A systeme of anatomy, treating of the body of man, beasts, birds, fish, insects, and plants illustrated with many schemes, consisting of variety of elegant figures, drawn from the life, and engraven in seventy four folio copper-plates. And after every part of man's body hath been anatomically described, its diseases, cases, and cures are concisely exhibited. The first volume containing the parts of the lowest apartiments of the body of man and other animals, etc. / by Samuel Collins ...

CHAP. XVIII. Of Hearing.

Hing discoursed the curious parts of the External and Internal Ear, in reference to their admirable structure; my design at this time is to Treat of them as subservient to Hearing, which is a Sense as noble as useful, styled Sensus Disciplinae, by which others communicate to us, the speculative Principles of Sciences, and the more practical Precepts of moral Philosophy, rendring us Wise, Skilful, and Virtuous.

By this pleasant Sense we caress each other in civil Converse, * 1.1 imparting our Souls, by affecting our Ears with vocal Sounds (variously modelled by the Organs of Speech) as so many different Characters, expressing the ma∣ny inward Conceptions, and Passions of the Mind.

The Sense of Hearing is determined by Objects, * 1.2 either taken in a com∣mon notion of Sounds in general, or in a more particular and excellent kind of Sounds, of significant Words, which are the various modifications of humane Voice.

As to the Sounds in general, they are loud or low, and greater or less, * 1.3 as the surfaces of solid Bodies make strong or faint Collisions upon fluid. Whence it cometh that Wooll, Spunge, or the like loose and porous sub∣stances, receive Air into their Cavities, making gentle, or no reverberations of it, productive of little or no sound.

For Sounds are percussions of solid upon fluid Bodies; whence the parts of Air being subtle, are easily broken against a more compact substance, by reason Fluids consist of many minute Particles, and as being verberated, receive various Configurations of Sounds, which being first conveyed to the Auricle, and afterward to the inward Ear, make different Appulses upon the sensory of Hearing. And the production of it may be celebrated (as I humbly conceive) after this manner: Sounds are the repercussions of Air upon solid Bodies; whereupon Air being made of fluid and subtle Particles, when reverberated from its center of motion, quickly diffuseth it self into an Orb, in some sort resembling the motion of Water, into which a heavy Body being injected, it commenceth its motion in small Circles, which more and more enlarge themselves, till they arrive their utmost confines: And this seemeth somewhat to favour this Hypothesis, that Auditors seated in a great Towre, have Sounds, the configurations of moving Air, conveyed by a kind of oblique Rays to all parts of the Orb in which the Hearers are pla∣ced, else they were not capable of Hearing, which is made good by expe∣rience, by reason all persons hear Sounds in such an Orb, that hath not too great a circumference, else when the motion of Air cannot reach its Dimensi∣ons, it maketh faint or no Appulses upon the inward Organ of Hearing. * 1.4

The noble and significant sounds of words, made up of various Elements of Speech, are the expresses of the Mind, and receive the First, and more rough draughts in the Larynx after this manner; The strong impulse of expired Air, running in an even current through the smaller Pipes of the Bronchia, and greater channel of the Aspera Arteria, till it arrive to the ex∣tremity

and head of it, where the confined Breath groweth curled, as recei∣ving greater or less vibrations against that of the Cartilages, called Arytae∣noides, rendred more or less stiff by the Contractions of the Musculi Thyro∣arytaenoidei, Arytaenoidei, Cricoarytaenoidei, Laterales & Postici; the Clausors and Apertors of the Rimula, by whose various motions of Contraction and Aperture (as by so many stops) are found many discriminations of sounds, the rudiment of Letters, and Words, made of modelled Breath, first vocali∣zed in the Larynx, and being thence transmitted to the Mouth, receiveth repeated repercussions against the sides of the arched Palate, which giveth to the sound of the Voice new accessions of increase and sweetness, and ren∣dreth it Articulate (as its great accomplishment) by the Organs of Speech, making the more perfect Configuration of the Voice, the most choice model of expired Air, which is thence conveyed by a quick undulating motion, through the diverse Maeanders of the Auricle, and spiral auditory passage, to the Tympanum of the Ear, which being well braced by the Muscles of the Ear, drawing by various motions the Membrane, inwardly and outwardly at the same time, which rendreth it Tense, and in a fit capacity to receive the several Appulses of articulate Sounds (upon the Surface of the Membrane) which make the same Configurations of the voice upon the Contiguous parts of innate Air, which moving after a Pyramidal Figure (whose Base is toward the Tympanum, and the Cone toward the Fenestra Ovalis) through the contracted model of innate Air, is transmitted into the Labarinthus, and from thence through the Fenestra rotunda, into the spiral Meatus of the Coclea, invested with fine Membranes, interwoven with various Fibrils of Nerves; so that Appulses being made of the innate configured Air, upon the thin Tunicle covering the Coclea, the sensation of Hearing is immediately and ultimately exerted: The manner of it may seem with some probability to be expressed by Sounds, which briskly recoiling from solid Bodies, do move the Air with so much agility, that in a moment its numerous subtle configured parts do enter into the Auditory passage, and immediately make many Appulses, First, upon the several parts of the outward surface of the Membrane, rela∣lating to the Tympanum.

And every particle of the outward modelled Air, maketh the like im∣pression upon the subtle Atomes of the innate Air, whose most near parts, contiguous to the inside of the Membrane of the Tympanum, are first com∣pressed (after the same Configurations of the outward Air) and afterward other parts of innate Air, are successively protruded in order one after ano∣ther, till the most inward Atomes do make appulses upon the Membrane of the Coclea, beset with nervous Fibrils; so that the diverse parts of the Coat belonging to the Tympanum, are moved with the several strokes of exter∣nal configured Air (contained within the Labarinthus, and Coclea) giving vibrations upon the tendrels of Nerves, interwoven with membranous Fi∣laments, in the Tunicle of the Coclea.

The Appulses made of divers motions of modelled external Air, upon the Membrane of the Tympanum above, and of the innate Air, upon the Tuni∣cle of the Coclea below, may be illustrated by a well-braced Drum, whose Head and Bottom being covered with a Skin of Velome; and the upper one being struck, the Air inclosed between the Two coverings is beaten backward, giving a forcible vibration upon the opposite Membrane, which is plainly evident from the motion of the Cords begirting it: And every Particle of the upper Membrane of the Drum, receiving the stroke of the stick, repel∣leth every part of the confined Air, which moving according to a proper

Line, createth a peculiar Radius: so that the whole Air, encircled within the Membranes of the Drum, is moved in several lines, and is as it were a Cylinder, made up of innumerable contiguous Rays; whence it may be inferred, That the Motion of the inclosed Air, (repelled from the higher to the lower Membrane of the Drum) seemeth to resemble that of the innate Air, lodged within the upper Tunicle of the Tympanum, and the lower of the Coclea, of which the inward is beaten back to the Coclea, wherein it affect∣eth the auditory Nerve.

The Compage of the innate Air (as I conjecture) is made up of many Radioli, moving in a Pyramidal Figure, whose Base is near the Tympanum, and its point (wherein the fine Rays are united) is placed about the Fene∣stra Ovalis, through which they pass into the Labarinthus, and from thence they are transmitted through the Fenestra rotunda, in order to make Appulses upon the spiral Flexures of the Coclea, clothed with a fine nervous Tunicle, the proper Sensory of Hearing.

Some are of an Opinion that the Radii of the external Air, do not pro∣pagate new ones in the innate Air, but the minute configured parts of the outward Air, do insinuate themselves through the Pores of the Mem∣brane belonging to the Tympanum, and do configure the contiguous Par∣ticles of the innate Air, and so one after another, till at last the moved Particles do affect the auditory Nerves, besetting the Tunicle of the Coclea. And this conjecture they endeavour to explain by the trajection of Rays of Light through Glass; which instance seemeth not to be satisfactory, be∣cause the Rays of Light, are much more subtle then those of ambient Air, whose Particles, if they could penetrate the Pores of the Membrane of the Tympanum, by the same reason the minute Bodies of the more pure and thin innate Air, would soon quit their confinement, and transpire into, and em∣body with the contiguous outward Air: whereupon the inward Recesses of the Ear would be left destitute of innate Air, which is generally believed to be the immediate medium of Hearing. But farther, say they, That Sounds being very many small bodies of Air diversly moulded, and by reason of their several Figures, various kinds of Sounds are formed; therefore how can the auditory Nerves be affected, to receive the impressions of various Figures of Air moving upon them, if the modelled Particles of external Air, do not permeate the Tunicle of the Tympanum: From this it might be argu∣ed as well, that the coat of the Tympanum is the Organ of Hearing, discern∣ing the variety of Sounds, as the diversly modified Particles of Air do after different manners affect the Coat of the Tympanum. But I humbly con∣ceive it more probable, that the said Membrane receiveth several Appulses from the different configured Particles of Air, contiguous to the outward surface of the Membrane of the Tympanum, which is thereupon diversly con∣tracted and moved, and then this Contraction and Motion being imprinted upon the inward surface of the said Membrane, immediately forceth a retrograde Motion in the innate Air, and conformeth it into Rays (accord∣ing to the first Model of the outward Air) making several strokes upon the auditory nervous Fibrils, branched through the Membrane enwrap∣ping the Coclea; from whence it may be deduced with good reason, that the Membrane of the Tympanum cannot challenge to it self the attribute of being the Sensory of Hearing: And though the Tunicle of the Tympa∣num be not wholly destitute of Nerves (which are common to all Mem∣branes) yet it is not furnished with branches of the auditory Nerves, and so is rather an instrument of Touching then Hearing.

Farthermore we may add this in opposition to the Hypothesis, in making this Membrane the prime seat of Hearing, by reason inward sounds are not formed solely by appulses of Air ad extra; as modelled upon the Coat of the Tympanum, but framed also by innate Air, configured within the Tympanum, in the inward Penetrals of the Ear, sometimes resembling the noise of run∣ning Waters, othertimes of a Drum, or of hissing, and the like, proceeding from gross, or more thin vapors, which taking their rise from within the Head, and passing through the Meatus of the Skull, do affect the innate Air, which is acted sometimes with uniform, othertimes with various, and a Third way with continued, or repeated Motions, which beating upon the auditory Nerves, derive their Birth from Vapours, arising out of neighbouring parts.

It seemeth also evident, that if the Ears be affected inwardly with Di∣seases, that the Bombus internus Aurium, is silenced by a vehement outward noise of the Membrane of the Tympanum, which is effected (as I conceive) by the faint inward motion of the innate Air, ceasing upon a new more vigorous motion super-induced, which quieteth, or at least confounds, or obscures the other by over-powring it. The innate undulating Air, as new Radii are formed in it, is conformed to the more lively confi∣gurations of the external Air; First imprinted upon the outside of the Tunicle of the Tympanum, and then the inside being contracted, the same impressions are made upon the innate Air, and afterward are trans∣mitted to the Membrane (covering the Coclea) interspersed with many nervous Fibrils.

Notes

• * 1.1

  The several kinds of Sounds.
• * 1.2

  The descri∣ption of Sounds.
• * 1.3

  The manner how Hearing is celebrated.
• * 1.4

  Vocal Sounds, or Words, how they are form∣ed.