healthy living body, the thoracic
sounds heard in percussion, or by means of the stethoscope, will vary
according to the locality operated upon, in consequence of the variable
thickness of those structures (muscular and osseous, &c.,) which invest
the thoracic walls. Uniformity of sound must, owing to these facts, be
as materially interrupted, as it certainly is, in consequence of the
variable contents of the cavity. The variability of the healthy thoracic
sounds will, therefore, be too often likely to be mistaken for that of
disease, if we forget to admit these facts, as instanced in the former
state. Considering the form of the thoracic space in reference to the
general form of the trunk of the living body, I see reason to doubt
whether the practitioner can by any boasted delicacy of manipulation,
detect an abnormal state of the pulmonary organs by percussion, or the
use of the stethoscope, applied at those regions which he terms
coracoid, scapulary, subclavian, &c., if the line of his examination be
directed from before backwards. The scapula, covered by thick carneous
masses, does not lie in the living body directly upon the
osseous-thorax, neither does the clavicle. As all antero-posterior
examination in reference to the lungs external to the points, I I,
between the shoulders cannot, in fact, concern the pulmonary organs, so
it cannot be diagnostic of their state either in health or disease. The
difficulties which oppose the practitioner's examination of the state of
the thoracic contents are already numerous enough, independent of those
which may arise from unanatomical investigation.

DESCRIPTION OF PLATES 1 & 2.

PLATE 1.

A. Right ventricle of the heart.

B. Origin of pulmonary artery.

C. Commencement of the systemic aorta, ascending part of aortic arch.

D. Pericardium investing the heart and the origins of the great
bloodvessels.

E. Mediastinal pleura, forming a second investment for the heart,
bloodvessels, &c.

F. Costal pleura, seen to be continuous above with that which forms
the mediastinum.

G. Vena cava superior, entering pericardium to join V, the right
auricle.

H. Upper third of sternum.

I I. First ribs.

K K. Sternal ends of the clavicles.

L. Upper end of sternum.

M. Lower end of sternum.

N N. Fifth ribs.

O O. Collapsed lungs.

P P. Arching diaphragm.

Q. Subclavian artery.

R. Common carotid artery, at its division