of his assuming the erect posture, he may be ausculted, with sufficient accuracy, in bed. Let his position, when necessary, be varied from dorsal decubitus to lateral, and even abdominal and facial. When his prostration by disease is considerable, the symptoms recognized from the anterior part of the thorax will usually be found decisive; and, consequently, the dorsal decubitus only will be necessary.

CHAPTER IV.

SUCCUSSION.

Of all the means of physical diagnosis, this is of the least importance. The term signifies a shaking; and the act consists in suddenly agitating a patient with the view of detecting the existence of a fluid in some one of the cavities of the body,-particularly, one of the pleural sacs. Seizing, by the shoulders, an individual, as he is ordinarily seated, strongly jolt or shock his whole frame. In this way, the sound of a contained fluid may sometimes be heard, like that of a liquid in a cask or bottle that is forcibly agitated. This has been called the metalic splash. Sometimes, the patient in bed is able so to shake himself as to give the splashing sound of the water, in the thorax. Even water in the pericardium has occasionally been, by succussion, detected. The art was known to Hippocrates, and has, hence, sometimes been termed Hippocratic succussion.

There is, however, but little occasion to employ this method of detecting the existence of water in a cavity, as ordinarily it is made perfectly evident by other means of diagnosis.

CHAPTER V.

PALPATION.

The matter of palpation is of a little more practical utility than succussion. The term signifies feeling or handling; and the act consists in the application of the hand or fingers to the part to be examined. Thus, if, while a person is speaking, the hand be ap

plied to the parieties of the thorax, a tremor will ordinarily be felt; and the character of this will vary according to the condition of the viscera immediately within. If no tremor appears, that negative circumstance has a language of its own. The enlargement of an internal organ, as the liver, the existence of a tumor or of an aneurism, an abnormal action of the heart, and the fluctuation of the liquid in some forms of dropsy may sometimes be detected by the hand.

Palpation, however, like succussion, is, at present, but little used; as, in most cases, we have surer and better means of diagnosis.

CHAPTER VI.

INSPECTION.

Rising a little higher in the scale of importance, we come to the subject of inspection. This consists in an ocular survey of the patient, for the purpose of judging, by some recognized want of symmetry, or other abnormal condition if it exists, in what manner and to what extent, there is a departure from health.

To apply, with effect, to the chest, this means of diagnosis, the clothing of that portion of the body, must be entirely removed, and the attitude of the patient must be such as not unnaturally to vary the relation of those parts which, in health, should be found symmetrical. In this condition, any considerable lack of symmetry is easily detected by the eye. So, also, are many such prominences and depressions as are created by disease, whether they destroy the relation which one part of the body bears to the other, or not. Of this nature, are the fulness of the precordial region, the enlargement or contraction of one of the sides, the elevation or depression of one of the shoulders, the contraction about the clavicles increasing their apparent prominence, and like variations from the standard of health. The phenomena, thus inspected, become signs of the disease existing within. So, also, do certain abnormal motions of the chest, neck, or abdomen, occurring in respiration or with the impulses of the heart. Even the absence of the proper movement may indicate disease; and this absence may be made known by inspection.

CHAPTER VII.

MENSURATION.

As an aid to inspection, and as a matter not far from tantamount in importance, is mensuration. This consists in the admeasurement of certain parts whose form is altered by disease, and in the comparison of that admeasurement with the standard of health. Passing a tape or measuring line around the thorax, we may, by means of it, learn very accurately the comparative fulness of the two sides. We may, also, by comparing the circumference at the superior with that at the inferior portion of the thorax, decide whether the relation of those portions is cousistent with the condition of health. By mensuration, too, we may determine the position of the nipples with reference to the sternum, to the clavicles, and to the spinous processes of the ilia; and, by so doing, may gain diagnostic signs of certain diseases.

CHAPTER VIII.

PERCUSSION.

None of the previously considered means of diagnosis compare, at all favorably in importance, with percussion. By this is meant the method of detecting the condition of internal organs, from the character of the sound produced, when the surface of the body directly over those organs receives the force of a light blow. It was invented by Avenbrugger.

The sounds produced by percussion are divided, generally, into two, the resonant and the dull.

The resonant sound is heard on percussion over a space filled with air or gas, usually termed an empty space.

The dull sound is heard on percussion over a solid or a liquid

substance.

The former of these sounds is illustrated in the case of striking upon an empty barrel or cask;-the latter, by the same act, when the barrel or cask is filled with liquid. Or we have a modified il

lustration in the case of a barrel partially filled with liquid. Strike upon that barrel above the surface of the liquid, and you hear a hollow or resonant sound. Strike below the surface, and you

hear a dull or a flat sound.

In percussing over any of the cavities of the human body, if no internal viscus lies near the paries or wall, we have a very resonant sound. If the cavity is filled partly with air or gas, and partly with solid viscera intermixed, or if there be within a viscus of a spongy character, we have a less resonant sound. If a solid of medium density lies within, we have a slightly dull sound. If a very dense solid or a liquid within receives the force of the percussion, we have a very dull, often called a flat sound. Hence we speak of very resonant, resonant, dull, and very dull or flat sounds. We even use other qualifying terms to mark nicer differences, according to circumstances, as the ear is able to distinguish those differences.

There is, however, one peculiarity of sound, or one adventitious sound of percussion, which deserves a moment's special consideration. It is usually called the cracked-pot sound,-in French, bruit de pot fêlé. The name sufficiently explains itself. It is a kind of cracking or chinking sound. It may be imperfectly imitated, by clasping the hands together, in such a manner, that the palmar surfaces shall constitute the walls of a small cavity, and then striking the dorsal portion of one of the hands on the knee or some solid substance.

The sound is heard when percussing over a cavity, with thin walls; as, for example, over a tuberculous cavity near the surface of the lung, when the pulmonary and costal portions of the pleura are united at the part concerned. It may be heard, when a disease of the lung draws a portion of it away from the thoracic wall, so as to leave a hollow space.

Percussion is either immediate or mediate. Immediate percussion supposes the blow to be made immediately upon the body of the patient, no substance intervening. Mediate percussion, on the contrary, supposes some substance interposed or placed on the part to be percussed, primarily to receive the impulse and to communicate it to the body beneath.

Immediate percussion was the form in which the art was first

practiced. By it, Avenbrugger threw much new light on the nature of many diseases; and, shortly after, Corvisart, adopting and advocating it, contributed much to establish its reputation. As thus practiced, however, the art was imperfect.

At length, M. Piorry, physician to the Hotel Dieu of Paris, invented mediate percussion, and applied it, with greater success, to the investigation of the nature of diseases; and now the increased advantages and accuracy of the latter mode have caused it entirely to supercede the former. In mediate percussion, as at first employed, a dense body, of a small superficial extent, was placed in contact with that portion of the patient to be percussed; and was made to receive an impulse from the fingers or some artificial percussor, used after the manner of a small mallet. This body took the name pleximeter, or, as it has been sometimes written, plessimeter, signifying a measure or measurer of percussion.

The object of the pleximeter is to gather the sound from some little extent of surface, and thereby produce a stronger impression. upon the ear. Besides, if the patient be thin in flesh and very sensitive, immediate percussion will give him uneasiness, and will be too impatiently borne for its practical advantages; or, on the other hand, if there be a rather abundant amount of adipose tissue, or if the areolar tissue be somewhat infiltrated with serum, the condition of the internal organs will not be truly represented.

The pleximeters in earliest use were made of metal and ivory. Afterwards, leather and other substances were tried; and, of late years, a square piece of caoutchouc, about one fourth or one third of an inch in thickness, and about two inches in diameter, has been recommended. This, which was first proposed by Dr. J. B. S. Jackson of Boston, Mass., has an advantage over the materials which are more solid and scarcely elastic, in its power of accommodation to any unevenness of surface, and the transmission thereby of a greater volume of sound. By being, too, of a density nearly similar to that of the tissues over which it is placed, it represents more truly the quality of sound created by the condition of the organs and space within. A hard unyielding substance necessarily gives some degree of sharpness even to sounds which would otherwise be measurably resonant; and, besides, if the instrument shall happen not to be applied with sufficient firmness