the consequent abbreviation of a Cable to be of so great efficacy that the violence of a Tempest the weight and jerks of a loaden ship of 1000 Tuns burden and the current of the Sea cannot by their united forces extend the Cable to its former length This ye will confess to be admirable that a little water insinuating itself into the Pores of the threds of which the Cable is composed should dilate those little and indiscernible Pores with such prodigious force as not only to swell the close and hard twisted Cable but to countervail nay exceed the aggregate of the forces of a furious wind a strong current of the Sea and the weight of so great a Ship with its whole Fraight Yet common experience testifies this to be true The Second Example will perhaps raise your admiration to a higher degree being of all of this kind that hitherto I have ever read or heard of the most memorable It is this In Rome there stands at this day an Obelisk of one solid stone a kind of Ophite or spotted Marble anciently consecrated to the honour of the great Iulius Caesar and erected in the Cirque of Nero but in the Year of Our Lord 1586. removed into a more eminent place at the vast charge of Pope Sixtus Quintus and by the admirable skill of Dominicus Fontanus an excellent Architect and Engineer This stone is in height 170 feet above the base in breadth at the bottom 12 feet and at the top 8 in weight 9586148 pounds and the weight of the Cables Chords Pullies and other moveable instruments used in raising it amounted to 1042824 pounds according to the computation of Georgius Draudius The removing and erection of this Obelisk was thought to be so rare a work of Art that the Engineer beside the great mass of treasure he received for a reward from his Holiness thereby acquired to himself immortal renown no less than 56 Learned men having since profestly written to describe his Machines then used and to celebrate his praises as Monantholius relates But all their praises notwithstanding he owed no small part of his honour to Fortune or rather to a Carter that stood by an idle Spectator For the Engineer a little mistaken in his forecast of the stretching of the Cables and Ropes found when he came to set the erected Obelisk upon the Pedestal that he had not raised it high enough by 2 or 3 inches and to raise it higher with those Machines so stretcht was impossible Confounded with shame and despair by this unforeseen faileur he begun to meditate flight to save his life which he had pawn'd to the Pope to be forfeited if he did not accomplish the difficult work he had undertaken when as good luck would have it out of the croud of vulgar gazers comes a Carter and advises him to cause all his Cables and Ropes to be wet with water Which done the Ropes quickly swell'd and shortned themselves so that they lifted up the Column to a due height and then the overjoy'd Fontanus with ease placed it upon the Pedestal Now if ye shall be pleased to reflect upon this Example and to consider that a little water only by dilating the Pores of the threds of the Cables and Ropes swell'd and shortned them with force great enough to overcome the immense gravity both of the Obelisk and of themselves with the rest of the Mechanic apparatus then used which gravity hath been computed to your hands I am confident you will no longer think it impossible for a few little drops of liquor diffused through the Fibres of the Heart and like wedges dilating their little Meshes or Pores so to swell and abbreviate them as to cause a constriction of the Ventricles and that too with a force if Borellus his estimate be right exceeding the force of 3000 pounds weight And as for the Probability of this proposition that cannot be obscure to any man of common sense who shall consider first the near similitude that is between the threds of a chord and the Fibres of the heart in Figure in tenacity and strength in aptness to swell and consequently to shorten themselves upon humectation and in the faculty of restoring themselves to their natural tone after extension and then the little or no difference betwixt water and the Sucâ—us Nervosus as to the power of insinuating into and dilating the Pores of bodies naturally apt to swell and shrink For since the two Agents viz. water and the Succus Nervosus are so alike in their efficacy as to the dilatation of the Pores of Tensile bodies and since the two Patients also viz. the threds of a chord and the Fibres of the heart have so full a resemblance in their nature it is highly probable if not necessary that like effects should be produced by them And this probability is the greater because of all other Efficient Causes hitherto excogitated by Learned men to solve the grand Phaenomenon of the Pulsation of the Heart none can be given which is either so intelligible or so congruous to the whole Mechanism of the Heart as this which I have in this Lecture endeavour'd to assert But this Chair doth not make me a Judge To hear and determine Most Excellent President and my most Learned Collegues is your right which I ought not to usurp I will therefore first to ease your memory reduce into few words the heads of what I have deliver'd concerning the Efficient Causes of the Motion of the Heart and then humbly and without reserve submit all parts of my Disquisition for I pretend not to know but only to inquire truth to your examen and judgment The summ of the Precedent Hypothesis is this I suppose First That the immediate Efficient of the Pulsation or Constriction of the Heart is the abbreviation of the Fibres of it arising from the dilatation or expansion of their Pores or little meshes Secondly That the Mediate Efficient is the Succus Nervosus derived from the Brain through the Cardiac Nerves which being instilled into and diffused through the Fibres of the heart fills and dilates their Pores and by necessary consequence abbreviates them with force sufficient to make the Systole or constriction of the Ventricles and to express the bloud contein'd in them Thirdly That the short quiets or pauses interceding betwixt the Systoles of the heart arise from equal pauses or intermissions betwixt the drops of the Succus Nervosus instilled into and swelling the Fibres of the Heart and that as the times of the droppings are equal among themselves so are also the Systoles of the Heart isochronic or aequitemporaneous Fourthly That the motion and guttulation of the Succus Nervosus into the Fibres of the Heart being accelerated or retarded by whatsoever causes the Systoles of the Heart must be more or less frequent proportionately thereto Which things if ye now at length shall judge to be consentaneous to right reason agreeable to the Animal Oeconomy
other nerves especially when their Function and office is different from that of all other nerves and no less than the Pulsation of the heart i. e. the conservation of life itself depends upon that difference I am not I confess so happy as certainly to know in what singular Artifice the difference doth consist but am notwithstanding fully convinced there is some difference And if so why may not the difference consist in such an Artifice as that which I have here supposed and described since the same is not only possible but facile also and sufficient to produce the effect required viz. the perpetual instillation of the roscid liquor drop after drop into the Fibres of the heart If this be granted the mighty Difficulty is solved If not I say Secondly That the multitude of Nerves elonged from the Brain to the Heart ought to be considered What reason can we imagine Nature to have had when she furnished the Heart with so many nerves more than are inserted into any two nay three Muscles even of the first rate Certainly she did it either for the more exquisite Sense or for the more copious nourishment or for the stronger motion of the heart for no fourth cause can be found The first is improbable because it doth not appear that the Heart excells any other Muscle in the sense of touching or feeling and because there seems to be no necessity of its being endowed with much of sense whether we respect the action of it which is not perception but Pulsation and that too with incredible violence such as is inconsistent with delicate and exquisite sense or whether we reflect upon the secure Situation of it which is in the Centre of the cavity of the Thorax where it hangs free and defended on all sides from harm and offence either from within or from without The Second also is improbable because the bulk of the heart holds no just proportion to the multitude of nerves inserted into it and there are many Muscles of far greater magnitude which yet are plentifully supplied with nourishment by much fewer nerves The third therefore is true and by consequence serves to disintangle our Hypothesis from the chords of the Difficulty proposed For so great a number of nerves importing into the Heart much more of the nutritive liquor than can be thought necessary for its nourishment of what use can the overplus be unless to maintain the perpetual motion of it And in this also there is a manifest difference betwixt the Heart and all other Muscles and such a difference as may be brought for one reason why no other Muscle but the Heart hath a Pulsation Thirdly I say that the aptitude of the Heart to Pulsation doth consist in its proper Fabric and conformation in its Conical Figure in its cavities within in the disposition and configuration of its Fibres in a word in its whole Mechanism which I have formerly described and which is far different from the Mechanism of any other Muscle whatsoever So that if there were no singular Artifice or knack in the structure of the Cardiac Nerves or if these nerves were fewer in number yet might the heart be apt for Pulsation of which all other muscles are incapable as wanting the like Mechanic conformation No wonder then if Pulsation be proper to the heart only though the Fibres of all other Muscles be of the same nature with the Fibres of the Heart though the Efficient Causes of the Motion of all other Muscles be the same with those of the Motion of the Heart and though they as well as the heart act by the contraction of their Fibres Now if no one of the three Reasons here by me alledged why the motion of Pulsation is not common to all the rest of the Muscles taken single be thought sufficient yet if ye please to conjoyn and twist them all together into a triple chord ye may then perhaps find them strong enough to pluck up the proposed Difficulty by the roots But hold a minute or two Have I not through hast or want of due circumspection run my self into the Bryers of a contradiction Did I not in my last Proposition affirm that the Mediate Cause of the natural Motion of the Heart differs in some respect from that by which all the rest of the Muscles are incited and invigorated to voluntary motion and have I not in the Paragraph immediately preceding this said that the Mediate cause both of the Motion of the Heart and of the Motion of all other Muscles is one and the same viz. the Succus Nervosus derived from the Brain Where then is the difference presumed I answer therefore that the difference lies not in any change or alteration of the nature and qualities of the Succus Nervosus itself which I grant to be the same utrobique on both parts but only in the divers Modes of its effusion from the Brain Into the heart I suppose it to descend through the Cardiac nerves gently slowly and by way of instillation drop after drop but into the rest of the Muscles I suppose the same to be immitted with great force and velocity swift as Lightning at the command of the Will And this seems to be sufficient to constitute a difference where the same cause used by Nature diversimodè and in Organs of different conformation produceth so different effects and consequently to extricate me from the Bryers ¶ ⸫ From which as well as from the former impediments being now at length free I come in the next place to establish the grand Pillar upon which the whole weight of this my rude structure relies that is to make it appear to be not only possible but also probable that a few little drops of liquor instilled into the Fibres of the heart should only by causing them to swell or by dilating their Pores abbreviate them with a force great enough to make a constriction of the heart This if I shall be able to do I shall not despair of finishing my Building as I at first designed for the remaining part of my work will be little and easie As for the Possibility of so great an effect from a cause that seems to be so weak and inconsiderable that may be without much difficulty proved from the just Analogy or similitude of this effect to many other as great if not greater effects commonly observed to arise from the like Causes For Mechanic Examples of this kind are every where so obvious to sense and so numerose that only to enumerate them would be a task hard and tediose Out of so vast a multitude therefore I will for brevitie's sake select only two such as are not only pertinent and adaequate to my subject but also in themselves eminently remarkable The First is of a new Cable which upon wetting will very much swell or become thicker shrink and shorten itself beyond the belief of any but a Mariner And Galilaeus hath well observed this swelling and
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
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
carry on the resemblance a little farther I soon discovered the disparities to be so many and so great that it was impossible to reconcile them into a just Analogy Whereupon condemning the extravagance of my fancy I soberly concluded that the Heart of an Animal is an Engine never to be imitated by human art and I found my self more inclined to applaud the judgment of that prodigy of Mathematical knowledge Archimedes of Syracuse for never attempting to counterfeit the motions of the heart than to admire his wit shewn in making a Sphear of Glass Athan. Kircher denies that any part of it was Glass but only the out-side that men might discern the wheels and motions within which represented the perfect order and motions of the Celestial Bodies and which Claudian describes in one of his Epigrams Now if we desire clearly to understand this inimitable Excellency of the Machine of the Heart and in what Proprieties of it the same doth chiefly consist we shall be obliged well to consider two things neither of which hath yet been explicated by us and without a due explication of both which all that we have hitherto said concerning the motion of the Heart will be maimed and unsatisfactory These are the Mighty and incredible Motive force of the Heart by which it expresseth the bloud out of the Ventricles and the Efficient Causes of its Motion Things so worthy to be known that I need not deprecate your impatience most Candid and accomplished Auditors if I detain you a few minutes longer while I enquire into them As to the FIRST therefore viz. The admirable Motive force of the Heart Since the round and Conical Figure of the Heart doth not permit us to attempt the measuring of its Motive power by the same way by which the most Learned Alphonsus Borellus hath with singular sagacity measured the forces of very many other Muscles of Mans body namely by weights suspended by them and since therefore in this disquisition we cannot from the effect procede to the knowledge of the cause we are compelled from some other Sign to raise a probable conjecture whence we may investigate the greatness of the effect And this Sign shall be the Similitude and Analogy which the Muscule of the heart seems to hold to other Muscles of the same Animal Let us then with the same excellent Mathematician Borellus in whose footsteps I now again tread suppose that all even the least Fibres or little Machines of the same or divers Muscules in the same Animal are equally strong and exercise an equal motive force in the same time in the state of health And because equal bulks of two Muscles contein equal multitudes of the least Fibres it follows that if we have foreknown the total motive power of one of the two equal Muscles we shall be able thence to conjecture what is the total power motive also of the other Therefore the fleshy bulk of the heart being of almost equal magnitude to the bulks of one of the Temporal muscles and of one of the Masseters and Borellus having demonstrated to us the total motive force of those two muscles we may probably infer that the motive force of the heart is equal to that which those two muscles shutting the mandible exercise Now because no intire Fibre of these two muscles is less than two inches long taking all the Fibres one with another that the excesses of the longer may compensate the defects of the shorter and because in an inches space of every single Fibre we may imagine more than twenty little Machines or Rhomboid Pores contained like the links of a chain in a Watch or the Meshes of a Net in a row one above another let us notwithstanding suppose no more than ten smallest Fibres to be conteined in that space therefore in the length of every one of the Fibres that compose the said two Muscles there will be conteined more than twenty of those most minute Machines And since the weight of 150 pounds may be suspended by one single Stratum or Layer of these small Machines of the same Muscles therefore that we may have the whole force that Nature exerciseth in those Muscles the force of that one Layer viz. that which is able to sustain 150 pounds ought to be twenty times multiplied Wherefore the whole force that Nature exercises to dilate all the Rhomboid meshes or pores of the said two Muscles when they act is greater than the force of 3000 pound weight and would if applied to the opposite end of the beam of a balance preponderate If then every most minute Fibre of the Heart exerciseth in the Systole of it a force equal to that which every Rhomboidal Machine of the Temporal or Masseter muscle makes when they act as most certainly it doth the motive power of all Fibres of the Muscles in the same Animal in the state of health being equal and if the multitude of least Fibres contein'd in those two Muscles be equal to the multitude of most minute Fibres contein'd in the Muscle of the Heart as the visible equality of their magnitudes warrants us to suppose it to be we may thence deduce this conclusion that the force which all the most minute Fibres of the heart when they are swell'd exercise to constringe the Ventricles i. e. when they act all together exceeds the force of 3000 pound weight and would preponderate if it were applied to the contrary end of the beam of a just balance Quod erat demonstrandum And thus have I given you a summary of what Borellus hath from a long chain of most ingeniose Propositions and Theorems in fine inferred I come therefore to the. SECOND and last considerable proposed to be inquired viz. the Efficient Causes of this so wonderful Motive force of the Heart These seem to be no more than two of which one is immediate the other mediate As to the the former viz. the immediate cause of the hearts Motive Power we are not to expect to learn either what it is or whence it procedes from the doctrine of the Ancients For they having observed that the heart was not as all the other Muscles of the body are moved ad arbitrium voluntatis at the command of the Will not only named the motion of those Voluntary and the motion of this Natural as they had good reason to do but also conceived and taught the cause of the motion of the heart to be divers from the cause of the motion of the rest of the Muscles and accordingly constituted and assign'd to the heart a certain blind and unintelligible Pulsifick Faculty whereto alone they ascribed as well the diastole as the Systole thereof which they had no just reason to do To evince this their palpable error I will assert this PROPOSITION That the immediate Motive cause of the heart is the very same with that by which the Muscles of the Limbs are moved Voluntarily First it is most evident to sense that
little Canales within must therefore be full of small asperities it is necessary that the Succus Nervosus whose consistence is not much thinner than the white of an Egg well beaten should pass through them with a slow and interrupted course and at length fall out of their lower ends in drops with equal pauses between the drops Where we find a parility of Causes we may rightly expect a similitude of effects Here I see two formidable Difficulties standing like Romantick Giants in my way to deterr me from proceeding and I cannot without shame and infamy decline to encounter them One is That after the Cardiac Nerves are cut off and the heart itself taken out of the body the Pulsation of it continues for some time To remove this therefore I say that the cavities of the Nerves annext to the heart may remain still full of and turgid with the roscid Succus Nervosus which being hindred from regress by their spontaneous contraction toward the heart and kept in a state of fluxility by the yet lasting warmth of the heart may for some time be instilled into the Fibres of it and by swelling of them cause them to constringe the Ventricles as before Then the heart being irritated by the prick of a needle or some sharp and pungent liquor may be able by its peristaltic constriction to squeez out the few remaining drops of the roscid liquor Which being done the Pulsation ceaseth for ever To the bloud this effect ought not to be ascribed for after all reliques of it have been with warm water and a Syringe washed out of the Ventricles and squeez'd out of the Vessels the Pulsation notwithstanding will continue for sometime Nor can it be with more reason ascribed to Convulsions of the heart because all convulsions are disorderly and unequal both in the times of their girds and in those of their intermissions whereas in this case the Pulsations are regular and isochronical with equal pauses Nor to the Heat communicated by the bloud to the heart before it was exsected and not yet quite extinct because that borrowed heat soon vanishes and no external heat will revive the languishing Pulsation after all the roscid juice hath been exprest out of the ends of the Nerves left in the heart Nothing then remains to solve this Phaenomenon but the instillation of a few drops of our roscid liquor into the Fibres of the heart to swell them and so urge them to constriction of the Ventricles The other Difficulty is this Why is there not a Pulsation after the same manner also in all the Muscles of the Limbs since their Fibres are of the same nature in all things their disposition and direction only excepted since the Orifices of the Nerves perteining to them are in the Brain as open to admit and imbibe the Succus Nervosus there elaborate and provided for them and since the same Nerves are equally spongy and permeable in their constitution and so apt to transfer that liquor as the Orifices of the Cardiac Nerves are to receive or their Canales to transfer it If the whole apparatus be the same on both parts whence comes it that the same effect is not produced in both At this Goliah I have in my Scrip three Pebbles to throw and though my arm be weak I will not despair of hitting him in the forehead First therefore I say that it is not yet certainly known to any mortal man by what mediate cause the Muscles of the Limbs are moved at the command of the Will whether by simple contraction of the Originals of the Nerves inserted into them or by the immission of the Succus Nervosus more copiosely and swiftly at the time of their being put into action though the Mechanism of their Fibres make it more probable that they are moved by immission of some liquor from the Brain by which the rhomboid meshes or pores of their Fibres being all at the same time swell'd and dilated a contraction of the whole Muscle must in the same moment be effected and therefore I prefer this opinion to the former and have followed it in many places of this rude Discourse But yet this opinion hath not led me to a discovery of the Cause of the difference this present difficulty compells me to hunt after Should I imagine Valves affixt by Nature to the Orifices of the Nerves of the Muscles as Mons Des Cartes did in the bodies of them though such an artifice be not impossible yet beside that no such Valves have hitherto been found in the Brain I should still be to seek for a Cause to open and shut them ad arbitrium voluntatis and so should be put to a stand in my disquisition Which to avoid some other Organical contrivement such as may be not only possible but probable also and facile and fit to untie this Gordian knot must be excogitated Let it then be supposed that in the Brain the Orifices of the Nerves thence elonged to the Muscles of the Limbs and their Canales are in such a peculiar manner formed as at no time to take in and convey into the Muscles more of the roscid liquor than what is sufficient to nourish them and recruit their vigor unless when at the command of the Will under whose jurisdiction they properly are the Nerves being twitched up or convelled at their Originals both their Orifices are dilated to receive and their Canales rendred more pervious to transmit in a moment into the Fibres of the Muscles to be used a greater portion of the same invigorating liquor viz. so much as is requisite to swell them up by replenishing their pores and force them to contraction which is the common action of all Muscles On the other part let it be supposed that in the Brain Nature hath framed the Originals of the Cardiac Nerves by a different Artifice namely such as that not only their Orifices may always be open to imbibe but also their Canales so easily pervious to transmit the roscid liquor as that without any Vellication without any Convulsive motion the same liquor may merely by the plenitude of the Canales themselves be effused guttulatim into the Fibres of the heart to cause the alternate constriction or Pulsation of it And it is the more lawful for me to suppose this difference of structure in Nerves ordained for different uses because it is above all doubt that the Optick Nerves have a peculiar fabric and contexture wherein they differ from the Auditory and all other Nerves inservient to the rest of the external senses and that the Organ of every sense hath its nerve of a peculiar constitution accommodate to the nature of its proper object though those differences consist in such minute and subtle artifices as have hitherto eluded our most curiose researches though assisted by the best sort of Microscopes Why then may it not be thought that Nature hath given to the Cardiac Nerves also a constitution divers from that of all
seen that the liquor found in the Pericardium is easily capable of coagulation either by heat or cold so as to become like gelly of harts-horn or the white of an Egg hardned by boyling as the Serum of the bloud will do and observed the various little Glands seated about the Basis of the Heart for which I could find no other equally probable use as to instil the Serum into the Pericardium to facilitate the motion of the heart which most certainly that liquor doth as the humor instilled out of the glandulae lacrymales upon the outsides of the eyes serves to moisten and make them more easily moveable every way when I had I say observed and considered these things I rejected that thought and embraced this of the absorption of the reliques of the Succus Nervosus by the Veins of the heart The Second is that the Diastole of the Heart is caused partly by the Relaxation of the Fibres of it spontaneously restoring themselves to their natural posture and length as all other Tensile bodies are wont to do after they have been distended partly by the force of the bloud rushing out of the Ears into the Ventricles of the Heart and replenishing them Wherefore the Wisdom of Nature is admirable also in this that she ordained these Two Causes of the diastole viz. the relaxation of the Fibres and the influx of the bloud into the Ventricles to be exactly coincident that with united forces they might cooperate more efficaciously Whence it appears that in the diastole the Heart is not wholly Passive as all Anatomists hitherto have believed it to be For unless the Fibres did restore themselves to their former longitude which is a natural action at the same time the influx of the bloud happens certainly there could be no room to receive the bloud because the insides of the Ventricles would continue to touch each the other and so there could be no diastole The Third and last is that it appears from the whole Series of this discourse that the Pulsation or Constriction of the Heart hath its force from that Mechanic power which is called the Wedge and that the bloud is expressed out of the Heart by virtue of another Mechanic power which is named the Praelum or Press and consequently that the Heart itself is as all Automata are moved not by Spirits nor by a Pulsifick faculty nor by rarefaction of the bloud nor Ebullition or Fermentation of the bloud nor by explosion of Saline and Acid spirituose liquors but by Mechanick necessity Which from the beginning I hoped I should be able fairly to prove If the success of my endeavours hath not been answerable to that hope I will not go about to extenuate the blame of my faileur by citing examples of much greater Wits which have before me in vain attempted to reveal the same secret of Nature but consolate my self with this that my Iudges are men no less beloved for their exemplary candor and humanity than honoured for their excellency in all kind of Learning and who need not be put in mind That Truth is a tree whose root is in Heaven and of which even the wisest of us dim-sighted Mortals here upon earth see nothing but the shadow of its branches I will therefore conclude this inelaborate Disquisition with that memorable saying of the Prince of Roman Orators De his statuat unusquisque ut libet Quid autem verius sit Deus ipse viderit hominem quidem scire arbitror neminem ¶ ⸫ MY Lectures such as they are much Honour'd Auditors Ye have with obliging patience heard Be pleas'd I beseech ye to hear also before ye rise a word which I have to speak in my own defence Were it not indecent to compare small things with great I should venture perhaps to advertise you that the reasons which induced me to attempt a reformation of the Borellian Hypothesis of the Motion of the Heart which Doctor Harvey himself call'd the Sun of the Microcosm seem to have some kind of Analogy to those which moved the Prince of Astronomers Tycho Brahe to dislike the Ptolemaic System of the Macrocosm or greater World and to excogitate a new one of more probability and neatness For as Tycho animadverting that the Celestial Orbs had been by Ptolemy distributed unhansomly that so many and so great Epicycles were in vain imagined to explicate the retrogradations of the Planets and their various respects to the Sun and that the equality of the Circular motion was measured not from the Centre of its proper Circle as it ought but from the Centre of another Eccentric Circle against the first principles of Nature and Art invented a new System exempt from all these incommodities which is in truth the Copernican inverted So I conceiving that in the Borellian Hypothesis and Explosion of I know not what Saline and Acid materials in the Heart was not only in itself extremely improbable and incongruous to the Wisdom of Nature which always constitutes certain and regular Causes to produce certain and regular Effects but also unnecessarily supposed to solve the Phaenomenon of the Hearts Pulsation set my dull Brain on work to reform it and soon invented another that seems both free from those inconveniences and more agreeable to the Organical Structure of the Heart to which above all things it was requisite I should endeavour to adjust it This I thought my self obliged to signifie lest any here should believe either that I have usurped to my self this whole System of the Motion of the Heart from that most excellent Mathematician Alphonsus Borellus whose Memory I highly honour or that I lay claim to more than a Candid attempt to reform it ¶ ⸫ EPILOGUS PRAELECTIONVM quidem vela jam tandem contraxi nondum tamen dissolutam video concionem Resistamus igitur hîc parumper Auditores Ornatissim◠si vobis ita videatur ad stupendam illam cujus rationem Mechanicam hactenus tam anxiè inquisivimus Cordis fabricam seriò respiciamus Inde enim etiamsi alia omnia in universitate rerum deessent Divinae Architecturae documenta cuivis hominum pronum est inferre quà m sit immensa illius caeterorumque omnium in hoc Mundo adspect abilium CONDITORIS solertia quámque parum ab immedicabili cùm animi tum mentis stupiditate olim abfuerit Epicurus Qui Animalia casu quodam in prima rerum procreatione genita fuisse vecorditer censuit opinatus est consequenter totam in iis membrorum varietatem dearticulationemque non aliunde quà m ex Atomorum fortè fortuna post infinitos inter se in spatio infinito vortices ita concurrentium atque commistarum dispositione extitisse Quamobrem neque ullam fuisse intelligentis Naturae prudentiam quae ossa cerebrum cor nervos venas quae oculos manus pedes viscera quae caetera omnia conformans ad fines certos seu functiones partibus congruas respexerit sed singulas partes ita