It is only within the last century that diseases of the lungs have been well understood. The greatest aid to their investigation has been rendered by the discovery by Laennic of the stethoscope, and the perfection of the several means of examination of the lungs employed in "physical diagnosis," which comprise inspection, palpation, mensuration, succussion, percussion, and auscultation. Of these, by far the most important are the last two. We have space here only for a very brief description of each.

Inspection Of The Lungs

This consists in critically viewing the chest. By this means we discover whether there is proper motion of the walls of the chest, or whether there is unequal motion. We also may discover bulging of portions of the chest from various causes.

By means of an instrument known as the laryngoscope, shown in Fig. 296 it is possible to inspect the larynx and even the upper part of the trachea. By means of the same apparatus the nasal cavity may be examined The instrument consists essentially of two mirrors, one of which, a small one, is attached to a handle, by means of which it is held at the back part of the mouth. A strong light is focused upon the small mirror by a larger concave one, which is held in position upon the head by means of a band encircling it By holding the two mirrors in proper positions, the light may be thrown into the larynx or nasal cavity, bringing all the parts into distinct view. When seen by means of the laryngoscope, the healthy vocal cords appear as seen in Fig. 297 in different stages of respiration. In Fig. 298 the same organs are represented as seen in a case of ulceration of the larynx.

Fig. 296. Using the Laryngoscope.

Fig. 296. Using the Laryngoscope.

Fig. 297. Healthy Vocal Cords in Different Stages of Respiration.

Fig. 297. Healthy Vocal Cords in Different Stages of Respiration.

Fig. 298. Ulceration of the Larynx.

Fig. 298. Ulceration of the Larynx.

Fig. 299 shows a very convenient form of tongue depressor which is very useful in inspecting the condition of the throat, and in connection with the use of the laryngoscope. In the absence of a better instrument for this purpose, the handle of a teaspoon may be used.

Fig. 299. Tongue Depressor.

Fig. 299. Tongue Depressor.

Palpation - Inspection Of The Lungs

Palpation is the term applied to examination of the chest with the hands. By the aid of the sense of touch, much may bo learned of the condition of the lungs. In health, the resonance of the voice gives to the chest a slight vibratory movement, known as vocal fremitus, which can be felt by means of the hand. This movement is most marked upon the right side, and is increased in diseases which cause solidification of the lungs, as in pneumonia.