Page:Proceedings of the Royal Society of London Vol 1.djvu/21

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part of the ear which was the subject of the present lecture, has always been considered as a common membrane, which, being stretched or relaxed by means of muscles belonging to the malleus, became ﬁtted in its various degrees of tension to convey the immense variety of external sounds to the internal organ.

Though this description have been generally adopted, yet it will appear upon further inquiry that, owing no doubt in a great measure to the extreme minuteness of the part, the structure and some of the properties of this membrane had not as yet been properly investigated. And the discovery here announced is brought forward with the greater propriety on this occasion, as it affords a new instance of the application of muscular action, which may ultimately account for certain phænomena in the sense of hearing in a more satisfactory manner than has hitherto been proposed.

This discovery we owe in some measure to the opportunity Mr. Home had to dissect the ear of an elephant, where the parts are so much larger even than they ought to be in proportion to the size of the animal, that the structure of this membrane, which is usually denominated the Drum of the Ear, becomes obvious even to the naked eye. On close examination it was found, that instead of being an uniform coat or skin, a great number of muscular ﬁbres, which seem incorporated in it, pass along its texture in a radiated manner from the rim which surrounds it, towards the handle of the malleus, with which the central part of the membrane is ﬁrmly connected.

Having thus been put upon the scent, the membrane in the human ear was carefully separated from its contiguous parts, and being viewed in a microscope, magnifying 23 times, exhibited the same Rh