But the late Dr. Drake, with great Ingenuity and Address, (like a Person so considerable for his Years, as he was in his Time,) not only establish’d this Notion of Respiration, but also carries it farther, making it the true Cause of the Diastole of the Heart; which neither Borelli, Lower, or Cowper, much less any before those great Men, have well accounted for. That the Heart is a Muscle, is made evident beyond all doubt by Dr. Lower. And that the Motion of all Muscles consists in Constriction, is not to be doubted also. By which means the Systole is easily accounted for. But forasmuch as the Heart hath no Antagonist-Muscle, the Diastole hath puzzled the greatest Wits. But Dr. Drake with great Judgment, and much Probability of Reason, maketh the Weight of the Incumbent Atmosphere to be the true Antagonist to all the Muscles which serve both for ordinary Inspiration and the Constriction of the Heart. The Particulars of his Opinion may be seen in his Anatomy, l. 2. c. 7. And in Philos. Trans. 281.
And I remember when I was at the University, my most ingenious and learned Tutor Dr. Wills, when he read Anatomy to us, was of Opinion, that the Lungs were blown up by the Weight of the incumbent Air, and represented the manner of Respiration in this manner, viz. He put a Bladder into a Pair of Bellows, turning back the Neck of the Bladder, and tying it fast, so that no Air might enter in between the Bladder and Bellows. This being done, when the Bellows were opened, the Bladder would be blown up by the Weight of the incumbent Air; and when shut, the Air would be thereby pressed forcibly out of the Bladder, so as to blow the Fire. This Experiment I take Notice of here; because (besides the Illustration it gives to Respiration) that great Genius seems to have had a truer Notion of this Phænomenon, than was very common then, viz. about the Year 1677 or 78; as also, because I have in some Authors met with the same Experiment, without mention of Dr. Wills, whose I take it to have been.
Another Use of great Consideration, the already commended Dr. Cheyne assigns; namely, to form the elastick Globules of which the Blood principally consists, without which there would be a general Obstruction in all the capillary Arteries. Cheyne’s Phil. Prin. of Nat. Rel. or Harris’s Lex. Tech. in Lungs.
[] Gen. ii. 7. vi. 17. and vii. 15.
[c] Because it would be endless to specify the curious Mechanism of all the Parts, concurring to the Formation of the Voice; I shall therefore for a Sample note only two Things, 1. There are thirteen Muscles provided for the Motion of the five Cartilages of the Larynx, Gibs. Anat. l. 2. c. 14, a Sign of the careful and elaborate Provision that is made for the Voice. 2. It is a prodigious Faculty of the Glottis, in contracting and dilating itself with such Exquisiteness, as to form all Notes. For (as the ingenious Dr. Keil saith) supposing the greatest Distance of the two Sides of the Glottis, to be one tenth Part of an Inch in sounding 12 Notes, (to which the Voice easily reaches;) this Line must be divided into 12 Parts, each of which gives the Aperture requisite for such a Note, with a certain Strength. But if we consider the Sub-division of Notes, into which the Voice can run, the Motion of the Sides of the Glottis is still vastly nicer. For if two Chords sounding exactly Unisons, one be shortened, ⅟₂₀₀₀ Part of its Length, a just Ear will perceive the Disagreement, and a good Voice will sound the Difference, which is ⅟₁₉₆ Part of a Note. But suppose the Voice can divide a Note into 100 Parts, it follows that the different Apertures of the Glottis actually divide the tenth Part of an Inch into 1200 Parts, the Effect of each of which produces a sensible Alteration upon a good Ear. But because each Side of the Glottis moves just equally, therefore the Divisions are just double, or the Sides of the Glottis, by their Motion do actually divide one tenth Part of an Inch into 2400 Parts. Keil’s Anat. c. 3. Sect. 7.
[d] Among the Instruments of Speech, the Tongue is a necessary one; and so necessary, that it is generally thought no Speech can be without it. But in the third Tome of the Ephem. Germ. is published, Jac. Rolandi Aglossostomographia, sive Descriptio Oris sine Linguâ, quod perfecte loquitur, & reliquas suas functiones naturalitèr exercet. The Person described is one Pet. Durand, a French Boy of eight or nine Years old, who at five or six lost his Tongue by a Gangrene, occasioned the Small-Pox. Notwithstanding which, he could (as the Title saith) speak perfectly, as also taste, spit, swallow, and chew his Food; but this latter he could do only on that Side he put it into, not being able to turn it to the other Side his Mouth.
In the same Tract, Chap. 6. is this Observation of ventriloquous Persons, Memini me à quodam sat celebri Anatomico audivisse, dum de duplicaturâ Mediastini ageret, si Membrana ista duplex naturalitèr unita in duas partes dividatur, loquelam quasi ex pectore procedere, ut circumstantes credant Dæmoniacum hunc, aut Sternomythum.
[e] The Variation of the Wind-pipe is observable in every Creature, according as it is necessary for that of the Voice. In an Urchin, which hath a very small Voice, ’tis hardly more than membranous. And in a Pigeon, which hath a low and soft Note, ’tis partly cartilaginous, and partly membranous. In an Owl, which hath a good audible Note, ’tis more cartilaginous; but that of a Jay, hath hard Bones instead of Cartilages; and so of a Linnet: Whereby they have both of them a louder and stronger Note, &c.
The Rings of the Wind-pipe are fitted for the Modulation of the Voice: For in Dogs and Cats, which in the Expression of divers Passions use a great many Notes, (as Men do,) they are open and flexible, as in Man. Whereby all, or any of them are dilated, or contracted, more or less, as is convenient for a higher or deeper Note, &c. whereas in some other Animals, as in the Japan-Peacock, which useth hardly more than one single Note, they are entire, &c. Grew’s Cosmolog. Sacr. Book I. Chap. 5. §. 9, 10.
[f] It is a farther manifest Indication of singular Design in the cartilaginous Rings of the aspera Arteria, that all the Way where they are contiguous to the Oesophagus, they are membranous, to afford an easie Passage to the Food; but after that, in the Bronchi; they are, some compleatly annular, some triangular, &c. And another observable is, the lower Parts of the superior Cartilages, receive the upper Parts of the inferior, in the Bronchi; whereas in the aspera Arteria, the Cartilages run and remain parallel to one another; which is a noble Difference or Mechanism in this (in a Manner) one and the same Part, enabling the Lungs and Bronchi to contract themselves in Expiration, and to extend and dilate themselves in Inspiration.