Contributions to medical science / by Alexander Ogston.

  • Ogston, Alexander, 1844-1929
Date:
1869
Catalogue details

Licence: Public Domain Mark

Credit: Contributions to medical science / by Alexander Ogston. Source: Wellcome Collection.

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    ear. A few reflections of this nature convince us of the truth of the terror which travellers attribute to the dead silence of the deserts, and explain why individuals who have lived long in an uninhabited district, catch and recognise as strange and import¬ ant warnings, sounds so faint as to be inaudible to the ordinary ear. It may not be permissible to adopt this effect of the plug in the ear as a complete explanation of the phenomenon, but it seems more rational than the previous notion about compressed air, and doubtless has at least some influence. At all events, the fact remains, that when one ear is lightly closed, the sound of a fork is more audible on that side, even when the handle is placed upon the temporal bone of the open side. Before adverting to the experiments with the fork, it was asserted that sounds transmitted through the skull to the ear are more audible than those arriving through the external auditory meatus. In the preceding remarks, this has been proved only of closed ears, in which any channel might naturally be expected to conduct sounds more distinctly than the occluded passage. But in ears which are not closed, the transmission is better°through the bones of the head than through the air con¬ tained in the meatus, and the reason why this is not generally perceived is, that sounds, in the usual course of things, are prevented from reaching the bones of the skull with great force, the force being intercepted and broken by the skin and tissues which everywhere cover them. By the only parts of the skull which are normally bare, that is, the teeth, sound is conducted far better than by the external ear, a fact easily demonstrable by comparing the sound of a tuning-fork placed with its handle close to the external ear, witli that perceptible where its shaft is placed on the teeth. The greater intensity of sound in the latter situation is a fact familiar to every musician. In the skin and soft parts themselves, common sounds excite vibrations quite capable of being perceived by the ordinary sensitive nerves, and therefore, when transmitted to the bones, sufficient to impress an organ specially adapted for receiving them. This is proved by the following case, selected from a small series of such observations. A gentleman suffering from chronic inflammation of the iris, from total adhesion of the pupil to the lens behind, volunteered the remark, that the circum- orbital pain, affecting principally the branches of the trifacial nerve supplying the scalp (frontal and auriculo-temporal), was always aroused to a great extent, or recalled when temporarily absent, by the sound of his children’s voices, and by my own voice, however quietly our remarks were made. Some other sounds, as the rustling of a newspaper, produced the same effect.