DEVIATIONS OF THE STERNUM.

389

of the middle part, and directing itself towards the trachea. The junction of the middle part with the ensiform cartilage, frequently forms an angular projection. The ensiform cartilage may be almost horizontal, while the middle portion of the bone may be perpendicular, or inclining back as it rises. The author has seen this articulation form an elbow. These deviations have usually arisen in childhood while the articulations have been feeble, or the bones particularly pliant. Distortions may arise at other parts before the bone has acquired firmness, or when the natural firmness is absent, as in rachitis.

The weight of the head and superior extremities seems in cases of rachitis greatly to tend to deformities of the sternum, but as has been well shown by Dr. W. T. Gairdner in the "Edinburgh Journal of Medical Science" for 1851, bronchitis and other chest diseases attended by dyspnoea are very frequent causes of the deviations from the natural form and position of the sternum as well as of the ribs. The author has seen several infants in whom great sinking of the ribs and elevation of the sternum have been in actual progress. The thorax along the course of the insertion of the diaphragm has been greatly depressed at every inspiration. In one remarkable example great dyspnoea was present, and after death the heart was found to be single and the pulmonary arteries taking their origin from the aorta. The chest goniometer is specially adapted for the measurement of these deviations.

Though phthisis and other diseases in the adult comparatively seldom give rise to alteration in the form of the sternum, they occasionally succeed in so doing. In some examples of phthisis, the author has seen the upper portion of the sternum manifestly drawn towards the trachea, when the action of the diaphragm has been forced, in consequence of more than usual dyspnoea. The same thing has been observed in severe chronic bronchitis, and in cases of long standing organic diseases of the heart. Cancers in the mediastinum, when extensive, will raise the sternum and impart an undue roundness and prominence to it. Aneurism of the aorta produces a similar result.

The deviations of the sternum which it is desirous more particularly to point out here, are those which relate to its position. In phthisis the author has remarked that the sternum very frequently loses its normal position in the transverse plane of the body. In almost all examples of old cavities in the apices of the lungs attended with flattening, the sternum

is found to have its transverse plane deviating from the transverse plane of the body. The edge of the sternum nearer the flattened cartilages and the cavity is directed backwards or to the interior of the chest. The sternum will be found to have rotated on that border which is nearer the sound side, to make in some cases an angular projection, and the transverse surface of the sternum, and the corresponding costal cartilages form one straight line. The depressed and retracted cartilages have succeeded in dragging the sternum with them.

This inclination of one border of the sternum to the interior of the chest usually holds with the bone throughout its whole length, but it may be more above than below, in which case the sternum acquires a somewhat twisted appearance.

But the deviation may not stop here. The sternum is not unfrequently at its upper part dragged over towards the cavity or the retracted side, and it thus loses its exact position in the middle of the body. It pursues an oblique course, and when twisted as above described presents a very remarkable appearance, and one almost always conjoined with phthisis in the third stage or with extreme hepatization, but much more frequently with the former.

At the present moment there is a fine example of lateral deflection of the sternum under consideration in the Brompton Hospital under Dr. Cursham. The patient is a lad named Brown, of about 17 years, having a large cavity on one side. In the same ward Dr. Cursham has another patient, with this deviation less marked. The patient is a man of about 55 years, and he too has a cavity in the lung. The sternum is occasionally seen inclined towards the healthy side in cavity cases, dragged over by excessive expansion of the ribs.

Though the clavicles and scapulae cannot strictly be said to form part of the thorax, it may not be without advantage to devote a few words to their behaviour in disease of the organs of the cavity of the thorax. The rising of these bones in cases of dyspnoea, emphysema, and empyema is very commonly known, but the lowering of them, though common too, is perhaps less attended to when proceeding from thoracic disease. In almost all examples of flattening, angularity, and retraction of the chest, these bones are the seat of deviations, greater or less, in their position. In single flattening these parts simply decline; the clavicle sinks as it proceeds outwards from the middle of the body. In cases of angularity where the ribs bend back abruptly, the clavicle frequently

does the same, as ascertained either by the chest-goniometer; and the sterno-clavicular articulation is, as it were, laid open, and the finger may be partially introduced between the extremities of the two bones. The sterno-clavicular articulation of one side may be found much posterior to the other when the sternum at one border has inclined inwards. A boy is now under the author's care at the Brompton Hospital with a large cavity on the left side, whose left sterno-clavicular articulation is more than half an inch behind the other. this case the fact attracts the more ready notice from the sterno-cleido-mastoideus of the right side standing out in consequence much more prominently than the other. The clavicle in this case, like the ribs, retires rapidly backwards.

In

VII. Lowering of the clavicle and scapula from descent of the upper ribs, consequent upon contraction of the lungs, is occasionally noted where there is comparatively little flattening in front; and where there is no curvature of the spine and no reason to attribute the change to mere posture, it may assist in diagnosis. It is a weight, though a light one, to be employed in estimating the probabilities of internal disease.

VIII. Depression of the first and second intercostal spaces on one side is occasionally seen without the presence of any other deviation. The depression is seen most frequently near the sternum. It appears to be a preliminary to the more general flattening. In some examples of flattening and hollowing of the costal cartilages, the depression of the interspaces is very marked, and outstrips the other flattening. A young German named Koch in the Hospital, under Dr. Thompson, who has great flattening from a cavity, presents the interspaces remarkably hollow. They appear as if the thumb had been deeply pressed into them.

The influence of disease in producing deviations from the natural form of the chest has been fully shown by the foregoing facts, which seem to be sufficiently numerous for the purpose. They might have been greatly extended, though, it is believed, with no corresponding advantage.

There yet remain two points to be mentioned. The first is that phthisis in its third stage, though almost always associated with deviation from the natural form of the chest, is occasionally seen without any obvious deformity, and may be associated with actual prominence over the cavity. A very fine large woman in good condition came to the Hospital. The left sub-clavicular region was full and prominent, but to

the surprise of the writer all the usual signs of a large cavity immediately beneath were discovered. Dull percussion, cavernous breathing and pectoriloquy were present. The explanation of this anomaly was found in a moderate curvature of the spine, which threw up the left shoulder and thrust forward the left side of the thoracic cone. The second point is this, that deformities of the chest, such as have existed from childhood, do not appear to favour the advent of phthisis. Comparatively few of the many examples of long standing, or, so to speak, of infantine deformity of the chest, which have presented themselves to the author at the Hospital, have been associated with phthisis. The diseases more especially observed have been chronic bronchitis recurring at intervals, some dyspnoea usually persistent, and disordered action of the heart. The explanation of this fact is probably to be found in a comparative immunity from tubercular tendency, which has been proven by bronchitis and other diseases having arisen under circumstances which are perhaps calculated to induce tubercles in others. Dr. T. W. Gairdner years ago proved that bronchitis and other diseases, not including phthisis, were the most frequent causes of the chronic deformities of the chest, and though these disorders may not exactly prove antagonistic to consumption, their presence and its absence rather argue a non-disposition to the production of tubercle, which probably holds in after life, and evinces itself in the fact now stated, viz., that comparatively few of the deformed chests presented at the Consumption Hospital are found to be associated with consumption,-at least, so far as the author's observations extend.

Table showing the proportions of each kind of deviation in 151 examples, with the respective numbers of each sex.

THE DIFFERENTIAL STETHOPHONE OR STETHOSCOPE. 393

THE DIFFERENTIAL STETHOPHONE, AND SOME NEW PHENOMENA OBSERVED BY IT.

[From the Proceedings of the Royal Society, No. 31, Vol. IX., 1858, communicated by Prof. Tyndall, F.R.S., and read April 22, 1858.]

ENGAGED for some years in investigations into the phenomena of audition, I have become cognizant of some facts which I believe have hitherto remained unnoticed, and which are certainly not generally known to physicists and physiologists.

The first of which I shall treat is the restriction of hearing external sounds of the same character to one ear, when the intensity is moderately, yet decidedly, greater in one ear than in the other, the hearing being limited to that ear into which the sound is poured in greater intensity. The sound is heard alternately in one ear and in the other, as it is conveyed in increasing degrees of intensity, and hearing is suspended alternately in one ear and in the other, as the sound is conveyed in lessening degrees of intensity.

Sound, as is well known, if applied to both ears in equal intensity, is heard in both ears; but it will be found, if the intensity in respect to one ear be moderately yet decidedly increased, by bringing the sounding body nearer that ear than the other, or otherwise, as by the employment, in respect to one ear, of a damper or obstructor of sound, or in respect of the other ear, by the employment of some intensifier, or good collector or conductor of sound, the sound is heard in that ear only which is favoured and has the advantage of greater intensity.

There is little doubt that this law holds with regard to sounds passing through the air, and carried to the ear in the ordinary manner, without the aid of any mechanical contrivance, as for instance those of a watch placed in front of the face; but as the restriction of hearing to one ear, and its suppression in the other, admit of being rendered more obvious by an apparatus that shall collect sound, prevent its diffusion through the air, and carry it direct to the ear, I propose to give the results of experiments made with an instrument which I have invented for hearing with both ears re