move but through a small space WHat a rapid Motion may enable a Body to doe may be judged by the powerfull and destructive Effects of Bullets shot out of Cannons in comparison of the Battering Engines of the Ancients which though I know not how many times bigger then the Bullets of whole Cannon were not able to batter down Walls and Towers like Bullets whose bulk compared with theirs is inconsiderable Other examples of a like nature might be without impertinency alledged on this occasion but because the latter part of our Proposition contains that which I chiefly aim at I shall proceed to Instances fit to prove That I have sometimes caused a skilfull Turner to turn for me an oblong piece of Iron or Steel and placing my naked hand at a convenient distance to receive the little fragments perhaps for the most part lesser then small pins heads as they flew off from the rod they were as I expected so intensely heated by the quick action of the Tool upon them that they seemed almost like so many sparks of fire so that I could not endure to continue my hand there And I remember that once asking an expert workman whether he as I had sometimes done did not find a troublesome heat in the little fragments of Brass that were thrown off when that metall was turning He told me that heat was sometimes very offensive to his eyes and eye-lids And when I asked whether it was not rather as Dust cast into them than from their Heat he replied that besides the stroke he could sensibly feel a troublesome heat which would make even his Eye-lids sore And that sometimes when he employed a rough Tool that took off somewhat greater Chips he had found the heat so vehement that not onely 't would scorch his tender Eye-lids but the thick and hard skin of his hands for proof whereof he shewed me in one of his hands a little blister that had been so raised and was not yet quite gone off And inquiring about these matters of a famous Artist imployed about the finishing up of cast Ordnance he confess'd to me That when with a strong as well as peculiar Engine he and his associates turned great Guns very swiftly to bring the surface to a competent smoothness the tools would sometimes throw off bits of metal of a considerable bigness which by reason of their bulk and their rapid motion would be so heated as to burn the fingers of the Country-people that came to gaze on his work when he for merriment sake desired them to take up some of those pieces of metall from the ground Which I thought the more remarkable because by the Contact and Coldness of the ground I could not but suppose their Heat to have been much allayed Not to mention that I learnt from an experienced Artificer that in turning of Brass the little fragments of that metall acquire an intenser Heat than those of Iron I remember also that to vary the Experiment mentioned just before this last by making it with a bodie far less solid and heavy than Brass or Iron I caused an Artificer to turn very nimbly a piece of ordinary wood and holding my hand not far off the powder that flew about upon the operation struck my hand in many places with that briskness that I could but uneasily endure the Heat which they produced where they hit Which Heat whether it were communicated from the little but much heated fragments to my hands or produced there by the brisk percussion on my hand or were the joint effect of both those Causes it will however be a good Instance of the power of Celerity even in very small bodies and that move but a very little way 'T is considerable to our present purpose that by an almost momentany percussion and that made with no great force the parts even of a vegetable may be not onely intensely heated but brought to an actuall Ignition as we have severall times tried by striking a good Cane of that sort which is fit for such Experiments with a steel or even with the back of a knife For upon this Collision it would send forth sparks of fire like a flint To the same purpose may be alledged that by but dextrously scraping good loaf-sugar with a knife there will be made so brisk an agitation of the parts that store of sparks will be produced But that is more considerable which happens upon the collision of a flint and a steel For though Vitrification be by Chymists esteemed the ultimate action of the fire and though to turn sand or stones though very finely poudered into glass 't is usually required that it be kept for divers hours in the intense fire of a glass-house and though lastly the glass-men complain that they cannot bring flints or sand to fusion without the help of a good proportion of Borillia or some other fixed salt yet both actuall Ignition and Vitrification are brought to pass almost in a moment by the bare vehemence of that motion that is excited in the parts of a flint when it is struck with a steel For those sparks that then fly out as an Ingenious person has observed and as I have often seen with a good Microscope are usually real and permanent parcels for the most part globulous ofstone vitrified and ignited by the vehemence of the motion And that this vitrification may be of the stone itself though steel be a metal of a far more fusible nature then a flint I am induced to think because I have tried that not only flints with steel but flints with flints and more easily pieces of Rock Crystal between themselves will by collision strike fire And the like effect of collision I have found my self in some precious stones harder than Crystall And afterwards inquiring of an ingenious Artificer that cuts Diamonds Whether he had not observed the like when Diamonds were grated on by the rapid motion of his mill He replied that he observed Diamonds to strike fire almost like Flints which afterwards was confirmed to me by another experienced cutter of Gems and yet having made divers trials on Diamonds with fire he would not allow that fire itself can bring them to fusion Nor are fluid Bodies though but of small Dimensions to be altogether excluded from the power of making considerable impressions on solid bodies if their celerity be great Whether the Sun-beams consist according to the Atomical Doctrine of very minute Corpuscles that continually issuing out of the body of the Sun swiftly thrust on one another in Physically-straight Lines or whether as the Cartesians would have it those beams be made by the brisk action of the Luminary upon the contiguous fluid and propagated every way in straight lines through some Ethereal matter harboured in the pores of the Air it will be agreeable to either Hypothesis that the Sun-beams refracted or reflected by a burning-glass to a focus do there by their concourse compose a small portion of
far as divers Earthquakes have done but that the fire passes through some little subterraneal clefts or channels or hidden conveyances from one great Cavity or Mine to another yet 't is not improbable but that the vehemently tremulous motion does oftentimes reach a very great way beyond the places where the explosions were made Since though Seneca would confine the extent of Earthquakes to two hundred miles yet observations made in this and the last Century warrant us to allow them a far greater spread The Learned Josephus Acosta affirms that in the Kingdom of Peru in the year 1586 an Earthquake reached along the shoar of the Pacifick sea 160 Leagues and adds that sometimes it has in those parts run on from South to North 300 Leagues And in the beginning of this our age Anno Dom. 1601 good writers relate a much larger Earthquake to have happened since it reached from Asia to that Sea that washes the French Shoars and besides some Asiatick Regions shook Hungary Germany Italy and France and consequently a great part of Europe And if that part of the Narrative be certain which relates that this lasted not much above a quarter of an hour it will be the more likely that this Earthquake shook great Tracts of Land beyond those places to which the fired matter passing from one cavity to another could reach in so short a time As you will the more easily guesse if you try as I have done that in trains of Gunpowder it self the fire does not run on near so swiftly as one would imagine But though I have been in more Earthquakes then one yet since they were too sudden and too short to afford me any considerable observation I shall say no more of them but proceed to take notice that oftentimes the motion of a Coach or Cart that passed at a good distance from the place that I was in has made the buildings so sensibly shake that I could not but wonder that so great a portion of so firm and sluggish a body as the Earth could by a cause that seemed very disproportionate to such an effect be made to tremble it self and manifestly to shake firm buildings that were founded on it And this observation made me the more inclinable to give credit to their Relations who tell us that in a calm night the march of a troup of horse may be felt by attentive Scouts watching at a great distance off by the shake that the ground receives from the trampling of the horses though I formerly suspected much and do yet a little that the impulse of the air conveyed along the resisting surface of the ground might mainly contribute to the effect that is ascribed onely to the motion of the soil Before I advance to the Second Member of this Chapter it may not be impertinent to note that in peculiarly disposed bodies and especially in Organical ones a very languid motion may have a far greater effect than it could produce by a bare propagation of it self For it may so determine the motion of the Spirits or other active parts of the body it works on as to make multitudes of them act as if they conspired to perform the same motions As when a ticklish man by having the pulp of one's finger passed gently along the sole of his foot or the palm of his hand has divers muscles and other parts of his body and face put into preternatural or unusual motions And most men by being lightly tickled with the end of a feather or straw within their Nostrils have their heads and many parts of their bodies put into that violent Commotion wherein Sneezing consists And I remember that having for some time been by a distemper from which God was graciously pleased a while after to free me quite deprived of the use of my hands it more than once hapned to me that sitting alone in a Coach if the wind chanced to blow a single hair upon my face in the Summer-time the tickling or itching that it produced was so uneasy to me 'till by calling out to a footman I could get it removed that though I could well bear it as long as I was wont to do when having the use of my hands I could relieve my self at pleasure yet if I were forced to endure the itching too long before any came to succour me the uneasiness was so great as to make me apprehend falling presently either into Convulsions or a Swoon But 't is time to proceed to the second Member of this Chapter 2. Others there are that cannot believe that Local motion especially if it be languid can be propagated through differing Mediums each of which save that wherein the Motion is begun must they think either repell or check and dead it To these I shall recommend the Consideration of an Experiment I remember I made before some Learned men in our Pneumatick Engine For having caused a large and thick glass Receiver to be so blown that it had a glass button in the inside of that part which upon the Engine was to be placed upwards I caused a Watch to be suspended by a little Silverchain fastned to that button by as slender and soft a body as I thought would be strong enough to support my watch and then the Glass being cemented on close to the Receiver to prevent a Commerce between the Cavity of it and the Air the watch that hung freely near the middle of the Cavity of the Receiver made it self to be heard by those attentive Listners that would hold their ears directly over the suspended watch whose motions were thereby argued to have been propagated either through the included air or along the string to the concave part of the Glass and through the whole thickness of the Glass to the convex part and thence through the interposed air to the Ear. And this mention of watches minds me of what I often observed in a small striking watch that I have worn in my pocket For when it struck the Hours and in some postures when the balance did but move I could plainly feel the brisker motions of the Bell and sensibly the languid ones of the balance through the several linings of my Breeches and some other interposed soft and yielding bodies and this though the watch as I said was small and the balance included in a double case and though the outwardmost were of what they call Chagrine and the innermost of Gold which I therefore mention because that closest of metals is observed more to dead sounds and motions than harder metals as Silver Copper and Iron That Motion may be propagated through differing Mediums may seem the more probable by the shakings that are often felt by men lying on beds that stand in rooms close shut when loud claps of thunder are produced perhaps at a great distance off in the clouds And whether it will be fit to add to this Instance that which you have lately met with in the III. Chapter
in the production of divers difficult Phaenomena of nature that are wont to be referred to less genuine as well as less intelligible Causes FINIS AN Experimental Discourse Of some UNHEEDED CAUSES OF THE Insalubrity and Salubrity OF THE AIR Being a Part of an intended Natural History of AIR LONDON Printed by M. Flesher for Richard Davis Bookseller in Oxford 1685. THE Preface HAving heretofore had occasion to draw together under certain Heads divers unpublish'd Observations and Experiments of my own and some of other men by way of Memorials for a Natural History of the Air I thought fit by more largely treating of two or three of the Subjects distinctly mention'd in my Scheme of Titles to give a Semplar or Specimen of what may be done upon the other Heads of the designed History Vpon this account I treated somewhat largely of the Salubrity and Insalubrity of the Air as a Subject which for the importance of it to Mens healths and lives I thought deserv'd to be attentively consider'd and have its Causes diligently inquir'd into And having observ'd that among the six principal Causes of the healthfulness or insalubrity of the Air namely the Climate the Soil the Situation of the Place the Seasons of the Year the raigning winds and Contingencies whether more or less frequent and especially Subterraneal Steams having I say observ'd that among these Causes there was one viz. the last nam'd about which I thought I could offer something that I had not met with in the Books of Physicians that treat of it I was thereby invited to set down my Thoughts and Observations by way of Conjectures which I was made to believe would appear uncommon and would not prove useless These Observations and Reflexions I referr'd for clearness and distinctions sake to four Propositions But when I had gone thorough the three first and made some progress in the fourth being hinder'd by divers Avocations to make an end of it I laid by the whole Discourse in a place which I thought a safe one but when afterwards I had some opportunity to dispatch what remain'd I found all the diligence I us'd to retrieve the entire Manuscript unsuccessfull At this surprizing Accident I confess I was somewhat troubled because whatever may be thought of the discursive part of those Papers the Historical part contain'd divers matters of Fact that I did not meet with in Books nor can now distinctly remember and will not perhaps be lighted on by even Physicians or such Naturalists as derive their knowledge onely from them 'T is upon this consideration that having afterwards met with many Papers that belong'd to most parts of the unhappy discourse I thought fit to put them together in the best order I could that I might not loose what might give some light to so important a Subject as the Theory of Diseases And this course I the rather pitch'd upon because before the Papers about the Salubrity of the Air I miss'd two other of my Manuscripts whereof the former contain'd a Cellection of Medicinal things and the second a defence of the Mechanical way of Philosophizing about Natural Things as it respects Religion And I remember'd that having formerly lost a Manuscript I was much concern'd for I purposely made a noise of it whence I suppos'd the Plagiary would conclude himself unable to make it pass for his And in effect the Book was in a while after privately brought back so that I found it laid in a By-place where I had before as fruitlesly as carefully sought it AN Experimental Discourse Of some Unheeded CAUSES OF THE Insalubrity and Salubrity OF THE AIR c. THE sixth and last thing upon which the Salubrity and Insalubrity of the Air depends is the impregnation it receives from Subterraneal Effluvia And though this be a cause not wont to be much heeded by Physicians themselves yet I take it to be oftentimes one of the most considerable in its effects The Effluvia that pass into the Air may be distinguish'd into several sorts according to their respective Natures as has been elsewhere shewn wherefore I shall now only take notice of the differences that may be taken from place and time upon which account we may consider that some of them arise from the Crust if I may so call it or more superficial parts of the Earth and others have a deeper Original ascending out of the lower parts and as it were Bowels of the Terraqueous Globe And to this difference taken from place I must add another perhaps no less considerable afforded by Time which difference relates chiefly to the second sort of Steams newly mentioned Of the Subterraneal Effluvia some are almost constantly or daily sent up into the Air and those I therefore call Ordinary Emissions and others ascend into the Air but at times which are not seldom distant enough from one another and those I call Extraordinary Emissions whether they come at stated times and so deserve the title of Periodical or else uncertainly sometimes with far greater sometimes with far smaller intervals and so may be called fortuitous or irregular But though I thought it might render what I am about to say more clear if I made and premised the two foregoing distinctions yet because in many cases Nature does not appear solicitous to observe them but at the same time imbues the Air with Steams referable to divers Members of these distinctions I shall several times though not always take the liberty to imitate her and consider the Effluvia of the Terraqueous Globe in the more general Notion that they are so I know 't is frequently observed and usually granted that Marrish Grounds and wet Soils are wont to be unhealthfull because of the moist and crude vapours that the stagnating waters send up too copiously into the Air. And on the other side dry Soils are because of their being such generally lookt upon as healthy Nor do I deny that these Observations do most commonly hold true but yet I think that besides what can be justly ascribed to the moist vapours or dry Exhalations we have been speaking of in many places the healthfulness and insalubrity of the Air may be ascribed to other sorts of Effluvia from the Soil than those that act merely or perhaps principally as these are either moist or dry PROPOSITION I. TO deliver my Thoughts about this matter somewhat more distinctly I shall lay them down in the four ensuing Observations or Propositions whereof the first shall be this It seems probable that in divers places the Salubrity or Insalubrity of the Air considered in the general may be in good part due to subterraneal Expirations especially to those that I lately call'd Ordinary Emissions For in some places the Air is observ'd to be much more healthy than the manifest qualities of it would make one expect and in divers of these Cases I see no Cause to which such a happy Constitution may more probably be ascrib'd than to friendly Effluvia
of mentioning this last Disease that he but borrowed his Encomium of Mercury from Begninus But however what has been related has invited me to consider whether there may not be some virtue as well as some danger in Amulets of Quicksilver that are by many extoll'd against the Plague But this onley upon the bye PROPOSITION III. It is Likely that divers Epidemical Diseases are in great part produc'd by Subterraneal Effluvia I Am very well aware that divers Diseases that extraordinarily invade great numbers of people at the same time and were therefore by the Greeks called Epidemical may be rationally refer'd to manifest Intemperatenesses of the Air in point of Heat Cold Moisture or some other Obvious Quality And therefore the Proposition speaks but of some Epidemical Diseases and imputes those it speaks of to Subterraneal Effluvia not as total but as partial and sometimes as principal Agents in the production of them In favour of the propos'd Conjecture thus explain'd I shall offer two things to Consideration I. And first it seems not very improbable that divers of those Morbifick Excesses especially if they be sudden that are observ'd in the Air may proceed from the unusually copious ascent of hurtfull Exhalations that mingle with the Air and diffuse themselves through it We are greater Strangers than we commonly take notice of to the Subterraneat part of the Globe we inhabit and if I had leasure and thought it necessary I could shew that there are a great many odd and surprizing things to be met with in the Structure and disposition even of those parts of the Earth that lie but a little way beneath the surface of it and partly have been and partly may easily enough be actually penetrated by the industrious Labours of men And as for the deeper Subterraneal Regions we are so much more unacquainted with them that we are scarce fit so much as to conjecture how far they extend or what kind of Materials they contain and what is the gross and if I may so speak the Mechanical Fabrick of the greater Masses whether solid or fluid they consist of And least of all can we determine what Motions whether periodical or others these Masses or other Portions of deeply lodg'd Matter may have On such grounds as these I conceive it possible that among the many and various Effluviating Bodies that the terrestrial Globe may conceal in its Bowels there may be some whose reeks ascending plentifully into the Air may occasion in it an excess of Heat Cold Moisture thickness or some other manifest Quality So that sometimes not to say many times even those manifest Intemperatenesses of the Air to which an Epidemical Disease is wont to be wholly imputed though perhaps not very justly may in part proceed from Subterraneal Bodies for I elsewhere shew that these by their Conflicts or Mutual Actions on one another may excite great and sudden Heats and on that account send up such copious Steams into the Atmosphere as may produce there sudden and excessive Heats Lightnings Thunders c. And I shall now add what perhaps will appear somewhat strange that I think sudden and unseasonable Refrigerations of the Air may proceed from the action of Subterraneal Bodies upon one another for Tryal purposely made has inform'd me that there are certain Minerals whereof some may be employed in their crude Simplicity and the other requires but a slight Preparation such as it may have in the Bowels of the Earth which Minerals being put together will produce by their Reaction an intense degree of Cold not onely as to sense but when examined by a seal'd Weather-glass The Changes of the Air that produce Epidemical Diseases are sometimes so great and sudden that they cannot in my Opinion with probability be imputed to the action of the Sun or the Moon which are causes that act in too general and too uniform a way to have those particular and anomalous Effects attributed to Them as probably as they may be to Subterraneal Bodies that often act with more suddenness and impetuosity and without any regularity at least that is known to us The difference we find in Seasons that bear the same name and should be alike in temperatureâ— is oftentimes very great and sometimes also very lasting It is proverbially said in England that a Peck of March Dust is worth a King's Ransom So unfrequent is dry Weather during that Month in our Climate And yet in some years and particularly the last 't was a rare thing to have a shower either in March April or May sometimes in the Month last named there are Heats greater than in the Dog-days of that same Year though usually here in England divers Mornings of that Month are cold and some of them frosty And now and then I have observ'd in the same Months and Days at no great distance from one another that the Weather has been sultry hot and has also produc'd a great Snow We have seen Summers like that which is remember'd for the Siege of Colchester that for almost the whole Season where more dark and rainy than several Winters have been observ'd to be To which purpose I remember that when I was about to write the History of Cold I was fain to watch almost a whole Winter to find two or three frosty days to make an Experiment or two I had need of that requir'd not a Cold that was either lasting or very intense But Instances of this kind are so obvious to those that are at all heedfull Observers that I may safely pass them by and inculcate that the Sun being in the same Signs at the same Times of the Year it does not appear how He should produce so great a disparity of the temperature of the Air in Seasons of the same denomination as the Winters or the Summers of differing and yet perhaps immediately consecutive Years And therefore I do not so much wonder that many Learned Writers fly to Astrology for an account of these irregular Phaenomena and ascribe them to the influences of certain Stars notwithstanding what divers eminent Philosophers and some great Astronomers too have said to prove the vanity of Judiciary Astrology I shall not now stay to discuss the Question whether the Stars have any influence distinct from their Light and Heat because my Opinion about it being somewhat peculiar I have discoursed of it in a Paper by it self But this I shall now say that the fixt Stars being but general and if I may so speak indefinite Agents almost unimaginably remote from us 't is nothing near so likely that such Effects as besides that they happen very suddenly and irregularly are oftentimes confin'd to a Town or some other narrow Compass should be produc'd by certain Stars as that they should be so by Subterraneal Bodies which are near at hand of very various natures and subject to many irregular and differing Motions commixtures reactions and other alterations I have known a great Cold in a
breathed in with the Air in Respiration or carried up and down by the Bloud or other Liquors of the Body may pass by other parts of it without doing them any sensible harm and attacking this or that determinate part produce there some Disease such as the fabrick and situation of that part peculiarly dispose it to be affected with And I shall add on this occasion that in our Hypothesis we may render a probable reason why in some Epidemical Diseases some persons may escape much better than other that seem likely to be at best as obnoxious to them without a recourse to the peculiar Constitutions of the Bodies of differing Persons for it may be conjectur'd that the noxious Corpuscles that infest the Air may especially in windy weather be very unequally disperc'd through the Air and many fly in far greater or lesser numbers within equal spaces of Air and consequently the Persons that have the ill luck to be in the way of the more numerous swarms of morbifick Corpuscles may be much more prejudiced by them than others though of weaker constitutions who happen to be attaqu'd but by few of them On which occasion I remember that a great many Trees in some Land that belongs to me having been suddenly much endamag'd by a wind that was not able to doe it by it's bare strength I had the curiosity to view somewhat heedfully a Tree that stood in the Garden and perceiv'd that all the considerable mischief was done to that side of the Tree which respected the corner whence the hurtfull Wind blew the Leaves of the other side continuing fresh and verdant as being by the other part of the same Tree fenc'd from the Wind and it was farther observ'd that even the expos'd side of the Tree was not every-where endamag'd for there were divers parts where the Leaves continued sound and green though neighbouring Leaves were some more some less for all that were prejudic'd were not totally blasted the sound Leaves and the discolour'd being so odly mingled that I conjectur'd the cause of the mischief to have been this that some Arsenical or other corrosive or poisonous Exhalations being suddenly emitted from the Subterraneal parts into the Air were by the Wind they chance to meet with there hurry'd along with it and blown against the Bodies that stood in it's way moving in the Air like Hail-shot discharg'd out of a Gun here in a closer and there in a more scattering order so that as more or fewer of them happend to fall upon the same Branch or Leafe they left more or less marks of their passage by destroying the texture and colour in the Leaves or parts of them they chanc'd to beat upon And this may possibly be the cause of some of those sudden and sometimes fatal Effects that I have known in some places the people talk much of complaining that such a one had his Eyes or his Face or onely one side of it blasted by a malignant Wind of which I thought I saw an Example in a Domestick of my own whilst in such a Wind he was riding after me who thanks be to God had no such mischief done me But the Vulgar have entertain'd such strange Conceits and Stories about these Blastings on which account some of them say that Men are Planet-struck that the fabulous things mingled with those that are possible have made intelligent Persons reject them all One thing more I shall take notice of in favour of our Hypothesis which is that it well agrees with what has been observed not without some wonder of the very short duration of some Epidemical Diseases in certain Times and Places For this may proceed from hence either that all the Morbifick Expirations ascended into the Air almost at once or at least within a short time and so were easily spent that is by diffusion or dispersion so weakned as to be disabled from doing much mischief or else the Subterraneal Commotion that produc'd them may pass on from one place to another and so cease to afford the Air incumbent on the first place the supplies necessary to keep it impregnated with noxious Exhalations And it agrees well with this Conjecture that sometimes we may observe certain Epidemical Diseases to have as it were a progressive Motion and leaving one Town free pass on to another Of which some Observations that I have made encline me to think that if Physicians would heedfully mind it they might take notice of several Instances One thing more may be added as consonant to our Hypothesis namely that sometimes an Epidemical Disease ceases in this or that place almost as sudden as it invaded or at least in a much shorter time than Physicians expected For according to our Hypothesis it may well happen that after one sort of Exhalations whose peculiar Qualities make them Morbifick have deprav'd the Air incumbent on a particular place there may by a new or farther Commotion of Subterraneal Bodies be sent up into the Air store of Expirations of another kind which meeting with those that formerly impregnated it may either precipitate them and so free the Air from them or by other operations on them and sometimes even by Coalitions with them so alter their nature as to disable them from doing any farther mischief This I shall illustrate if not confirm by that very remarkable Phaenomenon that is yearly observ'd at Grand Cairo in Aegypt for though I know not whether or no the Corpuscles that produce it arise from under Ground the affirmative part of the Question being not improbable it appears that by the intermixture of adventitious Corpuscles with the formerly Pestilential Air 't is so alter'd and corrected that within one day or two if not within a lesser compass of time there is a stop put to the progress of the Plagues that in that favourable time of year namely about the middle of Summer scarce ever misses of raging in that populous City and which is more admirable these sanative Corpuscles if I may so call them operate so powerfully that of those that are already seiz'd by that fatallest of Diseases the Plague few or none die of it after once these Antidotal Particles have sufficiently impregnated the Air. I confess so great and sudden a change is very wonderfull and I should scarce think it credible if I had not had the means and curiosity to enquire about it of divers persons some of them very intelligent that either curiously visited or also made some considerable stay in that great City and found them agree in the main about the truth of the matter of fact which is much confirm'd to me by so eminent a Testimony as that of the learned Prosper Alpinus who for several years practis'd Physick in Grand Cairo and as an Eye-witness delivers what he relates more authentically as well as more particularly than any I have met with And though he endeavours to give several reasons of this strange and sudden cessation of the