air is subject to purely from Humidity: and though there may be many and different Instruments of this Nature, which have been Invented by several Ingenious Persons yet we will describe this one: Of which (since it had its being first in this Court) we will say something out of gratitude concerning its Invention and Use, though perchance it is wrote of by others.  
It is part of a Cone of Cork hollow within, and pitched; and covered on the outside over with Tin: at the smaller end it is inserted into a Vessel of Glass with a Conical Point shaped as in the Figure, 
Tab. 1. Fig. 5.  and closed Hermetically: The Vessel being so made, and placed upon its Pedestal, is to be filled with Snow, or small beaten Ice; the water whereof as it melts, shall have its issue by the Pipe made in the upper part of the Glass. The Use of it is this, The subtle Moisture carried about by the Air, adheres by little and little to the sides of the Vessel, covering it at first but with a dew or mist, till by the coming of more moisture, it gathers into great drops, and at last stealing down the sides of the Conical Glass drops into a tall Cup in the shape of a Mum-glass divided into equal deg. and made on purpose to receive it. 'Tis evident, as the Air is more, or less full of moist Vapours, the force of the Cold condenses a greater or less quantity of Water, measured by the graduated glass Cilinder. Wherefore desiring to compare one Air with another; Observe in the first Air you would make use of, to what Degree the Cilindrical Glass is filled in a determinate space of time, and then throw away the Water, and carry the Vessel to the other place, and mark to what Degree the condensed Water then rises in the same time: and so the difference between the moisture condensed into Water at these two Experiments being found, gives the true difference between the Humidity of the two Airs proposed to be compared.  
We may likewise by exposing this same Instrument in the Air when the Wind blows, find which is the moister, and which the dryer. So we have observed, that when our South Winds prevail, the Glass sweats excessively, for the Air is then very damp, it may be from the South Sea, where probably the Sun's Influence being great, Exhales those moist Particles which afterwards incorporate themselves with the Winds; and in a strong South-West Wind, it happened, 
Libecciata Aquilonari Libecci▪  that from 35, to 50 Drops have fallen in a Minute of an Hour. One time, the North and South-West Wind striving together, the Wether being very thick, so that the Clouds encompassed the Hills, we told 84 Drops in the same time: but at last, the North Wind getting the better, it gradually gave over sweeting▪ and in little more than half an hour the Glass was dry, though there was still a great deal of Snow within it: and so it continued all that Night, and the next Day, while the same Winds kept abroad. Likewise when the West Winds blow, the Glass is observed to be very dry. 
Poneuti.  Indeed, no certain Rule can be given of these things, since they may be altered by so many Accidents, not only from the season of the Year, and temperament of the Air, but from the Nature of the Soils and Countries themselves, which sometimes alter the Criteria of these Winds. And we know in some Cities and Places the South Winds are colder than with us, because perchance they may be bounded Southward with Mountains of Snow, the winds passing over which, are chilled. Nevertheless, our Instrument remains still unalterably just to every place where 'tis made use of, corresponding in all respects exactly enough to the ordinary Indications of Nature upon these Winds.   

The Description of some Instruments to Measure Time.  
WE need not go far to seek an Experiment, requiring a true and exact measure of Time, such as that by Swings, and Sounds, or Strokes; since the foregoing Experiment is a sufficient instance, where a Comparison is made of the Humidity of Air, and Winds, to find the Difference and Proportion of Moisture which in equal Spaces of Time distils from divers Airs, by means of a Glass Vessel filled with Ice: Which Difference consists sometimes in so small, and scarce perceivable Minutie, that the Justness of the most Accurate Clocks cannot discover it, because we either count the time from Stroke to Stroke, and the Ears may possibly be deceived; or we take it from the Spaces shown by the Hand, and then much more easily may the Eyes commit an Error; we must therefore of necessity have recourse to an Instrument, that may be a more exact Time metre, than the sound of four Strokes of the Clock, or the Minutes shown by the Hand can be, in which the Judgement of the Senses is so subject to mistake. For (to pass by the Errors that may be committed in the dividing of a Clock, or other material Instruments) it is very difficult to distinguish, whether the Hand is just upon the Point marked, or not. And then of Sounds, we must when all is done conclude, That the time is already past, before the Clock has done striking.  
Wherefore, we take the Pendulum or Puppet, to be the most exact Instrument; the Swing and Return of which, being taken for one Vibration, we never knew that in the Number of many Vibrations one failure has happened, (a thing which seldom succeeds so well in Practice) nor the least Variation able to cause an Error worth the Regulating; but because the usual Pendulum hanging by a single Thread in that free Liberty of swinging (whatever is the reason thereof) in time deviates from its first direction, and towards the end when it approaches Rest, its Motion is no longer in a vertical Arch, but in an Oval Spiral, in which we cannot distinguish, nor number the Vibrations; wherefore to keep the Motion true to the same Path, we hang the Weight in a double thread, fastening each end thereof by itself at a little distance to an Arm of Metal, as in the Figure. 6. So the Ball or Weight being hung on this Thread by a small Ring or Staple, moves in the Figure of an Isosceles Triangle; for since it hangs free upon the Thread, (though at the first impulse of Motion the Figure may be rather a Scalne) yet by its weight, it slides down to the lowest part to which it can fall, and keeps itself fixed there: from this Triangle it comes, that the Motion of the Pendulum is regulated, while the Threads that make the legs of the Triangle (if we may use that similitude) serve to stay the Ball from swerving more to one hand, than the other, and keep it always directly in the same Path. Since all Experiments wherein the Pendulum is made use of, require not the same division of Time, a grosser sufficing for some, such as is made by longer vibrations: and others again ask a Division so nice, given by vibrations so quick one upon another, that the Eye can scarce distinguish them; to be able with expedition and facility to lengthen or shorten the Triangle without every time untying the Thread; let there be added below the upper, another arm of Metal also, filled with a square hole on the upright piece of the Instrument, so that it may slip up and down upon it, and be fixed at any height by a Screw on the back: this arm is cut through the midst, which slit being opened, and closed together by the means of Two other Screws, stops and holds fast the Legs of the greater Triangle at any desired space between the Ball, and the upper arm, the lower part remaining at liberty; while that part between the two Arms is immovable: by this means the lesser Triangle below the stop at the slit which is its Base, vibrates freely, and so much the swifter as the Ball is suspended shorter, and by consequence the Legs of the Triangle more contracted.  
To interpose here a word or two; Experience tells us, (as Galileo has already observed next the observation which he first made, of the very near equality of Swings, about the Year 1583.) that not all the Vibrations of the Pendulum fall precisely in equal spaces, but as they approach nearer to rest, so they dispatch themselves in lesser spaces of time than at first, as may be shown in its place. Wherefore in those Experiments that require a greater acuracy, and so long a time of observation, that the little inequalities of these Vibrations in a great number of them may at last happen to be sensible, 'twas thought good to apply the Pendulum to the Movement of the Clock: a thing which Galileo first Invented, and his Son Vincenzio Galilei put in practice in 1649. So the Pendulum is moved by the force of the Spring, or Weight, and still carried to the same height each way, with this great benefit, that not only the length of the Vibrations become exactly equal, but in a manner all the Defects in the other parts of the Clock are corrected and regulated. That we might be able to make use of such an Instrument in several Experiments (which require the time, some more, some less subtly divided) we made divers Balls of Metal fastened to small Iron Wires, of different lengths, each to be inserted into the same female Screw when desired: of these the shortest made its whole Vibration, in half a Second Minute of an Hour, the shortest needful; all other returns of shorter Vibrattons being so swift, that the Eye is scarce able to follow them.  
Let this suffice concerning those Instruments of a more frequent use in the following Experim 〈…〉   

Experiments appertaining to the natural Pressure of the Air.  
THat famous Experiment of the Quicksilver is now spread throughout all Europe, which first in the Year 1643. offered itself to the thoughts of the Ingenious Torricelli; nor is the noble and curious inference he makes therefrom less enquired after, and known, when he comes to contemplate the cause of that strange Effect; for he proposeth, that it is the Air pressing upon all Bodies under it, forces them, and removes them out of their places, when ever there is a void and empty space whereto they may retire, and betake themselves; and particularly fluids, from their great tendency to Motion: whereas solid Bodies, as Gravel, and Sand, etc. or pieces of greater Stones (when there is an endeavour to move them) are rather joined, and pressed together the closer by that means, from the roughness and irregularity of their parts, so locking the whole Mass together, that they sustain and prop up one another, and so resist more powerfully any force applied to move them: but on the contrary, Liquid Bodies, it may be from the smoothness or roundness of their Particles from some other Figure they are of, are easily moved, their parts standing as it were in aequilibrio upon a Point, that as soon as ever they are pressed, they yield every way, and spread themselves, as we see Water from the least Body that falls thereon, breaks away on all sides in orderly Circles: and who knows, that from this incoherence and looseness of the parts, it may not happen that 'tis seldom or never stable, though in its most proper receptacles, where it seems sometimes Stagnant so that the smallest breath of Wind curls and agitates it; and even in standing Lakes and Pools, where it seems most Sedate, though the Eye perceives it not, yet there the Water is in perpetual Motion, and obedient to all the undulations of the Air, which it may be is never at Rest; nor is this more peculiar to Water than any other Liquid; in all which, as some think, the force of the Airs Pressure is very evident; especially, when they are in a place which in any one part of its Superficies has a Vacuum, or as it were void space into which the Liquid may retire: for the Contiguous Air pressing the Fluid on the one part with so many Miles height, when on the other part (contiguous to the Vacuity) it touches not, nor can gravitate at all; it must necessarily mount it into that void space, till the raised fluid becomes an Equipoize to the Airs Pressure on the other part. This Equilibrium with divers Fluids, is at divers Heights, as they are more or less heavy in Specie; a lesser or greater quantity of which is able to resist the Force and Weight of the Air. We (following the common Practice, as likewise the first Inventor Torricelli) make use of Quicksilver, which being very heavy, is much more commodious for the Experiment, making a Vacuum in a far less space than any other Liquid can. What is needful to be seen in this Matter, the following Experiments will manifest.   

An Experiment,  
Suggesting to Torricelli the first Inventor thereof, that it might be the natural external Pressure of the Air which sustains the Mercury, or any other Fluid, at a determinate Height in the empty space of a Cane, etc.  
Tab. 2. p. 14.  
The space OF shall contain no Air, which is manifest by inclining the Cane about the Point C as a Centre, when you will find the internal Level F successively move towards A, but never rise above the horisontal pricked line FG, drawn from the point F, the first height of the Quicksilver, when the Cane was perpendicular; and if the end A be inclined quite to the line FG, the Cane will be full of Quicksilver, except a very little at A, whither still above the level of the included Mercury, gathers together either some air wherewith perhaps it is impregnated, or some other invisible effluvia exhaling there from. This is most conspicuous, when a small quantity of Water is in the Cane, which in making the Vacuum gets above the Mercury, and discovers in their Passage through the midst of it, that several small Bubbles rise out of the Mercury towards the empty space; as may be shown hereafter.  
This Vacuity of Air may likewise be proved by Water poured upon the Quicksilver in the Vessel DE. for lifting the Mouth of the Cane C out of the Quicksilver, as soon as it is every way encompassed with the Water, the Mercury will fall down, raising the Water in its place to the top of the Cane; 
17 Bra. ●/3  provided it exceeds not the length of 33 Feet 45 Inches, to which (as may be elsewhere discoursed) it is usual for Water to be sustained; probably from the same power that bears up the Mercury to 28 6/10 Inches; and indeed, there will be no great quantity of Air at the top of the Cane; since there is only some thin Effluvia forced into an almost invisible space, which (as we said) rise from the Quicksilver, or is some other subtle Matter capable of penetrating thither.  
Upon this ground we shall call (as before for brevity-sake) the space OF, (and any other left by the subsiding Mercury in a like Vessel) the vacuum, or void space, (i. e.) empty, and void of Air; at least such as unaltered, and in its Natural State encompasses the Cane; not presuming here to exclude Fire, Light, or the Ether, or any other very thin Bodies, which are either in part dispersed with little vacuities interposed, or wholly filled the space, which we call the vacuum, being stretched and attenuated as some think. Nevertheless, 'tis our intent in this place, only to discourse of the Space filled with Mercury, and endeavour to find the true cause of that wonderful Counterpoise of this Weight, without entering into any Dispute with the deniers of a Vacuity. And since many Experiments have been made for this end, (as well what is related by others, as what has been invented by our Academy) the success shall be faithfully set down; our Custom being always to deliver the Matter Historically, and not to defraud the Inventors either of their Invention, or due praise.   

An Experiment  
Of Mr. Robervals in favour of the Airs Pressure upon Inferior Bodies, tried in our Academy.  

Tab. 2. Fig. 2. 2. Brac.  LEt there be a glass Vessel A, to the bottom of which BC perforated at D; let the Cane DE 46 Inches long be affixed, over this hole set the square glass F, then close the Vessel A with the glass Cover GH, having an open nose HI, and a hole at G, through which let the Cane KING be put open at each end, and about 46 Inches long, 
2 Brac.  or not less than 30; let this down into the Glass F, but not quite to touch the bottom; and fasten it there with Mastic, or other Cement at the fire, to the hole in the Cover G; this Cement, or Paste, is made of Brick reduced to an impalpable Powder, and incorporated with Turpentine, and Greek Pitch; 'tis admirable to stop Glasses to exclude the Air; let it be luted close with the same, round about where the said Cover and Vessel join; and cover the lower mouth E with a Bladder: Then pour in at the upper end K so much Mercury, till running over the Glass F it falls upon the bottom BC, and thence by the hole D fills the lower Cane ED, and after that the whole Vessel A, the Air having its way out by the open Nose HI, which when the Mercury begins to run through it, close well with the Bladder I, and lift up the whole Cane to K till a little runs over, that not the least Air may remain when closed, which do with the Bladder K. Lastly, open the other Bladder at the Mouth E under the Superficies of the Stagnant Mercury MN, into which the Cane is immersed, and immediately the upper Cane KL, and the Vessel A will empty themselves; the Glass F and OPEN, part of the Cane DE being about 28 ½ Inches above the Level, MN remaining full. This done, 
Brac. ¼  the ingress of the External Air upon opening, or pricking the Bladder I, will immediately suppress the Cilinder of Mercury OPEN into the lower Vessel, and raise up another QR from the Mercury in the glass Cup F into the Cane LK equal to the former OPEN, 
1 Brac. ¼  and therefore 28 ½ Inches long; and this Cilinder will not subside until the External Air entering at the top K, rushes in upon it through the Cane LK.  
If in this Vessel A, a little Bladder be enclosed, taken carefully out of a Fish, the Air that is Naturally therein being first expressed, so as very little be left in the folds thereof, and then the Orifice well tied together, as soon as ever (by the subsiding of the Mercury) the Bladder shall be in vacuo, that little Air remaining in it will swell, and distend it; nor will it shrink again, till by opening the Vessel at K the External Air gets in to press upon it.  
But we have observed more clearly the like Expansion of Air in vacuo, 
Tab. 2. Fig. 3.  in a Vessel made after another manner, as ADB, wherein a Lamb's Bladder squeezed together, and almost wholly discharged of Air, is enclosed thus; fill the Vessel with Quick silver by the mouth D, and tie it over with a Bladder, the lower Mouth E being before stopped with the Finger, then immersing it into the Quicksilver, in the Vessel FG, open the Mouth E, and let the Quick silver subside; then will the Bladder C hung by a Thread in the empty Vessel ADB swell itself, and so continue, till by opening the Mouth D, the External Air enters a the Top, which at the same time will bear down the Cilinder of Mercury into the Vessel at the bottom FG, and press together the Bladder.  
Likewise, if in closing the Mouth D, there be put upon the Mercury a little froth made with whites of Eggs, or Soap-suds, still as the Vessel ADB empties itself, the Air imprisoned in these small bubbles will so swell them, that at length breaking through its thin Confinements, it shall be at liberty, and quite released from the Liquor, which will fall down upon the Mercury like Dew separated from that fine steam of Air contained in the froth.   


Tab. 3 p. 19   
Experiments  
Alleged by some against the Pressure of the Air, and the Answer thereto.  
THere have been Two Experiments, from which some of our Academy judged a considerable Argument might be raised against the Pressure of the Air upon Inferior Bodies, and the Effect of sustaining Fluids attributed to something else.  

Tab. 3. Fig. 1.  One was, by covering the Vessel A, and likewise the Cane with a great Bell of Glass BCD pasted down close to a Table round the edges: for than they imagine, that if it were true, that the weight of the whole Incumbent Atmosphere of Air did protrude the Mercury into the Cane, and counterpoise it with its weight; by defending (with this Cover of Glass) the Stagnant Mercury from so great a Pressure, the small, and scarce sensible weight of the little portion of Air included within the Bell, must of necessity be unable to keep the Quicksilver at the same height whereto the momentum of so vast a space of Air had raised it; but notwithstanding this, they never observed it to subside a jot from the usual height EGLANTINE.  
The Second Experiment was of the same Nature, but more Artificial.  

Tab. 3. Fig. 2.  We filled with Mercury a small Vessel AB (which at first was made without the Beak CD, added afterwards for another Experiment) and plunged into it when full, the Cane OF, and making the usual Vacuum, there was poured out from the Vessel AB a small quantity of Quick silver, so that a little Air might be in the space AH to bear upon the Stagnant Level HG, and then the Weight and Pressure of the External Air was kept off, by closing carefully with the afore-named Cement, the round space A between the Neck of the Vessel, and the Cane; and yet in this case, when the bulk of the External Air was so lessened to nothing almost, we saw no sensible abatement of the Mercurial Cilinder IF below the usual height.  
But the Assertors of the Airs Pressure answer these Experiments thus. That these Events on the contrary greatly favour their Opinion; for the immediate cause (as they say) that forces, and powerfully sustains the Mercury, to the height of 28 1/● Inches, 
1 Brac. ¼  is not the weight of the Incumbent Air; which indeed is taken off by the Bell in the first Experiment, and by the Cement in the second, but is in reality an effect of Compression, which was produced and wrought in the Air (contained in BCD Fig. 1. and in AH Fig. 2.) by that weight before they were Cemented close: whence 'tis no wonder, that the Quick silver subsides not from its usual height, the Air keeping in the same state of Compression as 'tis forced to do, from the resistance made by the glass Bell, and Cement, which supplies the place of all that vast Tract of Incumbent Air.  
And because 'tis yet believed by some, that the force of a supposed Spring in the Air acts wholly in this Effect, so as without it by no means it could happen; 'twas therefore attempted to insinuate the contrary, by the following Experiment.  
Taking the same Vessel AB, with its Cane OF (before we poured off any of the Mercury, as was directed in the former Experiment, or stopped up the Mouth of the Vessel at A with Cement) and then setting all in a great Vessel full of Water KLMN, the Quicksilver was observed to be sensibly depressed from A to GH; and on the contrary, raised in the Cane from I to O; this Ascent being about the fourteenth part of the whole height of the Water OF: then the Mouth A was closed, that so only the Water in the space AGH might press upon the Mercury, which nevertheless lost none of the height lately gained by the weight of all the Incumbent Water OF, above the First Levelly I; yet in this case the included Water AGH, not by virtue of any Springs (which perchance it had not) but because it had been forced by the Charge of the whole height OF into the space left by the Quicksilver rising from I to O, and kept there by the same force, and so hindered from Returning. The same may be said to happen to the Air.  
Lastly, Some desirous to see what Effect a greater, or lesser Rarefaction of the Air included in AGH would have, made this Trial.  
Joining to the Vessel AB the Beak CD (into which they fastened a Mouth of Metal with a female Screw), they adapted a Syringe; Then whenever a Suction was made of the Air in AGH, and so what remained attenuated and weakened, the Level I, might be seen to subside, contrarily when compressed more, by forcing in new Air; the same Level I was raised.  
The same happens from Fire or Ice approaching it; for the Mouth C being closed, when Fire is Externally applied to the Air in AGH, the Mercury rises, and by the application of Ice subsides; as if after the same manner, as it happened in the contrary operations of the Syringe; the Air had been Condensed, and enforced by Heat, and rarefied and weakened by Cold; from all which Matters it seemed probable, that this sustention of the Fluid does not absolutely depend upon the weight of the Air, but also upon the compression which lower parts of the Air receive from those above.   

An Experiment  
To know if the Air near the Superficies of the Earth, is pressed by the weight of the Air above, and if it be put in a void space at its Liberty; whether it will expand itself to a greater space, and how much when yet it is still unaltered by any new degree of Heat.  
THE Ingenious Observation made by M. Roberval with the little bladder of Air enlarging itself in Vacuo, moved some to believe, it might be determined how far the Air is capable of Expansion when at absolute liberty in any place; for it seemed probable to them, that in any Vessel proposed, a void space might be assigned sufficient for the whole increase of such a quantity of Air; whence whatever should happen to exceed that Quantity (requiring a more ample space to dilate itself in) must proportionably more, or less depress the Mercurial Cilinder below the usual height of about 28 Inches: and on the other side, what ever comes short of it, will easily permit the Mercury to rise to the usual height. The Experiment is thus,  

Tab. 3. Fig. 3. 2 Brac.  Let there be a Vessel of Glass ABC, with a shank BC about 46 Inches long, open at G; and let there be a tall Glass provided, DEF filled with Mercury to immerse the shank BC into, but such a Vessel as may not only serve to immerse it into, but capable when desired of receiving either all, or a great part of the Shank into itself as a Scabbard.  

Tab. 3. Fig. 4.  Let there be another Vessel GHI equal in all respects, as near as may be to the former ABC, in which make the usual vacuum, marking the height to which the Mercury is sustained at that time, KL; then fill with Mercury the Vessel ABC Fig. 3. being as was said of the same size by the Mouth C up to M, and let MC remain filled with Air.  
It is clear, that stopping with your Finger the Mouth C, and inverting the Vessel, the small quantity of Air left MC will pass through the Mercury, and take its place in A. Then plunge the Mouth C beneath the Level of the Stagnant Mercury DF, and removing your Finger make the vacuum PA. The height of the Mercurial Standard will be PQ, measure it, and if it be found equal to LK in the Vessel GHI Fig. 4. in which no Air was left to alter it, it shows that the Cilinder of Quicksilver PQ is not in the least influenced by that little Air remaining MC, because the space left empty from A to P is more than sufficient for its utmost Expansion▪ Proceed then gradually to depress the Cane, or Shank BC into the Mercury DF, that the Level P may be gradually raised also, suppose to R, successively lessening the space PBA left for the Air; continue this depression as long as the Height QR shall be found equal to KL. And Note that R is the fixed and utmost bounds of the whole height of a Cilinder of Mercury equal to KL, all the subsequent heights towards B (caused by a farther depression of the Cane into the Vessel DE) being successively diminished: whence 'tis probable, that the void space ABR is quite filled by the Expanded Air; because from R upwards, the Mercurial Cilinder suffers some force from within: an evident sign (as some think) that the Quantity of Air MC will not be contented with a less space, than ABR for its full, and free Expansion; the measure of this space ABR, and by consequence of the Expansion of the Air MC, is thus obtained.  

Fig. 3.  All things being as in the Vessel ABC, where the air MC has its utmost Dilatation in the space ARE; then seek the proportion between the space MC filled with air naturally compressed, and the space ARE filled by the same air dilated, which is found at one trial by weighing the water that may be contained in the space MC, and likewise that which may be contained in ARE; as suppose they are found in Proportion to each other, as 1 to 174, we may affirm the same of the air, that (when at its greatest Expansion it takes up 173 times a larger space, than when in the state of its Natural compression.  
Note, that having often reiterated this Experiment, and at divers seasons it has not always succeeded in the same proportion: for when at first we made it with another kind of apparatus, though the Operation was much the same, yet the Proportion was as 1 to 209. afterwards making use of the present Instrument we found it as 1 to 182; Lastly, the third time (which also seemed to be more exactly performed than before) it was (as is set down) as 1 to 174; nor is this diversity strange, considering that the Experiment can never be made with the same air, but still either more or less compressed, as the Season is warmer or colder, and as the place of Observation is higher or lower, whence 'tis impossible it should be Dilated in the same manner, or in the same fixed and unaltered Analogy.  

Fig. 4.  Note also, that the Ball GH was joined to the Cane HI, because if any Invisible Particles of air were disseminated through the Mercury, they might rise into the Ball, and have room enough to expatiate in without being able by their Pressure to alter the natural Height KL raised by the equipondium of the Air.   

An Experiment,  
Proposed to show, that where the Pressure of the Air is taken off, the Mercury is no longer sustained.  

Tab. 4. Fig. 1.  HAving chosen a small Cane of Glass AB not so long as the Mercurial Standard, close it's lower mouth B with a 
Tab. 4. p. 25.  Bladder, fill it at A with Mercury, and put into it a little Dart CA, the one end gently touching the Bladder tied at the bottom of the Cane, and the other a little above the Mouth A; which also close with a Bladder.  
Let there be another Cane DE▪ longer than 30 Inches, the Mercurial standard, made so that the Mouth thereof E may be easily covered with the Finger, and the end D large enough to receive the Cane AB, which already filled with Quicksilver must be put therein, observing to let it down so low, 
Brac. ¼  that its end B may be less than 28 6/10 Inches from the Superficies of the Stagnant Mercury FG, reckoning towards D; then fasten, and close stop the two Canes together at D with Cement, that the External Air be perfectly Excluded. After this at E fill the whole Cane ED with Mercury, and stopping it at E with the Finger, invert it into the Stagnant Mercury FG, and make the Vacuum in the upper part DH, that the mouth B may still remain immersed in the Quick silver HI; close again the Mouth E with your Finger, yet not raising it out of the Mercury FG; whence the Communication between the Quicksilver FG, and that in the Cane DE being hindered by the Finger, the Cane DE will be as a Vessel, into which the little Cane AB is immersed: then striking the end of the little Dart AC, thrust off the Bladder from the bottom B; as soon as 'tis opened, the Mercury will all run out of the Cane AB, (although 'tis shorter than the Mercurial Standard, and its Mouth B still in the Mercury HI) contrary to what would have happened, if the space DH now void, had been full of air: as the following Experiment will manifest.   

An Experiment  
Likewise proposed, to try if (when the Pressure of the Air is taken of) the sustained Fluids will subside, and upon its return be raised again.  

Tab. 4. Fig. 2. 2 Brac.  LET the Cane AB be about 3 Foot 10 Inches long, and Hermetically sealed at A; let the Beak AC be drawn so slender, that it may be easily nipped off with the Fingers, and with as little trouble sealed again with the flame of a Candle: fill the Cane with Quick silver at the Mouth B, which (as also the Mouths of all Canes and Vessels employed in making a Vacuum) ought to be ground, and rubbed smooth; so to be more securely stopped with a Finger. Then let there be another Cane DE made of the length of the first AB, 
Tab. 4. Fig. 3.  and seal it at one end, but let it be open at the other, not with a round Mouth as the former, but cut a slope; this when filled with Mercury, is to be put like a Sword into its Scabbard into the Cane AB, made large enough to receive it. Then the Mouth B being stopped with the Finger, invert both the Canes, and plunge them into the Mercury in the Vessel FG, making the vacuum as is usual; which will be at the same height in both Canes, Levelling the Mercury in the innermost and outermost two at H; then with the Finger stop the Mouth B of the Exterior Cane, while 'tis yet beneath the Superficies of the Mercury FG; so that the Mercurial Cilinder BH may have no farther Communication with the Mercury in the Vessel FG. But the Exterior Cane will be a Vessel to contain the inner Cane DE, as in the former Experiment; and the Mouth of the inner Cane E, will by reason of its Oblique Figure, remain open: this done, nip off the end of the Beak C, that the Air entering thereat upon the Quick silver H in the Exterior Cane, encompassing the other, and pressing thereon, may immediately fill the innermost Cane DE; which it will do, provided that in the Cane AB there is enough Quicksilver to fill it; and the space from A to H, which is the vacuum, 
Br. ¼  exceeds not 30 Inches This Experiment is easily made, and repeated in a short time.   

An Experiment,  
Proposed for the same end, to know if the Air acts in the sustention of Fluids'.  

Tab. 4. Fig. 4.  LEt there be a little glass Vial as ABC, whereof the Mouth C is drawn so small, that being filled with any Liquor, and turned downward, though open at C, yet it will not run out; fill this with Mercury with a small Glass funnel, and stop it at C with Wax, or Mastic, then place it in the Glass Vessel DE, so that the Mouth thereof C may rest upon it, and the cover F be closed with the usual Cement; then fill by the Mouth G, the whole Vessel DE with Mercury, and make the Vacuum; which done, apply a Candle (on the outside of the Vessel DE) to the Mouth of the Vial C, and so melt off the Wax: as soon as ever 'tis open, the little Vial will begin to run, and empty itself of the Mercury; but upon admission of air into the Vessel DE, it will immediately stop.  
If instead of Mercury the Vial be filled with Oil, or Wine, or any other Liquor, the Effect will be the same.   


1 Brac. ¼  An Experiment  
To show, that in any Vessel above 28 6/10 Inches long, filled with Mercury, provided it has a very small mouth, when it is inverted in the open Air, a Vacuum will be made in all that space which is above the Height of 28 6/10 Inches.  

Tab. 4. Fig. 5.  TAke a Glass Cane AB of what size and length you please, above 28 6/10 Inches, seal it at A, and let it be open at B, with a very small Orifice; fill it with Mercury, and hang it in the open Air Perpendicular, with the end B downwards, the Mercury will presently run out, (not by drops, but) in a continued stream till it subside to C, the usual height of about 28 6/10 Inches, and then it will stop of itself. 
1 Brac. ¼    

An Experiment  
To show more evidently, that where the Pressure of the Air is wanting, the bearing up of the Fluid is lessened in a Cane of any length; and upon the return of the same Pressure, raised up again.  
Tab 5 p 29  
Note that KL is about the fourteenth part of the whole height of the Water ML (for what Cause may be told presently) but when it does exceed it, (as it may sometimes happen) 'tis from two Causes; First, either the Water wherewith the Vessel is filled, was not poured in so hot, that the vacuum left by it, in condensing, is capable of receiving all the Quick silver falling from the Cane OF; for when the space AI left by the Condensing Water, is filled by the subsiding Mercury (which falling into the Vessel GB raises all the Water) there can no more Mercury descend out of the Cane OF, and so it will be above 1/14 of the height ML.  
Or Secondly, the other cause may be, when this void space AI is indeed sufficient for the Mercury in the Cane, but not for the Air; which may rise either from the Mercury in the Ball, or from the Water in the Vessel, which air requiring a larger field to expatiate in the● the void AI, may possibly make some impression upon the Superficies of the Water, and so communicate it to the Cane, and bear up the Mercury a little higher than the bare Weight and Pressure of the Water would have sustained it at.   

An Experiment  
From whence is shown, the efficacy which the Pressure of another Fluid joined with the Air, has upon the sustained Mercurial Cilinder.  

Tab. 5. Fig. 2.  THe Vacuum being made with the Cane ABC, wherein the simple Pressure of the air raises the Mercury to D, 
Brac. ¼  the usual height of 28 6/10 Inches, pour Water upon the Stagnant Level EBB, and fill it up to A, and you shall see the Level D raised to F, and the space FD will be 1/14 of the Water AB poured in: and that because, to the weight of the Cilinder of Mercury DF, the weight of the other Cilinder of Water will upon trial be found equal, having the same Basis, and of the Height of AB.  
But if instead of Water the same space AB be filled with Oil, the Mercury will rise to G only; if with Spirit of wine to H; whence we may (from the proportion of the height of the Fluid AB encompassing the Cane, to the height of the increase caused by that Fluid in the mercurial Cilinder above the first Height of 28 6/10 Inches caused by the air) find the Proportion of Specific Gravity between the mercury and any of the Ambient Fluids. 
1 Brac. ¼   
And likewise as easily that of the Specific Gravities of the Fluids, in respect of each other.  
The same may also be obtained without a Vacuum with a plain Cilindrical glass AB in the former Fig. into which by putting a little mercury, and the small Cane AC (now supposed open at each end) and then pouring an equal quantity of several Fluids, seperatim upon the Superficies of the mercury EBB, and all to the same Height, suppose A; from the different heights of the mercury in the little Cane FG, HD, caused by their respective gravities, we may not only have the Proportion of their Specific gravity with the mercury, but also that of the Fluids compared with one another.  
Note, that (in this, and all like Experiments) where it happens that the inward or outward Level of the mercury is altered by the Pressure of some fluid, or otherways, than the Letters pointing at those operations in the Figures, are supposed to be removed to the places requisite, and successively follow the Level, as it gradually moves from place to place.   

An Experiment  
Showing, that where the Air presses not at all, a Vacuum may be made not only with Mercury, but also with Water, to any height of the Tube, provided less than that whereto it used to be sustained by it.  

Tab. 5. Fig. 3. 1 Braccio  LEt there be a Glass Vessel AB containing about 6 l. of Water and the Mouth A big enough to receive the Cane CD 22 9/10 Inches long sealed at C, but Obliquely open at D: this Cane must have at A, (the place whereto 'tis let down into the Vessel AB) two small Anulets of Glass close together, that the Bladder with a hole therein may be tied very fast between those two Rugs: then fill the whole Vessel AB with Water as hot as possible, and the Cane CD with cold, put upon it at the lower end D the Plate of Glass E fitted to shut the Mouth of the Vessel AB: Immerse the Cane therein, turn down the Bladder, gather it together, and bind it close about the Neck of the Vessel, having first pressed out the Air from its Folds. Now as the Water cools, part of the Vessel FG will be empty, and likewise (as in the former Experiment) part of the Cane CH, where the Water will rest, nor move but upon some alteration of the External Heat, and Cold; but upon pricking the Bladder, the Air forcibly entering upon the Level of the Water in the Vessel, will refill the Cane as at first.  
It was thought by some, that the water in the Cane does not fall at first when the Vacuum is made to the same Level with that in the Vessel, (supposing the space AGNOSTUS capable of receiving it) it may be from a cause mentioned in a foregoing Experiment (i. e.) from some Air which raises itself from the Water into the void space, perhaps too narrow for its full Expansion: whence they imagine, that if the Experiment were made with wine, oil, spirit of wine, and other liquors, from a greater or lesser Vacuum remaining in the Cane, it might be determined which of the Fluids has most Air dispersed through its Particles.   

An Experiment  
First made in France, and after by our Academy; whence 'tis probable, a more cogent Argument for the Pressure of the Air may be drawn.  
M. Pecquet in his Book of New Anatomical Experiments, writes, that it has been observed by many, that the height of the Mercurial Cilinder in Vacuo, varies according to the places where the Experiment is made; whence in higher places 'tis less; and in lower places, and deep pits, greater: provided the height be pretty considerable, as that of the highest Mountain of Auvergne, at the top whereof the Mercury wants much of the usual height: which has been said to happen, because the higher Air which is found upon the tops of vast Mountains, having a lesser weight upon it, makes a more faint Pressure, nor is able to raise the Mercury to that height whereto the lower Air of Valleys and Plains easily mounts it. Howsoever, the truth of this assigned cause may prove, of which 'tis not at present our intent to discourse; yet we have observed the very same Effect on the highest Tower at Florence, 
Br▪ 142.  which is 271 Foot high: as likewise on divers of those small Hills which surround the City: and we find it manifest, that the height of the Mercury varies in different parts of the Tower, or Hill, subsiding as we ascend towards the top; and as we descend lower, and lower, it gradually rises, till being brought into the plain, it balances itself at the usual Station. 
Br. 50.  But to make this Effect sensible, at least 100 Foot is requisite This observation has given some ground to hope, this Instrument might be improved to show and determine exactly the state of the Airs compression; believing that the divers Heights of the mercurial Cilinder aught infallibly to show the various Pressures of the Air upon the Stagnant mercury, upon account of the different height of the Atmosphere above the said Level. But from the many inequalities, and irregular movements, which in a long Series of Observations we have taken notice of, this thought is rendered dubious; for this Instrument being let alone fixed and unmoved in any place, its variations were very small, and seldom above 2 or 3 degrees, which came only from the different temperament of Heat and Cold; and on the contrary, very notable variations to above 12 Degrees have sometimes happened from other reasons to us unknown and hid.  
Nevertheless, to arrive at this Knowledge by other means, more certainly and assuredly, we thought of making the next following Instruments, whereon though the External Accidents of Heat, and Cold have some Effect, altering them from their true and simple Operation: yet these disadvantages are not so insuperable, but the accuracy and care of the diligent Observer may easily avoid them.    


Tab. 6. p. 35   
THE DESCRIPTIONS OF THE Instruments: SHOWING, The various Alterations happening in the State of the Natural Compression of the Air.  

The first Instrument.  

Tab. 6. Fig. 1.  Choose out the smoothest and evenest Glass Cane you can, being somewhat larger than an ordinary Goose-quill, which must be bend in the Figure of ABCD, with its two Arms AB, CD Parallel, and very near of the same length, as is represented in the Figure; this must be acurately divided into equal Degrees, so that the Decimal Marks upon each Arm, may be upon the same Level: which to do more easily with the small Buttons of Enamel, 
Smalto.  you may glue on the outside of the Arms two Lists of Parchment, equally divided; which through the Transparent Glass Cane will readily point at the place where the Buttons ought to be fixed. The Arm CD is to be widened like a Trumpet at D, and the other Arm is to be joined to one, or more Glass Balls, as E, F, which are empty, and capable of containing some Quantity of air; the last of which must have a Beak GH drawn small to be Sealed with a flame, as occasion requires: Then pour in some Quick silver at the Mouth D, which (the Vessel being open at each end, and the Two Arms of an equal size) will stand both ways, at an exact Level, as I, K. The Instrument, being so prepared, is to be carried to the foot of some Tower, where let it rest till the air contained within the Balls, may be of the same Temperament with the Ambient: then presently Seal it with a flame at H, but be sure to be very quick in doing it, lest the included air should alter by heat of the flame. This done, let there be one upon the Tower, to draw up the Instrument with a Pack-thread (fastened to the upper part thereof, so as not to invert the Beak;) and when at the highest part of the Tower, let it stand upon a plain, as at the foot thereof it rested; then examining the Temperature of the air above, and finding it the same with that below; you may perceive, that whereas at the foot of the Tower, the Quicksilver rested at I, K; at the top of the Tower the Level I will be sensibly depressed, as to L, and the Level K in the same Proportion raised for the space MK: caused, as they say, by the more vigorous Pressure which the lower air makes upon that included in the Balls E, F, in comparison of that above; by which the Level K is more lightly pressed.  
Remember, that every little difference of Heat and Cold between the air above, and that below, is able to cause a variation in the Levels of the Two Arms AB, CD; and so alter what should have happened from the diversity of Pressures made by the air: wherefore this Instrument is a sort of Thermometer for the air; and that, for the most part, very nice. Therefore in the making this Experiment, choose the Dawn of the day before the Sun is up, or any other close Season; that the air above and below may be of an equal Temper, as near as possible; nor let the time between the observation made at the bottom and top of the Tower be long; take care also not to stand too near the Instrument, when you observe the Degrees, which should be done quickly, and be sure not to breathe upon it, lest it heat the Balls: which should be of as thick Glass as may be, to defend the better from any External Impressions, the air contained in them.  
All this diligence must likewise be used in the management of the Three following Instruments, they being not at all less Nice, and subject to cause the same mistakes as this first.   

The Second Instrument.  

Tab. 6. Fig. 2.  LET there be a Vessel of Glass AB containing about two Quarts, with its Beak CD open; pour into it so much Mercury as will cover the mouth E of a small Cane OF 11 ½ Inches long, and open at both ends, 
½ Brac.  but cut sloping at E, and round at F; which being divided into equal Parts, or Degrees, is to be immersed into the Stagnant Mercury GH; and the space left round the Mouth of the Vessel A is to be closed with Cement to shut out the air; being so made, carry it to the foot of a Tower, and let the internal air be reduced to the same Temperament with the External; immediately Seal it, and let it be drawn up to the top of the Tower; where having placed it on a Plain, you will find the Mercury somewhat raised within the Cane, suppose to I: which Rise, (they say) follows also from the same Reason which we gave in the Description of the former Instrument, viz. The lower air, such as is included in the space ACGH, has a greater force and power upon the Level of the Mercury encompassing the Cane, than the higher air has, which presses upon the Level I, entering in at the Mouth of the Cane F, so that it raises the little Cilinder IK, to make a just Equilibrium between those two Momentums, or Powers.   

The Third Instrument.  

Tab. 6. Fig. 3. ⅓ di Brac. ⅔ di Br.  BLow a Glass Ball A 7 6/10 Inches in Diameter, with its Neck BC about 15 2/10 Inches long, divided into very minute Degrees, pour into the Ball so much Water as will fill half the Neck, which is the space CD: stop the Mouth C with a Finger, and plunge it into the Water in the Bladder OF, which is kept from being filled to its whole Spherical Capacity, by means of a Weight at pleasure hung at F: close then the folds of the Bladder, and bind it very straight round the Neck BC, at E, taking care when you bind it, to pour in Water till it runs over; so to be secure that no air is included, which might any way alter or spoil the due and right Operation of the Instrument; Every thing being performed after this manner, at the foot of a Tower, fasten to the Ball at G, a string let down from the top of the Tower; and having observed the Degrees whereat the Water stands, let it be drawn up: when again observing, it will be found Depressed some Degrees lower, as to H, which will be more or less according to the present State of the air; and the greater or lesser height of the Tower.  
This also they say happens, for as much as the Bladder OF is encompassed with the air of the higher Region; and so not sufficiently armed externally to resist the Force made on it by the air of the lower Region (which is included in the space GD) in Dilating itself; whence it must necessarily yield to enlarge its internal Capacity, which the small Bulk of Water DH sinks down to fill out.   


Tab. 7. p 39   
The Fourth Instrument.  

Tab. 7. Fig. 1.  'Cause a Glass Ball to be made A, with its Neck BC like the Third Instrument, only it must have an open Beak drawn very slender D, round the Mouth of the Neck C bind the Bladder OF very close: this Bladder is to have in its lower Ligature F a small thread of Glass, or Brass-wire, which passing through the Bladder is to enter into the Neck of the Ball BC, and so point at the Degrees it is minutely divided into: let this Instrument be carried to the foot of the Tower, seal it as the other at D, and take notice of the Degree pointed at by the End, or Dart G: raise it then to the top of the Tower, and you will find the Dart higher than before, by some Degrees.  
To give the reason of this Effect, they consider, that the Vessel is filled with air of the same Temperament with that below, which as it finds one part of the Vessel less Solid than the Glass, yielding, and easy to be distended, such as is the Bladder OF, so it no sooner perceives itself relaxed from the Prison of the surrounding air, by being raised to a higher place; but it immediately endeavours to enlarge itself, and be at liberty; which it Effects, by swelling the Bladder a little more: Now whilst this by being so puffed up comes nearer to a Spherical Figure, the transverse Diameter of the Ellipsis OF is shortened, as the bottom F is gradually raised, when also the Index FG fastened thereunto, by obeying its Motion, rises higher in the Neck BC, and so comes to point at a higher Degree than G.   

Various Experiments made in Vacuo.  
FRom the Series of the aforementioned Experiments, Torricelli's thought touching the Airs Pressure upon all Inferior Bodies, seems fully confirmed. And though it may be a daring undertaking, and full of hazard, to determine of the Causes where Geometry gives no Illumination; yet this boldness is never more excusable, nor the danger more like to be avoided, than when our Understanding, only by a Path of many, and all agreeing Experiments, makes toward the attainment of its desire; which though it may sometimes fail off, yet it is satisfied in approaching as near as may be towards it. Since than it appears from the Effects already mentioned, that we have gained some reasonable probability of such a Pressure; it was judged not altogether a fruitless labour, to proceed to make divers Experiments in Vacuo: and observe, whether the manner of their operation would succeed contrary, or any way different to what they appear, when environed on every side with the free Air.   

Experiments  
To know whether small drops of Liquid Bodies, being freed from the Airs Pressure encompassing them, lose the Spherical Figure they naturally are off.  
SOme have Attributed to the Pressure of the air, that generally known Observation of the drops of Mercury, 
Tab. 8. p. 41.  or any other Fluid; which spurted, or raining through the air, or let fall upon any dry, or dusty body, always are nearly of a Globular Figure: wherefore they were willing to try it in Vacuo, imagining there might then happen some notable Variation. But Experience itself showed, That the Effect proceeded from some other cause, than the airs Pressure; for having made the Vacuum in the Vessel AB, the cavity A being quite void, 
Tab. 7. Fig. 2.  by turning the Stop-cock there was let fall some drops of Water, or Mercury out of the Ball C upon some Colewort-leaves included in the Ball A, (which had some drops of Dew hanging on them, with which they were gathered;) these Drops that were admitted, contracted themselves as round, as if they had been upon a growing Plant.  

Tab. 7. Fig. 3.  So when the air in the Vessel A was condensed, or rarefied by means of a Syringe CB; the Drops of Water, or Mercury, sprinkled upon the bottom of the Vessel were not altered from their usual shape.   

An Experiment,  
Showing the Effect of Heat and Cold, applied Externally to the void space.  

Tab. 8. Fig. 1.  BInd the Bladder ABC under the Ball D, make the Vacuum therein, turn the Bladder upwards to be tied there likewise; then with a Cane of Glass, or any thing else that will not alter, or bend, take the exact height of the Mercurial Cilinder HG, from the Stagnant Mercury OF: after this, fill the Bladder with hot water, and soon after measuring, you will find the Cilinder a little depressed below the former height. This Observation made, throw out the hot water, let it stand till it returns to the former height H, and then fill the Bladder with cold water mixed with beaten Ice, and Salt, and in a little while measuring (as before) you will observe the Cilinder notably raised.  
Nor will we omit, that the Hot Water made use of in this Experiment raised a Thermometer of 50 deg. to 48°. and with the same Heat shortened the Mercurial Cilinder one 146 th' part of the whole Height. And that the Cold Water increased to one 50 th' part, when in the same Water the Thermometer came to 11 deg. ●/2.  
If then a little air be admitted into the Ball D, this because it becomes very thin, by reason of the Dilatation it has in the void space; quickly imbibes Heat or Cold, and by its Rarefaction, or Condensation causes that the Alterations in the Rise, or Fall of the Mercury are much more sensible, and swift.   

An Experiment  
To manifest whether the Air be that which serving as a Foil to the lower Superficies of a Lens of Glass, reflects that second Image inverted more dimly and faintly which we see of a Flame, or any other Object Visible there, 
Astr. Opt.  as Kepler thinks it is.  

Tab. 8. Fig. 2.  ON the Mouth of the Glass Vessel AC we cemented with hard cement a Glass Lens AB: this Mouth had its Lips turned a little outward, and made smooth for the more easy fastening on of the Lens; then filling the Vessel with Mercury, we made the Vacuum; and inclining the Tube we tied it to the Rest, as in the Figure; and having made the Room dark, and bringing a Candle near it, we observed in the Lens, the two Images of the Object, as is usual: one of these was lesser, but very vivid, and always direct; which was reflected from the Convex outward Superficies. The other was indeed larger, but more obscure and languid, and inverted, which nevertheless was not lost, though the imagined foil of air was wanting (on the Concave inward Superficies of the Lens) by reason of the Vacuum made.  
In making this Experiment, we always used to put three or four Finger's depth of Spirit of Wine upon the Mercury, that when the Vessel was Inverted to make the vacuum, the Spirit getting uppermost might wash, and cleanse the Lens from all foulness left there by the Mercury, lest that should give some occasion to imagine it might serve instead of the Foil of Air. But nevertheless (as we said) the Appearance of the Two Images was the very same; and when we permitted the air to fill the void space, it gave not the least Difference.   

An Experiment,  
To know whether Amber, or other Electrick Bodies require the Medium of Air to make them Attract.  
PRepare a Vessel of thick Glass, big enough to stir, and turn the Hand within the upper part thereof AB. Let it have Three Mouths A, C, and DE; let A be open closed▪ C with a Bladder, 
Tab. 8. Fig. 3.  and rest it upon a little bundle of Cotton, or some soft Cushion Floating upon the Mercury in the Basin FG, that so the great weight of Mercury to be poured in may not burst the Ligature, or break the Cane. The Mouth DE made large enough to receive a Man's Hand, must have an Edge, or Lip of Glass round it, about which must be tied very close and fast a large Bladder open each way, as DE, HI, through this the Hand is to be put into the Vessel, with a small piece of the best yellow Amber, having first placed in the Vessel a little light bit of Paper, or Straw where the Amber may readily approach it, when it has been rubbed, and heated upon a piece of cloth K, fixed for that purpose within the Glass: then bind the other side of the Bladder HI, round the wrist, a little above the Pulse, that so the Hand may move freely in the Vessel; and let the place where the Ligature is made, be armed with a ring of Leather bound fast to the skin of the Arm, upon which Ligature the Bladder may be cemented to the Arm, which done, fill by the Mouth A, and the Vessel with Mercury, taking care in filling it, that the Folds and Wrinkles of the Bladder be all filled with Mercury, that as little air be left as is possible; when quite filled, close also the Mouth A with a Bladder, and untying the lower Ligature C, beneath the Stagnant Level FG, let the Mercury fall to make the Vacuum. Then holding the Amber between your Fingers, rub it strongly upon the Cloth K, and present it to the Paper or Straw; and observe whether it attracts it, as it does in the Air.  
Tab. 9 p. 45.  

Tab. 9 Fig. 1.  Yet still desiring some fruit of this Experiment, we thought of making another Vessel, as ABC: persuading ourselves, that therewith we might more easily obviate the inconvenience of the Airs entering, and also the difficulty of moving the Wooden Instrument forward and backward. Wherefore, filling at the Mouth A, this Vessel, having first closed its other Mouth C, and rested it as in the former Experiment upon the Cushion as was directed; we then bound the Bladder ABC about the piece of Wood, 
Tab. 9 Fig. 2.  and thrust it into the Mercury, so as the end thereof, whereto the Amber was fastened, might reach a piece of Cloth stuck to the side of the Glass. Then we threw in some small bits of Straw, and turning down the Bladder, we bound it fast down the Neck A, the Vacuum made, by moving the Wood or handle which stood out we rubbed the Amber upon the Cloth, and when we thought it might be hot, we applied it to several pieces of Straw, which in the Descent of the Mercury stayed to the sides of the Glass; but we could never perceive that any were attracted by the Amber▪  
But Note, that this Experiment is not to be much accounted of, nor the Effect to be Attributed absolutely to the want of Air; for in such a Vessel at least a small quantity always gets admission; nor could we ever so bind the Ligature, but by some unseen ways it deceived us, which it may be happened from the Motion required in this Experiment to heat the Amber; so that we may almost judge it impossible, but the Ligature must be relaxed; at least, so much as is needful to let in the subtle Air. 'Twas observed also, that when the Vessel was full of Air, though we rubbed the Amber with great force upon the piece of Cloth B, yet it had no Attraction; a thing which at first made us suspect that some Dregs of the Mercury adhered to the Cloth, whence the Amber by rubbing might acquire some foulness to close and stop up the imperceptible pores of those passages by which the attractive Virtue issues out; which suspicion seemed more probable, because we already knew some Liquors wherewith the Amber being wetted (or any other Electric substance) refuses to attract. But since we after found, that the same Amber rubbed upon a piece of Cloth often dipped in Mercury, did nevertheless draw with great force, we thought the humidity of the Gum (made use of to fasten it to the Glass, being imbibed by the Cloth) might impede the Effect: we therefore sealed a piece of Chamois instead of Cloth, with Wax to the side of the Glass, that all manner of suspicion of any wet soaked up, might be avoided. Nevertheless, all this diligence was in vain, for whether the Vessel were full, or Empty of Air, the Amber attracted not, which is all we can with truth report of an Experiment attempted so many ways unsuccessfully.   

An Experiment  
Examining what may be the motion of the invisible Effluvia of fire in Vacuo.  
BEing already satisfied by many Experiments, that the heat of Fire is not equally carried every way, but diffuses itself, and has greater Virtue upwards than any other way comparatively: 'Twas imagined, that on the contrary, if it were Experimented in Vacuo, some variation might happen, from whence some probable conjectures might be drawn of the Principles of the Natural Motion of Fire, and that by such an Instrument.  

Tab. 9 Fig. 3. 2 Brac.  Let the Cane AB be about 46 Inches, long into which (being open at A) put a Thermometer of 50 deg. from one end to the other, made flat at that end, where sealed to stand fast at the straight place of the Tube CD; and lest when the Quicksilver comes to be poured in at the Mouth B, this Thermometer should fall upon that placed above, and so by the collision of the Balls, one or both be broken; there may be fastened to the bottom a Thread coming out of the Mouth B, by which it may be stayed when the Cane is turned with the bottom upwards to be filled. The first Thermometer being thus placed, let there be put in another exactly correspondent to it; this enclosing the Mouth of the Tube A, must be fastened there by its sealed end with the same Glass Cement at the fire. The Instrument being fitted, the Mercury must be poured in, and the Vacuum made. Note, that the straight CD, must be above the height of 30 Inches, that the whole Thermometer may be exposed to the Observers view, and not buried in the Quicksilver. When the Cane is fixed, and immovable, apply a great Degree of Heat to the void space, by the help of Two Iron Balls heated red hot, and held at an equal distance from the Cane, but unequal from the Balls of the Thermometers, inclining more to the lowermost, that so the Heat (which is always carried upwards by the Air) may be the more equally distributed to the two Balls of the Thermometers; we having very often repeated this Experiment, yet cannot otherways Affirm, but the upper Thermometer was indeed most affected by the Heat; we confess the difference is very small, in comparison of what we observed in the open Air; for whereas that was sometimes five Degrees in the Vacuum, it never exceeded two. Neither did some think it would be otherwise, because the Air encompassing the two Balls, was more heated in its upper part, and so gave a greater heat to its neighbouring Thermometer.   

An Experiment  
Of the Motion of Smoke in Vacuo.  

Tab. 9 Fig. 4. Pastiglia Nera.  WIthin the Ball of the Vessel AB hang a Pastile of Perfume or other Bitumen of a dark Colour, upon which the Fire has an easy Effect. Then making the vacuum, cast the Rays of the Sun thereon with a Burning-glass, you may presently perceive the Smoke issue from the Cake, which instead of mounting upwards, as it uses to do, as soon as parted from the Ball, or Cake of combustible Matter, descends like the spout of a Fountain in a Parabola: the Air being admitted to move it, it immediately rises to the top of the Ball.  
Many Experiments having been made, that did not require any peculiar Apparatus of Instruments (as most of those hitherto related have) it will be advisable, to avoid tediousness in the Discourse, to give a short Description of an Instrument, and of its capacity, (the size of our Plates being too little to represent it in its full proportion;) and then succinctly Explain what Method we took to menage it most commodiously and easily. That so any who desire to try, and compare the Truth of our Experiments with their own, may be able to do it; at least, till they light upon a more safe and easy way.   


Tab 10 p 49   
The Description of a Vessel made use of in many of the following Experiments.  
THE Vessel than is AB made of Glass, whose M 〈…〉 AC is turned outwards flat. The bigness of the Neck or Mouth is three Fingers, the length of the Neck AD is four Fingers; the Diameter of the Ball DE is about 7 ½ Inches; the height of the Cane ED about 46 Inches. 
⅓ di Brac. 2 Brac.  Close the lower Mouth B with a Bladder, and set it upon a little Leather Cushion, swimming upon the Mercury in the Basin, (Tab 10. Fig. 2.) then fill it at the Mouth AC; but because in filling it, the Mercury falling directly upon the Tube, will intercept and detain a great quantity of Air therein; The small Funnel ABC (Tab. 10. Fig. 3.) was made to prevent it, being of equal length with the Vessel: keeping the Body of this AB always full of Mercury, there can no air get into the Shank BC: so the Mercury falling gently into the Vessel, raises the Air before it quietly. When filled, we cover the Mouth AC with a Glass Cover a little Convex (Fig. 4.) and then with a Bladder bound fast about with a waxed Thread below in the small of the Neck. Put then your hands under the Ball on each side; and gently lifting it up, take away the Cushion, and Immerse the Mouth B into the Stagnant Mercury in the Basin: loosen the Knot of the Ligature at B, and the Mercury by its weight falling, will open it, and make a Vacuum.  
When there is occasion to put such things in the Ball as may not be covered with Mercury, either to avoid mixing therewith, as Liquors; (which we put in the Vessel A, Fig. 5.) or to prevent their being stifled therein, as Animals; we then use to leave so much Air in the Neck of the great Vessel AD, (Fig. 1.) as may serve to receive this little Vessel, or the Animal we would include therein. This Air when the Vacuum is made, dilating itself to so large bounds as the capacity of the Ball will be so extremely rarified, as if almost it were not there at all, that in reality, it will be no impediment to any of the Effects desired to be observed.  
But when we would enclose Fish therein, we leave no air, nor do we fill the whole Ball with Mercury, but pour in so much Water, as when the vacuum, is made, and the Mercury sunk down into the Cilinder, the Water swimming thereon may fill about half the Ball, that the Fishes may move, and bear themselves thereon.  
When we had a mind to put small Animals therein, as little Lizards, 
Lucertole. Mignatte Fig. 6.  or Horseleeches, or the like, we shut up with them a little Ball of Solid Glass, which following the Mercury in making the Vacuum stops the Mouth of the Cane E, and keeps the Animals in the Ball to be more commodiously observed.  
All these Advertisements may perhaps seem superfluous to some; but those who are conversant in Experiments, and know the difficulties they often meet with in making them, through the impediments and inconveniencies of a material Apparatus, will rather approve of, than slight these niceties, it being almost incredible to tell their use, and how great an expense of time may be saved by them.   

An Experiment  
Of Sounds in Vacuo.  

Tab. 9 Fig. 4.  HHaving hung a small Bell by the thread, instead of the combustible Ball in the former Experiment, and making the vacuum, we began to shake the Ball forcibly, and the Bell gave the same Tone as if the Ball had been full of common Air; or if there was any Difference it was too little to be perceived; indeed, in this Experiment the sonorous Instrument (though the thing is impracticable) ought to have no communication with the Vessel, otherwise we cannot certainly affirm, whether the Sound proceeds from the Rarified air, and Effluvia of the Mercury in Vacuo, or from the Vibration communicated by means of the Thread from the percussion of the Metal to the Glass, and so to the External air encompassing it.  
Nevertheless, we thought of making this Experiment with a Wind Instrument, because it receives its trembling, not from Percussion as a Bell, but from the Impetus of the Air rushing out of it. And because it might be too hard a Task, if not impossible, to place such an Instrument in a Vacuum made with Mercury, we resolved to enclose it in a Vessel exhausted of its air by Attraction, so as it has been lately practised by Mr. Boil, with admirable success, in those his curious and noble Experiments; among which, this was thought of also, though it was not put in Practice for want of a fit Artificer to make the Apparatus. Now though the Vessel can never be emptied so perfectly by that way, as by Mercury; yet the air is always so far Rarified, as from the manifest difference which appears in those Effects that depend really upon the ordinary Natural Pressure of the Air upon them, we may easily come to form a right Judgement what they would be in a perfect Vacuum. We will here truly relate, what we happened to observe; confessing, that it is more to show the manner and Method we thought of to make the Experiment, than for any certainty we were able to gain thereby: since it may be said, we rather failed, than made the Experiment.  
For this purpose we made a little Organ, 
Tab. 10. Fig. 7.  as ABCD of but one Pipe, and with the Bellows having Communication with the Pipe by an hollow Conveyance in the Basis BC. This Organ we included in the Brass Box F, 
Fig. 8.  and put the handle HI through the Mouth G of this Box. This handle we rested upon the Pillar, or Prop KL, when we had first put it through the Ring M, sodered to a small Iron Rod passing each way through the boards of the Bellows, and fastened to them, so that by moving the handle this way, and that way, either the one, or the other was opened and shut, forcing the air into the Pipe. Then taking a Piece of soft Leather, and making an hole in it, we put it over the Handle, binding it fast upon the Mouth G, and likewise gathering it together, we tied it about the Handle (as in the Fig.) so that all Ingress of the air might be prevented; and through the pliantness of the Leather, the handle easily moved every way. All being so prepared, and the Cover E Cemented on very close; we began to exhaust the air out of the Box with a Pump screwed on to a Hole in the Cover N, 
Tab. 10. Fig. 9  and at every Draught turning the Stop-cock O, that when the sucker was forced down to drive out the attracted air at the valve, and Nose P, the air might not re-enter into the Box F, and frustrate the Labour of the Operator. After many draughts, that the air became so rerified, as the Leather which closed the Mouth G was quite drawn in, and the Force of a very strong Man was unable to draw back the Sucker, or Plug; we began to move this way, and that way, the Handle so to convey the Subtle air out of the Bellows, into the Organ-pipe, and listened to the Sound. But the Truth is, we could not perceive it to differ at all (not only) from that which was made in the same Box, when shut up full of air in its natural state, but (also) not sensibly from that made in the Box, when we had, by the Pump forced and condensed a great quantity of air therein: Wherefore (some did say jestingly, either that) the air has nothing to do in the Production of Sounds, or is able to do it alike in any state.   

An Experiment,  
Of the Operation of the Magnet in Vacuo.  
HAnging a Needle by the Thread by which the Bell was fastened before, 
Tab. 9 Fig. 4.  we applied a Magnet to the outside of the Ball, and found it was attracted at the same distance as when the Vessel was full of air.   

An Experiment  
Of the raising of Fluids in small hollow Canes in Vacuo.  
AMongst other Effects of the Airs Pressure, some have reckoned that of almost all Fluids rising up in small Canes therein immersed; believing, that the small Cilinder of air pressing through the little Cane upon (any fluid suppose) the Water, acts more faintly, by reason 'tis lessened or straitened by the great Adhaesion of the Fluid to the inside of so small a Vessel: as on the contrary they judge, that the air which freely presses upon the large Superficies of the Fluid round the outside of the same Cane, being permitted to bear upon it with its whole force; raises it therein, until the Momentum of the Water raised, together with that little Pressure within the Cane, counterpoise that of the external air. To have some light as to the Truth of this Discourse, we attempted to see what the Effect would be in Vacuo.  
We therefore prepared the former Ball as was directed for Fish, (Tab. 10. Fig. 1.) that is, by filling the upper half with Water, 
Tab. 11. Fig. 1.  into this we immersed the small Cane AB (represented in the Table of its full bigness) which was open at each end, and had Cemented upon it in the middle an hollow Button of Glass, counterpoised to keep the Cane upright in the Water; 
Tab. 10. Fig. 1.  Then closing the Mouth of our large Ball AC, we made the Vacuum, the Water standing to the midst of the Ball: 
Tab. 11. Fig. 1. Tab. 10. Fig. 1.  and the small Cane stood Erect, by reason of its hollow Button, and the Water rose in it up to C; then the lower Mouth being stopped with a Finger, that the air entering might not empty our larger Vessel, we unbound it above, and opened the Mouth AC, to see if (the air being admitted to press upon the Water) that greater and more violent impulse would cause any alteration in the Level C of the small immersed Cane; but it did not.  
After this Experiment, 'twas yet doubted, that the wet received by the whole Internal Superficies of the little Cane, when quite Immersed in the Water, before the Vacuum was made, 
Tab. 11. Fig. 1.  might serve like Glue to detain the small Cilinder of Water CD whereto it might be kept by Adhesion also, as well as it was before by the force of the External Pressure: wherefore it was resolved, first to rarify the air in the Vessel which we intended to try the Experiment in; that the first Immersion of the Cane might be made with the air already dilated, and rarified, and with the inside of the Cane dry, that there might be nothing in it to raise more Water than that which the weak Pressure of that thin air was able to do: and that afterwards reducing the air to its natural state, and then Artificially compressing it; it was thought we might discover some observable variation in the height of the Water contained in the Cane.  
Tab. 1. p. 54.  
There was also made another Experiment, which was this; Within the Ball so often made use of, we placed the Syphon ABCD, so hung, that when the vacuum was made, 
Tab. 11. Fig. 3.  it might remain upright in the midst of the Ball, and full of Mercury; we then observed, to what Degree the Mercury rose in the smaller Leg AB, and then upon admission of the air could observe no alteration. This Experiment was often repeated, always with the same success.  
Lastly, They that took the raising of Fluids to a determinate height, to be an undoubted Effect of the Airs Pressure, were desirous to see, if the air (which presses upon the Stagnant Level) when forced to pass through the hole of a very small Cane, and must necessarily do so to exert any Pressure, comes thereby to be so weakened and lessened, that any observable alteration follows in the height of the Fluid so pressed: which they thought would probably happen; because if one Momentum were weakened, the other must certainly preponderate, and so alter the first Aequilibrium.  
To this End, there was taken the Cane ABCD, whose height AB was 46 Inches, and the Return BC 11 ½ Inches, 
Tab. 11. Fig. 4. 2 Brac. ½ di Br.  drawn to a greater Degree of smallness than is represented in the Figure: this being open at A, and D, was filled with Mercury at the Mouth A, till it came to D, the Mouth of the Return which we then sealed at the Flame of a Candle, and completed the filling of the Cane to A, and tied it over fast with a Bladder; then we broke off the End D, and the Mercury began to run out very slowly, contrary to what we have observed, when the air pursued it at the other end; whereas, instead of air, the Cane had now a vacuity, which increased gradually from A, so that the Mercury was no otherwise forced out, but by the weight of that which was above 28 6/10, 
1 Brac. ¼  reckoning from C towards A: and it immediately stopped when it came to F the very same height above C, as the Mercury was off in another Tube immersed in a large Vessel at the same time. After this, holding the Cane Perpendicular to the Horizon, by lifting it gently up and down, we caused a Motion in the Mercury, so that by the Vibration of it backward and forward, in the two Arms of the Vessel, there ran out at each Vibration a little Mercury at the Beak D; so that when the Cane and Mercury were at rest, there remained a small part of the little Cane, empty of Mercury GCD. So the Air pressing upon G, though strained through so narrow a passage as D, yet had not lost so much of its force, as to cause any sensible abatement of the Height of the Cilinder F C.  
From all these Experiments, and some other of a like Nature, which we have now no time to relate, some thought they saw good grounds to Affirm, that That Opinion of a more Languid Pressure made by the air through so narrow conveyances, taken absolutely so, is not sufficient to produce this, and the like Effects; but they believed, That there must be at least allowed some other concurrent Cause.   

An Experiment  
Of Water in Vacuo.  
THat Noble Observation of Mr. Boils, of the boiling of warm Water in Vacuo, made us above measure curious, not only to see so rare, and surprising an Effect, but also gave us an hint, and desire to try the same Experiment with simple water, and also with Water brought to as great a Degree of Cold, as it is capable of; without Freezing.  
There was put into the Vessel (represented by Fig. 5. Tab. 10.) a quantity of natural water, unaltered from its ordinary temperament: in this, after the Vacuum was made, there appeared a shower of small drops, which though they were in great Plenty, yet came very slow, and the Water lost nothing of its Transparency: their Motion was upwards, till the Shower gradually ceasing, the Water became sedate, and quiet as at First.  
The warm Water, as soon as ever the Vacuum was made began violently to boil up toward the top of the Vessel, with a noise not unlike that made by a Cauldron boiling very fast; but upon opening the Ball, and taking out the included Vessel, we could not observe any heat acquired by this Ebullition.  
The chilled water threw up four, or five small Bubbles, and then rested, without any other sensible Change, or Alteration.  
Note, that upon the admission of the Air, the shower of small Drops ceased immediately in that Water of a natural Temperament; as likewise the boiling of the warm water.   

An Experiment,  
Of Snow in Vacuo.  
AT first we put in a small piece of Snow, of which upon the fall of the Mercury there scarce appeared other than the melted Water. This so hasty dissolution thereof seemed strange to us; wherefore to make the Experiment more clear, we repeated it with a larger piece made somewhat Cilindrical, as long, and big as could be put into the Ball: which being filled with Mercury, we thrust the Cilinder of Snow into it. But slipping out of his hand that immersed it, and so swimming upon the Mercury, we might perceive that in the very act of Immersion, the Mercury had preyed upon, and eaten off a good part thereof; and the dissolved Water swum upon the Mercury. So we concluded, that it was the Mercury which melted the first small piece of Snow so suddenly, and not the Vacuum, as at the first view it seemed to be; wherefore putting the Snow in again, closing the Vessel, and making the Vacuum, the little that remained, was as slow in Dissolving, as it used to be in the air.  
This Experiment was made in the Summer, so that the Snow was not in Flakes (Solla, we call the Snow at Florence, when it falls like Down, before it is frozen together;) but some of that taken out of the Conservatory where it was trodden down, and pressed together.   

An Experiment  
Of the Dissolution of Pearl, and Coral in Vacuo.  
THis Experiment we owe likewise to Mr. Boil, which was after this manner.  
Pearls, and Coral (as is well known) are dissolved in Vinegar. Tho this Action proceeds very slowly in the open air, and consists in the curious discharging of very small Bubbles, which rise from Bodies of the Pearl, and Coral themselves: yet they do not Rise so thick, as to hinder the Transparency of the Vinegar; especially, from the Coral, which if not finely powdered, is much slower in Dissolving: but Pearls being softer, afford a greater plenty of Bubbles. We desired to see each of them severally in Vacuo; and observed so great a quantity of Bubbles to arise from each; that the Vinegar was raised all in froth, and run over the Vessel, which therefore showed as if it had been full of Milk, or pure Snow: Then we gave admission to the Air, whereby the froth was immediately sunk, and the Vinegar with its Natural Transparency began to act as before.  
We will not omit here an Effect accidentally observed in this Dissolution, which was this: The Pearls when they sink to the bottom, gather into one, or more little bubbles of Air, which naturally rising up, carry the Pearl with them: but as soon as ever the Bubbles rise above the Vinegar, and by the chock of the Air break, their Covering is curiously scattered about. Then the Pearl sink down again, and at the same time other parts thereof gathering into new Bubbles, raise themselves. And so all the while the Ebullition, or Fermentation lasts, there is a continual Motion of them up and down through the Vinegar.    

A RELATION OF VARIOUS ACCIDENTS, Observable in some ANIMALS Included in Vacuo.  
FRom the very time Torricelli found out his First Experiment of Mercury, he had thoughts of including several Animals in the void space, to make Remarks upon their Motion, Flight, Breathing, and all other observable Accidents: But not being then provided with fit Instruments for this purpose, he was contented to perform what he was able to do: for small, and tender Animals oppressed by the Mercury, under which of necessity they must lie, to be at the top of the Vessel when inverted and immersed in the Stagnant Mercury, would be most commonly dead, or expiring; so that it would be hard to determine, whether they had received more damage from the Suffocation of the Mercury, or from the want of Air. And either for this cause he forbore, or was deterred from attempting the Experiment in an open Vessel, misdoubting the sufficiency of the Ligature to sustain the air, bearing thereon with its whole Weight: and besides, he was diverted soon after this Invention by other Employments which wholly took him up, that he had no time to apply himself to this, and give it a greater perfection, which it is probable he would have done, if a too hasty Death had not prevented him. But we being satisfied, that the force of the Air was not so great that the Cement, and a Bladder well tied down, was unable to withstand it; have always successfully made use of a Vessel open at both ends, as already hath been shown, and as we have also done in these. Wherefore, we will now proceed to give an account of the Accidents observed in divers Animals included in this Vessel; as follows.  

Mignatta  An Horseleech being kept in vacuo above an hour remained alive, and well; freely moving herself, as if she had been in the Air.  

Lumaca.  The same did a Snail; in both these, though deprived of the Air we could observe nothing to argue it had any Effect upon them.  

Grilli.  Two Grass hoppers were for a quarter of an hour very lively, continually moving up, and down, but not leaping: upon the admission of the air they leapt away.  

Farfalla.  A Butterfly, whether hurt by the hand in putting it into the Vessel, or whether it suffered from the want of air, 'tis certain, that as soon as the vacuum was made, she was quite deprived of Motion, except a scarce discernible, and languid Tremour in her Wings, which upon the Ingress of the air shaken very much; but we could not discover well, whether the Animal itself, or the Motion of the air caused it; but upon taking out of the Vessel, we found it dead.  

Moscone.  There are a sort of Fly's larger than ordinary, commonly called Moscone in Italian, that make a great Buzzing through the air with their Wings: one of these (which being shut up in the Vessel, continued to buzz very vigorously) as soon as ever the vacuum was made, fell down as if it had been dead: and the noise of its wings ceased; we presently gave it air, whereupon it moved a little, but the Remedy was too late; for it was scarce taken out before it died.  

Lucertola  A Lizard in vacuo quickly grew sick, and soon after closing her Eyes, seemed to be dead: but we agreed afterward, that we observed some Respiration, perceiving a little swelling in the Thorax, between the Forelegs: we continued the Confinement for the space of six Minutes, in which time it had lost all breathing, and appeared Dead: we then admitted the air, which so recovered it, that presently the Vessel being opened, she leapt out, and ran away; catching it again, we included it the second time, and she appeared sick, as before; but the air revived her again: we Imprisoned her the Third time, and in Ten Minutes after some strainings, as if poisoned, she vomited, and fell down quite dead in the Glass.  
Another little Lizard in less time suffered the same strainings, or Convulsions; and then had a little Rest, and as if she had taken breath, and gotten strength thereby, she endeavoured several times to creep up the sides of the Vessel; when the same Convulsions returned with strange Distortions of the Mouth, and swelling of the Eyes, as if they would have started out of her Head; she turned upon her Back, and after a little gaping for breath, died. It was after observed, that she had discharged something by the Mouth, and Anus; whence the Belly became flaccid and empty.  
Another beginning to suffer the same torments, had immediate Relief from the Air.  

Uccelletto.  A small Bird, as soon as the vacuum was made, began to gape, and pant for breath; and shaking its Head, hung down its Wings, and Tail; after half a Minute, when it seemed almost dead, we gave it air, and so at first it seemed to revive, but in few moments shutting the Eyes, it died.  

Calderugio.  A Goldfinch, and after that another, though presently succoured with the air, yet found it too late. So sudden is the irreparable hurt these tender Animals receive from the privation thereof.  

Allodola.  The almost Instantaneous Death of these Birds, may at first view seem to contradict an Experiment of Mr. Boyles, wherein he mentions a Larks living in the Evacuated Receiver, though one of its Wings was hurt, about Ten Minutes. 
Passera.  And a Sparrow taken with Bird-lime endured for Seven Minutes; at the end of which, seeming dead, she was recovered with the fresh air: and being again included, and the Vessel Evacuated, in the space of Five Minutes died. But whoever Reflects upon the different ways of making the Vacuum in the one, and the other Instrument, will confess that the two Experiments, how different soever they seem; do indeed wonderfully agree: for whereas in that, the air is thinned by repeated Attractions, and slow, and little more than insensible acquists at each draught: in our Instrument, 'tis reduced to the greatest degree of Rarity by the Instantaneous fall of the Mercury; to which, when the air is brought, 'tis no longer serviceable to their Respiration. And if (when we had included the Animals) we inclined the upper Mouth of our Vessel below the perpendicular Height of 28 6/10 Inches reckoned from the Level of the Stagnant Mercury in the Basin, 
1 Brac. ¼  and opening the lower Mouth, we gradually raised it by little, and little to an upright; we have observed the very same Effects, related by Mr. boil; the air then of necessity passing through all the intermediate degrees of Rarefaction, from a greater to a greater (as it does in Evacuating his Receiver) is not so soon rendered useless to the Respiration of these Animals.  

Granchio. Tenero.  A soft Crab at first putting in, moved; then grew feeble, and began to faint away; when he had stood a little while motionless, or rather with all his Members contracted, we gave him air, whereat he seemed revived, and began to move slowly; but taken out of the Vessel, soon died.  

Ranocchio.  A Frog was presently giddy, and notably swelled all over; but when the fresh air came in, with a sudden leap, he showed himself recovered.  

Granchio duro.  We enclosed at another time, in the same Vessel, an hard Crab, and a Frog together, the Crab seemed to move, till the end of the Experiment, which was a full half hour without any, alteration, except perhaps a little swelling.  

Ranocchio.  The Frog in ten Minutes was unmeasurably puffed up in every part, and two great Bladders appeared on the sides of his Jaws, and vomiting up a great quantity of froth at his Mouth (which stood wide open, filled with his Tongue, and all the membranes disformedly swelled, and blown up) in this posture he remained Motionless: at the entrance of the air the swellings fell at once, and he appeared quite changed, being extreme lank, and thin; so that we thought him much less than when he was first put into the Vessel; when we took him out, he was Dead. The Crab as we said before, was alive, but in few Minutes died.  
Another Frog, much swelled as the former, cast up a great deal of Froth, and other things at the Mouth: and in half an hour was found quite dead. At the Entrance of the air he appeared shrunk up, and lank as the other. The Thorax was opened by an Accurate Anaetomist, who at first could not find the Lungs, they were so shrunk up together for want of the air: but by blowing with a Straw in at the Ductus by which they breathe under their Tongue, (they were redistended; whence it was visible, the most part of the air which was contained in the Animal when first included, was got out to enjoy a larger Field in the Evacuated space, without tearing, or hurting any of the Vessels; for upon blowing they were all tied, and swollen up.  

Pescett●.  Several small Fishes which were very lively, were included with a sufficient quantity of Water; and as soon as the vacuum was made, they were remarkably swelled, and fainting turned up their Bellies. They endeavoured several times to keep their backs upwards; but they still turned again: when the Vessel was opened, they sunk to the bottom, where unable to recover, they died. We presently Dissected one of them, and compared it with another taken alive, which had not been in a vacuum; and examining the Entrails, we found the little air Bladder empty in this; whereas in the other, it was round and full, as is usual in all Fish.  

Barbio.  In a pretty large Barbel the Eyes were much swelled; the Fish turned on his back, stretching out the Finns, as if they had been stiff and frozen, with the Gills opened wide, and the whole Body distended with wind, and so it lay at the top of the water. It attempted by several jerks to turn to its natural Posture, but in vain▪ After six Minutes, upon the return of the air, the swelling of the Eyes assuaged; and though the Thorax returned to its due proportion, yet it was forced to keep at the bottom continually gaping, and unable to raise itself in the Water; and being put into fresh, it soon died: being opened, we found the Bladder all shrunken, when that of another Fish (dissected alive, though five times less than this) was yet much larger, and turgid.  

Anguilla.  An Eel stayed a long time without fainting, or any diminution of its vivacity: but at last in an hour that died also; and being opened, the bladder was empty, as they of the other Fish were.  

Barbio.  Another Barbel having been in vacuo, and refreshed again with the air; by great chance was taken out alive: wherefore we gave him his liberty in a Cistern where others were kept, 
1 Brac. ½  being above 34 Inches deep. This Fish, whether it was easier for him, or whether he was necessitated so to do by the emptiness of his bladder; 'tis certain, for the whole time he lived, which was about a Month, (although we chased him about, and frighted him, by stirring the Water) he was never seen to raise himself, as the other Fishes did; but still left a Mark behind him on the bottom, sweeping it with his belly: his bladder, when dead, to sight was swelled with Wind as it is Naturally, but was very much softer to the touch, than those of other Fish are.  

Observations upon the Bladders of Fish in Vacuo.  
THe Bladder of a great Fish swelled with Wind, as it was taken out, being put in vacuo, showed no alteration there: wherefore we opened the Vessel, believing that nothing else could vary the Experiment, except the Coats of the bladder were of too strong a Texture to be burst by the force of the air Naturally included therein: but upon the first Ingress of the Air, the Bladder appeared neither more nor less full than we had observed it in Fish killed in vacuo; a clear sign, that the greater part of the Air in the bladder, by forcing, or taring the Swim, gets out through some invisible Passages; and any little Portion that remains, by the increase which it receives in vacuo, serves to keep the bladder distended as at first.  
Then being desirous to find, where the air gets out of these Bladders, if by any Ductus naturally there, or made by the force of the air; we took, with the greatest care possible, the bladder out of another Fish, and tied the two Ends with a Silk, supposing, if there were any passage, 
Tab. 11. Fig. 6.  it must be at one of them: this in vacuo appeared full, as the other had done; but upon the Ingress of the air, it shrunk up after the same manner: wherefore, to find the Passage where the included air breaks away, we made a small hole, to put in a little Glass Cane, and bound the bladder fast about it, (the extremities being yet tied) and blue Wind into it through the Cane; which being in great plenty, swelled the bladder; but at the same time, we perceived it got out of a small crack at A, (which must be that, where the air in vacuo found a vent) to which, holding a lighted candle, we might perceive the flame to wave; and viewing it attentively, when distended, it was not so small, but it might be discerned with the naked Eye.  
Having thus found, that the air did not get out at the Ligatures made, whilst to free itself, it was forced to make a new crack, we had a mind to see if it gets out after the same manner in the bodies of Fishes killed in vacuo; that is, by breaking the thin Membrane of the bladder, or by finding some hidden passage: 
Tab. 11. Fig. 7. Lasca.  wherefore taking carefully the bladder out of a Roach that died in vacuo, we made a hole in the smaller end, and put a cane in, as before, and blew very strongly, but it held tied: an evident proof, that the air without breaking it, has some vent, which the weakness of our Eyes could not discover.  
We than thought of making the Experiment under Water, which perhaps might detect something to us: 
Tab. 11. Fig. 8.  so we took the bladder out of the Fish alive, and well tying it in a Net, fastened a convenient weight, and sunk it in water, and then made the vacuum, when we might see many small bubbles of air issue from the slender part thereof; where 'tis probable, the Natural Meatus is, which transmits' it; when the Vessel was opened, the air shrunk it like the other.  
Lastly, willing to see what way the air takes from the bladder to get out of the Fish's Body, whether by the Gills, 
Lasca.  or Mouth; we covered a Roach with the same Net, that by affixing a Weight it might be kept under water; the vacuum being made, we saw a great deal of air come out of his Mouth in large bubbles, as before from the submersed bladder.  
Here should have been the End of these Experiments; but while these Sheets were in the Press; one of our Academy having thought of a way to facilitate very much the management of our Vessel to make the vacuum, we will not omit to set it down here; and the rather, because we found it indeed very convenient. The Invention consists in joining to the Cane BE (Tab. 10. Fig. 1.) the Retum BFG (designed in the Figure by the Pricked Line) for putting as usual the Mercury in at the Mouth AC, when it comes up to G; in the Return, we tie it down close, and fill it up to AC, where being closed after the usual manner, it is sufficient to open the Mouth G, and without any immersion, 
● Br. 2/4  all the Mercury above 28 6/10 Inches taken from G towards E, runs out: and Note, that the Ball FG serves to keep in the Mercury in the fluctuating Motions it makes in the Two Branches of the Cane, (before it rests) caused by the impetus of its fall.  
This is all at present touching the Natural Pressure of the Air, and its Various Effects.    

EXPERIMENTS OF Artificial Freezing.  
AMong the rest of the stupendious Works of Nature, that admirable Power has been always much regarded, whereby she binds the slippery Waves, changing their fleeting Inconstancy into Solidity and hardness. This Effect, though daily before our Eyes, in comparison of others more secret and rare; yet has continually afforded Ample Subjects of Curious Speculation to the Mind of Man: for, whereas Fire, when disengaged in swiftly winged sparks, by insinuating itself through the close Pores of Flinty and Metalline Bodies; opens, melts, and reduces them to a perfect Fluid: so Cold on the contrary (a much stranger thing) stops and consolidates the most Fluid Liquors, changing them into downy Snow, and glassy Ice; which upon the least Ray, or warm breath, break Prison, and steal away in their first fluidity again. And (which is yet more amazing) so violent a force of Cold in Freezing, is observed penetrating not only Glass, but even the secret Pores of Metals. As in the Subterranean Caverns, and deep Mines, the Raging Flames impetuously divide, and in fury open all those dark Passages; so Cold in the Act of Freezing, cracks shut Vessels of thick and strong Glass; stretches, distends, and at last, tears those of pure Gold, and bursts asunder those of Cast Brass; and of such thickness, as to break them by dead weight would require perchance, nay assuredly, some Thousand weight: upon this strange Phenomenon of Freezing, observable in water more than any other Fluid: Some have thought, that where the Cold operates in its proper Laboratory with fit materials, it reduces the pure Water to such a temperament, that it turns it into even the hardest Rock-Cristal, and Gems of various Colours, according to the different Tinctures received from the neighbouring Mineral steams; nay, even into the Invincible hardness of the Diamond. And Plato was of this Opinion, That Diamonds were Generated of the remains of those Waters whence in the secret Caverns of the Earth he thought Gold was produced; and therefore a Diamond is called, the offspring of Gold, by that Divine Philosopher in Timaeo.  
But to return to the Causes of Freezing. The ingenious in all times have had various Sentiments thereof: whether it does indeed come from any real and proper body of cold (which in the Schools they call Positive) that (as Light, and Heat are Originally in the Sun) is either in the Air, or Water, or Ice itself; or any other part of the Universe as its proper place, and Residence, where it has its Repository and Treasury; 
Job 38. ver. 22.  in which sense the Words of the Divine Oracle in Sacred Writ may be taken. Hast thou entered into the Treasures of the Snow, or hast thou seen the Treasures of the Hail? Or whether Cold is nothing else but a Total Privation, or driving away of Heat. Touching this, and other curious Observations of the Artifice used by Nature in Freezing (whether she Achieves her End by Contracting, or Rarefying the Fluid; whether the Change proceeds slowly, or instantaneously, etc.) we were induced to try several Experiments of Artificial Freezing, made by the outward application of Ice, and Salt; fully persuaded, that the operation does not at all vary from the procedure of Nature, when by the pure and simple cold of the Air she Congeals Water.  
What hitherto we have had the good luck to observe, upon so vast and boundless a Subject, capable of so great and endless Observations, will be offered to you in the following Experiments.  

Experiments  
To know, if Water dilates itself in Freezing.  
IT was the thoughts of Galileo, That Ice was rather Water Rarefied, than condensed; because, (says he) Condensation consists in Diminution of Bulk, but increase of weight; and Rarefaction in the increase of Lightness and Bulk too; but water in freezing gains in Bulk, and Ice is lighter than Water, since it swims thereon, etc.  
This being supposed, (which Experience will sufficiently prove) we were curious to see what water would do when confined in a Vessel where it had not the least room to dilate, yet on all sides being encompassed with Ice to freeze it; since we still observed (agreeable to Galileo) that water as well frozen into great Mountains of Ice, as in the smallest pieces, and of what Figure soever, continually swims upon the Surface of other Water; a certain proof, that in the act of freezing, (the increasing of the Bulk considered,) it grows lighter; whether it be by the interposition of small and insensible vacuities, or interspersion of Minute Particles of air, or the like matter, after the manner of little blebs in Crystal, and Glass, (for such they appear to the Eye through the body of the Ice when held up against the Light) in some places thicker, in others fewer; and if the Ice be broke into small pieces under Water, they rise up through the Water in great Numbers.  

The First Experiment.  

Tab. 12. Fig. 1.  TAking a Vessel of thin Silver Plate, with Two Covers to screw on, such as we use to cool our Sherbet, and other Drinks in Summer; we filled it with fair water cooled with Ice, and then set it to freeze: it was cooled first, lest if it had been put into the Vessel at all rarefied by Heat, upon the first Refrigerating it should Contract, and by that means gain room to Dilate in afterwards in freezing. When 'twas thought the Ice outwardly applied, had done its work, we took the Vessel out, and opening the first Cover (which was Concave) we found the second Cover cracked, and covered over with a thin cake of Ice, caused by the Water forced thither, by the Rarefying of that within the Vessel as it froze.  
Neither can it be thought, that this crack was caused rather by condensation of the water in freezing; which being constrained by the violent force of the cold, to withdraw itself into a less space, for the avoiding a Vacuum, gradually drew down the Cover as it retired, till at last, unable to stretch any farther, it cracked. I say, this is improbable; for if so, we should have found the Cover bend inwards, whereas it was forced outwards, and considerably raised from the flatness it had before, as was also the Superficies of the Ice in the Vessel; moreover, the Edges of the Crack turned outwards: whence we gather, how great the Impetus must necessarily be, that caused it; and would have been much more considerable, if a larger proportion of water had been congealed; whereas, breaking the first Cake, we found almost all the Water Fluid.  
Tab. 12. p. 72.   

The Second Experiment.  

Tab. 12. Fig. 2.  FInding that the force of freezing far surpassed the Resistance of this our First Instrument; we thought of making a Ball of Cast Silver of the thickness of a Crown piece, 
1 Piastra  and of an Oval Figure, to open in the middle with a screw, and with a Top screwed on at the End of the Neck, as in the Figure: Then shutting this Vessel, and screwing fast the middle screw with a Vice, we filled it with Water at the Neck, and screwed on the little Cover, and set it in a mixture of Salt and Ice to Frieze, and in a little while taking it out, we found it perfectly sound, and whole; opening it in the middle, we took out a shell of Ice, but it was very tender, and less Transparent than usual; and perchance more dense and close; for being put in Water, it did not seem to buoy up so well, but rather (as all thought) dived towards the bottom: in the midst was a Cavity as big as a large Almond without the Shell. This Experiment was repeated after by us, with the same success.   

The Third Experiment.  
THere were some that wondered at this unexpected accident, seeming at first view to contradict, not only the Opinion of Galileo, but what is more, to be inconsistent with itself; seeing though this Ice appeared Condensed, and heavy, in respect of that made by the cold of the air without any art; yet it must necessarily be lighter than Water, because it in some measure still swum thereon: and so much the less could they satisfy themselves, as they saw the vacuity always in the middle of the Water Congealed: whence it seemed necessary to conclude, That the Water, which fluid, sufficed to fill the Ball; being frozen, withdrew itself into so much a less space as the aforementioned vacuity; from so manifest an inconvenience, they were inclinable to think, there must be some fallacy, and therefore set themselves to observe very nicely the whole progress of the Experiment; So taking the Vessel very often out of the freezing mixture, and carefully viewing it on all sides, they perceived an almost insensible boiling, and bubbling out at the middle Screw, from time to time; a manifest sign, that the Water (so great is the force of its rarefaction) crept through the Spiral Passages of the Screw; upon this, the Screw being waxed, and the Ball again filled, it was set in the Ice and Salt to freeze; and though 'twas many times taken out, there was never observed any bubbling, or any hissing heard as before; but after the freezing was done, upon taking it out of the mixture, the Vessel was open on one side of the middle Screw, the rarefying power of freezing being great enough to force the Screw; The Experiment being often repeated, had still the same Effect; and being again tried in a Ball of Brass with a Screw of twice as many threads as the silver one had, it still showed the same trick.   

The Fourth Experiment.  

Tab. 12. Fig. 5. & 6.  TO avoid this inconvenience of the Screws, we got some Balls made of glass half a finger thick, and filling them with Water, set them to freeze, being first sealed at the Flame of a Candle: The Effect was exactly the same as that of the first Vessel made of Plate; for they all were diversely broken, and split: some had their Necks quite thrown off; others through the unequal thickness of the glass, or irregularity of their Figure, 
Fig. 5. Fig. 6.  were burst on one side; others were 
Tab. 13. p. 75.  cracked all over. And 'twas observable, that the Neck was generally broken off; when the whole ball was covered in the mixture of Ice, and Salt, so that the Water in the Neck being of the least bulk, 'twas first frozen Solid there, and by that means stopped, and forced the Ball: for in the procedure of the freezing, the remaining Water endeavouring every way, and either finding the neck the weakest part, or the Ice therein being as a Cone, or Wedge to split it, it still most easily broke through there; which never happened when the upper part of the Ball was left uncovered with the freezing mixture. How great the force of this Rarefaction was, may be gathered from this; that when the Necks were not turned downwards, upon the Vessels bursting they flew off into the air, five, or six feet high, throwing up a great deal of the Ice, with which the Balls were covered.   

The Fifth Experiment.  

Ottone 2 Piastre  AT last we resolved to cast a Ball of Brass all of one piece about Two Crowns thick, having but one Mouth at the foot thereof, 
Tab. 13. Fig. 1.  so made as to be very close shut with an exquisite Screw. Then to take the Lump of Ice out whole, we made a small crease round it, where by putting it again in the Lare, it might be cut in two in the midst, which showed a strange accident in the Water; for this small inequality, as little as it was, made the Ball burst in that place.  
Whereupon we made another Ball, and without weakening it in any part, set it to freeze; but this was broken, as all the other (for we tried it often) in that place which the water found most defective.   

The Sixth Experiment.  

Tab. 13. Fig. 2.  THE Last Experiment was made with a ball of fine Gold of the size represented in the Figure: this having undergone many freezings without any visible crack, caused at first no little wonder: and some began to doubt, whether, or no, the space requisite for the freezing by the Diminution of the Thickness of the Metal, by the force of the Water, and by reason of its softness, might insensibly be compressed, (as Tin, Silver, and Gold itself, become more compact by being hammered:) but at last observing, that whereas the Ball before freezing, was flatted so, that it would stand upon the bottom; when it was taken out of the freezing mixture, it would not stand upright; every one was well satisfied whence this happened: and because it seemed to us perfectly Spherical, to be the better assured thereof, whether it would remain of its first Size (if it did not burst in repeating the Experiment) or whether it would stretch bigger; 
Ottone.  we made a Ring of Brass exactly fitted to the Vessels greatest Circle. All along in the freezing, by examining it with this Ring, we still found it grow bigger, and bigger; that pure metal, by reason of its softness and pliantness, still dilating and stretching itself: and perhaps, if it had been made of cast Metal, the Effect would have been more conspicuous; but being made of Two pieces, it at last burst at the place where it was sodered with Silver, and the Crack beginning at the Soder, ranslanting down into the Gold also.    

An Experiment,  
To measure how great the force of Rarefaction may be in Water shut up in close Vessels, to Frieze.  

Ottone.  TO obtain this, we thought of making a Metal Ball of brass, like the former, but perfectly round, and according to our Estimation, so much thicker, that the force of Rarefaction should be unable to break it; and filling it with Water, to set it to freeze, as before; the Cover being fast screwed down.  
This was done, and at first we found that the Water was frozen without any running out, or cracking the Vessel: wherefore we put in the Lare, and (keeping it as near as possible of the same Figure) there was taken off every where a thin coat of Metal; and than 'twas set to freeze the second time with water; and not being burst also, although it was frozen; we again turned off a thin skin from the Ball; this Experiment we repeated with three Balls, the thickest whereof is represented by the 4. Fig. which seemed to us the greatest thickness the force of Rarefaction in freezing Water could overpower: having proceeded so far, 
Tab. 13▪ Fig. 4.  we were desirous to reduce this to the force of dead weight, and the most probable means we thought of, was to cast a Ring of the same Metals and hardness, and exactly of the thickness of the Ball, turning the inside conical, and fitting thereto an Iron Cone, so that the Iron might rise about the breadth of the Ring, above the upper Edge thereof; being thus prepared, we thought of putting the Ring over an hole made in the midst of a thick Stone Table, something larger than the bore of the Ring; we than thought to proceed to lay on Weights upon the top of the Iron Cone; or at least, force it down with Weights hung to an hook made at the lower End thereof, that so the force being Perpendicular, it might equally drive the Iron into the Ring, and then leisurely adding small leaden Weights, we might know the least Weight capable of bursting the Ring: and to be secured, that the bearing of the Ring upon the roughness of the Table might be no hindrance to its breaking, we thought to fasten round the hole of the Table, a Plate of Polished Steel, and smooth the under-side of the Ring, that it might upon the least touch slip upon the Steel: but because an immense Weight was but sufficient to Conquer so great a Resistance, we thought to obtain our End, by making the Experiment with several much smaller Rings, but of different Sizes, and with more managable Weights; and so by examining the Resistance of these Rings, and comparing the repeated Trials, to come near the knowledge of what would break the first Ring, of the same thickness of the Ball; and by consequence, the force of Rarefaction in Freezing.  
These were our thoughts; but still finding upon cutting our Balls that were cracked in the freezing, several inequalities, and defects in the founding, proceeding either from the wind, or dregs of the Metal; when infusion, we were discouraged from Prosecuting the Experiment, upon so many uncertainties; nevertheless, we forbear not to relate our intentions freely, though we came short of our End; yet it may serve for an Advertisement to others, not to take a wrong Path; and perchance, excite the Ingenious to find out a means to obviate these difficulties, or a happier Journey another way.   

Experiments, To Measure the utmost Expansion of Water in Freezing.  

The First Experiment.  
WE made this Experiment two ways, by Measure, and by Weight; that by Measure, was after this manner: We procured a glass Cane, drawn as equal as possible; we Sealed it at one End; and filling it to a certain Mark with Water, we set it in Ice very well powdered, and incorporated with Salt to freeze: then comparing the height of the Cilinder Frozen, with that of the Cilinder Fluid, having the same Bases, the Proportion was found to be as Nine to Eight.   

The Second Experiment.  
WE did not think fit to rest satisfied with this one Experiment, judging it little less than impossible, to find a Glass Cane, (which has no other Rule to draw it by, than the equal breath of the Artificer) so truly Cilindrical as to take away all scruple of the Proportion of the Cilinders of Water contained therein: wherefore to have a more Regular Vessel, we took the Barrel of a Pistol, and turned it within to the truest Cilindrical Figure attainable by a Material Instrument, shutting the touchhole with a Steel Screw, and covering that with a Polished Steel Plate, we poured in Six Finger's Water, and thrust in a turned Cilinder of Box, of the exact Size of the remaining part of the Tube, well oiled and greased, that it might not imbibe any Water: when it was driven in so far, that the Mouth of the Barrel was well stopped, we inverted the Cane, that the Water might all rest upon the Base of the Cilinder, and unscrewing the touchhole, we forced the Cilinder; of Box in further, till the Water began to run out; then screwing in the Pin again, we set the Barrel upright, and marked how much of the Wood stood out, and covered it with the Freezing mixture sprinkled with Aqua vitae, which, as is well known enforces the freezing very much. When it had lain there about 12 Minutes, the Mark made at the Nose of the Barrel upon the Box, was raised the thickness of a Crown, and presently after two more, where it stayed, though we reinforced the Cold by a great quantity of fresh Snow and Salt: after a full hour, we took the Barrel out, and found it so cold, that we could scarce endure it in our hands; whence we gathered, it was throughly Frozen: and that the rather, because unscrewing the Touchhole, and striking the end of the Box Cilinder against the Wall, we were not able to force it an Hairs breadth in; and except a few drops at the Touchhole, we could not observe any Water between the Cilinder and Barrel; and by trying with a Piercer, we found it Solid Ice: for all this, we were not certain the Water was all frozen; nor could we be easily satisfied, because of the opacous Tube. And 'twas possible some Water might get out at the Screw of the Touchhole; and so part of the Tube between the Cilinder of Ice and Box, remain empty. Or in fine, the Water when at perfect liberty, may Rarefie in a greater Proportion, than it can do when under the constraint of a close Vessel, as it was here; for the Box was so fitted to the Barrel, and by imbibing the Water, notwithstanding the Oil so swelled, that after the Ice was Thawed, and the Water poured out at the touchhole, we were not able to pull it out with a pair of Pincers, or a Vice; so that we were forced to burn it out.   

The Third Experiment.  
BEing sensible of the many Difficulties we encountered in endeavouring to gain these Proportions by the Height of the Cilinders upon the same Basis, and a Metalline Tube, we betook ourselves to the other Experiment of weight: this we tried with a Transparent glass Cane, and Weighed the Water put therein to freeze, and afterwards, as much Ice as filled that same space in the Cane, in a pair of Scales that turned with the 1/48 part of a Grain; and the Proportion was found to be, as 25, to 28 1/19, little less than that observed in the First Experiment of measure, which was as 8 to 9, the same as 25 to 28 ⅛; finding so great an agreement in the proportions not to flatter ourselves with this success, we repeated the First Experiment with the same Cane, and found it as at first, as 8, to 9: and we were satisfied, that the weight was not altered for keeping the Glass Cane close shut the whole time of the freezing, and till it Thawed again; our Balance showed it to be of the very same weight as at first.    

Experiments,  
Touching the Procedure of Artificial Freezing, with their wonderful Accidents.  
THe first Vessel we made use of in these Experiments, was a Bolt-head of Glass, 
⅛ di Brac. 1 Brac. ½  about 2 8/10 Inches Diameter, with a Neck about 34 Inches long, slender, and divided into Minute Degrees; into this we poured fair Water to a Sixth Part of the Neck, 
Tab. 41. Fig. 1.  then setting the Bolt-head, or Ball in the freezing Mixture, as we used to do to freeze Liquors; we attentively observed the Motion thereof, by viewing its Superficies: we knew before, (as indeed, few are ignorant of) That from the first Application of Cold, it contracts all Liquors, lessening their Bulk; and this we found true, not only in the Aqua vitae of the Thermometers; but also, we had often made the Experiment with fair Water, Oil, Mercury, and many other Fluids; on the other side we had taken notice, That the Water passing from a Simple Coldness, to lose its Fluidity, and receive consistency, and firmness by Glaciation, does not only return to its first Bulk, but so far Exceed it, as to burst Vessels of Glass, and Metal with great violence. But we were yet ignorant, what Period these several alterations (produced by cold) observed; neither was it possible for us to attain it in Opake Vessels, as those of Silver, Brass, and Gold were, hitherto made use of in the Freezing: wherefore not to fail in this, which seemed to be the very Life of all these Experiments; we had recourse to Vessels of Crystal, and Glass, hoping by the Transparency of the materials, to be satisfied in the procedure of the Experiment; since upon every Motion of the Level in the Neck, we might take the Vessel out of the mixture, and mark the correspondent alteration therein. But the truth is, we found greater trouble than at first we imagined; to gain any certainty as to the Periods of these Accidents.  
But to relate the success more distinctly, you must know, That upon the first immersion of the Ball, as soon as ever it touched the freezing Mixture, we observed in the Water in the Neck a little rising, but very quick, which soon subsiding, it fell in the Neck, with a Motion regular enough and a moderate Velocity retiring to the Ball, till arriving at a certain degree, it stopped for some time, as far as our Eyes could judge, immovable. Then by little and little it emounted, but with a very slow Motion, and apparently equal, and then of a sudden without any proportionate acceleration it flew up with a furious Spring: at which time it was impossible to follow it any longer with the Eye, instantaneously running through the Decades of Degrees. And as this fury began of a sudden, so of a sudden it ceased, changing from that great swiftness to a movement, though very fast, yet incomparably less swift than the precedent: and with this it continued to rise most commonly, till it ran over the Top of the Neck; and all the while these things happened, were observed several little corpuscles of air, or some other more subtle Body to arise, and pass through the Water, sometimes in a greater, sometimes in a less Proportion: this separation was not visible, till the Water began to receive an intense Degree of cold, as if the force of the Cold had the faculty of secreting such a matter from the Water. After this, we were willing to see, if these Alterations kept any kind of equality or proportion with each other; wherefore we repeated the freezings, scarce one Ice being dissolved, but we set it again to freeze: but the Water always froze with the same Series of Changes: yet because they did not still every time rise to the same Marks or Degrees in the Neck, we began to imagine, there was no fixed Period; for which, it seemed we had some reason. At last it happened, that in often repeating these Experiments, we by chance let the Water in the Bolt-head frieze in the Neck first: (of which we spoke in the Fourth Experiment of freezing, 
Tab. 14. Fig. 2. ) and so broke our Vessel. Whereupon, we were forced to make another; this we blew less than the former, that the cold might soon Insinuate itself through all the Water; we also made the Neck longer, to the height of 45 ●/10 Inches, 
2 Brac.  that it should not run over. This we filled to 160 deg. and set it to freeze in Ice very diligently; heeding it we found at first, that all the accidents of subsiding, rising, resting, remounting, swiftly running up, and stopping again, were the very same; (i. e.) happened always when the Level of the Water was at the same Mark or Degree in the Neck; for upon putting it in the Ice, we observed, it was reduced to the same Degree, as in the former Trial: that is to say, at the same Temperament of Heat and Cold; taking the whole Instrument for a nice Thermometer, by reason of the largeness of the Ball, and proportion of the Neck; being satisfied so far, we proceeded to find the exact time of freezing; and to obtain this, we took the Ball out of the Mixture often, yet as often as we tried it, we were never so successful as to find the first small Veins, or stiriae of Ice, but it was either all Fluid, or all over Frozen; whence it was easy to gather, that the Act of Glaciation must be very quick: and whoever should happen to take it out of the Mixture in the very instant that the Water begins its swift carrere; might certainly observe some Notable alteration therein: and because we had so often taken out, and immersed the Ball into the Mixture, we were not well assured of the Point of its Change; we let it stand therefore, and be reduced to its first Mark, and placed it again in the mixture, and took notice of the Degrees whereat it began to mount so swiftly; and half a Degree before it came to it, we took it out, and very needfully regarding it with the Eye, the Water in the Ball, through the Transparency of the Vessel was easily discerned to be yet all Fluid; but the before received Impression of cold still acting (though it▪ was now taken out of the Ice) when it was just arrived at the Point, with a swiftness indiscernible by the Eye, and therefore scarce to be conceived, forced the Water through the Neck, and in an instant took away all Transparency from the Ball, and changed its Fluidity into Ice. There was no reason to doubt of its being wholly converted into Ice; and that it was not only outwardly crusted over, because in Thawing it loosened first from the sides of the Glass, lessening by degrees, till at last it was like a small Lens of Ice which was in the End Dissolved.  
We were well satisfied by often repeating the Experiment, that it was just as we have related it; and that we were not imposed upon.  
Tab. 14. p. 81.  
We were after this, very desirous to see the Order and Method observed by divers Liquors in freezings which for brevity are set down in the following Tables; wherein  

Stato Naturale.  STATE NATURAL, signifies, the Degree whereat the Water, or other Fluid stood (before Glaciation) in the Neck of the Vessel.  

Salto dell Immersione.  RISE UPON IMMERSION, is the first Leap made by the Water upon the Balls first touching the freezing Mixture.  
This, (as the following Experiments will more clearly show) proceeded not from any Intrinsic Alteration of the Fluid; but from the Extrinsic cause of the Vessel: whence it is, that varying sometimes a little, it Communicated some variety to the other Changes through which the Liquor passed in freezing; but whereas this is itself but small, its variety is also but little, and what it communicates to the subsequent Changes very inconsiderable.  

Abbassamento. Quiet.  ABATEMENT, or Fall, denotes the Degree to which the Water is reduced (after the Rice upon Immersion) when it just begins to receive the Impression of Cold.  
REST. Is the Degree whereat the Water stands for some time after its fall, without any apparent Motion.  

Sollevamento.  REMOUNTING, shows likewise the Degree to which the Water is raised from its lowest fall, by means of Rarifaction, with a very slow, and seemingly equal Motion, altogether like the first, wherewith it subsided.  

Salto dell Agghiacciamento.  SPRING UPON GLACIATION, signifies the Degree to which the Water rises with that extreme Velocity upon the very point of Glaciation.  
We said before, that after this Spring or Start, the Water does not stop upon a sudden, but continues to rise with a Motion swift enough, though incomparably less than the preceding: but of this Subsequent Motion, we have taken no account, it proceeding only from the Prosecution of Rarifaction in the Ice already made, or to say better, from the Ice shooting in the Ball by little and little, as it hardens after the fury of the first Impetus. This we call the first shooting of Ice, which is (as we have found upon breaking the Balls) from a very tender and weak beginning; and like Sherbet, when it is a little too hard, being of no closer a Consistence than the first coagulations of Liquors. Moreover, it happens that this way of Freezing, shows not the utmost Rarefaction of Fluids' violently frozen, it being impossible without bursting our Instrument to reduce the Ice to a perfect Solidity.  
We have likewise, to show our utmost diligence, and exactness, made use of a Thermometer and Pendulum in each Experiment of freezing: that with the Thermometer we might see at what Degree of cold, and with the Pendulum at what time every change happened to the Liquors: wherefore in the same Box with the Ball, 
Tab. 14. Fig. 3.  or Bolt-head, we put a Thermometer of 400 deg. but indeed, we found great inconveniencies, both in Noting the Degrees of cold shown by the Thermometer, and the spaces of Time given by the Vibrations of the Pendulum; so that we must confess, all our diligence was fruitless through the difficulty and impracticableness of applying an equal Proportion of cold to the Ball, and to the Thermometer; by reason of the inequality of the Pieces of Ice, and quantity of Salt sprinkled. And the cause is, That in Artificial Freezing we make use of Snow or Ice, which though ever so well bruised, and as it were ground to powder; yet upon mixing it with the Salt, they become one Solid Mass, and as hard as Stone; so that it is impossible to close it round about the Vessel, or be assured, that it touches every where alike: yet rather than be deficient, we have set both down in our Tables, that is, the Degrees of the Thermometer, and the Vibrations of the Pendulum; leaving it to the discretion of the Reader, to make a due Estimation of such remarks.  

The First Freezing  
Of Spring Water.  
 The Deg. of the Vessel. Differ. Deg. of Therm. Differ. Vibrat. Diff. State Natural 142  139    Rice upon Immer. 143 ½ 1 ½ 133 6 23 23 Abatement. 120 23 ½ 69 64 255 232 Rest. 120  49 20 330 75 Remounting. 130 10 33 16 462 132 Spring upon Glaciat. 166 36 33     
Note, That 65 of the Vibrations of the Pendulum set down in this, and the Four following Tables made one Minute.   

The Second Freezing  
Of the same Spring Water.  
 Deg. of Vessel. Diff. Deg. of Therm. Diff. Vibrat. Diff. State Natural. 144  141 ½    Rice upon Immers. 146 ½ 2 ½ 118 23 ½ 25 25 Abatement. 119 ½ 27 38 80 280 255 Rest 199 ½  28 10 415 135 Remounting. 131 11 ½ 17 11 882 467 Spring upon Glaciat. 170 39 17      

The Third Freezing.  
Of the same.  
Deg. of Vessel. Diff. Deg. of Therm. Diff. Vibrat. Diff. State Natural 143  141 ½    Rice upon Immersion 145 2 125 16 ½ 23 23 Abatement 119 ½ 25 ½ 51 74 369 346 Rest 119 ½  44 7 565 196 Remounting 129 ½ 10 38 6 933 368 Spring upon Glaciat. 169 39 ½ 38     
From these Three Examples of Freezing, the same Water may be observed, That the state Natural of the Water was not all three times exactly at the same Degree caused by the different temperament it had at one time, from what it had at another, from the External Accidents of Heat and Cold; whence likewise all the other alterations happening to the Water, did not precisely keep their Degrees; nevertheless by reducing in the second and third Experiments the state Natural to 142 deg. and also substracting in the like Proportion from all the other heights, you will find that they differ from the Degrees noted in the first Table very inconsiderably.   

The First Freezing  
Of Myrtle Flower water drawn off in a cold Still. 
Acqua di fiori di Mortella   
 Deg. of Vessel. Diff. Deg. of Therm. Diff. Vibrat. Diff. State Natural 145 ½  141 ½    Rise upon Immers. 147 1 ½ 133 8 ½ 31 31 Abatement 109 38 49 ½ 83 ½ 347 316 Rest 109  45 4 ½ 387 40 Remounting 125 16 25 ½ 19 ½ 925 538 Spring upon Glaciat. 230 105 25 ½      

The Second Freezing  
Of the same Water.  
 Deg. of Vessel. Diff. Deg. of Therm. Diff. Vibrat Diff. State Natural 146  142    Rise upon Immers. 149 ½ 3 ½ 131 11 18 18 Abatement 108 41 ½ 35 96 460 442 Rest 108  32 ½ 2 ½ 518 58 Remounting 126 ½ 18 ½ 19 ½ 13 ½ 1327 809 Spring upon Glaciat. 232 106 19 ½     
In the following Experiments of Freezing, we changed our Pendulum taking one 60, of whose Vibrations made an Exact Minute.   

The First Freezing  
Of simple Rose-Water stilled in a Cold Still. 
Acqua Rosa.   
 Deg. of Vessel. Diff. Deg. of Therm. Diff. Vibrat. Diff. State Natural 140 ½  142    Rise upon Immers. 143 2 ½ 138 4 20 20 Abatement 116 27 50 88 351 331 Rest 116  46 4 389 38 Remounting 127 11 ½ 26 20 745 356 Spring upon Glaciat. 194 67 26      

The Second Freezing  
Of the same Water.  
 Deg. of Vessel. Diff. Deg. of Therm. Diff. Vibrat. Diff. State Natural 140 ½  141    Rise upon Immers. 142 ½ 1 125 16 21 21 Abatement 115 ½ 27 39 86 354 333 Rest 115 ½  29 ½ 9 ½ 522 168 Remounting 127 11 ½ 18 ½ 11 1257 735 Spring upon Glaciat. 194 67 18 ½      

The First Freezing  
Of Orange-flower Water drawn off in a cold Still. 
Acqua di fiori di Aranci.   
 Deg. of Vessel. Diff. Deg. of Therm. Diff. Vibrat. Diff. State Natural 137  142    Rise upon Immers. 139 2 130 12 ●● 14 Abatement 111 28 46 ½ 83 ½ 311 297 Rest 111  44 ½ 2 375 64 Remounting 127 16 20 ½ 24 880 505 Spring upon Glaciat. 250 123 20 ½     
In all the Tables of the Second Freezing of the abovenamed Liquors many be observed how much longer time was requisite to Frieze it the second time, than the first; which we taking notice of, were willing to discover, whether it arose from any intrinsic cause in the Liquors after their suffering the first Freezing; or from an External cause in the Ice's being less cold after it had suffered the first incorporating with the Salt: and for this intent, we emptied the Case, and putting in fresh Ice and Salt, we made Trial of   

The Second Freezing  
Of the same Water.  
 Deg. of Vessel. Diff. Deg. of Therm. Diff. Vibrat Diff. State Natural 137 ½  142    Rise upon Immers. 140 2 ½ 120 22 29 29 Abatement 111 ½ 28 ½ 46 74 366 337 Rest 111 ½  44 2 384 18 Remounting 127 15 ½ 31 ½ 12 ½ 907 523 Spring upon Glaciat. 248 121 3● ½     
So that the Disserence in time between the First and Second Freezing must not be attributed to the Liquors, but to the Ice, which being much dissolved, and weakened, its Freezing Power arising from the salt requires a longer time to perform its Operation; and indeed, the whole difference between the two Freezing of the Orange Flower Water amounted but to a Minute and 46 Seconds; whereas, when the mixture was not changed, it arose to 7 minutes 29 seconds; nay, to 13 Minutes 20 Seconds; as appears by the comparing of the First and Second Freezing of the Rose-water, and the First and Third Freezing of the Spring water; and that the small difference of 1 Minute 46 Seconds observed in the Second Freezing of Orange-flower Water, was merely accidental, and not from any resistance acquired by the Water in being once before Frozen; is Evident from the seeond Table of the Freezing of Strawberry-Water, following, where the Ice being changed, the second Freezing happened in 3 Minutes 15 Seconds less time than the First.   

The First Freezing  
strawberry Water stilled in Balneo. 
Aqua di Fravole.   
 Deg of Vessel. Diff. Deg. of Therm. Diff. Vibrat. Diff. State Natural 137  143    Rise upon Immers. 139 2 120 23 30 30 Abatement 111 28 37 83 437 450 Rest 111  36 1 450 15 Remounting 126 15 18 ½ 17 ½ 988 538 Spring upon Glaciat. 215 89 18 2/●      

The Second Freezing  
Of the same Water.  
 Deg. of Vessel. Diff. Deg. of Therm. Diff. Vibrat. Diff. State Natural 139  143 ½    Rise upon Immers. 141 2 134 ½ 9 18 18 Abatement 114 27 42 92 1/9 420 402 Rest 114  41 1 427 7 Remounting 129 15 21 20 873 446 Spring upon Glaciat. 215 86 21     
Note, That the Spring upon Glaciation is more or less high, as likewise more or less swift in Different Fluids: and it seems to be higher and swifter in those that Frieze stronger.   

The Freezing  
Of Stilled Cinnamon Water. 
Acqua di Cannella.   
 Deg. of Vessel. Diff. Deg. of Therm. Diff. Vibrat. Diff. State Natural 139 ½  141    Rise upon Immers. 141 1 ½ 133 ½ 7 ½ 13 13 Abatement 111 ½ 29 ½ 45 88 ½ 360 347 Rest 111 ½  39 6 420 60 Remounting 120 ½ 9 27 12 720 300  
The Water rising with a very slow Motion from the State of Rest to 120 deg. ½ instead of springing up as it then uses to do, it only mounted with a quicker pace; which perceiving, we immediately took the Vessel out of the mixture, and found the Water shot into a very tender Ice, which melted as soon as ever it was sensible of the Air. And Note, That of these Artificial Freezing, some were more weak and tender, as the Ice of Cinnamon Water, and that of Rose-water; others more firm and hard, as that of Orange, and Mirtle-Flower-waters; than which we found no Liquors so hardened at the first instantaneous Freezing.  
We have omitted the repetition of this, and the following freezings, since their agreement may be sufficiently seen in the Examples given of each Liquor.   

The Freezing  
Of Snow Water. 
Acqua di Neve Strutta.   
 Deg. of Vessel. Diff. Deg. of Therm. Diff. Vibrat. Diff. State Natural. 136 ½  141    Rise upon Immers. 139 2 ½ 132 9 27 27 Abatement. 111 28 54 80 345 318 Rest. 111  48 4 377 32 Remounting. 116 ½ 5 ½ 40 8    
And then with a somewhat quicker motion (though very slow in comparison of that which the other Liquors sprung up with upon the point of Glaciation) it began to congeal at the sides of the Glass, and successively from the more outward parts approached the Centre of the Vessel with the same equal slowness of Rarefaction, and raising of the Level in the Neck. The Ice was not throughout equal as the other, but broken, and shot into irregular Veins and Rays, and every where interwoven: being repeated, the second Freezing was in all respects the same as the first; And making it with the same Water boiled, we found no great difference.   

The Freezing  
Of Fig-Water. 
Acqua della Ficoncella.   
 Deg. of Vessel. Diff. Vibrat. Diff. State Natural 98    Rise upon Immers. 100 2 19 19 Abatement 71 29 288 269 Rest 71  363 75 Remounting 83 12 816 453 Spring upon Glaciat. 200 117     

The Freezing  
Of the best red Florence Wine. 
Vini Rosso di Chianti.   
 Deg. of Vessel. Differ. Deg. of Therm. Diff. Vibrat. Diff. State Natural 141  141    Rise upon Immer. 143 2 137 4 15 15 Abatement. 77 ½ 65 ½ 27 ½ 109 ½ 600 585 Rest 77 ½  23 ½ 4 695 95 Remounting. 81 4 15 7 ½ 1035 340  
From the 81 ½ Deg. it visibly accelerated the Motion of the Level, and by little and little froze without any other motion in the Vessel,   

The Freezing  
Of white Muscadine. 
Muscadello Bianco.   
 The Deg. of the Vessel. Differ. Deg. of Therm. Differ. Vibrat. Diff. State Natural 140  139    Rise upon Immer. 142 ½ 2 ½ 132 7 16 16 Abatement. 77 65 ½ 24 108 660 644  
Being come to that Degree of 77 without any rest or stop, it began to rise with a little swifter Motion than we observed the Liquors used to remount with, which Frieze in the instant of that they exert their violent spring. When we took it out, we found the Liquor began to have some Ice next the sides of the Glass.   

The Freezing Of Distilled Vinegar. 
Aceto Bianco.   
 Deg. of Vessel. Diff. Deg. of Therm. Diff. Vibrat. Diff. State Natural. 141  140    Rise upon Immers. 143 2 134 14 11 11 Abatement. 75 68 24 110 735 724 Remounting. 79 4 19 5 1175 440 Spring upon Glaciat. 273 194 19     
Which Velocity was less than that of the Freezing Water, but considerably greater than that of Muscadine, Cinnamon Water, and Simple Vinegar.   

The Freezing  
Of the Juice of Lemons 
Agro di Limoni.   
 Deg. of Vessel. Diff. Deg. of Therm. Diff. State Natural 142  143  Rise upon Immersion 144 2 134 9 Abatement 84 160 32 102  
When it was fallen to the 84 th' degree of the Vessel, it began to rise again with a very slow motion, gently freezing.   

The Freezing.  
Of Spirit of Vitriol. 
Spirito di Vitriolo.   
 Deg. of Vessel. Diff. Deg. of Therm. Diff. Vibrat. Diff. State Natural 140 ½  140 ½    Rise upon Immers. 142 1 ½ 133 7 ½ 15 15 Abatement 90 52 37 ½ 95 ½ 420 405  
This Liquor did likewise not rest at all, but being reduced to 90 deg. began to remount in the Neck of the Vessel with a slow uniform motion, and at the same time shot itself in several planes of ice from place to place in the Liquor, as is the manner of fair water set to freeze by itself in the open air.   

The Freezing Of Oil. 
Olio.   
 Deg. of Vessel. Diff. State Natural 140  Fall upon Immers. 122 18 Abatement    
When it had contracted itself all within the Body of the Vessel it there congealed without the least Rarefaction: for it may be the Frozen Oil sinks to the bottom of the Fluid, whereas all other Ice swims upon their Fluids.  
Spirit of Wine condenses extremely, but never Rarefies afterwards, nor affords any ice.     

EXPERIMENTS OF Natural Freezing.  
ALthough the Freezing we have hitherto Treated of, have been called by us Artificial; yet that takes not from their being the true Works of Natures own hand. Now the same Nature Acting by other Methods, and it may be with the only ingredient of the Air, we were curious to know, if any variety in the Procedure of the Operations, might be discovered in producing the same Effects by other means. And when we already had this before us, we attempted to draw thence some other Conclusions; as will appear in the following Discourse.  

The First Experiment. Of the Freezing of common Water in the Air.  
IT is already declared, in the foregoing Experiments, that the Artificial Ice (in the then described Vessels) proceeded from a beginning very soft, and incompact; especially, in regard of those made in the Winter air; which, though they are not so suddenly made, but begin from a thin coat, or hair-like Vein, scarce discernible; yet those Veins, or Coats (excepting their brittleness, which comes from their being so very small) are more firm, and hard Bodies, and as it were more Cristaline, and Solid Ice. And very admirable is that Lusus Naturae which for many years we have observed in Natural Freezing, viz. Setting Water taken out of the same Spring in several Vessels, as of Earth, of Metal, and of Glass; in the shape of tall Glasses, or broad Bowls, some part-filled, some quite-filled; some open, others covered, and in several sorts of bottles, with different Mouths; some only stopped with Cotton, others sealed at a Flame, being all set in the same place undisturbed, or beside one another upon a Table: sometimes that Vessel which had least, was first Frozen; sometimes that which had most, and so in all the Vessels, without any regard had of the form, or fullness thereof.  
As to the Materials, we may positively aver, That Earthen Vessels frieze the contained Fluid sooner than either Metal, or Glass. But as to the rest, we have found nothing so constant, as the perpetual irregularity of the Accidents; and among others, there have some Vessels stood all Night without the least Coat of Ice, when some next to them have been frozen in an hour. Moreover, in the same sort of Vessels set to freeze, in the same Night, we have observed the like varieties, whether placed North, South, East or West; and as well those Vessels which have stood more Southwardly have been frozen first, as at other times, those that stood more Northwardly, though the Cold generally comes from that Tract with us: and sometimes those Eastward, sometimes those Westward have got the better; nay sometimes both have surpassed the North, and South, and at other times been vanquished by them.  
The Method also observed in Freezing, is very curious: The water begins first to congeal at the top round the edges, and from that List of Ice shoots several small Threads to the middle, after which it sends others downwards, and that indifferently from all parts; by degrees these Threads became ragged, yet thicker, and broader at one end, and more acute at the other, like little Daggers; from the sides of these shoot out other small Threads close together like feathers, or Palm branches; these are as it were the first warping, and with a confused, and disorderly filling up, they proceed shooting and increasing till the Woof closes all with a total freezing of the Water; the Superficies whereof may be perceived to be all razed, and full of straight Lines, like Crystal scratched with a fine Graver. At first the Superficies of all these Ices appears plain; but when the freezing is throughly finished, and all the Water Congealed, it at last becomes raised in hillocks, but without any regular Figure. This Effect made some call to mind what was Registered in our first Experiment of Artificial Freezing, where the innermost Cover of the Silver Vessel was found cracked, and all Coated over with a thin Ice made of the water that got out of the Vessel at the crack in the instant of freezing; thereupon they said, that the first Crust of Ice which spreads itself over the Superficies of the Water, and shuts it closer than any Cover can, by sticking fast to the sides of the Vessel; does not leave space enough for the Water under it to rarify in, as it freezes, but it is forced to seek room where it can; and finding the Cake of Ice weaker than the sides of the Vessel, it makes its way there, and heaps itself up more in one place than another, according to the inclination of the plains in which it breaks, when the first Cake splits, which afterwards likewise freezing, forms that little swelling mentioned: this happens sometimes to break the Vessels, which (as they think) is most probably caused, by the slowness of the Waters freezing at the bottom; whereby the Cake of Ice at the top becomes so hard, that it is easier to break the sides of the Vessels than the Icey Cover: but no certain Rule can be given concerning these matters, since there may be many cases wherein either the Vessel is only burst, or the Cover only: or first one, than the other; or both at the same time, according as the External accidents of the Air vary; as to cold, calmness, or winds; and from the inequality of the Vessels Resistance, or from the Nature of the Liquors themselves.  
Before we put an End to this Discourse; it will not be amiss to Relate a trifling Accident observed this year, which though of small Moment, may nevertheless be some help to the former Opinion. A cup of Water being exposed to the Air in the Evening, we found in the Morning all the Water frozen; and in the highest part of its Superficies it had a Point of Ice a Finger high, like a small sharp splinter of Rock Crystal: This in all likelihood was no other than the Water issuing out at a crack in the first incrustation, being forced by the freezing, underneath, which violently rising in a small stream, (and predisposed to Frieze,) by the Cold of the external Air, was congealed to an hard Ice, in that very instant, not having time to fall.   

The Second Experiment Of the Freezing of Water in Vacuo.  
WE have likewise tried to Frieze Water in a Vacuum made with Mercury: and that we might compare it with that made in the Air, we put Water in a Vessel like that included in the Vacuum. Therefore exposing them all Night, we found in the Morning both frozen: yet with this Difference; that the Ice made in Vacuo seemed more equal and hard, and less transparent and porous than the other; and upon Examination, was heavier in specie. The way we took to discover this, was by turning a piece of each Ice like a Cilinder, and of the same bulk, as near as we could, and putting them in Spirit of Wine, upon which gently pouring some Red Wine, we saw the Ice made in the Air rise up before that made in Vacuo; and when upon the top of the Water, it swum about lighter, and quicker because the Fluid covered less of it, than of the other.   

The Third Experiment Of the Freezing of Stilled Water.  
HAving set common Stilled Water in several Vials to freeze, we found the Ice more limpid and transparent than usually the water is: only in the midst there was as much as a small Nut of a more opaque Ice, and whiter than the rest, and round about it divers spiculae of the same kind of Ice: in fine, to give a true Picture of it, in each Vial 'twas like the Burr or Husk of a Chestnut, frozen in a piece of Rock-Cristal, as we see Flies, Worms, or Butter-flys entombed in Amber; or like little bits of Straw, Herbs, etc. in Crystal itself.   

The Fourth Experiment, Of the Freezing of Sea Water.  
TO see the Freezing of Sea water, we exposed one Evening to the Air (when a Thermometer of 50 deg. stood at 9 °, two Glasses full of it, to freeze: in an hour we found the shallowest began to freeze; but in a manner somewhat different from common Water; for it showed like a great many small scales of Talk broken to pieces, and put in Water. These took away the Trasparency of the Water, and gave it the consistence of Sherbet, which is drank frozen in the Summer, when the Externally applied Snow growing more Languid, it begins to dissolve. In a while looking upon it again, we observed it a little firmer, as the Multiplying of the Scales lessened the Fluidity of the water; in the morning it was yet harder, though it came nothing near the hardness of common Ice; for upon any little agitation, it turned to water: the Figure of the Scales was narrow, and longish, and between them it was for the most part Fluid: moreover, the Mass stuck no where to the sides of the Vessel; but turned freely about in it. The Superficies was altogether plain, without any prominences, or Risings: And the Difference consisted wholly in a more loose and thin Order and Texture then that of ordinary Ice.   

The Fifth Experiment, Of the Efficacy of Sal-Armoniac, Nitre, etc. in Freezing.  
IT is well known, that Ice is most efficaciously cold when sprinkled over with Salt. As to this we have observed, That Sal-Armoniac invigorates it more than any other; for we have experimented it upon the same water, of the same Temperament, and in like Vessels of the same figure, capacity, and thinness, equally encompassed with the like quantity of beaten ice, and the one being sprinkled with Sal-Armoniac, the other with the same proportion of Nitre, they were not frozen in the same space of time: for a Thermometer of 100 deg. being (when it stood at 20 deg.) Immersed in Water set to freeze with Nitre, subsided but to 7 ½ deg. when at the same time a like Thermometer put in Water, encompassed with the mixture of Sal-Armoniac, fell down to 5 deg. and the Water began to be skinned over.  
We have already said, upon another account, That not only Salt, but strong-Waters wonderfully intend the freezing; and if besides the strong-Water, you add salt, it will prove most powerful: nay, sugar produces such an Effect, but not much in comparison of common Salt, Nitre, and Sal-armoniac, which we found much more successful in the operation of freezing, than all the Rest.   

The Sixth Experiment. Touching what Metal preserves Ice best.  
PUtting Ice in Vessels of several different Metals to observe which kept it the longest unthawed; yet, of this we could obtain nothing certain, though we may say at large from a very great number of Experiments which we made, that it was preserved best of all in Lead, very well in Tin, 
Piombo Stagno Rame Ferro oro Argento.  but a short time in Copper, and Iron, less in Gold, and yet a lesser time in Silver; nevertheless, at sometimes this order was changed, it melting sooner in Tin and Lead, than in Silver and Gold: wherefore (as we hinted) this Experiment is not to be much confided in, but proposed here rather to excite others to attempt it by some more secure way, than to show any certainty we obtained in our Observations.   

The Seventh Experiment Of Freezing a Piece of Ice to a Table.  
GAssendus Writes, and it is very true, That if a Plate of Ice be laid upon a flat Table, and well sprinkled above with Salt, it will freeze fast down to the Table: we were desirous to make the same Experiment with Nitre, but it succeeded not, so as to show us the least beginning of Adhaesion: we have often observed in those stuck down with common Salt, that we much more easily separated them from the Table, by lifting them up Perpendicularly (or at one end first, as a Board nailed down is raised up with a Lever) than they could be forced along parallel to the Plain; moreover, the Water on the under-side of the Ice was Salt, and that side also thereof was Opake, and covered with a white hoariness made of innumerable small particles of Salt: and brought to the Light, it appeared rough, as if it had been prettily razed with the point of a Diamond; like the Glass of those Vessels, which from the Artificial similitude they have to Ice, we call Ice-glasses.   

The Eighth Experiment. Of freezing the Dew upon the outsides of Vessels.  
THat Dew which covers the outsides of Glasses, containing any cold Liquor, or Ice, is sometimes observed to congeal there: and the same happens, when the Ice or Snow in the Vessel begins to alter with the strong Water or Salt: there is also an Exhalation, or cloudy moist Vapour rises up as it seems from the bottom of the Vessels, whence proceeds a very cold air, which besides that it sensibly affects the hand, is likewise more discernible, by the agitation which it causes in the flame of a Candle brought near it.  
This Experiment we repeated, by putting Ice sprinkled with strong water and Salt in several Vessels of different Figures and Metals; 
Acquarzente.  to observe if either the one, or the other afford any variety in the smoking: and as to the materials, we could not perceive any diversity, whether the Cups were of Glass, Earth, Wood, Metal, or precious Stones. But as to the Figure, it seemed to us, that whereas in Beer-glasses, 
Bicchieri▪  and all other tall, narrow Vessels, the smoke began above, 
Tazze Sparse.  on the contrary in wide bowls it smoked from the bottom freely upwards for a short space.  
In a Golden Boul, we observed an effect which ought to be Universal in all Vessels, though it is less observable in some by reason of their shape: it was this; when the smoke ceased, that crust of Ice began to let fall after the manner of dew, a fine Ice, like powdered Glass, and continued till the ice in the Boul being dissolved, that thin outward covering likewise melted.  
The Exhalation said to proceed from the ice seems very different from that of any combustible Matter, and much resembles the Morning mists that rise from the Earth.   

The Ninth Experiment. Of Reflected Cold.  
WE were willing to try, if a Concave Glass set before a mass of 500 l. of Ice made any sensible repercussion of Cold upon a very nice Thermometer of 400 deg. placed in its Focus. The truth is, it immediately began to subside, but by reason of the nearness of the Ice, 'twas doubtful, whether the direct, or reflected rays of Cold were more Efficacious: upon this account, we thought of covering the glass, and (whatever may be the cause) the Spirit of Wine did indeed presently begin to rise; for all this we dare not be positive; but there might be some other cause thereof, besides the want of the reflection from the Glass; since we were deficient in making all the Trials necessary to clear the Experiment.    

EXPERIMENTS, Touching an Effect of HEAT and COLD, Lately observed as to the Alteration of the inward Capacity of Glass, and Metalline Vessels.  
WE said in the Experiments of Artificial Freezing, that the first Motion observed to be made by the Liquors (exposed in Vessels to freeze) was a small rising up, there called Rise upon Immersion; because it happens upon the Vessels first touching the freezing mixture: and you must know, the contrary to this is observable, when it is immersed in hot Water; for the Levels of the contained Fluids sensibly subside, and then (as it were) take time to Rise again, which they do with a quick Spring, up to the degree they stood at when first immersed in the hot Water, and thence successively rise, as the heat received continues to rarify, lighten, and raise them. On the other side, though they are raised upon the first immersion into cold Water, or ice, yet they not only subside again to the former height, but continue to do so for many Degrees, till at last (sometimes after a little Rest, sometimes without any) they all remount (Oil, and Spirit of Wine excepted) until the whole freezing is finished. This Effect was by some attributed to a cause much favoured by several following Experiments: their apprehension was, That the appearance of this sudden motion in water, and other fluids, was not really from any intrinsic alteration of rarity, or density at that moment wrought in their natural temperament by the power of any 
Tab. 15. p. 105.  contrary quality of the outwardly applied ambient, which some by a noted Word call Antiperistasis; but rather, (to speak first of the subsiding upon the immersion of Vessels in hot Water) their thoughts are, that it comes from the fixing of several volatile Corpuscles of the fire, (evaporated from the hot Water) into the external pores of the Glass, which as so many wedges, forcing, and separating the parts thereof, must necessarily distend, and enlarge the internal Capacity thereof; till they find a way through the hidden Passages of the Glass to the Liquor therein contained. That on the other side, Cold binding up, and contracting those pores of the Glass, makes the Vessel become too scanty for the bulk of Water in it, before that bulk of Water, yet unaffected by the Cold, contracts likewise. In fine, that the Vessel being first sensible of Cold or Heat, by shrinking or enlarging itself also first, is the true cause of that Phenomenon of the Rise or Fall; as it becomes more straight, or large to the contained Liquors, yet not vitiated by the quality of the ambient. This Opinion was rendered more probable to us, by the following Experiment.  

An Experiment,  
Proving, That in the Instant that the External Heat or Cold dilates, or contracts the vessel; yet than the natural temperament of the Liquors therein contained is unaltered.  

Tab. 15. Fig. 1. Smalto.  WE included in a Globe of Glass filled with Water, several small bubbles of Coloured Glass, empty, and sealed Hermetically: these were all near the Specific gravity of the Water, by means of the air they had in them; whence the Floaters upon the top of the water upon the least breath of warmth sunk down, and those at the bottom, upon any accession of Cold, mounted upwards: hanging this Instrument in the air, and suffering the bubbles to rest, we began to approach to it underneath a pan of Water heated, and after that of Cold Water mixed with Ice well broken; And though upon the application of these different Ambients, we observed the same Effects in the Level, of raising itself upon the touch of the Cold, and subsiding upon that of the hot Water; yet we could not find, when the water seemed condensed, and contracted, that any of them at the bottom rose up, nor when the Water seemed rarefied, and enlarged, any of the Floaters sunk to the bottom: but these were observed to fall, and those to rise, when the Water after its abatement upon the first impression of heat, began to rise again, and when after its rising upon the impression of Cold it began to subside again: an argument to insinuate, that, the water, and so any other Fluids in this first Motion, do not really move themselves, but only obey the alteration of the Vessels they are contained in.  
Yet it may be objected, That these first alterations did really proceed from the inward changes of the Liquors, which though discernible by the Eye, by means of the small Neck of the vessel, yet were not great enough to be discerned in changing the aequilibrium of the Bubbles; of which it may be thought, that, in that very instant, they began really to move, though in their first parting from Rest, the Eye could not perceive it.  
To this is answered, That, the true Rarifaction, and the true Condensation of the Water (that is able to make it rise or fall so very little a space as it does rise or fall at the entrance into the Icey mixtture, or hot Water,) is sufficient to alter the Aequilibrium also between it, and the bubbles, apparently to the Eye. And indeed, when the Water really rises or falls from a true Rarifaction or Condensation, the bubbles likewise begin correspondently to move, before ever it comes to the same Degree, at which (the same bubbles remaining immovable) it stood at the instant of its first immersion. Nevertheless, the discovery of this Effect ought not to cause in us the least scruple of the truth of our Thermometers; since the whole contraction or dilatation in Vessels containing an Ounce and half, at most amounts but to a grain; whence proportionably how small will that be in Vessels of a few grains content, such as our Thermometer of 50 deg. which are the most convenient, and exact, and upon that account most made use of to discover the Alterations of the Air?  
Now to manifest by divers ways, even to sense, the Truth of this Phenomenon, we made the following Experiments: which first founded in the Theory, are confirmed by the Effects.   

The First Experiment,  
Showing the Alteration of the Size of a brass-Ring put in the Fire, and in Ice, its Figure still remaining unaltered.  
THere was ordered to be cast a Ring of Brass, 
Armilla di Branzo. Tab. 15. Fig. 2, & 3.  and by turning it was fitted exactly to a Cilinder of the same Metal: this was put in the fire for a short space, and then being put upon the Cilinder while hot, it was sensibly loose; being dilated by the heat into a Ring of the same shape it was of before, but its concavity was 9/100 parts larger: when it had remained some time upon the Cilinder, and had communicated its heat thereto, between the increasing of that, and the shrinking of the Ring by little and little as it cooled; they not only came to fit as at first, but were so firmly united, that before they were quite cold, a considerable force was but requisite to separate them.  
The contrary in all respects happened when we intensely froze the Ring.   

The Second Experiment,  
Whereby it appears that Bodies are dilated by the imbibing of moisture, as well as by the insinuation of heat.  

Tab. 15. Fig. 4. Fig. 5.  WE made a Conical Ring of Box, whose concave Superficies was curiously turned, and polished: there was also made a stock or Conical Mandril of Steel turned, and well smoothed, and nicely divided with many circles Parallel to the Base: fitting the Ring upon this, we marked which of those Circles the bottom thereof just touched; taking it off, we let it lie in Water three whole days; that it might have time to penetrate through the whole stubstance of the Wood; then we put it on again, and observed, that the Concavity was stretched, the bottom of the Ring falling much lower upon the stock, than it did at first.  
This Ring was made two several ways, in one the Ligneous Fibres were Perpendicular, in the other Parallel to the Plane of the Basis; the first after soaking in the water kept its spherical Figure exactly, the other came near to an Oval, and put upon the stock sunk down much short of the former.  
Observe to make these Rings of firm, clear Wood, that is without Knots, and of an uniform hardness; especially, when the Fibres are cut transversly; that so all being swelled by the steeping, their enlargement may be the more sensible. Note also, (as was said at first) that the Rings must lie so long in the Water, as their whole substance may be penetrated: for the Effect will be different; if those that are but a little soaked on the outside, be put upon the Stock; because they will not slide down so far, as when they were dry. Therefore let them be well impregnated, and satiated with moisture, that their dilatation may be the more visible.   

The Third Experiment,  
Which discovers more evidently the readiness of Glass to contract and dilate itself upon Heat and Cold.  

Tab. 15. Fig. 6. 1 Brac.  THere was made a hollow Ring of Glass (as in the Figure) about Two Foot in Diameter, with Two Funnels, that when the Liquor was poured in at one, the Air might have vent at the other: then was made a Cross of Glass just to touch with its Extremities the Concave of our hollow Ring, 
Ciambella.  and filling the Vessel with hot Water by the Funnel, as it proceeded in dilating itself; so visibly, either the one, or the other of the Glass Rods lost their hold; for they did not bear equally stiff against the Instrument, and at last both were loosened; so that the Cross being at liberty, fell down upon the Table whereon we set the Instrument, within the Circumference of the Ring. After this, pouring the hot Water out, we filled it with a mixture of Salt and Ice dissolved; and it not only held the Cross again, but with greater firmness than at first.   

The Fourth Experiment,  
To find the same Effect in Metals.  

Stagno. Tab. 16. Fig. 1.  HAving bend a small Plate of Tin like a Stirrup, and hung it up, so as the two Extremities might touch a Plane put under them, upon which we drew two Lines, where the aforenamed Extremities must necessarily strike, if they had been prolonged: we than put a live Cole over the bending of the Plate, and attentively observing one of the Points, we discerned, that by little and little it parted from the line drawing within it; and this was when the convex of the Plate only being heated, dilated itself, and the Concave was contracted: but when it had penetrated (which it soon did) the whole thickness of the Tin, being then equally dilated, the point not only again reached the Line, but passed beyond it, more or less in Proportion to the Heat communicated by the Fire to the bending of the Stirrup.   

The Fifth Experiment,  
To observe by the Sound the like Dilatation in a Stirrup of Glass.  

Minugia. Tab. 16. Fig. 2.  WE fitted a Minikin to a broad Stirrup of Glass, as in the Figure, and tuned it an Octave to the string of a Guitarre, and applying the heat to it after the same manner, as we did to the Stirrup of Tin, when it had not yet affected the Concave Superficies thereof, but only the Convex, 
Tab. 16. p. 110.  the Tone was flatter, because as in the foregoing Experiment the aperture was lessened, and consequently the string slackened; but when the heat had penetrated quite through, the String was straitened so, as the Sound was sharper than the first tuneing.   

The Sixth Experiment,  
Discovering the same Effect more clearly to the Eye.  

Tab. 16. Fig. 3.  WE fastened to the same String with a bit of Thread, a small Leaden Plummet, and put under it a little Plate of Glass, so as not quite to touch the Weight; and applied fire to the usual place: the Effect as to the stirrup was the very same as at other times; for being at first drawn together, the Cord became slacker, and the Weight Rested upon the plate of Glass; but at last extending the Aperture, it strained the Cord, and raised up the Plummet; the contrary Effect was wrought by Ice made use of instead of the Coal, but sensibly less, in proportion as its activity is less; than the fires.   

The Seventh Experiment▪  
Showing the same effects in Wire strings. 
Minugie.   

Rame Ricotto.  A Leaden Plummet being fastened to a nealed Brass-Wire, and hung over a Glass Plate, at a little distance therefrom, drew nearer to touch it as the Wire became heated, by applying a lighted Candle to it, and still retired from it upon every little Rubbing with Ice.  

Ottone.  In like manner, two wires of mixed brass tuned unisons, so that one being struck, the other sounded, were made discordant, either by approaching to one of them a live Coale, or a piece of Ice, that by lengthening the wire made the Tone flatter; and this by shortening it, sharpened the Sound thereof.   

The Eighth Experiment,  
Whereby from the appearance of a contrary Effect 'tis confirmed, That the first Motion of Liquors comes from the Capacity of the Vessels being altered in the instant of Immersion.  
IT may happen upon the first Immersion of Vessels into the Ambient Hot or Cold Body, that the Level of the contained Liquors shows a different Effect from that beforenamed; that is, That it may immediately rise in a hot Ambient, 
Tab. 16. Fig. 4.  and subside in a Cold one: this will be always if the Vessel be made in the shape represented by the Figure; in this upon the first touch of warm Water, the Liquors will presently Rise, because (in the lateral Angles, being very strong and thick of Metal in comparison of the hollowed faces,) the heat acting, first upon the outward Superficies, lessens those Angles (as we said before it does to the Stirrup of Glass) and so necessarily comes to stretch the thinner hollowed parts, which Dilating inwards, happen at first to lessen the Capacity of the Vessel, and to raise the Liquor in the Neck: which falls again from that space new filled, when the heat has penetrated the whole substance of the Glass, and the Vessel begins to enlarge itself uniformly, returning to its first size, and larger; and at last the Liquor Rises again, when impregnated with the fiery corpuscels it begins to Rarify. And it is manifest, that the contrary to this, is observed from Cold, the same causes acting contrarily. And Note, That the Capacity of the Vessel was lessened, by the pressure of the Hand only, made upon two opposite hollow sides; nor could the Rising of the Liquor be attributed to the heat of the Hand Rarifying it; for it was raised after the same manner, by pressing the Vessel with two pieces of Ice.  
The use of the next Instrument may easily be comprehended from its Figure; being only a Plate of Steel, 
Tab. 16. Fig. 5.  perforated with Circles of divers Measures to observe the different increasings, caused by different Degrees of Heat given to the same, or several Conical Rings of Metal.   

The Ninth Experiment,  
To show, That a Vessel may be distended, not only by Heat, or by soaking up of moisture, but also by Weight.  
THere were made Two Vessels of Glass, 
Tab. 16. Fig. 6.  the one Conical, the other Pyramidal; and letting them into a thick Table, we marked round the outside of the Vessels how far they sunk down; then taking them out, we filled them with Mercury, and put them again into the holes in the Table; but they would not go down so low as the Mark made at first, because they were distended by the force of the Mercuries weight▪    

EXPERIMENTS About the Compression of Water.  
THat Experiments do not always reach the truth aimed at, is not from any defect of the Idea conceived of them in the mind; but rather happens from the necessity we have of material Bodies, and corruptible Instruments, to put our Conceptions in Practice; which though of themselves unable to blemish the Theory and Speculative part, yet through the Defaults in their substances, are not always capable of seconding our thoughts: but we must not hence conclude, the Experimental Method fallacious in the Quest of Natural Events: for though by it we may sometimes come short of the very depth of that Truth, which we first sought after; yet it is hard, if it does not give some glimmerings and marks to discover the falsity of any contrary supposition. This has been our Fate in our Research, Whether water can suffer any Compression, as air does; in which attempt, for as much as the weakness of our Vessels came short of affording us a perfect knowledge of the Truth, we making use of Glass ones as most fit, because of their Transparency; yet at least we gained this much, that Water cannot be compressed with a very great force; and so far we have proceeded, That a power able to reduce Air into a space 30 times less than what it first filled, that power not only thirty times, but a hundred, nay perchance a Thousand times increased, was too weak to compress a quantity of Water a Hairs breadth, or the least visible Space from its Natural Extent; the Methods we took were those that follow.  


TAb. 17. p. 115.   
The First Experiment.  

Tab. 17. Fig. 1.  LEt there be at the Ends of Two Glass Canes AB, AC; two balls of Glass also, the one larger than the other; fill both with fair water to D, and E, and join them together with a Lamp, remembering to leave a passage open in sealing them at A, and to draw the beak OF very long, and open; then apply to each Ball a Glass full of beaten Ice, burying them therein, that by condensing the water there may enter as much air as possible into the Canes; and the better to force it down, you may rub a piece of Ice backward and forward upon the outside of the Syphon DAE, which by its Coldness contracting the air in the Canes, there will enter in more to fill it at the Beak F; then Seal it at a Flame, and the contained Air will remain pressed and thronged together; after this as it is Sealed, take the Ball B out of the Ice, and at first immerse it in tepid Water, next in warm, and at last in boiling; keeping the Ball C all the while covered with Ice, to reduce the Water therein to the utmost condensation, which suppose to be at E; moreover, endeavour to compress the Cilinder of Air GE to its greatest density by the force of the Water rising to G, being Rarified by the received heat from the Water supposed to boil round about the Ball B; now if the Water could suffer any Compression, it ought to subside from the pressing Air below the Mark E; but with us it still happened otherwise; for when the Water at E was once reduced to its utmost Condensation by the Cold, etc. the force of the Air GE pressing thereon, was unable to gain a Tittle, and did sooner burst out the bottom of the Ball C, than force the Level E a jot; 
Rame.  and when to add a greater strength to the Instrument we made the two Balls of Copper, the Water in the Ball C has sustained the Force between the Air pressing at E, and Solidity of the Metal with insuperable Resistance, rather bursting the Syphon, (which must be of Glass to discover the Internal Motion of the Water) joined fast to the Copper with Mastic, or the usual hard Cement.   

The Second Experiment.  

Tab. 17. Fig. 2.  LEt there be prepared a Vessel of Glass AB, contained about 6 l. of Water, the Mouth large enough to receive a Glass Cane bound close about with Lead to keep it from bursting: fill this Vessel with Water up to CD, immersed the Cane OF open at each end therein, and Soder it close at A with the usual Cement, remembering to lift up the lower End a little from the bottom of the Vessel FB, that the Liquor poured thereinto, may have free passage into the Vessel: then begin to pour Quick silver down the Cane into the Vessel, raising up the water, till the Vessel is quite full (the air having its exit at the Beak H) and to be certain all the air is gone, let some Water out at the Beak H, and immediately Seal it with a Flame; noting, at the same time, the Degree the Mercury stands at in the Vessel IK: afterwards, pouring in more Mercury, fill the Cane to the Top; then if the Water by this force is compressed, the height IK will gradually increase, as the Water yields: we by a charge of 80 l. of Mercury, 
Brac. 4.  in a Cane above 91 Inches long (for so much our Instrument held without cracking) could not perceive the Levelly IK raised an Hairs breadth, the Water obstinately resisting the force of so great a momentum.   

The Third Experiment.  

Tab. 17. Fig. 3.  WE ordered a thin large Vessel of Silver to be cast, and filled it with Water cooled very well with Ice, and screwed the Cover on with a very close Screw; then we began to hammer the Vessel gently every where, and the battered Silver (which being so little Ductile did not at all thin, and distend itself, as refined Gold, Led, and other soft Metals do) lessened, and compressed the inward Capacity of the Vessel by Degrees; yet the Water for all this suffered not the least Compression; for at every stroke we perceived it to sweat through the Vessel at all the little Pores of the Metal, as Quicksilver when pressed with a piece of Leather spirits through in little drops.  
This is what we thought worth relating of these three Experiments; but are not yet able to say, whether, if the same Experiments be repeated in Vessels of greater strength, and if the Rarefaction of the Water be Augmented in the first Experiment, and so the Pressure of the Air; or if the height of the Mercurial Cilinder be increased in the second; or if in the last, the Vessel be successively made of thicker Silver; I say, we are not positive, whether the water may not at last happen to be compressed; this is certain, That Water in comparison of air resists the Compression (we may almost say infinitely) more: which confirms what we said at the beginning of these Experiments, That if Experience does not reach the very bottom of the enquired Truth, yet it goes hard if it strikes not out some Light.    

EXPERIMENTS To prove there is no Positive Levity.  
ANcient, and Famous is that Question, Whether those Bodies that we usually call Light, are so really in their own Nature, and mount upwards from any proper tendency; or whether their Motion be no other than a chase, or flight they are forced to by more heavy Bodies; which having the greater force, and desire to descend, and place themselves undermost; press, and as it were, compel the other to rise? This Opinion, which chiefly seems to have been entertained in these latter Ages, was yet not unknown to the Ancients: Nay, it was Asserted from rational grounds by many Philosophers in those times; among the rest clearly by Plato in Timaeo; and he advanced so far upon the probability of that thought, that he not only holds, That the heavier Bodies force up the less heavy, as Fire does Air: but also the more heavy, as Water in respect of Air, when ever it is made lighter by the interspersion of Fiery Particles: and this he seems designedly to insinuate in the above-cited Dialogue of Timaeus, when he says, That the fire rising from the hot Entrails of the Earth, and not entering into a Vacuity, thrusts forward the Air that is contiguous to it; which not only gives way thereto, but even divests it of those moist Particles wherewith it ascends; and then helps it forward, and raises it up unto the seat of fire, and that by no other, than by the natural gravity of those humid parts, being (by means of the Coalition with it) attempered by the new acquired Levity: however this may be, in confirmation of this Opinion, we will produce only Two Experiments, whose weight may perchance make up the deficiency of their Number.  


Tab. 18. p. 119.   
The First Experiment.  

Tab. 18. Fig. 1.  LET there be a Cilinder of Wood ABC, whose base BC exactly touches the Horizontal Plane DE; and that the Ambient air getting between the Two Superficies', may not hinder the trueness of their Contact, let the Base of the Cilinder be lined with a Plate of Metal plained, and well polished, and another like piece Leaded into the Horizontal Plane, then making a Ridge with Wax, or Plaster round about the Cilinder, pour Mercury into the Trench up to F, that the Contact may be every way covered and hindered from the ingress of the air: Then fasten the end of the Cilinder A to one of the equal Arms of a Beam GH, whose Centre is I; at the other End H, hang the weight I, equal to that of the Cilinder ABC: it is manifest to sense▪ that to raise the Cilinder from the Plane, the Weight L is insufficient, but several weights must be added to the End H, till at last (suppose) L and M raise it, resisting now with a double force; that is, with that of its own weight equal to L, and with that of the Contact, or Repugnance to Vacuity, or what else it may be termed. The Superadded weight M must not only equal, but exceed the power of the said Superficial Contact.  

Tab. 18. Fig. 2.  To measure this force (which in our Instrument was about 3 l.) put the Cilinder into a Cilindrical Vessel of Wood, or Potter's Clay glazed NOP, of an equal, or greater height therewith, that the Base of the Cilinder may touch exactly the Plane of the Vessels bottom; let that also be covered with a polished Metal or ground Glass. Then pour Quicksilver into the Vessel NP, to what height you please, even to the Top of the Cilinder, which will never separate it from the bottom; but if with the hand you move the Base BC from the Plane OPEN, it will with great force rise up, and swim upon the Quick silver.  
Seek then how great this Raising power is, supposed to proceed from lightness; by us 'twas so found: we loaded the Top of the Cilinder A with so much Weight Q as would sink it to the bottom: which Weight in our Experiment being about 5 l. we concluded, the force enquired to be so much: Next we considered, That the Resistance of the Contact of the Superficies' was no more than 3 l. (as was said) and the force of the supposed Levity of the Cilinder was found to be 5 l: wherefore in this case, that of the Levity was more than that of the Contact: wherefore again, considering the Cilinder of Wood AB closed down with its Base BC to the Plane OPEN, there were then two contrary Powers acting; viz. That of 5 l. from the Levity to raise it; and that of 3 l. from the Contact which held it down: now the lesser force ought to yield to the greater, and so the Cilinder be raised: but it was not so here; for the Contact was not loosed: wherefore it seems we must conclude something besides Levity buoyed it up.   

The Second Experiment.  

Tab. 18. Fig. 3.  LET there be a Wooden Vessel ABCD, in the thickness of the Bottom whereof a Concave Hemisphere is turned EFG, exactly fitting a Ball of Ivory H, adapted to its greatest circle EGLANTINE; then the whole Vessel was filled with Mercury, so that the Globe was quite covered therewith; it is manifest, that the weight of the Mercury incumbent upon the bottom of the Vessel, and hindered from running between the lower Convex of the Ball, and Concave of the Vessel by the closeness of the Contact at the circumference EGLANTINE, was not able by descending thither to raise the Ball by pulsion, but the Natural Levity of the Ivory, if there be any such thing, might easily buoy it up in the heavy Ambient of the Quicksilver. But this did not follow; the Ball remaining unmoved in its socket under any height of Mercury.  
Nor can it be objected, That Nature's avoiding a Vacuum (which must follow upon the first loosening of the Ball from the concave of the Vessel) hindered the Natural Levity of the Ball from its Effect; for though we made an hole through the bottom of the Vessel FI, whereby the air had admission to fill the space left void upon severing the Ball; yet for all this it was not raised.  
And because it may be said, That the Ball being touched by the air below, is not lighter, but heavier than it; we again stopped up the hole, and enlarged the Socket (as it appears) ELG, so that only the Edge, or upper circle of the hole EGLANTINE remained equal to the greatest circle of the Ball; but the Hemisphere EFG was not now fitted to the concave ELG, as is plain in the Figure: we then filled ELG with Mercury, and forcibly thrust down the Ball till its greatest circle touched the Edge of the concave: now though it was but slightly held by the Circle EGLANTINE, so that with a very little force it might be turned about; yet we filled up the Vessel with Mercury, and it was not raised, nor moved.  

Tab. 18. Fig. 4.  Lastly, That it might not be suspected, that the Mercury poured on, by pressing upon the Ball, held it down with its weight from swimming; we took instead of the Ball H a Conical Glass Vessel ABCD, and fitted a lesser circle thereof to the Edge OF, and pouring Mercury round about it, it kept still unmoved: and to be satisfied, if the supposed tenacious Union between the Glass, and the Mercury, together with Nature's fuga vacui, were able to surpass the power of the Glasses Levity; we tried the force of that Contact by taking away the Mercury from about the Glass, and fastening of it to the one Terminus of an equal Balance GH, hanging a weight I at the other H, till the glass was loosened from the Socket OF, which weight was with us about a Pound▪ than filling the Vessel again with Mercury, we set the Glass to swim therein, and loaded it (as in the other Experiment) till it sunk it to the bottom, and kept it there: this Weight (which with us was about 2 ½ l.) may be the true measure of the momentum, believed to proceed from the Levity of the Glass ABCD, which is more than that whereby it resisted a vacuity which was but one Pound. Then if the Lightness is that which causes the Glass to swim, it would have produced its Effect, dissolving the Contact, since its force is much greater than that of the Contact resisting it: but it does not do it; therefore it seems, that the same is confirmed by this Second Experiment, which was concluded from the former, viz. That it is some other Cause besides the Levity, that lifts up the Ivory Ball, and the Glass Vessel.    

EXPERIMENTS Magnetical.  
Although the strange Effects of the Magnet are so boundless an Ocean, that though many Discoveries have been made thereon; yet 'tis probable, enough remains to satisfy the Labour and Curiosity of future Adventures: yet we have not hitherto been so hardy to launch forth into it; well knowing, that any thing new therein, requires a long application, and uninterrupted by other speculations: wherefore we would not have it thought by any, that with two or three Observations upon this Subject, we should be so vain to boast, that we have brought any Light to the Magnetic Philosophy; for we rather own, that these hints are mean enough, and it may be not altogether new, being such as have not been aimed at in a designed Application of our Endeavours Magnetical; but either have been accidentally found out, or sought after upon some particular end by some one of our Academy. But such as they are, we were unwilling to conceal them; our intent being to communicate all that has any agreement with Truth, though of but little Value.  

The First Experiment,  
To discover if (except Iron or Steel) there be any Solid, or Fluid Body, which interposed between the Magnet and Iron, will cause any variation, or quite cut off the Passage to the Magnetic Virtue.  

Tab. 19 Fig. 1.  AT one end of a Wooden Box ABCD, we fixed a Compass, and opposite to the Dart (respecting the point E) at the other end of the Box, we moved a Magnet, and gently approaching it nearer till the Dart was removed one Degree, that is, from E, to F, we there fixed the Loadstone, and in the space remaining between it, and the Compass, we set either glasses filled with Mercury, or Wooden Vessels filled with Sand, or filings of Metal, (except of Iron, or Steel) or solid Parallelipipid's of the same Metal, or of divers Stones, and Marbles; but still we found the Dart unmoved from the Point F. Lastly, we filled the same Vessels with Spirit of Wine, and set it on fire, yet that Flame did not in the least divert the Power attracting the Dart to F: and a thin Plate of Iron or Steel, only was able to vary it, and make it return to E, as is already known. And not only the abovenamed Causes were unable to obstruct the Magnetic Activity; but we have laid upon one another 50 pieces of Gold, and laid a Needle upon the uppermost, which has obeyed the Motion of a Magnet, moved under the lowermost.  

Tab. 19 p. 124.    

The Second Experiment,  
To show yet more nicely, Whether the Magnetic Virtue suffers any change by passing through divers Fluids.  

Tab. 19 Fig. 2.  WE hung upon a small stick cross a Glass Vessel AB, a Needle touched with a Loadstone, and in the bottom of the Vessel placed a little Cilinder of Lead; upon the upper Surface thereof we fixed two Points of Brass, (they may be of any metal but Iron) one placed in the Centre, the other the breadth of a Crown off it; then we adjusted the Needle exactly Perpendicular to that in the Centre, and placed the Magnet at such a distance, as not to move it; Then we gently approached it toward the Needle, keeping the Pole still direct upon it; which to be certain of, we slid the Stone with one of its sides along a Ruler CD fixed in a Frame, and levelled exactly upon the Two Points, whereof that which was not in the centre respected the Pole of the Magnet, as well as that which was: coming nearer and nearer, at last its virtue began to act upon the Needle, which sensible of it, moved softly toward it. The Observer did not rest there, but thrust the Loadstone a little forwarder very slowly, till the Point of the Needle reached to the Second brass Pin, which was nearer to the Loadstone: then he stopped, and gave a Mark upon the ruler, at the distance between the Magnet and Needles Point, which was just over E. After this, the Magnet was removed, and fair Water poured into the Vessel about the Needle, and the Operation was repeated as before, by approaching the Stone gently till the Needles Point touch upon E; and again, the Distance upon the ruler was marked: and throwing out the Water, 'twas reiterated with several fluids, the Distances being taken every time between the Point of the Needle and Magnet: from all which it appeared, that the Magnetic Virtue was neither weakened, nor enforced by the differing Fluids through which it passed: indeed the distances were divers, but that happened according as a lighter or heavier medium facilitated more or less the motion of the Needle in it; whence the same Virtue and Power moved it at a further or nearer Distance; for 'twas observable, That those several Distances at which it acknowledged the Loadstone, were in reciprocal Proportion to the Specific Gravity of the Fluids; that is, to the making the Needle lighter. Amongst all the Liquors experimented, the Needle was drawn at the greatest Distance in Sea-water, at a lesser in common-water, lesser in Spirit of Wine, and least of all in the common Medium of Air.  
Note, That Repeating this Experiment at several times, it may happen, that this Distance varies at one time from another; but it is to be considered, That this may arise from External Accidents, viz. the different Temperature of the Air, a rustier or brighter Needle, or the fortuitous nearness of some Iron, which makes the direction of the Magnetic Virtue to deviate some way or other, etc. Wherefore we still took care to make this Experiment upon a large Table glued together, and fastened with wooden Pins instead of Nails: and the Observer (and every body else that came near) was very careful to lay aside any Iron they had about them, it being well known, That to approach the Table with a Key or Knife in their Pocket, immediately caused an alteration in the Experiment; but when all sort of Iron was laid away, the Effect was always the same: but for what depends upon the other forenamed accidents, such as the Temperament of the Air, and the like, which cannot be helped; we have found, that they do indeed cause some difference in the Distances; that is, The Distance whereat the Needle was moved Yesterday, is not the very same to Day, in the same Mediums; yet the Differences observed at these divers times, were still found nearly proportionate to each other.   

The Third Experiment,  
To try if the Activity of the Poles of a Magnet altars, being placed respecting the opposite Poles of the Earth.  
Tho' in this Experiment we have not yet proceeded so far, as to satisfy in order the many particulars depending thereon; yet in general we will touch upon those few which we think we may aver upon any more certain grounds; as these: The North Pole of the Magnet when respecting the same Pole of the Earth, draws a Needle hung freely in the Air, at a greater distance, than when it respects either the South, or East; placed Westward, its Sphere of Activity is larger than Southward, and a little less than Northward.  
On the contrary, the South Pole not only seems to us, to act at the same Distance Southward, as the North Pole Northward; but also in a North Position happened to draw the same as it did when Southwards; towards the East or West it becomes more faint and languid, as the North Pole does also.    

EXPERIMENTS, Touching AMBER, and other ELECTRIC BODIES.  

Ambra Gialla. Cera Lacca. Diamante. Zaffiro Bianco Smeraldo. Topazio Bianco.  THE Electric Virtue, as all know, is excited by a slight, or violent rubbing in all Substances not Mineral. Yellow Amber is of all others best stored with this Power: next to which, the best Sealing Wax seems to take place; these are followed by Rose Diamonds, the White Saphire, the Emerald, the White Topaz, the Spinelle, and the Ruby Baleis; after them, are all the Transparent Gems, as well White, as Coloured; all which, more or less show themselves to be Attractive.  
And in this it does not seem, that they keep any Scale or proportion in respect of their hardness: for we find that the soft Spinelle and Ruby-balleis, not at all to give place to the hardest Diamond, or Saphir, in Electricity. Next precious Stones, 
Ambra Bianca e nera.  come Glass, Crystal, Yellow Amber, and Black; between all which Bodies, there is little difference of force, they being all very weak in Operation. For the rest, neither Lapis Lazuli, 
Lapis Lazzali, Turchine, Diaspre, Agate, Coralli, Pearl, Metalli, Lapilli de Sali.  Turquoise, Jasper, Agate, nor other the like Precious Stones not Transparent, nor Rocks, nor the finest Marble, nor Marine Bodies, as Coral, and Pearl, nor Metals, nor Cristalized Salts, have any attractive Virtue, as some have wrote they have; and it may be the mistake came from their observing some light Bodies, as bits of Straw, and Paper, etc. stick to them, which we have also observed; but perchance that might happen (as some think) from a Superficial roughness, or inequality in the Substances, whose Points piercing the light Bodies, raise them up therewith: willing to avoid this Cheat, we resolved to attribute Electricity to no Substances, that after a due Friction did not attract those light Corpuscles at some small distance, which we only found done by the above named.  
We have also Noted, That whatever External accidents altars Amber (whether by heating, or freezing, or wetting with any Liquor) the same has the like Effect upon Gems, and all other Electrick Bodies: yet indeed it is more manifest in Amber, as it is impregnated with a greater Virtue: wherefore omitting all others, we will here only treat of that.  
Amber then, of all sorts of Bodies presented to it, refuses only to draw Flame; although Plutarch says, 
Saggina. Bassilico.  That it does not attract any thing steeped in Oil, and Grease; or as some say, Basilicon, which we found a mistake: yet Smoke is attracted; and it is very curious to observe, how by holding a piece of Amber rubbed hot, to the smoke of a Candle blown out, it will presently bend, and wave towards the Amber; part of it will be arrested by the Amber; and part, as if reflected from a Glass, will mount upwards, while that which remains, unites itself like a small Cloud, and as the Amber cools rises in smoke again, and vanishes.  
On the other side, Flame, not only refuses to yield itself; but if a piece of Amber, after it is well rubbed, be a little while held to it, it loses its Virtue, and a repeated Friction is but necessary to make it attract; and if after it has taken up any small thing, it be held to the Flame, it will immediately let it go again.  
But the Heat that comes from burning Coals, is not so great an Enemy to the power of the Amber, it being sometimes capable of exciting it without rubbing, and indeed by the heat received from the Fire only, it acts faintly; but then becomes more vigorous, by adding friction thereto.  
Ice alone is not prejudicial to the Amber, but when altered by mingling therewith Salt, or Aqua Vitae, it so quells the Virtue, that some time is required, as likewise a long and violent rubbing, to regain it. So that it has been thought, that this stupifying of its force proceeds not from the increase of Cold in the Ice, from the sprinkling of Salt, or Aqua Vitae; but rather from some fine Rust, or hoariness, as it were, contracted by the Amber, from the Salt; or rather indeed, from the imbibing the Aqua Vitae, which is one of the Liquors that destroy the Electricity of Amber.  
Neither are all matters capable to draw forth this Virtue from the Amber; for being rubbed upon Bodies of a smooth Superficies, such as Glass, Crystal, Ivory, and polished Metals, or Gems, it still continues asleep, and shows no sign of Life; so that it needs some small inequality and asperity of the Superficies; as Cloth, Linen, and a thousand other things have, unnecessary to be named here: and likewise Human Flesh excites this Power; but some more, some less: and we have known some, that let it be rubbed never so long on their hand, yet could not happen to make it attract.  
It is commonly believed, That Amber attracts the little Bodies to itself; but the Action is indeed mutual, not more properly belonging to the Amber, than to the Bodies moved, by which also itself is attracted; or rather, it applies itself to them: of this we made the Experiment; and found, that the Amber being hung at liberty by a thread in the Air, or counterpoised upon a Point like a Magnetical Needle; when it was rubbed and heated, made a stoop to those little Bodies, which likewise proportionally presented themselves thereto, and readily obeyed its call.  
Liquors also are sensible of this Power of the Amber; the smallest drops of which, it attracts, even those of Mercury: indeed it is unable to manage them, except very minute; whence it soon lets them go, after they have been attracted: but when we have presented it to the Superficies of standing Liquors, and Mercury itself, it did not raise up one drop; but as it were, made the Level of the Superficies swell under it; which raised itself in a little Bubble toward it, but inverted so, as to respect it with its pointed part. This Effect may be better observed in Oil, or Balsam; than other Fluids  
There are some Liquors wherewith the Amber being wetted, after rubbing, draws not; and there are others not producing this Effect; they that so act, are generally all Natural Waters, Distilled Waters, Wines, Vinegar, burning Waters, all Acids; the Juces of all sharp Fruits, all Liquors distilled from Animals. Balsams, and all Artificial Liquors, as Juleps, Essences, Spirits, and Oils made by Distillation: on the other hand, these are ineffectual; Oil of Flints, Salad Oil, Oil of sweet Almonds, and bitter, made by Expression. Tallow, Fat; and Lastly, all Butter, whether simple, or Perfumed, with any Flowers, Ambergrice, or Musk; provided unmixed with Essences or Oils.  
A particular Effect has been observed in Diamonds, 
Gruppiti Tavole.  whereof the Roses (as we said) are reckoned among the most Electrick Gems; but the Tables were found so weak, that they seemed sometimes quite deprived of that virtue; and some thought that their plain Superficies had no part in the Effect, seeing when the Diamond has depth, though smoothed and polished upon the Wheel, it draws vigorously; whereas the flat Table-Stones, that are shallow, such as are set in Lockets at the end of Necklaces, commonly called Spear, though very large, when strongly Rubbed, will yet not draw; or if they do, 'tis so faintly, that you must make them touch some hairs of the bit of Paper, or Straw, to make them raise it up; yet 'tis not to be doubted, but some may be found that have a little force; yet of these, we at least were so unsuccessful as to find but few. We indeed had one which by many trials for several days, we were never able to make attract; but a Year after, desirous to see the same tried again, we took the same Ring in which the Stone was set, and having but slightly rubbed it, as we used to do upon the Cloth, as soon as ever it was held to the bit of Paper, it drew it vigorously: this same Effect was often observed with wonder by all those that the year before had often attempted in vain to make it draw: and on the contrary, (as we said at first) the fausets (i. e.) those that are ground of their own Octoedral Figure, seldom or never failed.  
In fine, since Amber, and all Electrick Bodies have been observed to be obstructed by a very thin Veil placed between them, and the thing to be attracted; therefore taking a sheet of Paper, we made several little Lattices in it; and the first of them was covered with a close Network of hair, another with the Lint of a fine Rag, a third with a Leaf of Gold; the success was, That the Electick Power of the Amber did not penetrate them.   

EXPERIMENTS ABOUT Altering the COLOURS of several FLVIDS.  
THere is nothing more frequent amongst the Niceties of the Chemists, than their Fantastic humour of changing Colours; we indeed do not professedly meddle therewith; and if any such Trials were made, we were moved thereto, from the occasion we had of making use of some Liquors, fit to examine the Qualities of Natural Springs. Concerning which, we will relate the little that came to our Knowledge; again reminding the Reader, That by the perfixt Name of Essays, we would intimate, That we do not presume, we have examined these Matters with all the Experiments which may be thought on; but only barely given some hints of those things we were most inclined to take pains about.  

The First Experiment,  
Of altering Water.  
WAter Distilled in a Leaden Still, thickens and muddies the Water of all Rivers, Baths, Fountains, or Wells wherewith it is at any time mixed; and losing their Transparency, they both look white like Whey; only Water Distilled in Glass Vessels, and of Spring Water, that of the Conduit of Pisa remains Limpid and Transparent. But all those Waters so muddyed, become clear and pure again by a few drops of strong Vinegar shook together with them.  
The same Waters are changed by a dropping in of Oil of Tartar, 
Olio di Tartaro e d' Anici.  and Oil of Anniseeds, which give the Appearance of a little white Cloud higher, or lower, therein; which by shaking, diffuses itself through all the Liquor, and inturbidats it. This also is brought to its former clearness, by a small Quantity of Spirit of Sulphur, which at first raises a few little bubbles. 
Sp. di Zolfo.   
Note, That all Waters indifferently do not become turbid by the abovenamed Oils; and those Waters that are not altered by waters stilled in Lead, are likewise left Transparent by Oil of Tartar and Aniseeds. Moreover, inflammable Waters, Waters stilled in Glasses, and that of the Conduit of Pisa, are not at all changed from their Natural clearness; and we find that in Waters generally held the lightest, purest, and noblest, the little cloud is thinner and higher, which is raised therein; and only in heavy Waters, and those that are impregnated with Minerals, or dreggy, it thickens it like Milk; whence some have pretended to prove Waters with some of the abovenamed Liquors; for thereby is discovered the more hidden Quality of them, and so their Goodness or Badness found.  
If at any time the Thickness, and Turbidness of the Water is very great, and not to be Clarified by the ordinary proportion of Liquors, it may be increased by some drops still agitating the Water, till you see it become clear.   

The Second Experiment.  
Of Altering Wine.  
OIL of Tartar, not only in Water, but also in Wine, produces the same Effect; for through its Natural cleansing Quality (as is known) it makes a separation in all Liquors, of what ever is mixed with them, from the purer parts, by a sediment that it lets fall; whence that which shows like a white Cloud, higher, or lower in the Water, according to its different Qualities and Weight, in all sorts of White Wines that we Experimented, appears like a thin Cloud of a Red Colour, which by shaking the Wine, quits its first place, and disperses itself uniformly throughout the whole Body; it makes no other change in Red Wines than a little ting deeper; especially toward the bottom.  
On the contrary, Spirit of Sulphur shows no alteration in the natural Transparency of the Wine; and likewise restores it to those deprived thereof, by the Oil of Tartar.   

The Third Experiment.  
Of the Tincture of Roses.  

Tincture di Rose rose.  A Tincture of Red Roses (extracted with Spirit of Vitriol) being mixed with Oil of Tartar, shows a fair Green: with a few drops of Spirit of Sulphur, it ferments all into a Vermilion froth, and at last returns to its first Rose Colour, without losing its smell at all; nor will it be again altered by dropping Oil of Tartar into it.  
We found the best way of getting the Tincture of Roses for this Experiment, as follows.  
Taking a good handful of dried red Rosebuds, we cut them, and putting them in a Glass, with one Ounce of strong Spirit of Vitriol, stirred them together for a quarter of an hour, in which time the Roses were well Macerated, and the Tincture Extracted; to this must be added, at Three or Four times, about half a pound of Spring Water, still shaking the Glass till the very deep Colour of the Spirit being Diluted, the Water is all tinged therewith: then we let it stand an hour, and so obtain a lively and beautiful Tincture of Roses. To half an Ounce of this, put Ten or Twelve drops of Oil of Tartar, and afterward as much Spirit of Sulphur, which suffice to produce the Related Effects.   

The Fourth Experiment,  
Of the Tincture of Saffron.  

Safferano  WAter tinged with Saffron, helped a little with the Tincture of Roses, but not so as to lose its golden Colour, changes green with Oil of Tartar, and again yellow with Spirit of Sulphur.   

The Fifth Experiment.  
Of Greene's.  

Verde Giglio. Vinato.  WAter Coloured with Iris Green, mixed with Spirit of Sulphur, makes a Purplish Colour, and with Oil of Tartar takes its own again.  
This Green is a Tincture taken from the Purple Flower-de-luce, which prepared with a mixture of Quicklime, gives a pleasant lively green, much demanded by Limners; then 'tis set to evaporate and dry in Muscle-shells, as shell- Gold and Silver.  
See more fully the ways of making the like Extracts in Antonio Neri's Book of the Art of Glass-Painting, Printed at Florence, 1612, Lib. 70. cap. 108, 109, and 110. as likewise, how to take the Lake of any Flower.   

The Sixth Experiment. Of Violet Colours.  
JUice of Lemons, Spirit of Vitriol, and Spirit of Sulphur, change the Violet Colour of Lacca to heighten Gold, 
Lacca Muffa.  and the Tincture of Blue Violets, into a Vermilion; which with the Oil of Tartar again, makes a Purple: also Vinegar gives them a red Colour, but 'tis fainter.    

EXPERIMENTS About The Motions of SOUNDS.  
SOund, that Noble Accident of the Air, keeps so unchangeable a Tenor in its Motions, that a greater or lesser impetus wherewith the Sonorous Body produces it, is unable to alter it. This strange Propriety of Sounds is related by Gassendus, who affirms positively, That all sounds, whether great or small, pass the same space in the same time: and he declares, That he had Experimented it in Two sounds, the one much louder than the other; that is, one of a Musket, 
Moschetto. Artiglieria.  and the other of a Piece of Ordnance: in repeating this Experiment, which we found undoubtedly true, we happened to observe some Particulars which we did not think fit to conceal, since possibly they may offer something not thought upon by every one; or if thought on, yet all Persons may not have the opportunity and means of satisfying themselves Experimentally.  

The First Experiment,  
Of Sounds passing equal Spaces in equal times.  

Spingarda. Smeriglio Mezzo-Cannone.  WE made this Experiment in the Night, with three several sorts of Pieces, with a Harquebus, a Falconet, and a Demi-canon, planted at Three Miles distance from the place of Observation, whence we could well discern the flash of the powder in firing the pieces; from this flash then, we always counted an equal Number of Vibrations of the Pendulum of a Clock, whether the Shot was of the Harquebus, or the Falconet, or the Demi-canon, and that upon all Levels and Directions of the Barrels of those Pieces.  
Since Gassendus was so taken with that known Example brought by the Stoics to represent to the Life how the invisible propagation of sounds is made by the Air, we will take this opportunity to consider it: they say, That, as we see standing Water move in Circles by casting in a little stone, which Waves successively enlarge into greater and greater Rings, till at last they reach the Bank of the Water, and there vanish; or dashing themselves against it, are reflected back again: so they assert, That the air every way undulates from the sonorous Body in successive Circles for an immense space, which Wavings meeting with our organs of Hearing, and finding them soft and yielding, impress upon them a certain Tremour, which we call Sound: hitherto the Stoics, without Prosecuting it any farther: but Gassendus was so pleased with the aptness of the Example, that he desired to go through with it, and make it capable of explicating the peculiar properties of Sound; one of which, as was said, is the unalterable Velocity of its Motion: whereupon he says, That the undisturbed Proportion of the swiftness of sounds, agrees with a like observable also in the undulations of Water, which he affirms, are neither swifter nor slower, but always with the same degree of Velocity approach the Shore, whether made at first by a great or small Stone, whether falling only with its own weight, or forceably cast thereinto: which nevertheless (with due respect to so great a Man) we have not found to answer; for we have observed by frequent Experiments, that by how much the Stone is larger, and the force greater, wherewith 'tis thrown into the Water, by so much the Circles approach the shore swifter.   

The Second Experiment,  
Of Contrary, and favouring Winds.  
THere is another strange observable in the Motion of sounds, related also by Gassendus: (i. e.) That it is neither retarded by a contrary blast of Wind, nor accelerated by a favouring Gale; but always travels the same space, with an uninterrupted course, in the same time. This likewise we desired to bring to the Test, and found it true, thus:  
At a Season when the West Wind blue, we made Two Discharges of two Pieces, one planted Westward, the other Eastward, at an equal distance from the place of Observation: so that the one was favoured by the Wind, the other crossed; but for all this, they both transmitted their sound to the Observer in the same space of time, measured by the equal Number of Vibrations of the same Clock: though indeed, that which was Eastward, and so against the Wind, was observed much more Languid, than that which was Westward.   

The Third Experiment,  
Of the Equability of Motion in Sounds.  
ONE of our Academy took occasion from those Experiments to think, that the Motion of all Sounds might be equable, as well as equally swift; we arguing, That thence, if true, many curious and profitable hints might be gained: but first, to be fully satisfied if there were really any such equability, we made the following Experiments.  
At the distance of one of our Miles exactly measured, which are about 3000 of our Braccia, or 5925 Foot, 
Spingarda. Mastio.  we fired several Pieces, that is Six Harquebuses, and as many Chambers; at each whereof from the Flash to the arrival of the Report, we counted Ten whole Vibrations of the Pendulum, each for which was half a second. Repeating the Experiment at half a Miles distance, that is, at the mid way, we observed it to be exactly in half the time, always counting at each Report, about five Vibrations, wherefore we rested satisfied of the certainly of this equability.  
The Consequences which we pretend will follow from this equability, amongst the rest are, That by the Flash and Sound of divers shot, we might obtain an exact Measure of the Distances of places; particularly at Sea, of Ships, Rocks, and Isles, where we cannot come to take several bearings, as is requisite in using the common Instruments: we may also by a single stroke made upon Wood, Stone, or Metal, or any other sounding Body; judge how far off he is that gives the blow; telling the Vibrations between the stroke seen, and the hearing of the Noise, which if the Wind be favourable, may be heard for some miles, and it will be easy as well as curious, to find the Distance of clouds from us, and of what height from the Earth, Thunder is generated, counting the Vibrations between the Lightning and the Blow.  
If we would likewise know the Distance of Places, which because of the Roundness of the Earth, or interposition of Hills, we cannot have a sight of, yet with ease we may obtain it, and that by Two Discharges, answering each other; so that to our firing at one place, they must return another at the other place; and taking the middle time between our discharge, and the arrival of their Answer, the half of the Sounds Journey will be found, that is, the whole Distance of the Places sought.  
By the same way of sounds, the Maps of particular Places may be adjusted, and truly laid down in plano; taking first the Angles of Position of the Cities, Castles, and Villages, to place them in their due situation; with several the like curious Inventions very, useful, nor to be disesteemed.  
Then to gain the unknown Distances of each, we may make use of time for a Scale, the sound travelling with us the known space of a Mile in Five seconds.    

EXPERIMENTS About Bodies Projected.  

Dialog. 2d. de Sistemi Colubrina.  IT was Galileo's Opinion, That if a Culverin be planted upon the top of a Tower, and a Shot be made point-blank (i. e.) Horizontal, according as the Charge of Powder in the Piece is greater or less, so should the Ball fall at a proportionate distance of 1000, or 4000, or 6000, or 10000 Braces, etc. and that all these shot would be made in equal time to each other, and all equal to the time of the Balls falling from the Mouth of the Piece to the Ground, without any impulse; but only dropped Perpendicular, when there is no accidental hindrance from the Air, which may in part impede the swift Motion of the Shot: we were desirous to bring this to the Test of Experience, and it seemed to us, that we succeeded very well; wherefore we will relate what little Remarkables we can with certainty say that we observed on this Subject.  

The First Experiment,  

Falconetto.  Of Horizontal Shot, with a Falconet from the top of a Tower.  
UPon the Top of the Tower of the Old Fortress at Legorn, about 94 Foot high, with a Falconet carrying an Iron Ball of 7 l. ⅓ with a Charge of 4 l. fine powder, 
50 Brac  we made several Shot Horizontal into the Sea with the Balls, and observed them to fall into the Water at about ⅔ of a Miles Distance in 4 ½ Vibrations, 
Their mile is about 5925 f.  each whereof was an half second: and examining the Perpendicular fall of other Balls of the same size from that Height of 50 Braces, we found there were 4 of the same Vibrations.   

The Second Experiment,  
With a Demiculvering. 
Colubrinetta.   

Fasciate.  WIth a Demiculvering carrying 14 l. Ball of Iron, and 10 l. of fine Powder, the Balls being wrapped about in 5 of the abovementioned Vibrations, fell into the Water; and without being wrapped about in 5 ½ Vibrations; 
Ignude.  whence it seems, that they flew farther than the other.   

The Third Experiment,  
Of Perpendicular Shot with an Harquebus. 
Archibuso   

Dialogo 40 deal Trattato delle 2 nuove Scienze.  GAlileo writes in his Discourse of Bodies Projected, Words to this purpose: From the height of 100, or more Braces, fire an Harquebus with a Leaden Bullet Perpendicular to a stone Pavement, and with the same Charge shoot another at the distance of one or two Braces upon the like Pavement; examine then which of the two Balls shall happen to be more battered; for if that from above shall be less battered than the other, 'tis a sign that the Air has retarded it, or diminished the Velocity imparted thereto by the Fire at the beginning of its Motion; and consequently, that the Air will not permit such a Velocity to increase by falling from any great Height. That when the Velocity communicated by the Fire to the Ball, excceds not that which the same Ball would naturally acquire by descending, the stroke of the Ball downward then ought to be rather more violent than faint. I have never made the Experiment (Galileo subjoins) but am inclinable to think, that the Ball from an Harquebus, or piece of Ordnance coming from any great Height Perpendicular, will not give such a blow, as it will when discharged upon a Wall some few Braces off (i. e.) so few, as that short passage, or (we would say) cutting of the Air, shall not have taken away the Excess of the unnatural violence communicated by the Fire.  
We made this trial with a Harquebus, not firing it against a Stone Pavement to observe the battering of the Bullet, but against an Iron Breastplate, 
Pettabotta.  and in this we found that the Shot from a lesser height made a deeper Impression than that from a greater; because as was urged by some (after Galileo) in a longer Passage the Ball loses continually (by cutting the interposed Air) some of the Impetus, and preternatural force received from the Violence of the Fire.   

The Fourth Experiment.  
That the power of Motion already impressed, is not destroyed by a new direction.  
IN Confirmation of what Galileo Affirms in several places, viz. That the Virtue impressed upon Bodies projected, is not destroyed by a new direction of Motion, it was by some proposed to make the following Experiment.  
We fitted upon a Carriage with Six Horses, a Saltamartino, carrying 1 l. Ball of Iron) so as it stood Perpendicular to the Horizon; with this we made divers Shot with the same quantity of Three penny weight of Musket Powder; 
3 Danari  some we made with the Carriage standing still, others while it ran a full Career upon a Level Plain: at the first Trials the Ball fell near the Mouth of the Piece: at the Second, after the Carriage had run 64 paces from the Firing, to the Return of the Ball, it came short of the Piece but about 7 ½ Foot, where it fell; 
4 Br.  all the times were very near equal in all the Trials.   

The Fifth Experiment  
Much to the same purpose.  

Balestrone. Br. 78.  WE made the like Experiment with one of those Crosbows that are bend with a Bender, its Bullet of Lead weighing Three Ounces, and in 149 Foot Course (we mean from the Discharge to the Return of the Ball) it came short of falling upon the Carriage but 11 ½ Foot, and a Ball of common Clay in running 191 Foot, 
Br. 6. Br. 100 Br. 17. ½  fell short Three Foot. Whence some confirmed themselves more in the Opinion of the same Galileo, That the Air takes not a little from the force of heavy Bodies, that cut it, but more sensibly of light Bodies.    

MISCELLANEOUS EXPERIMENTS.  
THough it has been always chiefly endeavoured in our Academy to keep a continued Thread of Experiments upon what Subject soever they were made; yet that did not hinder the admission of any particular Observations as they were still suggested by any of our Members, arising from their proper Studies, though from the design then chiefly intended: Now of these irregular Experiments, there being some Quantity, since they have little or no Connection together; although they may be instructive, we have reserved some Essays of them, like the former, for the last place, as a Conclusion of the Work.  

An Experiment,  
To know the absolute Weight of Air in Respect of Water.  
THere was taken a Ball of Lead, closed every way, and full of Air; because this being immersed in Water, swum thereon, we charged it on the outside with so much Led as sunk it; and weighing all in exact Scales, we found it 31216 gr. being plunged in Water, the same altogether weighed but 4672 gr. so the difference was 26944 gr. which was the absolute weight of a bulk of Water equal to that of the whole Ball, and Led.  
Then pressing the Ball together, as much as its thickness would bear, without letting the Air out, and weighing it in the Air with all the Lead, 'twas found 31209; and this we concluded was the absolute Weight in uncompressed Air, as that was, which was in the Ball before it was battered together.  
In this State all being put into the water again, and weighed, 'twas found gr. 12518, which substracted from gr. 31209, (the weight of the Ball pressed together in the Air) there remained gr. 18691, the weight of a bulk of water, equal to the bulk, of the same Lead, and battered Ball. This Weight then of gr. 18691, being substracted from the other of gr. 26944, left 8253 gr. which was the Weight of a bulk of water equal to such another bulk of Air as weighs 7 gr. (which bulk was equal to the diminution of the bulk of ball by the battering:) whence we concluded, That the Weight of that sort of Air which we weighed, is to the weight of so much water, as 7, to 8253; that is, as 1, to 1179.  
This Experiment being by us repeated at divers times, the Proportion was not always found the same. Indeed, the variations have not been great, consisting in one, two, or three Hundreds of grains, more or less: Which is all we can pretend in making the Comparison between one body that, as we may say, never altars in its weight; and another, never twice the same.    

EXPERIMENTS Touching some EFFECTS of Heat and Cold.  

The First Experiment.  
Of a Steel Wire, seeming to grow lighter by being heated.  
PUtting in the Essay-Scales two Steel Wires of equal Weight, the one heated, the other cold; it seemed that this was heavier than the other: but holding a lighted Coal, or red-hot Iron near it, it soon came to an aequilibrium with the hot one. The same would have happened if they had been of Gold, or Silver, or any other Metal: likewise, if a lighted Coal be held over one of the Basins of a pair of Scales, when empty, it raises it; and if held under it, it causes it to descend. For all this, some of us could not apprehend, how the bare heating could any ways alter the usual weight of the Metal; nay, 'twas thought by some, that the Pressure of the Air might have its part as well as any other cause, in producing this Phenomenon.   

The Second Experiment.  
Of the vast force of Heat in raising up an included Liquor.  

Tab. 19 Fig. 3. 1 ½ Br.  HAving filled with Sp. vin. half of the Vessel AB, whose slender part was 35 8/10 Inches long, with two Sealed Balls of equal capacity, we set the Ball A in a Glass of Oil, over the Fire, and the Sp. vin. began to give notice of its Rarifaction by Rising: but afterwards, when the Oil boiled very fast, it retired all into the upper Ball, leaving that below quite empty with the lower half of the Cane. It is also necessary to promote this Effect, besides a strong Fire, to blow the Coals continually about the Glass; (this must be done through the hole of a Plank, serving to defend the Operator; behind which also the Observer must stand to look thorough a Glass in the same Plank) for when the Sp. vin. is all forced into the upper Ball, 'twill be thrown off: and not only that, but the lower will be burst with such force, as one time amongst the rest, making use of a brass vessel, instead of the Glass, for the Oil, it broke the bottom thereof, and tore off a Band of Iron of the thickness of a Crown, and cracked a Stone in the Pavement. But we made choice of Oil, and of Glass Vessels; because their Transparency makes the Procedure of this admirable Effect more visible. Else Wax, Pitch, or Lard, or it may be any unctuous Matter may produce the same Effect.   

The Third Experiment,  
About Antiperistasis.  
TO do something upon the score of Antiperistasis, we filled with Ice finely powdered, a Leaden Vessel, and putting thereinto a Thermometer of 50 deg. we let it stand still, and it composed itself to about 13 ½ deg. Then we plunged the Vessel into a Cauldron of boiling Water, regarding nicely the Thermometer, if in that instant that the Ice became encompassed with its contrary, it than gave any show of greater Cold, by subsiding. But that, as often as we repeated the Experiment, was never seen to alter a hair: nor was it ever observed to rise, when the Vessel being full of hot water, we plunged it in water mixed with Ice: nay, than it was readily seen to subside; for as much as the Fluid water more easily gave a passage to the Quality of the Ambient, than in the first Experiment the Ice could do. Nor let it be thought that all the Care possible was not taken to prevent the Air Encompassing the Thermometer from receiving any alteration, upon immersing the Leaden Vessel in Different Ambients, the said Vessel being let into a Plank, which was very broad round it, and so cut off all Communication between the basin under it, whereinto the bottom was immersed, and the air above; but for all this, we observed no difference from what is related.   

The Fourth Experiment,  
Whether Cold be caused by an intrusion of Frigorific Atoms.  
TO gain some light, Whether the chilling of Bodies were caused by the insinuation of any kind of peculiar Atoms of Cold, as the opinion is, They are heated by those of Fire; we caused to be made two Glass Vials like each other, with very slender Necks: being sealed Hermetically, we put one of them in Ice, and the other in hot Water; letting them remain some time, and then breaking the neck of each, off under Water; we observed in the Hot one a Surcharge, or Repletion from something got into it, observable by the Bubbleing of the Water, from a strong breath issuing from the Vial as soon as ever it was broke open. Some might think the same should have happened in opening the Cold one, if the Chilling of the Air therein had proceeded after the same manner, as the heating of that in the other; (i. e.) by the Intrusion or soaking of the Atoms of Cold exhaled from the Ice, through the invisible Pores of the Glass: but the quite contrary happened; for instead of breathing forth any surcharge of Matter, it showed an emptyness, or loss of something, (if there was not a condensation of what was there) since it sucked in so much Water in place of it.   

The Fifth Experiment.  
Of heating and cooling of Water by Salts, etc. And of hot and cold Ebullitions, etc.  

Vetriole.  VItriol, the Spirit being drawn off, remains like a Tartar, or Grumous Body, of a lively Fire colour, which with a long and continued Fire distils a blackish Oil, almost like Ink, highly corrosive. This being mixed with Water in a certain proportion, produces an immediate Heat, which increases without raising any Bubbles, or perceivable smoke, till the Glass wherein this mixture is contained can carce be endured in the hand: the like happens by mixing it with all other Liquids, except Oil, and Strong Waters; of which, the First is not in the least altered from its Natural State: and the Second, if a tall, scarce sensibly.  

Sal Nitre Sal Armoniaco.  On the contrary, 'tis a known Experiment, That Nitre dissolved in Water, chills it: and Sal Armoniac congeals to that Degree, that if in the Water wherewith 'tis mingled in a due proportion, you set a thin Glass of other Water (cooled, before well with Ice) the Cold produced by the said Salt, as it dissolves, will freeze it.  

Cold Ebullition.  Having mingled together one Third part of Sal Armoniac and two Thirds of the forementioned Oil of Vitriol, there followed an unusual Effect: for still as the Salt dissolved therein, it smoked, and boiled up furiously, and so much the more if we stirred it together with a little Stick, for than it rose up much easierly in froth, so as it then filled a space 25 times bigger than the Bulk of the Two separate Bodies, of Oil and Salt: but for all this fury of smoke and boiling, we not only could observe no sensible beginnings of heat, but a strange degree of Cold produced therein, chilling the Glass that contained it; and the Spirit of Wine, of a Thermometer immersed thereinto swiftly subsided, till the Salt being dissipated, and evaporated, the Boiling ceased, and the Oil returned to its former Natural state.  
Such a Production of Cold we have known, when ever we have repeated the Experiment; indeed that, as well as the Ebullition and smoking, is more or less, as the Salt is stronger, or the Liquor more refined. We have also observed, That a few drops of strong Water, 
Acquarzente. Sp. di Vetriolo. Olio di Tartaro. Sp. di Zolfo.  or Sp. of Vitriol put into the Oil in its greatest fury of Ebullition, stops it, and makes the Mixture immediately hot; adding Oil of Tartar, the Heat is augmented; the Smoke, and Ebullition returning; but by dropping in of Sp. of Sulphur it quickly cools again.  
It is worth a little Reflection: That as Oil of Vitriol mixed with all Liquors, heats them, (Oil and Strong Water excepted) so contrarily Shall Armoniac stirred together with all Liquors, cools, and refrigerates them more or less; (Oil, and Strong-water likewise excepted, upon which two only 'tis ineffectual:) and again, that upon mixing together▪ the same Oil of Vitriol, and Sal Armoniac, there should follow so wonderful a Cold Ebullition as is related.    

SOME EXPERIMENTS, TO KNOW If GLASS and CRYSTAL be Penetrable BY ODOURS and HUMIDITY.  

The First Experiment,  
Touching Odours.  

Olio dicera Quintes. di Zolfo. Estratt. dorina di Cavallo. Sp. di Cedrato.  OIL of Wax, Quintessence of Sulphur, and Extract of Horse's Urine, which are reckoned the most acute, and strong smells that are; do not sensibly transpire through a Sealed Glass Vial, as could by many persons that tried it, be perceived, though 'twas heated.  
The Halitus also of that thin Spirit that flies away upon cutting an Orange, or Lemon Peel, or which in a small Thread spins out of the same Peel when it is squeezed, did not penetrate to give any smell to a little Water contained in a Crystal Glass Sealed Hermetically.  
In like manner, Sealing up a Partridge in a small Glass Vessel, 
Starna  and setting it in a corner of the Room, and bringing a Setting Dog in, we led him round, near the place where it was set; but he showed no sign of perceiving the Partridge.   

The Second Experiment,  
Of Humidity.  
A Glass Ball being filled with Salt, well ground to Powder, and dried, was sealed up at the Flame of a Lamp, and put for ten days at the bottom of a Cistern of Water; and after that, as long in a Conservatory of Snow; but it did not increase at all in Weight; and when broken, the Salt was taken out so dry, that it fell to powder.  
Yet we have sometimes chanced to find in the Ball of Salt some little part thereof dampish; but we can not argue a Penetration from thence; for if it were really so, it ought not to be more in one place than another; whereas, that little moisture being always found in one place, 'tis very probable it was only a little of the Humidity which the force of the Cold drove out of the Air remaining in the Ball, and sticking as a Cover to the inside thereof▪    

SOME EXPERIMENTS Concerning LIGHT, and its EFFECTS.  

The First Experiment,  
Of the Instantaneous Motion of Light.  

Pag. 43. Edit. Lugd. 1638.  GAlileo in the First Dialogue of his Treatise of Two New Sciences; suggests an easy way to discover, Whether Light moves in time, or with an Instantaneaus Velocity: the Trial consists in the Confederacy of Two Companies of Men to expose Two Lights to each others view, so that the discovery of the one, may answer immediately to that of the other: that when the one uncover their Light, and expose it, they may at the same time perceive the Light of their Confederates. This being often practised at a small distance Galileo desired to have the same tried by observers at a greater Distance; to see, if the mutual Correspondence of Exposing and Covering their Lights, kept the same Measure as when nearer; that is, without any observable Delay.  
We tried it at a Miles distance (which in the going forward, and Return of the Light must be reckoned Two, and could not observe any. If in a greater Distance it be possible to perceive any sensible Delay, we have not yet had an opportunity to try.   

The Second Experiment,  
Of Fi●ing Bodies with a Burning-glass.  

Acquarzente. Pastiglia. Balsamo Bianco, etc.  THE Light Refracted by a Crystal Lens, or reflected by a Burning Concave, will not fire Spirit of Wine, though made opaque by a Tincture. Amongst other combustible matters, Gunpowder fires upon the uniting the Rays of a Lens or Concave. But the Perfumed Pastils, white Balsam, Storax, and Incerse, melt, but will never take fire.  
Likewise Paper, and fine white Holland, when exposed flat to the Reverberatory of a large Concave, at length Fire: wherefore 'tis a mistake, that the Light will not inflame any white Bodies, as is generally thought; indeed they take Fire with more Difficulty, than Coloured Bodies, and it may be with a small Concave or Lens they will not Fire.   

The Third Experiment.  
Of Bodies affording Light.  
BEsides Fire-stones, there are other Bodies that seem to be greater Conservatories of Light; for by striking them together, or by breaking them in the Dark, they Sparkle. Such are White-Sugar, Loaf-Sugar, and Salgemme in the Stone; all which being broken in a Mortar, give forth so great a Light, as distinctly to discern the sides of the Mortar, and the shape of the Pestle thereby: but we have not succeeded to see the same appearance in pounding Common Stone-salt, Alumn, or Nitre; nor in Coral, the Yellow or Black Amber, Gr●●ats, or Marchasites: But Rock-Chrystal, and Agate, and Oriental Jasper, either struck together, or broken, give a clear Light.    

EXPERIMENTS ABOUT The Digestion of some Animals.  
Wondered is the Force wherewith the Digestion of the Hen, and Duck-kind is performed; for they being crammed with little Balls of Solid Crystal, were dissected by us in a few hours, and opening their Ventricles in the Sun, they seemed to us covered all over with a glittering Coat, which examining with a Microscope, we found it to be only strewed over with tightly fine and impalpable powder of Crystal.  
In others, likewise crammed with hollow Bubbles of Crystal-Glass with a small hole in them, we were amazed to find of the said Bubbles some already broken, and powdered; others only cracked, and filled with a Whitish Substance, like curdled Milk, got in at the small hole; and we also observed, that those were better powdered, (than the others) which had in the Maws with them a greater Quantity of small Stones. And 'tis less strange, that they break, and grind to pieces, Cork, and any hard Woods, as Cypress, and Beech, and rub to Powder Olive-stones, the hardest Pineapple Kernels, and Pistaches put down their Mouths, with the Husk on. Pistol bullets in Twenty four Hours we have found much Battered; and several little hollow square Boxes of Tin were observed to be some scratched, and battered, others tore open from one side to the other.  
FINIS.   

A TABLE OF The Principal Matters Contained in this Work.  


A.  
Academy del Cimento intends not to dispute of the Experiments. Page. 16, and 33.  
Air diminishes the force of all Bodies that cut it. p. 146. perhaps in continual motion. p 14.  
Presses together those Bladders that seemed full in Vacuo. p. 18.  
Dilates and Expands itself in Vacuo. ib. What remains in the void space above▪ the Mercury presses not thereon. p. 23.  
When it is Dilated beyond the state of its Natural Compressure, p. 23. The measure thereof, ib. Proportion between Air Natural, and Air Expanded, as 1 to 174. p 24 When most rarifyed, unfit for Respiration of Animals, p. 61.  
Of Altering the Colours of several Fluids. p. 133.  
Amber in Vacuo loses its Electric Quality, p. 43. Which sort richest in that Quality, p 128. Attracts any thing but fl●me, p. 129. Rubbed upon smooth Bodies Attracts not, p. 130▪  
Acts no more upon the attracted Body than it suffers thereby, p. 130. Acts upon all Liquids. ib. By what Liquors hindered from attracting, p. 131.  
Antiperistasis, Experiments against it, p. 151.  
Attraction by what hindered in Amber, by the same also in other Bodies of Electic Virtue, p. 129. A peculiar Effect observed in the Attraction of Rose and Table Diamonds p. 13●    


B.  
Balls of Glass burst with great Violence, p. 150  
A Barbel taken alive out of a Vacuum, and kept in a Pond, with some observables thereon, p. 66  
Birds soon killed in Vacuo, and why, p. 63  
Bladders of Fish in Vacuo, p. 66  
Bl●bs in Ice what, p. 71  
Brass, to what thickness, burst by Frost. p. 77  
Bullets not wrapped about, fly farther with the same charge of powder than those that are p. 144    


C.  
Canes of Glass how made to be stopped with a Finger easily, p. 26  
Cement to join together the mouths of Vessels. p. 17  
Change of Air produces an alteration in Experiments, p. 1  
Changing of Colours in several Liquors, p. 133  
Circles in Water move swifter, as the force that makes them is greater, p. 139  
Clocks uncapable to show the Minute divisions of time, p. 10.  
Why made use of in the Experiments of Freezing, p. 82  
Cold whether reflected by Glasses as Heat and Light are, p. 103  
Cold and Heat, Clouds and Mists increase and lessen the weight of the Air, p. 15. supposed by some the parent of Rock Crystal, and Gems, p. 70. Whether any thing Positive, or only a Privation of heat, p. 70. Once impressed upon a Fluid shoots it into Ice after 'tis taken out of the freezing mixture, p. 80. * whether caused by an Intrusion of frigorifique Atoms, p. 152:    


D.  
Dew upon the outsides of Glasses frozen, p. 102  
Diamonds how generated according to Plato. p. 70  
Table Diamonds less Electric than Roses p. 131  
Digestion of some Animals how performed, Several Experiments thereon. p. 160  
Drops of Liquors thought to be Spherical from the Airs Pressure, p. 40  
Disproved p. 41    


E.  
A Cold Ebullition, caused by a mixture of Sal Armoniac, and Oil of Vitriol p. 153  
A strange Effect of Heat in subliming Liquors, included in Vessels p. 150  
Electricity, what substances impregnated therewith p. 128  
Experiments requiring an Exact measure of Time p. 11  
the best way of Examining Nature p. 1●4  
Extrusion, or pulsion of Bodies, a thing known to the Ancients, more especially evident from a Passage in Plato's Timeus, p. 118    


F.  
Fire and its Effluvia what Effect they have in Vacuo. p. 46  
Fishes kept a while in Vacuo dye, disgorging some Air. p. 65  
Flame diverts, and abates the Virtue of Amber, p. 129  
Fluids aptest to move, and why? p. 13  
Why different Fluids are raised to different heights by the incumbent Air p. 14.  
Fluids' added to the Airs Pressure, raise the Mercury above the usu● height p. 30  
Force of Rarifaction in freezing Water, how great p. 77  
How thought reducible to dead Weight ib.  
Freezing, how caused in Fluids', p. 95  
Artificial, with its procedure and accidents, p. 77 * 

Made in a very short time, almost instantaneous, p. 80 *  
What order it observes in divers Fluids p. 83    
Tables of Freezing p. ib. 

The Expl●catian of the Terms used in the Tables of Freezing, p. 81  
Those of the same Fluids Repeated, still uniform p. 84    
Natural Freezing, with the procedure thereof p. 95 

Diversity of the Figure of the Vessels causes some little diversity in the Freezing, p. 96  
Whether caused by the intrusion of Frigorifick Atoms p. 70    
Froth in Vacuo expands itself p. 59  
A sort of Funnel to fill Vessels with narrow Necks p. 3    


G.  
Gems Transparent, all Electric more or less, p. 128  
Glass Vessels enlarged by hot Water, and lessened by cold, p. 104 

Stretched by the weight of the contained Mercury, p. 113  
Impenetrable by Odours, and Moisture, p. 155  
Glass Balls burst with great violence, p. 150  
Glass and Crystal Electrical, p. 128    
Gold Vessels distended by the force of freezing, p. 76  
Gunpowder fired with a Burning glass, p. 144    


H.  
Height of Liquors set in hot Water, or Ice altered by the dilating or contracting of the Vessel p. 105  
Horizontal discharge of Cannon dispatch the Ball in about the same time that it falls from the Mouth of the Piece perpendicular to the ground, p. 143  
Humidity of Winds how distinguished, p. 9    


I.  
Ice according to Galileo is Water Rarifyed, not Condensed, p. 71 

Has not its full hardness at first, p. 95  
Produced by Art tenderer than the Natural ib.  
Made in Vacuo, wherein different from that made in Air p. 98  
How to find that difference ib.  
Sends forth a moist Exhalation p. 102  
Sprinkled with Salt destroys the Virtue of Amber p. 129  
The cause thereof proposed by some p. 130    
Instruments showing the heat and cold of the Air p. 2 

Showing the moisture of the Air p. 8  
To measure time p. 10  
Showing the different Pressure of the Air p. 14  
Showing the Alteration of the Natural Compression of the Air p. 35.  
An Instrument convenient to make the Vacuum p. 49  
Made use of in Artificial Freezing p. 77 *  
Iris-green what; p. 136      


L.  
Light: Bodies most impregnated therewith p. 158 

Whether its Motion instantaneous p. 157  
Transcurs the space of 2 Miles in an undiscernible time p. 157  
The supposed positive Lightness of Bodies does not raise them up p. 118  
Experiments thereon 119    
Liquors making other Fluids turbid and clear again p. 133    


M.  
Magnet not hindered by the interposition of any Fluid, or Solid Body p. 124 

Its North Pole weaker when placed Southwards than Northwards p. 127    
Mercury fittest to make the Vacuum p. 14 

At what height sustained in Vacuo p. 15  
Altered by External accidents ib.  
Raised higher in an ambient of water than air ib.  
A Vial filled with Mercury not running out p. 27  
How high raised in a Tube by the simple pressure of Water, p. 30  
Rises or falls as the place of observation is higher or lower, p. 35  
Dissolves Snow put into it p. 58  
Is attracted by Amber p. 130    
Metal of the Vessel causes no alteration in the Liquors freezing p. 96 

Which sort preserves Ice best p. 101  
Dilated by the Heat of Fire p. 110    
Moisture of the Air shown by Instruments p. 8  
Motion observed in the heights of Liquors, when first the containing Vessels are set in several ambients p. 105  
Muscadine, its Effect in freezing p. 92    


N.  
Nitre chills water when mixed therewith p. 100, 153    


O.  
Oil of Vitriol mixed with Water produces a great heat p. 153 

And with all Fluids the like except Oil, and Spirit of Wine ib.  
That, and Sal Armoniac together, make a cold Ebullition ib. etc.      


P.  
Paper white fired with a Burning-glass p. 158  
Pearl with what Effect dissolved in Vacuo p. 59  
Pendulums the best Time-meeters p. 10 

Their description and use p. 11  
Their Vibrations quicker or slower according to their length p. 12  
First applied to Clocks by Galileo ib.    
Plato's thoughts of the raising up of Fire and Water by the Air p. 118  
Poles of the Magnet when most efficacious p. 127  
Prejudices against material Instruments p. 114  
Pressures of the Air acts upon all fluids p. 13 

Its difference shown by Instruments p. 35  
Experiments in favour of that Pressure p. 17  
Objections against it p. 19  
The Reply of some persons thereto p. 20    
Procedure observed by some Liquors in freezing 77*  
Proportion of Air Natural, to that Rarifyed, not still the same p. 24 

Whence it may proceed ib.      


R.  
Raising of fluids higher in small Canes not only to be attributed to a weaker pressure of the Air in them p. 56 

The Reflection of the object by the Lens the same in Vacuo as in the open air p. 42    
Reports of a Demi-canon etc. pass equal spaces in equal times p. 138  
Rings turned out of Wood, by imbibing moisture dilated p. 108 

Cilindrical Rings of Brass dilated, by heating in the fire p. 107  
The same vigorously frozen, contracted p. 108  
Rods of Steel seem lighter hot than Cold p. 149      


S.  
Sal Armoniac, most efficacious in producing Cold p. 100 

Mixed with water arrives to a degree of freezing p. 153    
Scale for the Velocity of Sounds p. 142  
Scope of the Academy in their Experiments with Mercury p. 33  
Smoke descends in Vacuo in a Parabola p. 48  
Snow melted by Mercury p. 58 

Dissolves as slowly in Vacuo, as the open air ib.  
Snow-water longer in freezing than other Liquors p. 90  
Yet the same after boiling ib.  
Sounds pass equal spaces in equal times p. 138  
How propagated, according to the Stoics p. 139  
Unalterable in their Velocity p. 140  
Sound of a Bell and Organ the same in Vacuo, as in the Air p. 50    
Spirit of Wine makes no sediment p. 3 

Sprinkled upon Ice increases the Cold p. 100  
Not to be inflamed with a Burning-glass p. 158  
That, and Spirit of Vitriol ferment with water, with Ebullition, and Heat. p. 154    
Spirit of Sulphur stops fermentation, and chills p. 154 

A cold steam from Vessels filled with Ice p. 102    
Sugar promotes freezing p. 100  
Superficies of Ice, how raised in the midst p. 97    


T.  
Tables of freezing p. 83  
Thermometer what, p. 2 

How sealed p. 3  
Used in Experiments of freezing, and why, p. 82  
Their exactness unalterable by the small alteration of the capacity of their head or ball p. 107    
Tincture of Roses how made p. 136 

Tinctures altered to several Colours by an infusion of divers Spirits ib.      


V.  
Vacuum what intended thereby p. 16 

Made better with Mercury than by Suction p. 51    
Velocity communicated by the Powder to the Bullet, when fired downwards preternatural thereto, according to Galileo's sentiment p. 144 

Confirmed by Experiment 145    
Vessels with small Necks how filled p. 3 

One made use of in many of the Experiments of Vacuity p. 49  
Of several Materials burst by frost p. 72  
Of Earth contribute most to the freezing of the contained Liquor p. 96  
Of Metal, and Glass alter their capacity by the external application of heat and cold p. 104  
The Temperament of the contained Liquor yet unaltered p. 105    
Vibrations of the same Pendulum not always equal p. 11 

Vincenzio Galilei first adapted the Pendulum to Clockwork p. 13    
Vinegar styled, dissolves Pearl and Coral p. 59  
Virtue Electric in what substances most conspicuous p. 128 

Hindered by the least obstacle interposed p. 132  
Virtue, or Force already impressed upon Bodies not alterable by a new direction of Motion p. 145      


W.  
Water, in Vacuo rises not above 33 Foot 5 Inches p. 15 

How tried with other Liquors p. 31  
With what care it ought to be set to freeze in Vessels p. 79  
After Remounting upon freezing continues to Rarify p. 81  
In specific gravity to Ice, as 9 to 8; or as 28 ½ to 25 p. 79  
In freezing, forces through the Screws of Vessels p. 74  
Frozen in Vacuo p. 98  
Difficult if at all to be compressed p. 114  
Attempted by Rarifaction of Air p. 115  
Dead Weight p. 116  
Percussion p. 117  
Stilled in Lead thickens fair water p. 133    
A way to open, and close again quickly, and easily any Glass Vessel p. 26  
Weight able to enlarge the capacity of Vessels p. 113 

Specific Weight of Air in respect of Water how found p. 147    
Winds contrary or favouring neither Retard, nor accelerate the Motion of Sounds p. 140 

The contrary only weakening the vivacity thereof ib.