By changing the direction of the speculum, the posterior nares and pharynx may be also examined. This apparatus is called the laryngoscope. It is a valuable addition to our means of physical exploration, and its successful employment is not to be despaired of, because a first or a second trial may happen to disappoint the expectations of the physician. Practice may at length make him a Czermack or a Türck. The subjoined woodcuts represent the speculum and the perforated concave reflector. The mode of employing them is also exhibited.

The division of the chest into regions is of great practical importance. A table of regions is to be found in the following page. The sternal regions are strictly confined to the sternum and ensiform cartilage; and the lateral regions are bounded by lines drawn perpendicularly from the anterior and posterior borders of the axilla.

NOTE. This Table has been adopted, in great measure, from the work of Dr. Williams on Diseases of the Chest.

MENSURATION OF THE CHEST.

361

PART III.

ON MEASURING THE CONFIGURATION OF THE CHEST IN DISEASE.

[From Dr. Beale's "Archives of Medicine," No. II. 1858.]

THE mensuration of the thorax affords much aid in the diagnosis of the diseases of that portion of the body, and materially assists us in deciding whether a morbid condition there located be increasing or in process of abatement. The information which mensuration procures is remarkable for that precision and certainty which mark the data of physical science. In this respect it greatly surpasses in value that large portion of medical evidence called symptoms, on which medical diagnosis and prognosis are greatly founded, for these being in a great measure simply the sensations of the patient, may vary from hour to hour, although the important fundamental pathological conditions of organs may remain the same; and because the language, which is their exponent, is less fixed and precise than the symbols of physical science, and is often, in degree at least, determined by the temperament or even the varying temper of the patient. This contrast, drawn in favour of mensuration, is not intended to depreciate the importance of symptomology, without which testimony, most valuable in itself, would be lost, and cues for the application of physical tests themselves could not be obtained.

The mensuration of the chest, by which is meant that measurement which is effected by physical appliances, was, until lately, accomplished almost exclusively by the application of the tape measure. To determine the circumference of the chest it is passed round the part; but as it is the comparison of one side with another that is chiefly desiderated, the tape is applied in almost all cases to compare the semicircumference of the one side with the semi-circumference of

the other, and this is done by placing the end of the tape on a spinous process and carrying the measure round to a point at the middle of the sternum. This done on one side and then on another, the difference in the two measures gives the difference of the two sides. By means of this mode of measurement, we obtain the dimensions of the entire halves of the thorax, but it fails to determine any particular part where the increase or diminution of dimension in a half of the chest, may be present; thus, the semi-circumference so taken would not inform us, in a case of protuberance of the præcordial region from great hypertrophy of the heart, that the excess in the measurement was due to fulness of the præcordial region, it would simply notify an excess in the general dimension of the side. It is true that, for the measurement of a part of the thorax, the tape is employed; thus the distance from the nearest part of the sternum to the nipple, and the distance from the sterno-clavicular articulation to the nipple, are ascertained by the tape; but we find that a material increase of size and deviation from the natural configuration may be present, which can with difficulty be represented by this measure. Thus a præcordial fulness, perfectly obvious to the eye, frequently fails to pronounce itself in a decided manner by the tape thus topically applied.

The distance of one part of the thorax from another, including the cavity between them, has been ascertained by means of callipers, and this instrument has afforded some valuable information, not obtainable by the tape. This instrument gives that information respecting the magnitude of a part of the half thorax which is not obtained by the tape; thus, where a deficiency is found on the right side, from consolidation of the front of the middle lobe, this may give rise only to a flattening of the third or fourth ribs in front, the callipers will declare this, while the tape will not detect it. The callipers have been recently improved for the purposes of thoracic mensuration by Dr. Edwards, who has added to it a delicate and useful graduated scale.

Perhaps it may be permitted to say a word or two respecting some other mechanical contrivances employed in the diagnosis of thoracic disease. The elevation of the ribs in inspiration is measured by the stethometer of Dr. Sibson; during the elevation of the chest the instrument is carried forward, and the degree of its movement is indicated by a scale which is connected with the part resting on the chest. This instrument requires to be fixed at one end, and this is generally effected by supporting the arm on the back of a chair. Dr. Quain is the inventor of another instrument for

measuring the elevation or expansion of the chest. It is more portable, and better fitted for the examination of different parts of the chest, and is more delicate than Dr. Sibson's. It consists of a thread, which is placed across the part to be measured, one end of which is fastened on the chest with the finger, while the other is connected with a spring which moves a handle on a dial duly graduated. The slightest expansion of that part of the chest under the thread moves the spring, and this movement again indicates itself upon the dial.

The sphygmoscope which the author invented to denote the pulsations of the heart, is capable, when slightly modified, of proving a good measurer of the movements of the chest. When so used it is placed upon a fixed stand, and is then called a pneumatoscope. It consists of a small projecting bag of water, which is placed upon the chest, and has connected with it a graduated scale. The elevation of the chest in inspiration, as well as the fall in expiration, are delicately measured by it; by no other means can the absolute and the relative duration of these acts be so delicately measured.

The ingenious and interesting instrument, the spirometer, invented by Dr. Hutchinson, measures the quantity of air expired from the thorax; but while it serves to indicate the total capacity of the chest for air, or for the vital capacity, as it is incorrectly called, it is utterly null, as an index of the capacity of any particular part of the breathing apparatus.

The instruments above referred to measure magnitudes, movements, and capacity, but deviations from the natural configuration of the thorax present themselves, which do not come under the description of magnitudes, movements, or capacity, and which cannot be measured by any of the means above enumerated. The deviations not so included are of very frequent occurrence, many of them are observed at any early period of disease of the contained organs, and may be made subservient as elements in diagnosis, whether other evidence be more or less complete.

The deviations here referred to relate to the angles and curves formed by the bones composing the chest; by the junction of one bone with another part, and of bones with cartilages. Angles may replace curves, and curves may so alter as to belong to greater or smaller circles or radii than natural. Such deviations from the natural configuration being not at all or very imperfectly gauged by the appliances already described, the goniometer or stetho-goniometer has been introduced for their measurement as an instrument of diagnosis, &c., in diseases of the chest.

The chief deviations for the measurement of which the