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Circumference. And l conceive, the action of this Muscle does ordinarily and constantly draw the Tympanum to a moderate Tension; but when we have occasion to listen, and give a more particular attention to some sound, the action of that Muscle is then more intense, and the Tympanum[errata 1] is drawn to a more then ordinary tension, so to facilitate the passage of the Sound.
Now as to the case of the young Gentleman before mentioned, I supposed either the Muscle by that convulsive starting Motion in the Womb to be overstrained, and to have lost its Action; or the Membrane by that greater aperture of the Organ to be over-stretched, and afterwards to remain so flaccid, that it was beyond the activity of the Muscle and curviture of the Ossicles to give it a due Tension; or peradventure there was a concurrence of both Causes. Which due tension, if by any remedy it might be restored, I assum'd, that he might recover his hearing in that Ear: To which end, I advised the Excellent Lady his Mother, to consult with Learned Physitians, if by some adstringent Fumes, or otherwise, he might find help.
And for Experiment, I thought of a Temporary Way, by the impulse of any Vehement sound; as of a Drum beaten near him: which sound, during its continuance, must needs give the Tympanum a Tension, by driving and swelling it inwards, as a fresh gale of wind fills the sayles of a ship; and the Experiment succeeded according to my exspectation: For so long as I beat a Drum fast and loud by him, he could hear those who stood behind him, calling him gently by his Name (which he understood, having learned to speak and pronounce it among other words;) and when the Drum ceased, he did not hear the same Persons, when they again very loud called him by his Name. And by this we tryed several times, by beating the Drum again, and ceasing it; and he still heard them, when the Drum beat, and heard them not, when it stopt.
Since that time, a Gentleman about Oxford-shire, sometimes Student of Christ-church, being in a great degree of Deafness, after I had told him of this Experiment, call'd to mind, that he never heard so well and easily, as when he was discoursing with Company in a Coach, whilst it went fast, and made a great rumbling noise in London-streets: by which he was induced to be-
