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parts may be bruised, wounded, swelled^ or removed 

 out of their natural place. 



It is a wonderful provision which nature makes in 

 one of the most dreadful calamities incident to the 

 solids. When a bone is broken, let it only be replaced 

 and preserved in that situation, and nature does the 

 rest, by supplying the divided parts with a callus- 



This oozes out from the small arteries and 

 fibres of the divided -parts, in form of a jelly, and 

 soon fills up the cavities between them. It soon 

 grows cartilaginous, afterwards bony, and joins the 

 fractured parts so firmly, that the bone will be more 

 easily broken in any other part than in that. 



A callus of a different kind is formed on our hands 

 and feet. This is composed of several layers of 

 particles loosely connected. These, if stepped in fair 

 water easily separate, and then are found, if viewed 

 through a microscope, to be all of one shape, re- 

 sembling that of a weaver's shuttle, broad in the 

 middle, and pointed at each end. Being steeped 

 again, they divide into a great number of smaller par- 

 ticles, allot' the same figure with the first. 



The thickness of the skin in the hands of those 

 who labour hard, is wholly owing to vast numbers 

 of these particles, which combine together, but so 

 loosely that they are easily separated on moistening. 

 That thick skin is composed of several layers of dif- 

 ferent thickness, which have been added from time to 

 . - time, each of which layers is only a congeries of 

 almost an infinity ol these particles. 



But people who labour ever so hard, will have little 

 callus on their hands if they wash them often. .The 

 washing the hands daily rubs off' a great quantity of 

 these scales. Indeed it is surprising to see how large a 

 quantity of them is daily thrown off from our hands 

 and feet,though from no other part of the body. We 

 may learn from this, the great bounty of nature, in 

 so carefully supplying the parts designed for walking 

 or labour, with an additional matter for their de 

 fence, which is not in any other part of the body. 



