act continually but interruptedly or per vices short and almost isochronic or equal quiets interposed So that the bloud express'd by the heart doth not flow thence in a continued course as rivers and fountains do that are without intermission carried on by the weight of their waters but gush forth and stop alternately though this vicissitude be exactly regular and proceeds in a constant order Now these things considered it may seem consentaneous to conclude that the motion of the bloud cannot be continuus since two pauses or quiets are interposed betwixt every two pulsations or Systoles of the heart during each of which the motion ceases but on the contrary ought to be esteem'd and call'd an interrupted and mixt motion And yet notwithstanding the verisimilitude of this conclusion I doubt not to lay down and expose to your examination this First PROPOSITION That the bloud is carried in a round through the body of an Animal in a truly continued and never interrupted motion This perhaps may sound like a Paradox but that shall not a-whit discourage me from asserting it while I remember that remarkable sentence of Minutius Felix in Octavio Inest in incredibili verum in verisimili mendacium Though it be true and evident that the heart doth not in the time of its pauses express any Bloud into the Arteries yet it is not true that the bloud contain'd in the Arteries in the Viscera in the habit of the body and in the Veins doth at the same time stagnate and stop its course but on the contrary is always carried on in its journey though with unequal velocity First the Verity of this appears in the Arteries For the afflux of bloud from the heart being wholly intercepted either by a Ligature applied to the aorta at its original or by cutting out the heart it self as is commonly done in Frogs and Vipers we see that nevertheless the bloud wherewith the Arteries were fill'd is by degrees squeez'd out so that they are soon after left altogether empty And doubtless this exinanition of the Arteries happens because they by their own spontaneous motion constringe themselves and contracting their Circular Fibres express the bloud into the habit of the parts and are at the same time compress'd also by the contraction and tension or the peristaltick motion of all the Muscles of the Body From the observation of this vulgar Phaenomenon viz. the emptiness of the Arteries in dead bodies the Ancients perhaps took occasion to believe and teach that not bloud but only Vital Spirits are contein'd in the Arteries Secondly this appears also in the Veins For that the bloud doth continually flow on in them likewise not only when it is urged forward by the Arterial Bloud pursuing it but even in the time of the hearts pauses is evinced from this that then the bloud runs on through the trunk of the Vena cava to replenish the right Ventricle of the heart But why do I mis-spend time in alledging reasons to prove a truth that is manifest to sense in Phlebotomy no sooner is a Vein open'd than the Bloud flows forth with a swift stream and while the wound is open continues to flow without pauses or interruption which is a demonstration of the thing proposed viz. of the continual motion of the Bloud in the Veins Being thus assured of the effect let us proceed to investigate the Causes which are not equally evident nor can we hope certainly to solve this Problem without enquiring the Mechanical reason of the continual motion of the Bloud through the Veins This therefore I will now attempt to do That Nature hath instituted no immediate Communication betwixt the Capillary Arteries and the Capillary Veins per anastomôsin is manifest to sense and now acknowledged by all Learned Anatomists and therefore it cannot stand with reason to imagin that the Bloud in its Circular course is emitted immediately out of the Arteries into the Veins these vessels being separate And though we opine that there is some secret communication betwixt the extreme Orifices of the Arteries and those of the Capillary veins by the intermediate Spongy substance of the flesh Viscera and glandules or by the Cribrose substance of the Bones as by the Pores of a Pumice stone yet we are still to seek by what motive force the bloud may be carried on from those intermediate Porosities and insinuated into the veins First because 't is consentaneous that the impulsive force whereby the Systole of the heart squirts the Bloud into the Arteries is by degrees weakned and at length languid in those streights of the extreme vessels and of the intermediate Porosities Secondly Because the Orifices of the Capillary veins cannot continue always open and dilated their consistence being not hard and bony but membranose soft and slippery so that they are apt to be closed by conniving and consequently to hinder the ingress of the bloud newly arrived Thirdly Because here we can have no recourse to the compression of the Viscera and the Muscles whereby the bloud should be squeez'd into the Orifices of the Capillary veins for we see that the bloud is suckt up by the Capillary veins not only when the Muscles are invigorated and upon the stretch but also when they are quiet and relaxed and do not exercise their compressive power as is most evident in sleep when the Circulation proceeds without intermission This is confirm'd from hence that in the Brain in the Medullary substance of the bones where no compression can be admitted the Capillary veins receive the bloud as freely as in the softer flesh it self Seeing then that the effect cannot be denied viz. that all the bloud effused out of the Arteries is after absorpt and carried off by the Veins to be brought back again into the heart and seeing also that this is not effected by way of Attraction there being no such thing as attraction in Nature as I have more than once elsewhere proved we are compell'd to assert that the Bloud is imbibed by the Capillary Veins for the same reason and by the same Mechanick action by which Syphons Sponges Filtres Chords and all Porose bodies are penetrated by water with which they are moistned which power is no other than the gravity of the fluid it self which is augmented by the impetus of its proper motion and by the impulse communicated to it from external force So the motive force of Gravity which the bloud can want no more than water can when it finds the small chanels of the Capillary veins open for they can never be so closely constringed by the flagging and connivency of their thin membranes as to leave no entrance for a fluid as appears in the Pores of Ropes how hard soever twisted must of necessity overcome the weak resistence of the streights in all Filtres and Porose bodies and consequently the bloud may be insinuated into the Capillary veins by a Mechanic action like that of Filtration If this proposition
be true the greatest difficulty occurring in the whole mystery of the Circulation of the bloud is now at length solved The bloud having in this manner passed the aforesaid streights and entred into the Canales of the small veins by the same motive force whereby it was insinuated for such an ingress is not possible without motion may be advanced a little farther in its way by its proper force and by external force and also by the impulse of the new bloud following behind as we see water suckt up by a Filtre to be carried on to the end of the list Afterward because many small veins meeting together make one wider ductus or pipe and because in this larger pipe the former impulsive force of necessity grows more and more languid and faint by degrees and by consequence the motion of the bloud is retarded therefore it stands in need of some auxiliary forces to be carried on the rest of its journey These are First the force by which the Circular Fibres of the Veins that naturally have a peristaltic virtue contract themselves always after they have been stretch'd as all Nervose and other tensile bodies are observ'd to do Secondly The Compression of the Veins by the weight of the Circumambient air or Atmosphear and the Elastic virtue of the air inspired Thirdly The Tonic motion of the Muscles when they act together with the various motions of the Viscera and of humours discurrent through the body all which more or less compress the veins Now that the manner how this compression promotes the continual decurse of the bloud in the Veins may be the more fully and clearly understood I will take liberty to lay down this Second PROPOSITION That by the artifice of the Valves the Compressions of the Veins protrude the Bloud toward the heart with a motion doubly swifter not indeed in a continual flux but with little pauses interpos'd and with unequal velocities We here behold in the Crural vein slit open from end to end certain Valves placed at unequal distances in the inside of the Vein which for demonstration sake are accurately represented in this Figure expos'd to sight These Valves ye see are nothing but half pockets of a membranose substance or little bladders affixt to the sides or walls of the Vein and resembled by AONMP and BONQR They are found sometimes single sometimes in pairs placed one opposite to the other and laterally touching each other as at NO the convex tops of which pair respect the Capillary beginnings of the Veins beyond HL but the Orifices of their cavities PO RO open toward the heart have respect to the parts IK Now I am to demonstrate that from this structure and situation of the Valves it is necessary that the Bloud be protruded toward the heart Imagine then that the same portion of the Vein HMQL is replete with bloud and because by the circular Fibres of the Vein itself and by the ambient Muscles and perhaps also by the gravity of the Atmosphear one part of the Vein is constringed after another all along it must be that the lateral walls ST come nearer to each other toward V and then the Vein so girded will lose its Cylindrical form and be turn'd into two little funnels HVL MVQ which are less capacious than the former Cylinder and therefore the bloud which was contained in the spaces VHS and VLT will be expell'd out of the Orifice HL but the remaining quantity of bloud contained in the spaces VSM and VQT will be squeez'd without the Orifice MQ toward IK It appears then that from the above-mentioned compression of the sides or walls of the Vein the bloud is express'd in equal quantity to the opposite parts and this would certainly happen if the Valves were removed But because to the walls of the Vein within MP QR are fastned two Valves it is necessary that the bloud impuls'd by a compression made in ST be forced through the narrow chink NO because the yielding fluid contain'd in the cavities of the Valves and urged by the advenient bloud is constringed and thrust out of them and then instantly the sides of the Valves that before touched each other NO receding one from another leave an open way by which the flux of bloud coming on from MSTQ may be insinuated and pass forward beyond AB Again after the bloud hath passed the confines of the Valves PO RO there necessarily follows a restriction of the little chink NO For the bloud it self must by reason of its heavy bulk and fluidity fill the little baggs of the Valves and so their soft and pliable sides being dilated till they mutually touch ought closely to shut the rimula NO Moreover because the Vein is not constringed in all its parts at the same time but part after part successively therefore after the bloud is transferr'd beyond the Valves within the little funnel ABCD there follows a constriction of the walls AD BC in the same time in which ST is not constringed And because by reason of the close shutting of the rimula NO half the bloud that was contain'd in the spaces EAG FBG cannot flow back toward AB finding the obstacle AOB fill'd with bloud and retain'd by the Valves it is compell'd with a reflex motion like that of a Tennis-ball rebounding from the wall to flow toward DC and since by the same compression the Bloud that was contain'd in the spaces EDG FCG is protruded beyond DC therefore a double quantity of bloud is in the same time in which the compression is made expelled through that same aperture DC but when a double quantity of a fluid is in the same time emitted at the same Orifice it must run out with a double Velocity Thus is our Proposition verified And as to single Valves from what hath been said of the use of double it may easily and genuinely be inferred that they also help to promote the course of the bloud though but half so much as the double Wherefore Natures wisdom is admirable in placing single Valves both at less distance one above another and for the most part where the Cavity of the Vein is a little narrower or where a less Vein laterally exonerates it self into a greater in both which cases the necessity of this demonstrated acceleration of the motion of the Bloud seems to be less In the trunk of the Vena cava no valves are found as well because of its ample Cavity as because of its contiguity to the trunk of the great Artery by whose pulsations it cannot but be somewhat compress'd and consequently the Bloud flowing through it proportionately promoted In the Iugular veins also none have yet been observed probably because in them the bloud descends swiftly enough from its own weight and fluidity In small veins they are not placed unless in the Coronary veins of the heart just at the place where they empty themselves into the right Ventricle of the heart and of these
too the use is not to promote the course of bloud of which there is no need in so small a circuit but only to prevent the reflux of it out of that Ventricle in the systole of the heart as appears from their situation and from their conformation Nor are any found in the Arteries in which the bloud with mighty force impulst by the constriction of the heart and of the Arteries needs no additional machine to accelerate its motion except those that are placed in the inlet and outlet of the left Ventricle to obviate the regurgitation of the bloud into the arteria venosa and out of the aorta into the left Ventricle and the two very little Valves sited in the two Coronary Arteries at their origine from the aorta to prohibit the regress of the bloud into the aorta ¶ ⸪ If this Artifice of the Valves affixt within the veins be so necessary to promote the reflux of the bloud toward the heart certainly he that first discovered them deserves to be remembred with honour But who was that fortunate man Fabricius ab Aquapendente put in his claim to the glory of the invention as wholly due to himself in these very words De his itaque ostiolis nempe venarum locuturus subit primùm mirari quomodo ostiola haec ad hanc usque aetatem tam priscos quà m recentiores Anatomicos adeo latuerint ut non solùm nulla mentio de ipsis facta sit sed neque aliquis prius haec viderit quà m Anno Domini Septuagesimo quarto supra millesimum quingentesimum quo à me summa cum laetitia inter dissecandum observata fuere But Padre Fulgentio professly ascribes the invention to that prodigy of Wisdom Learning and Virtue Padre Paolo the Venetian at the same time openly accusing Aquapendens of disingenuous arrogance and theft for challenging to himself the honour of having first discovered the Valves to which he had no right and for stealing the glory due only to Father Paul The sence of his impeachment is this The whole Tractate concerning the Eye which passeth under the name of Aquapendens or at least so much of it as contains new and rare Speculations and Experiments is the work of Padre Paolo whereof I have had speech with some that were eye-witnesses and knew that a due part of the praise was not attributed to him that deserv'd it all But much more in another matter of more moment which was the finding out of those Valvulae those inward shuts or folds that are within the Veins Of which argument I do not find that any either ancient or Modern hath made mention because it was a thing unthought of till these times when Aquapendens moved the question in a publick Anatomy But there are still living many eminent and Learned Physicians among whom are Santorio and Pietro Asselineo a Frenchman who certainly know that it was no Speculation nor invention of Aquapendens but of Padre Paolo Who considering the weight of the bloud grew into an opinion that it could not stay in the Veins except there were some bunch to hold it in some folds or shuttings at the opening and closing of which there was given a passage and necessary Aequilibrium to life And upon his own natural judgment he set himself to cutting with more accurate observation and so found out those Valves c. Having thus faithfully recited the Pleas of these two great men I leave it to you to decide the controversie and to fix the Laurel on the head of which of the Competitors you please For my part if my judgment were considerable I should declare my self on Padre Paolo's side as to the invention and allow to Aquapendens the honour of being the first that by writing made the thing known to the world Understand me I beseech you only of the Valves themselves not of the true use of them which neither Aquapendens nor the Father had the happiness to discover Not Aquapendens because of the two uses by him assign'd to these Valves which he most improperly named Ostiola namely the corroboration of the Veins which might otherwise be by the bloud every where distended and broken into varices and the retardation of the bloud in the Veins that so all parts of the body might have time to take in their due shares of bloud for their nourishment and not have their meat forsooth snatcht away before they have fill'd their bellies of these two mighty uses I say neither is true and both are raised upon this Supposition that the course of the bloud is out of the greater and superiour Veins into the smaller and inferiour which is most evidently false even by the testimony of the sight But lest I be thought either not well to understand or to misrepresent his meaning I am obliged to recite his own words Nam cùm in varicibus in quibus aut laxari aut rumpi Ostiola par est plus minusve dilatatas semper venas conspiciamus dicere proculdubiò tutò possumus ad prohibendam quoque venarum distensionem fuisse Ostiola à Summo Opifice fabrefacta c. Thus far then I have done him no wrong He proceeds Erat profectò necessaria Ostiolorum constructio in artuum venis quae non exiguae sed vel magnae vel moderatae sunt magnitudinis ut scilicet sanguis ubique eatenus retardetur quatenus cuique particulae alimento fruendi congruum tempus detur quod alioqui propter artuum declivem situm confertim ac rapidi fluminis instar in artuum extremitates universus conflueret ac colligeretur idque tum harum partium tumore tum super positarum marcore Here also I have faithfully interpreted his words and ye see that he thought the contrivement of the Valves necessary to retard the motion of the bloud because he took it for granted that the bloud descended through the greater Veins into the less grossly erring in both opinions For that the former is false we have seen demonstrated from the construction and situation of the Valves themselves and that the latter also is false and absurd is known to all who understand any thing of the Circulation of the Bloud To these errors he hath in the same Page added a third much more extravagant which is that the bloud is by a flux and reflux perpetually carried forward and backward in the Arteries For attempting to give the reason why Nature hath framed no Valves in the Cavities of the Arteries he saith Arteriis autem ostiola non fuêre necessaria neque ad distensionem prohibendam propter tunicae crassitiem ac robur neque ad sanguinem remorandum quòd sanguinis fluxus refluxusque in Arteriis perpetuò fiat It appears then that this famous Anatomist who in many other things deserved well of the Commonwealth of Physicians had no just title to the honour of having first invented the true and genuine use of the Valves
nay that he understood no more the Mechanic reason of their conformation than if he had never heard of or seen them Nor in truth did Father Paul whom yet I never can mention without secret veneration if the afore-recited account and what follows immediately after given by his most intimate friend during his life and after his Historian Fulgentio be true and full For in Fulgentio's narration of the manner how the Father came first to find out the Valves there is this passage And upon his own natural judgment he set himself to cutting with more exquisite observation whereupon he found out those Valvulae and the right use of them which do not only stop and hinder the bloud from dilating it self by its weight into the Veins as we observe in some crooked and swell'd knots but also that bloud running up and down with so much liberty and in so great quantity it might easily suffocate the natural heat of those parts which ought to receive their nourishment from it Whence it is plainly apparent that the Father also attributed a double use to the Valves one the very same with the former dreamt of by Aquapendens who probably borrowed it of the Father viz. to prevent the dilatation of the bloud into Varices by stopping its impetuous motion up and down in the Veins the other quite contrary to Aquapendens's second use viz. to prevent a surfeit of the parts upon too much bloud and an extinction or suffocation of their natural heat by that excess whereas Aquapendens fear'd they would be famisht if the Valves did not detain their food as Tantalus is feign'd to be Now if these were truly the Father's Sentiments concerning the Valves certainly he had no right conception of Natures design in making them as may be collected from the precedent demonstration of their true use To come then to a conclusion and draw all the lines of this scrutiny to a point since it is evident that neither Father Paul himself nor his disciple Aquapendens had a right notion of the proper use of the Valves and that both believed the bloud to flow out of the greater Veins into the less which the Fabric and situation of the Valves plainly contradict it necessarily follows that neither of them could be Author of that much more noble and more difficult invention of the CIRCULATION or the bloud which it was morally impossible for any man to deduce from their absurd opinions concerning the use of the Valves and the glory of which is wholly due to that incomparable man Dr. HARVY Who by admirable Sagacity of Spirit by numerose Experiments and Observations Anatomical and by assiduous Meditation perhaps also by the secret Manuduction of Fate that had reserved the secret for his knowledge attained at length to the invidiose felicity of finding it out and revealing it to the world I wonder therefore that some men of not obscure names in the Catalogue of Anatomists have shewn themselves so ungrateful and envious toward this immortal man as to ascribe this divine invention to Padre Paolo I mean Ioh. Walaeus and Tho. Bartholinus The former of whom doubted not to write thus Vir incomparabilis Paulus Servita Venetus Valvularum in venis fabricam observavit accuratiùs quam magnus Anatomicus Fabricius ab Aquapendente postea edidit ex ea Valvularum constitutione aliisque experimentis hunc sanguinis motum puta Circularem deduxit egregioque scripto asseruit quod etiamnum intelligo apud Venetos asservari Ab hoc Servita edoctus vir doctissimus Gulielmus Harveius sanguinis hunc motum accuratiùs indagavit inventis auxit probavit firmiùs suo divulgavit nomine The other had the confidence to affirm that Veslingius had communicated to him as a secret never to be revealed forsooth to any third person that the Circulation of the bloud was the invention of Father Paul the Servite who had written a book of it which was in the custody of Fulgentio at Venice To refute this palpable fiction to what I have already said of Father Paul's ignorance of the right use of the Valves I need add only this that if Fulgentio had had in his hands any such Manuscript of the Fathers as these Detractors have imagined 't is wonderful strange he should never so much as mention either that or the Circulation in his whole History of the Father's life when of all the subtle Speculations and discoveries of natural secrets by him attributed to the Father nothing would have so much conduced to the propagation of his glory as that Here therefore I put an end to this long digression to which the necessary contemplation of the Valves gave an inviting occasion and which being intended only to do right to the venerable memory of Dr. Harvy all lovers of truth as well as all Members of this Noble Society will I presume easily pardon ¶ ⸫ Having inquired into the velocity of the motion of the bloud in the Veins and the mechanic causes thereof let us next consider the velocity of the motion of the same bloud in the Arteries For the clearer understanding of which I lay down this Third Proposition PROPOSITION III. That the Arteries of an Animal their constriction or pulsation being complete do not remain wholly empty of Bloud Evident it is even to sense that all the veins of a Sanguineous Animal taken together are larger or more capacious perhaps in a quadruple proportion than all the Arteries put together and the whole mass of bloud runs through all both Veins and Arteries which mass in full-grown men commonly exceeds not 18 or 20 pints and though the Veins by reason of their transparent coats always appear full of bloud yet a man may doubt whether the Arteries also be always full that is whether they only give passage to the bloud in the time of the pulsation and then in the time of their quiet remain wholly empty or not To resolve this doubt therefore I say that the Arteries if they were wholly empty in the intervals of their pulsations then being laid naked to the sight they would appear constringed and lank like chords extended but our eyes assure us that on the contrary they retain their round and plump figure and being press'd by the finger resist the pressure neither of which can possibly consist with a total exinanition Again the Veins being laid naked if after the pulsation of the heart the Arteries remain'd empty then certainly would the pipes of the Veins by the quantity of 5 pints of bloud crouded into them more than what they are proportion'd to contain be distended at least a third part more than they ought but this is sensibly false for their coats are not distended beyond their usual rate Ergo the Arteries are at no time wholly empty Moreover in Animals whose Arteries are transparent as in Snakes Vipers Eels Froggs c. we may from their Purple or bluish colour perceive the Arteries to be full of
bloud Which is alone sufficient to evince that the Arteries do not remain empty after the pulsation of the heart but contain at least a 4 th part of the whole mass of bloud which in a man is about 5 pints Yet farther the Arteries in the moment of their pulsation are highly turgid when yet not above 3 ounces of bloud is emitted into them by the Systole of the heart Therefore if before the Systole the Arteries were wholly empty a space 20 times greater than their bulk is would inevitably be filled by the 3 ounces of bloud emitted by the heart but this certainly is impossible without such a rarefaction of the bloud which no man of common sense will admit Therefore to replenish so great a vacuity in the Arteries there must come into them five pints of bloud either from the heart or back out of the Veins but neither of these is possible in nature Let us add that 3 ounces of bloud emitted by the Systole of the heart cannot fill a space greater than half a foot of the next Arteries to the heart Therefore if the Arteries were empty before the Systole truly all the rest of the Arteries would remain empty also in the following Systole and consequently could not beat at the same time with the heart and the Circulation of the bloud through them would be interrupted or discontinued contrary to the mechanic necessity thereof In fine we are convinced by common experience when an Artery whether it be great or small is cut the bloud is in every pulsation squirted out with mighty violence Now it is impossible this should happen unless all the Arteries were full of bloud all along from their beginning to their end because the violence of the stream of bloud gushing from the incision hath no other efficient cause but the protrusion of the bloud coming on behind and urging the antecedent But in the following pulsation there is an accession of no more than 3 ounces of bloud which cannot by its quantity replenish half the capacity of the Arteries Therefore unless there remain after every pulsation 5 pints of bloud in the Arteries they cannot be made turgid again in the following pulsation So that nothing is more certain or more evident than this that in a living Animal the Arteries are never empty Quod erat ostendendum From the praecedent Theorem naturally arises this Consectary That after the pulsation of the heart there remains in the Arteries the 4 th part of the whole mass of bloud conteined in the body of an Animal and in a man commonly about 5 pints and that the proportion of bloud expressed by the Systole of the heart into the Arteries is about one twentieth part of the bloud contain'd in them As also that 3 ounces of bloud ejected out of the heart into the Arteries fill a space in the Arteries next to the heart no greater than half a foot namely so much as is triple or quadruple to the latitude of the Ventricles of the heart PROPOSITION That the motion of the Bloud in the Arteries is threefold swifter than the motion of the Heart that impells the Bloud Because in the same time are absolved all these motions viz. the dilatation of the Pores of the heart the restriction of its Cavities by the swelling inward of the walls of the Ventricles the expulsion of the bloud contein'd in the Ventricles the motion of the expulsed bloud in the Arteries and the promotion of the mass of bloud praeexistent in them caused by the urgency of the new bloud coming on out of the heart all these actions I say are performed in the same time And it appears that the three former operations are performed with the same velocity in the heart because the Fibres of the heart by reason of their abbreviation are with the same motion moved through the same space of the amplitude of the Ventricles through which they are moved by restringing the same Ventricles and squirting out the bloud that was conteined in them And the two last operations likewise are performed with the same velocity For look how much space the bloud expelled out of the heart runs through in the Arteries just so much space must the mass of bloud praeexistent in them be driven through in the same time because one part of the bloud must give way to another urging it forward as fast as that comes on behind But if the motion of the constriction of the heart be compared with the progressive motion of the bloud in the Arteries then doubtless they will not be found to be of equal velocity because the former motion viz. of the constriction of the heart is made through a space equal to the latitude of the Ventricles of the heart which at most excedes not 3 inches breadth but the space through which the 3 ounces of bloud expressed out of the heart run in the Arteries is equal to the length of half a foot Therefore the space will be triple at least to the space of the former motion and yet both these motions are performed in the same time Ergo the motion of the bloud in the Arteries is threefold swifter than the motion of the heart that causes it Quod erat propositum I add this remark that the motion of the bloud in the Arteries is always the same whether the three ounces of bloud emitted into them out of the heart exactly fill the space dilated in them or whether any portion of it be after their repletion expell'd out of them For in both cases the bloud praeexistent in the Arteries is just so much promoved in its course as 3 ounces newly emitted take up of space which run through more of length than half a foot ¶ ⸪ Here I cannot fairly decline to encounter a vulgar error that stands in my way Which is That the bloud is expelled out of the Orifices of the Arteries into the substance of the Parts by no other cause but the constriction of the Heart To refute which I will assert this PROPOSITION That the cause expelling the Bloud out of the Arteries is not the Systole of the Heart alone but the constrictive or peristaltic motion of the Arteries themselves naturally and necessarily succeeding their expansion To the pulsation of the heart two effects are subsequent viz. the repletion of the Arteries by the bloud emitted into them and the expulsion of the same bloud out of them into the habit of the parts Now certainly these two operations cannot be performed together or at the same time because the former is done by dilatation and the other by constriction of the same Arteries which two contrary motions cannot be coincident Wherefore it is of absolute necessity that the repletion of the Arteries be precedent and the evacuation be subsequent But the repletion cannot be made without a violent distention of the transverse or circular Fibres of the Arteries and we all know that all the Fibres of vessels no less than those
of the Muscles of the Guts Stomach Tendons Membranes and the like Fibrose parts naturally resist distraction and have a power of contracting themselves after extension Yea more we see that all Fibres even in their natural posture are somewhat upon the stretch for when they are cut they instantly shorten themselves toward both ends which would not happen if they had been constituted in a middle state betwixt laxity and extension as a Bow unbent is quiet suffering neither contraction nor distraction of its parts Now if all Fibres even in their natural state suffer some degree of stretching certainly when the Arteries are replenisht with bloud their cavity must be dilated and in the dilatation of their cavity their transverse or circular Fibres must suffer much more stretching than they did before And because to this dilatation of the Arteries a constriction immediately succeeds which is not possible to be effected without an abbreviation of the circular Fibres of the Arteries and because that abbreviation or contraction is connatural to the Fibres themselves therefore it is impossible that the Arteries after that violent stretching caused by their repletion and turgency should not exercise by natural necessity that mechanic power they have of contracting themselves by vertue of their circular Fibres girding them inward and equally impossible that the Arteries should so contract themselves without expelling at the same time out of their Orifices the bloud that dilated them Whence it appears beyond dispute that the spontaneous constriction of the distended Arteries is the cause of the expulsion of the bloud out of them into the substance of the parts contrary to their opinion who ascribe this expulsion only to the Systole of the heart ¶ ⸪ The natural method of acquiring Science ye know is to begin from things more known and then to advance to things less known to procede from effects to their causes Seeing therefore that we are now certain that the bloud in Animals is carried by a perpetual circular motion through all parts of the body our next business is to enquire what are the Causes of this admirable motion as well the final as the efficient I begin from the final it being a question worthy our consideration why or to what end Nature all whose counsels and actions are ordained by an infinite wisdom hath instituted this rapid Circulation of the bloud Constant it is even from common experience that whenever the bloud is quiet or ceases from motion whether within or without the body of an Animal the red and grumose part of it soon curdles and is separated from the serose or albumen and so the constitution or contexture of it is dissolved and corrupted whereas on the contrary while the bloud continues in perpetual motion within its vessels in the body of a living Animal so long the ordinate mixture of its elements due temper and vital constitution of it is conserved for mechanical reasons in our ensuing discourse to be explained It seems then that such a mixture of the constituent parts of the bloud upon which the vitality of it doth necessarily depend cannot be otherwise conserved than by a continual agitation and concussion made in the vessels first by the heart with strong force impelling the bloud through the Arteries then that impulsive force languishing by filtration in the spaces intermediate betwixt the Arteries and Veins next in the Veins by the constriction of their circular Fibres by the compression of the Muscles and the Viscera and the inspired air All which compressions would not suffice were not Valves placed commodiously within the Veins by which the motion of the bloud is accelerated and a farther conquassation of it made And here we meet with a fair occasion to reflect upon the mutual Anastomôses of the Capillary Veins and the infrequent distribution of Valves in one and the same Vein for both these contribute also their proportions toward the end now under our disquisition For the texture of the Veins being indeed lax and soft yet such as may by virtue of their circular Fibres be constringed and contracted hence it is that by the bloud regurgitating in those tracts of the Veins that have no Valves by the great quantity and force of its regurgitation or recoiling the lowest part of the Vein is much dilated and on the contrary the highest part is contracted So that the bloud being by this reflux though inobservable agitated and conquassated may revive its due commistion and conserve its vital constitution It appears then the defect of Valves also hath its use Within the cavities of the Arteries as I said before no Valves are placed because the grand force by which the bloud is impell'd through them is more than sufficient to conquassate and commix it by wedging in as it were the more fluid albugineous particles among the red grumose particles that from both sorts comixt per minimas moleculas as they say and yet mutually reluctant the Vital Mication or Oscillatory intestine motion of the bloud may be continued So then here is neither need of nor place for a Fermentation Now from the consideration of these things premised I conclude that the Circulation of the Bloud was instituted for the conservation of its requisite temper and vital constitution Which was to be inquired and which leads us to The admirable effects and benefits arising to the Animal Oeconomy from the same Velocity of the Circulation of the Bloud Which being certainly so great that the whole mass of bloud runs its circular race in the twentieth part of an hour or thereabouts even in a sedentary and sedate man as hath by many been demonstrated from the quantity of bloud commonly contein'd in the body from the number of Pulses made in an hour and from the quantity of bloud exprest by every pulse of the heart and we having already seen what advantage redounds to the bloud it self from this velocity our curiosity spurs us on to enquire also what other scopes or ends Nature may probably be conceived to have proposed to herself when she instituted this so rapid motion or what emoluments and benefits from thence redound to the Oeconomy of the whole body Of these the first seems to be this that in every pulsation of the heart a great quantity of bloud is effused and protruded out of the Capillary Arteries into the habit of the parts for their refocillation by influent life of which I have formerly discoursed copiosely in this place For by how much swifter the motion of any liquor or other fluid through a pipe or canale is so much a greater quantity of it is in equal time effused at the Orifice thereof as hath been ingeniously demonstrated by B. Castellus and therefore the bloud is like a full and rapid torrent impelled into the Pores of the flesh and Viscera The second is the energy of the stroke with which the bloud projected by the heart dashes against the same extreme parts which energy is
marrow which are sent down directly into the substance of the heart as if the more easily to convey some influence into it No great difference this and yet the cause that induced Nature to make it may be great What it is is difficult to find out It may probably have some respect to the prone posture of Brutes which being horizontal must cause the ponderose machine of the heart to swagg and the cone to point not toward the midrif as in erect man but toward the Sternum and therefore in them there might be need of more auxiliary Nerves to assist the hearts motion in that position But whatever may be the true reason I do not assent to their conjecture who say that because the heads of beasts look downward therefore the providence of Nature hath furnished their hearts with more Nerves lest Animal Spirits should not in sufficient swarms be sent every moment from the prone head into the heart of a Brute that position of the brain forsooth rendring the transmission of these Spirits more difficult and slow And the reason why I do not assent to this witty conjecture is because neither the Authors of it nor any other man whose writings I have read have sufficiently proved that there are such things as Animal Spirits in rerum naturâ In some books indeed whole Common-wealths of them are found so that ye can hardly pass along without meeting crouds of them But till I see their Existence otherwise than precariously asserted I am justly excusable if I doubt thereof The Heart being thus composed of many myriads of strong Fibres of various orders by most dense contexture compact and of various Nerves intersperst it required to be continually cherished with due heat as well without as within Wherefore the Heart having no heat but what it receives from the bloud in which only the true Calidum innatum the lar familiaris resides Nature hath furnished it with two Arteries for its own peculiar use divided almost from their origine into two trunks the Orifices of which open themselves near to the beginning of the aorta immediately without the Valvulae Semilunares They are fitly called Coronary Arteries because their trunks do not presently enter into the parenchyma or substance of the heart but first make their tour or circuit the more commodiously to disperse their branches round the basis of it in manner of a crown or rather a Diadem and though from their very original they divide and recede the one from the other to the opposite regions of the heart yet they meet again in their extream branches and by mutual Anastomóses or inosculations communicate betwixt themselves so that if any liquor be injected into either of them it will in a moment appear to diffuse it self also through the other And this mutual Communication seems to be design'd to a good end For since the necessity of influent heat or life is equal in all parts of the heart that necessity could not be more commodiously satisfied any way than by this Artifice of mutual inosculation betwixt the extremities of these two Arteries No sooner hath the bloud thus imported communicated its vital heat to the substance of the heart than it is thence exported by the two Coronary Veins which in like manner encompassing the heart and by their numerose emissary surcles imbibing the bloud effused out of the Arteries reduce it into the right Ventricle thence to be brought through the Lungs back again into the left So that here is a private circulation in a small circuit instituted for the peculiar benefit of the Heart As the extreme surcles of the Coronary Arteries are mutually inosculated so also are those of the Coronary Veins as is apparent from ocular inspection For if you take the heart of a Calf or any other very young Animal for in such these vessels are most easily discernable and with the back of a pen-knife gently impel the bloud from one side of the heart toward the other you shall see it flow out of the Vein of one side into that of the other and vice versâ Nor is it to be doubted but that in all other parts of the body there is the like mutual communication per anastomôsin betwixt Capillary vessels of the same kind Besides the proper vessels of the heart now described there are annext to its basis also two Subsidiary Muscles hollow and round from thence call'd Auriculae cordis framed with no less art than the Heart it self though of less bulk For they are composed of robust Fibres too and disposed in the same order and as their motion precedes that of the Heart so have they Nerves from surcles of the Eighth pair before they reach to the heart it self Besides their intermediate fleshy Fibres which form little musculose columns are elonged to opposite Tendons For the Tendon at the basis of the Heart is common also to the ears of it and serves them for a fulcrum or prop and on the other part of the right Ear where it respects the Vena Cava it is firmed by a harder and Tendinose circle betwixt which two Tendons the Fibres tending to each are terminated as appears in the right Ear of a human heart inverted Of these Ears the right is always greater than the left Perhaps because the flux of the bloud being less rapid out of the Vena Cava into the right Ventricle of the heart than out of the Arteria Venosa into the left whither it is impell'd by the compression of the Lungs and by the coincident elasticity of the inspired air it was therefore requisite the capacity of the right Ear should be proportionately larger to receive and transfund into the right Ventricle a quantity of bloud sufficient to fill it For evident it is that the office of these Ears is like that of funnels to transmit the bloud into the Ventricles of the heart For the same reason the trunk of the Vena Cava when it approaches to the heart participates somewhat of the nature of a Muscle For there it is furnished with fleshy circular Fibres by which it is constringed and consequently the bloud running through the canale thereof is urged the faster into the right Ear in the same manner as when a gut or bladder is outwardly constringed by the hand the liquor therein contained is expressed and its regress hinder'd We have now survey'd the Structure of this admirable Machine the Heart at least so much thereof as may serve to render more plain and intelligible what I am about to say concerning the Action thereof To which I now pass ¶ ⸫ Evident it is both to the sight and to the touch that in the act of Pulsation the whole fleshy substance of the heart is stretcht and hardned with very great force as all other Muscles are when they act and certainly this tension and induration arises from the very Structure of the heart For the Fibres of the columns of it and their
of the Ventricles of the heart is the sole and immediate cause of the expression of the bloud that was conteined in them into the Arteries For the swelling or incrassation of these opposite walls being all inward toward the Centre of the heart and withal so great as to fill up the cavities of the Ventricles it is necessary that the bloud contained in the cavities being on all sides vehemently compressed give way and flow forth through the apertures or Orifices by Nature provided for its efflux the resistence of the fluid bloud holding very little proportion to the mighty force of the solid compressing it But so grand an intumescence of the fleshy substance of the heart could not otherwise be made than by a great swelling and turgency of its Fibres and therefore we may infer that the thickness of the Fibres of the heart is in the act of Pulsation doubly greater than in the diastole This being granted I consider that the external Fibres of the heart exercise very great force not by shortning themselves but by resisting distraction as the iron hoops of a hogshead that the perimeter of the heart be not augmented and at the same time they are inflated in their Concave part or under side as we have said the threads of a glome are and in like manner the internal Fibres when they are swell'd and incrassated exercise very great force by making folds and turgid wrinkles so tense and rigid that they do the office of wedges by which not only the cavity of the heart is filled up but the bloud therein conteined is by vehement compression squirted out by a motion very much resembling that by which we spirt Plum-stones with our Thumb and fore-finger compressing them behind But the slender fleshy Columns holding in the opposite walls of the Ventricles of the heart are at the same time also incrassated and withal shortned their Fibres being swell'd and corrugated to help fill up the cavity Yet they exercise greatest force to perform the office of wedges They exercise none towards the drawing together the opposite walls of the Ventricles because themselves are lax by reason of the corrugation and shrinking of the length of their Fibres and besides this they could never exactly conjoyn the opposite walls because being of a musculose constitution they cannot be totally shortned the nature of the Muscles being such as suffers not contraction greater than the third part of their length Yet it cannot be denied but these musculose Columns serve as cords to retain and conserve the due disposition of the internal parts of the heart and to prevent the immoderate distension and distraction of the Ventricles which too great a quantity of bloud rushing into them out of the Veins might otherwise cause Finally the Papillae or little fleshy teats standing up within the Ventricles and to which the membranose filaments of the triangular valves of the heart are fastned do also act their part in this Scene not only by admitting the like inflation of their Fibres but also by firmly erecting themselves ad instar penis All these things are verified in the left Ventricle and in the Ears of the heart but in the right Ventricle where is not found an equal number of Columns the constriction is made by incrassation of the external wall namely by inflation and decurtation of the Fibres thereof so that the hollow crookedness of it by swelling inward comes near to a Plane and the Arch within becomes streight Also the inflation and swelling of the Septum cordis or middle wall of the heart of great thickness naturally contributes not a little to the repletion of the right Ventricle For hence it is that the Convex superfice thereof doth become more prominent and stretched out whence that space resembling the figure of a concave Lens is filled up and the walls mutually touch the circuit of the Lenticular cavity remaining still the same Now this whole operation is exactly conform to the institute of Nature which primarily fills and amplifies the Pores of the Spongy Fibres by the humectation above explained from which she attains to a double effect For in the Muscles of the Limbs that swelling of the Pores of the Fibres produces a secundary effect which is the decurtation of the Muscle and the strong traction of the joynt but in the heart from the very inflation of the Fibres and consequent incrassation of the walls she effects the repletion of the Ventricles But the Machine is the same in both namely the force of a wedge dilating the Pores of the Fibres But that this expression of the Bloud out of the heart is not made by a Spiral contorsion or twisting of the heart such as that by which water is commonly squeez'd out of a wet napkin as some late Writers have thought is easily to be proved I acknowledge it to be most true that the expression of the bloud out of the heart no less than the wringing of water out of a wet cloth is made by constriction of the Cavities and Pores which were filled by the fluid but at the same time I deny that such a constriction is made in the heart and such an expression of the bloud thence by the same cause the same Organs and the same Mechanic action by which water is squeez'd out of wreath'd Linnen For in a Linnen cloth before its Contorsion the threds were all lax and therefore they admitted many Interstices that might be filled with little drops of water Afterward the cloth being strongly twisted the threds are forced to make many circuits about the twist of almost the same altitude and so they must not only be much elonged in those prolix Gyres but also extenuated and stretch'd and consequently their sides being made smooth by extension of their folds and wrinkles will mutually touch and their interstices vanish whence the little drops of water that were in them before will presently be squeez'd out But in the heart the repletion of the Ventricles is performed in a manner far different from this For in the act of Pulsation the bulk of the heart is not extenuated or diminished but rather augmented in a double proportion nor are the Fibres of the heart elonged but rather contracted as the nature of all Muscles requires The same Fibres do not mutually touch nor are their interstices fill'd up by reason of violent traction and extension but of their inflation Notwithstanding this we are not to think that the Spiral disposition of the Fibres of the heart is of no use For they serve to the firm binding or hooping as it were of the walls thereof that the face and configuration of the heart may continue still the same which Nature hath provided for also by Girths of other Fibres wound round about from the external Tendinose Orifices of the Vessels of the heart to the Columns within and with admirable Artifice decussated and woven together And thus we have made good our
solid meats and together with the drink serve as a fit Menstruum to extract the laudable and alimentary parts of them ad modum tincturae But this liquation of solid meats in the Stomach seems to be effected by motions placid gentle and imperceptible in the state of health not by those violent commotions and irrequiet agitations that always proceed from and accompany Ferments properly so call'd during their working as all men that enjoy good health feed soberly and keep a regular course of diet may easily observe in themselves And therefore this Acid Phlegm cannot properly and in Philosophical strictness be referr'd to the family of Ferments The same may with equal reason be said also of the Bile and Pancreatic juice commixt in the Duodenum They may perhaps conduce somewhat to the farther attenuation and exaltation of the Chyle they may also promote both the separation of the Nutritive from the Excrementitious parts of the same Chyle and the insinuation and permeation of the former through the coats or membranes of the Guts into the milky veins all this they may do and yet not by way of Fermentation whereof there is neither necessity nor sense in statu sanitatis and to argue from a preternatural state to a natural is a Paralogism Now if neither of these two so much celebrated Ferments hath any more right to that denomination than what is precariously derived from some remote and slender analogy or semblance imagined to be betwixt their nature qualities and effects and those observed in genuine and true Ferments as certainly neither of them yet appears to have What ought we to think of all the rest of invisible Ferments supposed to reside in places where hitherto they have never been found Why may we not till they shall be by Anatomical and other convincing experiments shewn to us believe that they have existence no where but in the brains of fancyful men For my part I blush not even in this venerable Assembly of most Learned men where I have as many Judges as Auditors openly to profess my self to be of this belief because de non apparentibus de non existentibus eadem ratio est and because I have heard an eminent Member of this first and more ancient Royal Society a man renowned over all Europe for his Philosophical and Anatomical Writings deliver this judgment of the multiplicity of Natural Ferments fancyed to be in the body of an Animal that they were a new-found asylum ignorantiae I say of Natural Ferments lest what I have said should be detorted to the exclusion of Praeternatural Fermentations which I do not deny to be incident sometimes to the bloud and other humours of the body more signally in Fevers and some other acute diseases though perhaps not so often as vulgar Physicians imagine What I have hitherto said may perchance seem to some of my Auditors to be a digression and they may be apt to think that I have made my first step in a wrong path I am therefore obliged in my own defence to advertise them that having proposed to my self to enquire strictly into the natural necessity or Mechanical reasons of the Motions of the Bloud and finding the aforesaid Comment of Ferments lying like a block in my way I thought it concern'd me rather to remove than to leap over it and leave it for others to stumble at For some there are and those too men whose names are deservedly celebrated for their profound knowledge both in Anatomy and the Mathematicks who in their books have professedly taught that even the bloud it self the seat of life also undergoes a certain natural Fermentation in the heart lungs and greater arteries as necessary to its perfection and vitality A doctrine which to me I profess seems very improbable and inconsistent with the wisdom of Nature Improbable First Because of all the various liquors found in the body of an Animal in statu Naturae the bloud seems of it self least prone to Fermentation which is incident chiefly if not solely to new and musty liquors whereas the greatest part by much of the bloud is old and by repeated Circulations well defaecated in its proper Emunctories and by insensible transpiration and by consequence needs no Fermentation True it is indeed that new Chyle is ever now and then brought into the rivulet of the bloud out of the common cistern thereof by the ductus thoracicus and the Subclavian vein for a recruit but in a quantity so small a few drops perhaps at once for more will not be found to bear a just proportion either to the capacity of the common Receptacle of the Chyle which is but little or to the narrowness of the Pipe leading from thence to the Subclavian vein as cannot in reason be thought sufficient to perturb and excite a fermentation in the bloud with which it is mixt If a greater quantity of Chyle were mixt with the bloud at one time certainly the bloud would soon lose its native purple and put on the white livery of the Chyle especially in the descending part of the Vena cava where the commixture is first made which yet no Anatomist for ought I know hath ever observ'd Secondly When Ferments are commixt with liquors consisting of heterogeneous particles they are generally slow in exerting their power and by degrees insinuate and diffuse their active particles through the whole mass before they can so far prevail as to raise an universal commotion and tumult in them as common experience testifies but the newly commixt Chyle and bloud are in a moment at most in the space of a few pulses of the heart rapt out of the Vena cava first into the right Ear and then into the right Ventricle of the heart so that here is no morula no competent space of time given to excite an actual fermentation Thirdly Here is wanting also convenient place To all Fermentations is required fit room wherein the liquors may have liberty to undergo an impetuose commotion and agitation of all their dissimilar and contrasting particles nor will the Must of Wine it self ever ferment if it be kept in close and strong casks as appears from the making of Stum but the Vena cava the Heart and Arteries are fill'd with bloud even to distention till by their Systole they squirt it forth and then in the next moment they are replenished What room then is left for the bloud to ferment in Seeing therefore that the bloud is by its own constitution unapt to ferment as bearing a greater analogy to the nature of Milk than to that of Wine whatever the Willisians have said to the contrary and seeing that neither the small supplies of Chyle which it daily receives are sufficient to induce nor the shortness of the time in which it passes through the praecordia nor the want of convenient room permit a fermentation what reason have we to assent to their opinion who teach that a fermentation of the bloud
Actions and Uses of the Ears and Valves of the heart first discover'd by our immortal Dr. Harvey and since confirmed by various experiments of other excellent Anatomists Being then certain of the Phaenomena it remains only that we endeavour to explore the Mechanic causes of them In the first place because the Ears of the heart are Muscles round hollow and composed of fleshy Fibres wound about Spirally and intersecting each the other decussatim and because they end into little columns and trenches in the same manner as the left Ventricle is framed therefore must they operate by the same Mechanic necessity and Artifice by which the heart operates viz. by the force of a Press and by wedges insinuated into the Pores of their Fibres they must be swell'd and so constringed and consequently express the bloud contein'd in them Secondly That the constriction of these Ears ought to precede the contraction of the Ventricles of the heart though both motions seem to be performed at one time may be thus demonstrated For if this be not true then either the Ears and Ventricles of the heart are constringed in one and the same moment of time or the heart is first constringed and then the Ears If the first because the triangular valves have no use before the heart is constringed nor after the constriction of it is complete because the shutting of the Valves would be in vain when the bloud cannot flow back and slow back it cannot before the heart is constringed because then the bloud is not yet in the Ventricles and so cannot be impelled by the Systole of the heart and after the constriction of the heart the expulsate bloud can much less flow back therefore it is necessary that at what time the Ventricles are constringed at the same time the Venose orifices ought to be exactly shut by the Triangular Valves that the bloud may be impelled not backwards but forwards into the Arteries But if at that same time the Ears were constringed they would inevitably vomit out the bloud contein'd in them into the Ventricles and so open the clausure made by the triangular Valves because they are so disposed as to be opened and dilated by the very coming of the bloud Wherefore at the same time the bloud would be impell'd by the Ear into the heart and repell'd by the heart and so these two contrary motions would mutually destroy each the other and both be in vain Besides when two outlets are at the same time open in one Ventricle of the heart the whole compressive force of the heart is divided into two equal parts which impell the two halfs of the bloud one backward the other forward into the Arteries and therefore Nature would foolishly by a double endeavour attain but half her end We may add that the triangular Valves would be wholly useless since they would then urgente necessitate be open when they ought to be shut Wherefore it seems impossible that the Ears of the heart and its Ventricles should be constringed at the same time But if we suppose the natural order to be inverted i. e. that first the Ventricles of the heart are constringed and then the Ears compressed this would be much more absurd for half of the bloud contein'd in the Ventricle would flow back into the Ear on both sides open and thence into the Vein It must therefore be confessed that the constriction of the Ear ought to precede and then immediately ought the constriction of the Ventricle to succede and then all the operations procede regularly and compendiously For the Ear being comprest first the regress of the bloud into the Vein is hindred next the bloud is expressed out of the Ear into the cavity of the heart Thirdly the Orifice of the heart is shut by the constringed Ear Fourthly the Ventricle of the heart being filled with bloud and distended the Membranes of the triangular Valves are expanded These actions being in this order of succession done then in the fifth place follows the swelling of the heart by which all the bloud in the Ventricles which cannot by reason of the double clausure slow back is forced to run forth by the open door of the Artery Thirdly it is observable that the action of the right Ear differs from that of the left because the bloud ought to flow out of the Arteria Venosa or as some call it the Vena Pulmonaria which is very ample into the left Ventricle of the heart with a swift current by reason of its gravity and of the compression of the Lungs For this reason a little Ear is sufficient to transmit the bloud so swiftly running into the left Ventricle and with the help of the mitral Valves also exactly to shut the aperture of the heart On the contrary in the right Ear the slowness of the blouds influx ought to be compensated by the amplitude of the Canale And moreover because the right Ear ought not only to close the Orifice of the heart but also to impel rapidly the slow paced bloud into the right Ventricle therefore Nature hath made the Muscle and cavity of the right Ear stronger and larger than that of the left Fourthly We may farther gratifie our curiosity by considering the manner how the triangular Valves exactly shut the Orifices of the heart which seems to be this Because these Membranose Valves have their bases fastned to one part of the circular Tendon of the Orifice of the heart as flags are fastned to their staves and their other sides are by many Tendinose Filaments or strings fastned to the fleshy teats in the opposite part of the cavity of the Ventricle as Webs of Linnen exposed to the Sun are kept upon the stretch by many small cords tied on each side Hence it comes that by the stream of bloud rushing in the cavities of the Ventricles are dilated and so these Membranose Valves which before were lax and flagged are drawn and expanded transversly so as to spread themselves through the whole space of the Orifice Necessary it is therefore that the points and sides of these Triangular Valves thus drawn by the little cords decussated should be conjoyned and being conjoyned make one Conical superfice greater than the plane of the Orifice or of the circle of the basis of the same Cone After this follows the Systole of the heart when the insides of the Walls of the Ventricles are united and therefore those little cords of the Valves are at the same time relaxed and united also and so the faces of the Triangular Valves themselves must be united and acquire a Sinuose or embowed figure their Superfice not diminish'd because their membranes are not contracted Whence it comes that the bloud filling the Ventricle doth by repelling the membranes and inflating them bow them as the Sails of Ships swell'd by the wind are bowed into a hollowness Again since those membranes thus embowed are transfer'd toward the Tendinose Orifices of the heart the round area of
congruous to the Organical structure of the Heart to all which I have been careful to adjust them and in fine consistent among themselves then I shall with assurance conclude that the Heart is as all Automata are moved by Mechanic necessity Which is what I proposed to demonstrate even without that incredible displosion of Saline and Acid spirits in the Heart first imagined by Doctor Willis and since asserted by a man of much greater Erudition and more solid judgment namely Alphonsus Borellus as necessary to be supposed in order to the Solution of this great Probleme of the Pulsation of the Heart and that of the motion of the rest of the Muscles Which pretty conceit I will first revive in your memory by reciting a few of Borellus's own words faithfully and then offer to your consideration the reasons that have induced me to reject it Restat igitur saith he quòd sicut omnes musculi contrahuntur inflatis vesiculis eorum pororum sic quoque immediata causa tensionis Cordis erit inflatio vesicularum pororum ejus facta à fermentativa ebullitione tartarearum partium sanguinis à succo spirituoso ex orificiis nervorum instillato c. The Reasons that disswade me from assenting to so great a man in this matter are these First We have the testimony even of our sight the most certain of all our senses that in an Egg after a day or two's incubation of the Hen the Punctum saliens first and then the Vesicula pulsans are agitated by a manifest Pulsation in the Centre of the Colliquamentum or genital humour which is a pure and homogeneous liquor even before any the least sign of bloud can be discerned Here therefore the supposed immediate cause of the Hearts motion viz. an inflation from a Fermentative ebullition of the Tartarous parts of the bloud meeting and conflicting with the spirituose juice instilled out of the Nerves into the Heart certainly can have no place For at that time in the Egg neither Heart nor Brain nor Nerves are yet formed nor is any part of the Colliquamentum converted into bloud causarum in rerum natura nondum existentium nulli dantur effectus Beside the same Vesicula pulsans is from the beginning of the change of the genital liquor into bloud not only the Conceptacle of it but also the Engine that gives it motion and therefore the new made bloud can contribute nothing toward the Pulsation thereof Secondly If not only the natural motion of the Heart but also the Voluntary motion of the rest of the Muscles procede from an explosion of mutually hostile spirits concurring and combating in them as Borellus affirms why have not all other Muscles as well as the heart a perpetual Pulsation in them when the same bloud and the same Succus Spirituosus perpetually concur in them no less than in the heart And what dominion could the Soul have over the Muscles of the Limbs to exercise which of them she pleases and as long as she pleases and give them rest when she pleases if they were agitated every moment by Squibbs or Crackers breaking within them certainly she could never moderate such violent and tumultuose explosions Besides it is wonderful strange if those explosions be made in a Muscle when it acts that we should never perceive it to be distended or heaved up outwardly but that on the contrary we should plainly perceive the Muscles in all voluntary motion to be strongly constringed inwardly to be minorated and become harder which is a certain indicium that they are moved in a manner quite contrary to inflation Thirdly Such an explosion made in the heart might indeed cause the Diastole of it by inflating and distending the Ventricles but would hinder the Systole or constriction of them inwardly which is requisite to the expression of the bloud For the supposed explosion consisting like that of aurum fulminans or Gun-powder in a motion expansive would of necessity dilate the cavities of the heart Fourthly If an explosion of Acid and Saline liquors meeting commixt and warring in the heart be the immediate efficient of its motion it is consentaneous to infer that where the ingredients of this explosive mixture are more copiose there the explosions ought to be more frequent è contra But in sucking infants who being nourished only with milk cannot reasonably be thought to have much if any thing of Acidity in the nutritive juice or of saltness in their bloud the Pulse of the heart is notwithstanding even in the state of health at least doubly quicker or more frequent than in full grown men nay such who delight to feed on salt meats and drink plentifully French and other subacid Wines Ergo 't is highly improbable that the Pulse of the heart should be the effect of such explosion These are the reasons that moved me when I came to this instable bogg to withdraw my judgment from the conduct of Borellus whom before I had so closely followed and to divert into a private way which seem'd to promise me smoother and firmer sooting and which notwithstanding I will not commend to others unless your approbation shall encourage me to pave it Meanwhile the hour-glass admonishing me to reserve till I meet with some other opportunity what may be farther alledged to confirm the precedent explication of the Efficient Causes of the Systole of the Heart I will now add no more than three short Advertisements and resign you up to the more profitable and more pleasant entertainment of your own better thoughts The First is that is probable that in every Diastole of the heart the few and little drops of the Succus Nervosus which by wedging themselves into the small Rhomboid Pores or meshes of the Fibres of the Heart and so dilating them caused the immediately precedent Systole are by the restitutive motion of the same Fibres squeez'd out of those Pores into the Parenchyma of the Heart whence they are absorbed and carried off with the bloud by the Veins and so make room for the next succeeding drops to cause the next Systole and so the Systoles and Diastoles of the heart come to be alternately repeted and the Circulation of the bloud to be perpetuated This I say is probable because Nature hath instituted the like absorption of the redundant Succus Nervosus by Veins in many other parts of the body more eminently in the upper part of the neck where the Iugular Veins imbibe whatever humour distills from the bottom of the Brain as Doctor Lower expressly affirms and with good reason in these words Humor omnis è cerebro proveniens in venas jugulares resorbetur I had heretofore I confess a thought that the humour contein'd in the Pericardium might have no other fountain but the reliques of the Succus Nervosus expressed out of the Fibres of the Heart in the Diastoles when after violent Tension they exercise their natural faculty of restitution But when I had
March 28. 1683. ORdered that the Three Anatomic Lectures read on the 19 20 and 21 days of this present Month in the Theatre of His Majesties Royal College of Physicians in London by Dr. Walter Charleton Fellow of the same College be forthwith Printed and Published Tho. Coxe President THREE Anatomic Lectures CONCERNING 1. The Motion of the Bloud through the Veins and Arteries 2. The Organic Structure of the Heart 3. The Efficient Causes of the Hearts Pulsation READ On the 19 20 and 21 days of March 1682 3 IN THE Anatomic Theatre of His Majesties Royal College of Physicians in London BY WALTER CHARLETON M. D. And Fellow of the same College Published by Command of the most Learned President LONDON Printed for Walter Kettilby at the Sign of the Bishops-head in St. Paul's Church-Yard 1683. PRAELOQUIUM CVM non ita pridem Clarissime Ornatissiméque PRAESES mandatum tuum ut ad Saxum hoc anatomicum hîc denuò volvendum me accingerem ad obsequium paratus accepissem mox apud me ultrò citróque agitare coepi quodnam argumenti genus prae caeteris mihi seligerem quo Excellentiae tuae expectationi aliquatenus satisfacere possem simul caeterorum è Doctissimis meis Collegis quorum hîc florem video tota urbe delibatum auscultationi prolixiùs gratificari Plurima quidem tunc temporis anxiae ac in diversa distractae sese offerebant menti nec ad gratiam vulgi conciliandam fortassis incommoda Sed Principum virorum quos in celeberrimo hocce Theatro placidè considentes venerabundus aspicio erudita curiositate prorsus indigna judicabam omnia Tandem verò animo se meo ingessit summum illud necdum etiam Medicorum vulgo satis intellectum Naturae mysterium Sanguinis nempe motus Circularis quo de quidem plerique omnes passim gestiunt garrire paucos tamen reperias qui de causis ejusdem de conditionibus atque circumstantiis quod caput est rei de ratione Mechanica cogitarunt unquam quod seriò dolendum adhuc pauciores existunt qui malè se habentibus consilium daturi respicere soliti sint ad fidissimam illam morbis sive acutis sive chronicis medentium Cynosuram His ego igitur adeò pudendam adeò etiam valetudine adversa languentibus periculosam nunc demum ut excutiam incuriam utque aliquod remedium illorum inscitiae adhibeam mecum statui arreptâ hâc nuper demandatae mihi provinciae occasione de veris hoc est Mechanicis causis quibus in orbem perpetuò sanguis movetur pro ingenioli mei tenuitate inquirere Affulsit quippe animo spei scintillula quaedam ex iis quae ist â de quaestione apud vos dicenda habeo lucis nonnihil afferri posse ad eam penitùs explicandam Quamobrem ne spem alnisse videar inanem permissu vestro primùm agam de Sanguinis per venas ad Cor recurrentis motu rapidissimo itemque de causis istius tantae velocitatis deinde Cordis ipsius conformationem Organicam perscrutabor postremò conabor causas cordis Pulsationem efficientes quae hactenus omnium elusisse videntur Anatomicorum solertiam explorare Haec autem dum viritìm enucleare molior clarioris doctrinae gratiâ demonstrationes aliquot Mechanicas ad institutum meum apprimè facientes ex Alphonsi Borelli omnium quotquot hoc saeculo nostro floruêre Mathematicorum facilè solertissimi scriptis mutuabor omittendo interea caeterorum ferè omnium qui post Harveum nostrum de Circuitione Sanguinis conscripserunt opiniones idque ne aut tempus frustrà conterere aut memoriae vestrae fidelitati diffidere censear Habetis itaque Auditores Aequissimi praesentis mei summam consilii eorumque quae dicere aggredior seriem Quam dum ingenii toto impetu persequi contendam nolo existimetis me mihi veritatis arbitrium arrogare Semper equidem verum quaero quinetiam Senecae illustri exemplo animatus quaero sine inveniendi spe tantum abest ut credam esse me aliis docendis parem Neque etiam adeò sum mihi Suffenus ut cujusquam expectem conatibus meis applausum Novi enim quà m difficile sit diligentiae laudem simul gratiam celeritatis mereri Caeterùm unum illud me solatur quòd fermè rebus suâ naturâ difficillimis venia sit prolixior apud prudentes viros quibus non ignotum quà m sit arduum novis autoritatem obscuris lucem dubiis fidem afferre PRAELECTIO I. Of the Circular Motion of the Bloud and the admirable Effects thereof SO plausible and favourable hath the Hypothesis of various Ferments congenial to and perpetually resident in the various parts principally in the Viscera of Sanguineous and more perfect Animals seemed to many of the Virtuosi of this our inquisitive age that they have not doubted to ascribe to them a powerful energy and necessary influence in all the divers Motions all the Mutations all the Concoctions all the Secretions and other operations instituted by Nature in such Animals either for the conservation of them in their single beings or for the propagation of their respective Species Nor is it easie for us to name any particular function any action though really and manifestly Organical which the Sectators of this Hypothesis will not presently attribute to some peculiar Ferment lurking and operating in the part by which that action is done and conferring forsooth somewhat of efficacy toward the doing of it as if the organical constitution of that part were insufficient to the function and uses for which it was designed without the help and cooperation of a Specific Ferment or as if the whole Animal Oeconomy depended upon no other Harmony but that of numerose Fermentations In a word they make them only not Omnipotent As Heraclitus the Ephesian dreamed 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉 that all places are full of Spirits and Daemons that presided over human actions So these Gentlemen imagine all the parts of Animals to be full of I know not what Spiritual Ferments that by occult influence regulate and diversifie their functions And this Comment many have endeavoured to assert by their Writings with as much confidence as if the verity of it were evident either from cogent reasons or by Autopsy when in truth they are no more able to prove by solid Arguments or by sensible demonstration the existence of many of their imaginary Fermentative liquors or Spirits in the dissected parts to which they are pleas'd to consign them than Heraclitus was able to exhibit to mens sight any one of his Daemons I say many of their imaginary Ferments I do not say any Because the Acid Phlegm found in the Stomachs of various Animals may perhaps so far emulate the nature of a Ferment as to deserve the same name For being endowed with an incisive penetrating and dissolving faculty 't is not improbable but it may conduce to the dissolution and liquation of
composed of the degree of velocity and of the quantity of bloud impulsed as that excellent Mathematician Io. Alphonsus Borellus hath fully demonstrated By this stroke it is that the newly emptied and conniving porosities of the Muscles and Viscera are forced open and replenished with the impulsed bloud that communicates to them vital heat and fresh vigor and that the torpid useless and excrementitious particles there remaining are protruded and expelled partly through the pores of the skin partly through vessels destined to their transportation and expulsion So that by this rapid rushing in of the bloud nature attains to not only a reviving of the solid parts of the body but also to the expurgation of the bloud it self from its unprofitable and excrementitious parts in the Emunctories ordained for that office A third advantage is that by the same rapid velocity of the bloud and its vehement intrusion into the narrow meatus of the parts the current thereof dislodges rinses away and carries with it many other amoveable particles of various kinds Saline Sulphureous c. principally the reliques of the nutritive and nervose juices brought thither from the brain which though unprofitable now to the refection and invigoration of the parts in which they were left may yet be of some use to recruit and conserve the Crasis of the bloud and to expedite the secretion of its excrements This artifice of nature we may more easily comprehend by observing that the foreign particles now mentioned are extricated and rinsed away by the bloud not in ample vessels but after the egress of the bloud out of the Capillary Arteries in the intermediate spaces betwixt them and the Capillary Veins where end innumerable small Canales some of which bring in the nutritive and nervose liquors others export the superfluous and less profitable particles of them which small pipes are like the Capillary roots of plants almost every where disseminated into the fleshy parts into the Viscera and most frequently into the glandules And this seems to be done to the end that so many particles of these spiritual and noble juices being rinsed away by and commixt with the the bloud may advance and conserve the due consistence and constitution of it Now of these three considerable benefits no one seems to me possible to be attained otherwise than by the perpetual and rapid motion of the bloud Wherefore I am not destitute of a rational ground to support my conjecture that for these ends Nature thought fit to institute the swift motion of the bloud in its Circulation ¶ ⸪ But what may we conceive to be the reason that induced Her to institute also so multiplied a repetition of this course of the bloud through the same ways A River we know though the water be in a continual flux is yet still the same river because the elapsed parts are continually succeeded by new waters coming on with the same degree of speed to supply it But to maintain this perpetual succession and supply upon which the identity of the river necessarily depends there is required either an immense quantity of waters from a spring to feed the current or the same elapsed water must be brought back again to the fountain whence it flowed that so by perpetually reiterated circuitions the course of the river may be conserved which otherwise would soon fail and cease We are then no longer to admire that Nature having designed to bring the river of bloud with a most rapid course through the whole body of an Animal for the various ends above explained and resolved to make that course perpetual during the life of the Animal made use of the same expedient viz. to repete the circuition of the same bloud without intermission For the whole mass of bloud commonly found in the body of a man not exceding 20 pints and that quantity not sufficing to maintain the course above 5 or 6 first minutes of an hour lest the current might cease and so life also fail it was necessary that the circulation of the same mass of bloud should be continually reiterated for the conservation of life Besides this necessity there are many admirable uses and advantages which Nature brings to an Animal by often repeating the period of the circuition of the bloud through the same ways For if the Circulation were not in this manner reiterated the bloud could not be defaecated from its biliose excrement in the Liver nor according to the vulgar opinion from the matter of Urine in the Kidneys nor could either the Chyle be commixt with the bloud in the heart or the Lympha be brought to temper and dilute it in the Veins nor could various other operations necessary to the Animal oeconomy be performed All which it were not difficult for me to deduce from this repeted circuition of the Bloud if the shortness of the time appointed to me for the administration of my present province did not oblige me to pass by all collateral disquisitions and to peruse my principal Theme the Motion of the Bloud From the final causes of which I will therefore in a direct order procede to the Efficient ¶ ⸪ PRAELECTIO II. Of the Heart and its Pulsation TO measure the Divine Wisdom elucent in every Organ of an Animal by the short line of human Reason is indeed extreme folly and yet I doubt not to applaud and follow the counsel of Erasistratus who as Galen relates advised Physicians to solve all the actions naturally done in the body of an Animal by Mechanic Principles so far at least as the dim light of my limited understanding may serve to guide me in my researches For not to depend upon the authority of Plato who said 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉 that God always works by Geometry or of his greatest disciple Aristotle who from thence called God 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉 the Mechanic of the world we have the greater authority of the Sacred Scripture itself that God hath framed all things in number weight and measure Whoever therefore intends with due care to study any part of his works must therein chiefly consider number weight and measure i. e. the Mechanism of it otherwise in the end he will find his mind rather swell'd with opinion than fill'd with knowledge Why then may not we who are Christians as well as Natural Philosophers take those parts of an Animal to be Machines or Engines which evident reason and chiefly sense shew to be such or who hath prohibited us to investigate the formal reason and manner of their operations It is not more certain that no mortal can know enough of Gods works than it is that the more we are able to discover of his wisdom power and goodness discernible in the mirrour of his Creatures the more we shall find our selves obliged to admire love and adore him Equally certain it is also that no kind of devotion is more acceptable to him than that which procedes from knowledge of his infinite
Proposition That the proper Action of the heart is the Constriction of its Ventricles and the consequent compression and expression of the bloud contein'd in them not by a Contorsion of its Spiral Fibres but by an inflation and corrugation of them Here some perhaps may be willing to propose to me this question If it be true that in the Systole or act of Pulsation neither the exterior Superfice of the heart is augmented nor the Cone of it drawn up toward the Basis both which we have asserted how then comes it that in every Systole the Cone of the heart knocks against the left side of the breast Which may be thus Answer'd Because the heart is hung in the middle of the Breast by strong Ligaments and yet in every Systole is brought to touch and strike the inside of the Breast therefore it is necessary that this be done either by a dilatation of the heart or by local motion and translation of it or by erection of the whole or by flexion and incurvation of the Cone thereof And as our observation and experience rejects the three former causes of this Phaenomenon so it obliges us to embrace and acquiesce in the last Wherefore it remains only that we investigate the Mechanic reason of this effect Which seems to depend first upon the disposition of the Fibres of the heart For we see that a crooked gut tied about with a thred and not wholly fill'd with water is by the weight of the water extended directly or in a strait line but if the water be impelled toward either end by compression then the gut becomes crooked again as the nature of it exacts and the other pendulous extremity will be erected and strike against your hand held a little over it This plainly follows from the curve figure of the membrane of the gut which is longer in the convex part and shorter in the concave So in the left part of the Ventricle of the heart the left wall is shorter less fleshy and less crooked than the two walls that make the right Ventricle Wherefore in the Systole of the heart the Cone of it ought to be erected toward the left side of the breast and to strike against it more or less strongly according to the degree of violence with which it is erected This may be somewhat helped also partly by the erection of the heart lying obliquely partly by the situation and disposition of the Fibres which are wound about obliquely and spirally from the right side of the Basis of the heart toward the left side of the Cone whence in the act of Pulsation when the Fibres are shortned the Cone may be a little distorted and erected by the fasciculus or combination of Fibres forwards toward the left side and so the Percussion may be made Seneca as ye may remember in epist. 57. most elegantly describes first the inevitable horror that invaded him while he was passing through the dust and darkness a darkness so thick as even to be seen of the Crypta Neapolitana now named the Grot of Pausilype in the way between Naples and Putzole and then the chearfulness he calls it alacritatem incogitatam injussam that returned to his mind upon the first sight of the restored light The same surprising alacrity methink I now feel within my self after my passage through the no less darkness in which Nature had through a long Series of ages involved her great secret of the Motion of the Heart made more obscure by the dust of mens various opinions and my arriving at the light of knowledge both what is the proper Action of the Heart and by what Mechanic necessity that Action is performed In the ardor of this alacrity I proceed to the use and action of the Ears of the Heart and of its Valves The end of the Vena Cava which is conjoyned to the heart is as hath been said before in greater Animals Musculose round about that the trunk of it may be constringed as Sphincters are closed by virtue of their circular Fibres But the end of the Vena Pulmonaris wants the like fulciment and therefore cannot constringe itself Then both these Veins end into the Musculose Ears which are hollow like little bags affixed to the sides of the heart and whose structure much resembles that by which the left Ventricle of the heart is contexed in the hollow part of it For the Ears also consist of fleshy Fibres intersecting each other like a St. Andrews Cross which within are bound together into many little Cylindrical Columns and trenches connecting the sides of the bags To these Ears succede three membranes in the right Ventricle and two in the left which are of a very strong contexture of a triangular figure the bases of which are closely affixed to the whole Circuit of the Tendon of the Orifice of the heart Then the areae or middle spaces of these little membranes are branched within the Ventricles of the heart into many little Tendinose Strings or cords which are fastned to the tops of the papillae or teats that stand pointing upwards placed on the opposite side Now this admirable structure being known let us enquire the design or use of it First the extreme part of the Vena Cava seems not to be made Musculose for strength lest it should be broken by the current of the bloud rushing in but rather by its constriction to protrude the bloud into the oblique Sinus of the right Ear and to render the same turgid Which action is helped by the peristaltic constriction of the whole trunk of the Vena Cava and by the compression of the Muscles and Viscera of the whole body as was yesterday demonstrated when we considered the motion of the Bloud Hence it comes that the bloud impelled through the open aperture of the Ear fills the cavity of it and then runs into the right Ventricle and by the like necessity the bloud flows out of the Vena pulmonaris into the left Ear and thence into the left Ventricle of the Heart No sooner are the Ears filled and distended with bloud but they both at the same time constringe themselves by a contractive and compressive action common to all Muscles resembling that of a Press in this order that first by shutting their apertures they hinder the regress of the bloud into the same Veins out of which it came in then by the great force of compression they squeez it into the Ventricles of the heart until they be filled and made turgid To this action of the Ears immediately succedes the compression of the press of the Heart itself by which the bloud itself by reason of its abundance inflating and distending the triangular and mitral valves exactly shuts the Orifices or mouths of the Veins and so prevents its own recoiling into them Whence it is of absolute necessity that the same bloud be expressed into the Pulmonary Artery or Vena Arterialis and into the aorta These are the
which they far exceed therefore it is necessary they should exactly shut those Orifices before the Systole of the heart is complete Wherefore it is also necessary that the bloud contein'd in the cavities of the Ventricles should by the process and continuation of the constriction of the heart until a total union of their walls be effected be all expressed thence through the Arteriose Orifices which are then open to give it free egress Fifthly If the clausure of the Ears did not precede those little and thin Valves would not be able to resist that mighty violence with which the bloud comprest by the heart invades them and otherwise would certainly break them therefore to secure them provident Nature hath put a fleshy fornix or Vault viz. the constringed Ear that she might with a double door shut the ample Orifice of the heart Hence naturally arises this remarkable Corollary that the action of the Ear is longer in time than the Systole of the heart For the constriction of the Ear begins while the heart doth not act and ends in the same moment in which the Systole of the heart is completed Finally It is worthy observation that in the Arterial Orifices or outlets of the heart there is no need of the like apparatus to prevent the regress of the expulsed bloud into the Ventricles For after the exit of the bloud and after the greatest part of it is expulsed without the Capillary Arteries it cannot be impell'd back again as well because it is not urged by the force of an Antagonist Muscle of equal strength with the heart as because it is already expell'd out of the extreme Arteries Wherefore Valves of little strength are sufficient here such as is proportionate to the force which the not-intire fulness of the Arteries can make which is very inconsiderable And therefore the Semilunar Valves are far weaker than those Triangular but yet strong enough to hinder the regurgitation of the bloud expulsed by the heart Thus have we run through all the proper actions and offices or uses of all the parts of this incomparable Machine of the Heart in their natural order and found them all to be plainly Mechanic i. e. necessarily consequent from the structure conformation situation disposition and motions of the parts by which they are respectively performed If the Mechanism hath been by us rightly explicated as I am perswaded it hath in the precedent discourse no man has reason longer to believe that the manner of the motion of the heart is a thing to human wit wholly impervestigable Probable it is therefore that when that excellent Anatomist and our worthily honour'd Collegue Dr. Lower said Cùm nimis arduum sit de ratione quâ Cordis motus perficiatur quicquam ritè concipere atque Dei solius qui secreta ejus rimatur motum quoque cognoscere praerogativa sit in eo ulteriùs perscrutando operam non perdam he was out of modesty willing to limit his own curiosity in that particular but not to set bounds to the future disquisitions of other men ¶ ⸫ PRAELECTIO III. Of the Efficient Causes of the Pulsation of the Heart DElighted with the Contemplation of the Structure of this Master-piece of Nature the Heart I have sometimes revolved the Books of the most Celebrated Authors who have professedly written of Architecture and of Hydraulic Engines in search of some example of a Machine that might be at least in a few respects compared with it Of many that occurred that which seemed to me to come nearest in similitude to this inimitable Prototype of Nature was the Hydraulic Mint at Segovia mentioned rather than described by that every way Noble Gent. Sir Kenelme Digby in these words This Engine or rather multitude of several Engines to perform different Operations all conducing to one work is so artificially made that one part of it distendeth an Ingot of Silver or Gold into that bredth and thickness as is requisite to make Coin of which being done it delivereth the Plate it hath wrought unto another that prints the Figure of the Coin upon it and from thence it is turned over to another that cuts it according to the print into due shape and weight And lastly the several pieces fall into a reserve in another room where the Officer whose charge it is findeth treasure ready Coined c. For betwixt this Engine and the Heart I fancied something of Similitude at least in the few particulars following First As the design or end of the former was to Coin mony which is the bloud of all States as well Monarchies as Republicks for the support of the Government so the office and work of the latter is to stamp the character of Vitality upon the mass of bloud for the maintenance of life in all parts of the body and regulation of the whole Animal oeconomy Secondly As the one is moved by a stream of Water so is the other by a current of bloud as to its diastole at least Thirdly As the Artificial Engine was composed of many less Machines each of which performed its proper office by a distinct operation yet all conspired to one common end So the Natural being also complex consisteth of various smaller Machines viz. the Ears Valves Ventricles Musculose flesh Fibres of different orders Chords Columns Papillae c. all which have their peculiar functions and motions yet so combined that they all co-operate to the Vital motion or heat of the bloud and diffusion of the same Fourthly By the Segovian Engine Ingots of Silver were distended to a bredth and thinness requisite to make mony by the heart and its Ears vehemently constringing themselves and repeting their strokes the Silver Chyle or publick revenue of the Animal is attenuated its viscid and grumose parts dissolved the cruder parts concocted and all by conquassation and compression so perfectly commixt with the bloud as to be fit to make good and current bloud Fifthly From the Mint-engine the new stampt Coin was quickly transferred into a receptacle in another room thence to be distributed by orders of the Mint-master From the Heart is the new Coined bloud instantly transmitted into the Arteries to be distributed according to the ordinance of Nature Sixthly As the various parts of the greater Engine were so situate disposed and connected as that if any one of them were by chance displaced broken or hindred in its motion and action presently all the rest must fail to procede in their respective operations and the work of making Coin cease So in the much more subtile and mysterious Machine of the heart if any the least part though but the chord of a Valve be broken or arrested in its motions all the rest will soon be at a stand and the grand work of making the bloud vital be at an end Thus far methought the Parallel held fairly enough and I was not ill pleased with the ramble of my imagination but when I had attempted to