l66 PHILOSOPHICAL TRANSACTIONS. [aNNO 1757. 



ing entire within. At other times wood thus incrusted is eroded by the matter 

 which covers it, having something acrimonious in its substance. We may add 

 to these, ckisters of the twigs of shrubs, and small wood, which we find flakes 

 of, incrusted with sparry or calcareous matter, in many places; parts of which 

 are totally changed into that matter, whilst others are only enveloped with it. 



Bones of j^nimals — We see by daily experience, that the human skeleton 

 moulders to dust in a very few years, when buried in mould : so it does even in 

 vaults, where the coffins are kept dry. In the first case, the moisture and salts 

 of the earth divide and dissolve the texture of the bones; in the latter, those 

 of the air, which gradually insinuate themselves into them, and at length destroy 

 them. How long a skeleton whose bones are well dried and prepared, being to- 

 tally deprived of its medullary substance, will last, as they are now ordered for 

 anatomical purposes, is unknown ; but it may be reasonably conjectured, that 

 they will undergo the fate of the softer kinds of wood, such as beech, which 

 grows rotten in no great number of years; because their internal substance is 

 spongy and cellular, and their crust very thin, except about the middle of the 

 bones of the arms and thigh. The same destruction would happen if bodies 

 were deposited in a sandy soil ; because water finds its way either by dripping 

 downwards, or by springs underneath. But human skeletons have been found 

 entire within a rock, where neither moisture nor air could get at them. Mr. 

 Minors, an eminent surgeon and anatomist of the Middlesex hospital, when he 

 was in the army at Gibraltar, saw an entire skeleton, standing upright, in a dry 

 rock, part of which had been blown up with gunpowder, in carrying on some 

 works in the fortifications, which left the skeleton quite exposed. Indeed, the 

 bones of elephants have been found in Shepey island, but much destroyed; their 

 size and substance being so considerable, as to resist for a long time that decay 

 which those of the human could not withstand. To these may be added the 

 horns of large animals, as the elk, and others, which have been found in bogs, 

 preserved as the bog-oak, &c. above-mentioned. 



leetk and Palates of Fishes and other Animals. — ^These are of so hard and 

 firm a texture, as to suffer no great change, wherever found; for no erosion 

 appears in them, their enamel and its polish being entirely preserved; yet some- 

 times their roots will be found changed, especially in the yellow ones, having no 

 enamel to guard them in their roots. 



Parts oj P^egetab/es. — The leaves of plants, whose fibres are firm and dry, 

 will endure for a long time ; but those of a succulent nature never can, as they 

 putrify very soon. We see the leaves of ferns of several kinds, polypodium, 

 trichomanes, and other capillary plants, with nodules of stone fomied about them ; 

 flags, reeds, rushes, equisetum, and many such, of a firm texture, are found in 



