On the differential stethoscope and its value in the diagnosis of diseases of the lungs and heart / by George L. Carrick.

  • Carrick, George L., 1840-1908.
Date:
[1873]
Catalogue details

Licence: Public Domain Mark

Credit: On the differential stethoscope and its value in the diagnosis of diseases of the lungs and heart / by George L. Carrick. Source: Wellcome Collection.

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    demerits when compared to other stethoscopes, will not be consid¬ ered out of place. History.—The principle of binaural auscultation was first demon¬ strated by Dr Leared, who exposed, at the Great International Exhi¬ bition of 1851, an instrument by means of which sounds produced at one part of the chest were transmitted to both ears simultaneously. Dr Leared’s stethoscope was made of gutta-percha entirely. It consisted of a hollow cylinder, expanding into a cup (which was applied to the patient’s chest) at one end, while to the other were attached two immovable tubes. The free extremities of these tubes ended in circular flat ear-pieces, like those of the ordinary stethoscope. In the same year (1851), Dr Marsh of Cincinnati published a description of a binaural stethoscope, of which he was the patentee as well as inventor. The idea, however, of auscultat¬ ing with both ears at once, had previously occurred to many phy¬ sicians, while by some it had been even carried into practice. Dr C. J. B. Williams informed Dr Alison that, many years prior to 1851, he was in the habit of exhibiting to his class an instrument which he had had constructed for binaural auscultation. In all these stethoscopes, however, there was no self-adjustment. More¬ over, they were heavy, unwieldy, and inflexible. Their ear-pieces were like those of the ordinary stethoscope, t.e., plane or concave gutta-percha or wooden discs, instead of the small rounded ivory knobs now in use. The latter, by entering the meatus auditorius externus, conduct sound infinitely better than the former, which simply press against the pinna. All these defects detracted largely from the value of what would otherwise have proved most useful instruments, and prevented their introduction into general practice. Binaural auscultation as a practical art may be said to date from the year 1852, when Dr Cammann of New York described his flexible stethoscope.1 It is constructed upon precisely the same principle as Dr Leared’s instrument, but differs from the latter,—1st, In having the tube flexible at one part; 2d, In small ivory knobs supplying the place of the- ordinary ear-pieces ; and, 3dly, In being- kept in position by a movable joint and elastic band, thus leaving the auscultator one hand free. These were improvements suffi¬ ciently important to convert an unpractical instrument into a very practical one. Dr Cammann’s binaural stethoscope (Fig. I.) consists of a 1 Until the publication of the latest (sixth) edition of Professor Aitken’s admirable text-book, I had laboured under the impression that it was Dr Cammann who had patented in the United States the instrument known by his name. It appears, however, that it was not Dr Cammann, but Dr Marsh, who had patented a very inferior kind of binaural stethoscope, of which he professed to be the inventor, but which, as Dr Cammann pointed out, had been simply borrowed without acknowledgment from Landouzy of Paris ; whereas Dr Cammann’s valuable and ingenious instrument was freely placed at the disposal of the profession.—See Science and Practice of Medicine, by Wm. Aitken, M.D., 6th edit., 1872, vol. ii. p. 497.