182 
LECTURES ON HOUSES. 
The Chest. 
Of this inclosure the spine forms the roof, the ribs its sides, and 
the breast-bone its floor or bottom : all which parts are more or less 
excavated or rendered concave in their shape internally, in order 
that its cavity might be as extensive in every direction as the 
nature of the fabric would allow. The smooth bodies of the ver- 
tebrae are the parts presented to the interior of the chest, from 
which proceed, on either side, the ribs, describing in their course 
downward so many elliptical arches abutting upon the breast-bone. 
The foremost arches are short and straightened; the middle,. large 
and circular ; the hindermost ones diminishing in length, and be- 
coming straight again. Altogether, the chest presents in the skeleton 
a conical figure : small and contracted in front ; broad, deep, and 
capacious in the middle and posterior regions. 
The connexion between the ribs and the bones of the spine 
is by means of small joints which admit of a limited hinge-like 
motion between them ; but to the breast-bone the ribs are attached 
by distinct cartilages — long pieces of gristle, so formed as to appear 
like a continuation of the ribs themselves, and virtually, indeed, 
to answer in some respects a like purpose ; for they complete the 
inclosure inferiorly, and to the contained parts offer, to the extent 
they reach, as effectual protection as the ribs themselves. But 
they serve purposes bones could not answer. They enable the 
ribs to enjoy that motion, outwardly, which their joints with the 
vertebrae intended they should have, for the purposes of respira- 
tion ; they also enable the ribs to accommodate themselves, by 
partial turns, twists, and inclinations, to the various movements of 
the animal : further, by their own elasticity, they endow the ribs 
with that power of yielding, that high degree of resiliency, which 
proves the means of their resisting fracture in hundreds of instances 
where, without the cartilages, fracture must have ensued. The 
blows, the pressure, the squeezes, the hard rubs, the ribs get, 
would over and over again break them to shatters were it not for 
their cartilages. How rarely do we hear of a horse getting his 
ribs broken, even from the heaviest falls, from the hardest blows, 
from the greatest weight imposed upon them ! when any shock of 
this description is given, we hear a sudden burst of air from the 
chest, occasioning momentary exhaustion ; but we rarely indeed 
find it productive of fracture of the ribs. Far other and fatal must 
have been the consequences had the entire rib been one solid 
piece of bone : to say nothing about the difficulty any act of exer- 
tion must necessarily have occasioned in the breathing, any violent 
blow or fall, or great weight jolted upon the back, must have 
