•l6 PHILOSOPHICAL TRANSACTIONS. [aNNO 1724. 



pillar, it is capable of supporting, without hazard, such prodigious weights, as 

 we find it does. 



Another particular, which bespeaks the utmost wisdom and design in the 

 contrivance of this part, is the remarkable difference there is in the thickness of 

 the cartilages, placed between the bones of the spine. The vertebrae of the 

 breast requiring but little motion, the cartilages are there but thin, in com- 

 parison of those of the loins, which being very thick, the lowest more 

 especially, the motion is there vastly greater; and the cartilages being abundant- 

 ly thicker before than behind, this is the reason that we bend our bodies so 

 much more forward than backward. And by this admirable method of dis- 

 posing of the thicker parts of the cartilages forward, it is, that in all violent 

 exercises, the parts contained in the belly and breast are, in a great measure, 

 secured from any damages they might have been liable to, because by the 

 pliableness and elasticity of these cartilages, they break the violent shocks the 

 viscera must otherwise have necessarily sustained on such occasions. 



From what is here remarked, in regard to these peculiar properties of the 

 cartilages placed between the bones of the spine, we may reasonably suppose 

 them to be certain compressible, dilatable, elastic bodies, which like other 

 bodies, endued with the same qualities, will naturally yield to any incumbent 

 weight, sufficient to force the particles of matter of which they consist, into a 

 more strict and close union, and that when this compressive power is removed, 

 they will of themselves recover that state they enjoyed before they were obliged 

 to give way to that pressure. Now the lowest of all the cartilages of the loins 

 is the thickest, and so consequently it contains a greater quantity of matter 

 than any of the rest ; by which means it becomes more disposed to have its 

 thickness diminished, and that all of them gradually become thinner, even to 

 the top of the spine. Now all superior bodies, if they come to an immediate 

 contact, pressing on their inferior, it must necessarily follow, that the whole 

 weight of the body, except the lower limbs, must press upon and be sustained 

 by the lowest vertebrae and their cartilages ; but these cartilages, as has been 

 observed, being much thicker in this part than the other, and the incumbent 

 weight bearing liarder upon them, they must be compressed more than the 

 other ; and so consequently, when this weight is removed, their expansion, 

 from their natural elasticity, will be greater also. 



This being the natural state and disposition of these parts, during the whole 

 space of time we are usually employed about our necessary avocations, till we 

 dispose ourselves to rest, the cartilages of the spine will, by their compressible 

 and yielding properties, become more close and compact from the perpendicular 

 pressure they sustain, and so consequently the spine, the only support of the 



