58 
OF MECHANICAL ARRANGEMENT 
to secure the body of the vertebrae, not only from accident¬ 
ally slipping, but even from being pushed out of its place 
by any violence short of that which would break the bone. 
I have often remarked and admired this structure in the 
chine of a hare. In this, as in many instances, a plain ob¬ 
server of the animal economy may spare himself the disgust 
of being present at human dissections, and yet learn enough 
for his information and satisfaction, by even examining the 
bones of the animals which come upon his table. Let him 
take, for example, into his hands, apiece of the clean-pick¬ 
ed bone of a hare’s back; consisting, we will suppose, of 
three vertebrae. He will find the middle bone of the three 
so implicated by means of its projections or processes, with 
the bone on each side of it, that no pressure which he can 
use, will force it out of its place between them. It will 
give way neither forward, nor backward, nor on either side. 
In whichever direction he pushes, he perceives, in the 
form, or junction, or overlapping of the bones, an impedi¬ 
ment opposed to his attempt; a check and guard against 
dislocation. In one part of the spine, he will find a still 
farther fortifying expedient, in the mode according to 
which the ribs are annexed to the spine. Each rib rests 
upon two vertebrae. That is the thing to be remarked, 
and any one may remark it in carving a neck of mutton. 
The manner of it is this: the end of the rib is divided by 
a middle ridge into two surfaces; which surfaces are join¬ 
ed to the bodies of two contiguous vertebrae, the ridge ap¬ 
plying itself to the intervening c artilage. Now this is the 
very contrivance which is employed in the famous iron 
bridge at my door at Bishop-Wearmouth; and for the same 
purpose of stability; viz. the cheeks of the bars, which pass 
between the arches, ride across the joints, by which the 
pieces composing each arch are united. Each cross-bar 
rests upon two of these pieces at their place of junction; 
and by that position resists, at least in one direction, any 
tendency in either piece to slip out of its place. Thus 
perfectly, by one means or the other, is the danger of slip¬ 
ping laterally, or of being drawn aside out of the line of the 
back, provided against: and to withstand the bones being 
pulled asunder longitudinally, or in the direction of that 
line, a strong membrane runs from one end of the chain to 
the other, sufficient to resist any force which is ever likely 
to act in the direction of the back, or parallel to it, and 
consequently to secure the whole combination in their 
places. The general result is, that not only the motions of 
the human body necessary for the ordinary offices of life 
