26 NATURAL HISTORY 



been found of late 2 . Besides the oak, I have also 

 been shown pieces of fossil wood of a paler colour, 

 and softer nature, which the inhabitants called iir : 

 but upon a nice examination, and trial by fire, I could 

 discover nothing resinous in them ; and therefore rather 

 suppose that they were parts of a willow or alder, or 

 some such aquatic tree 3 . 



a Old people have assured me that, on a winter's morning, they have 

 discovered these trees, in the bogs, by the hoar frost, which lay longer 

 over the space where they were concealed than on the surrounding 

 morass. Nor does this seem to be a fanciful notion, but consistent with 

 true philosophy. Dr. Hales saith, That the warmth of the earth, at 

 some depth under ground, has an influence in promoting a thaw, as well 

 as the change of the weather from a freezing to a thawing state, is 

 manifest from this observation, viz. Nov. 29, 1731, a little snow having 

 fallen in the night, it was, by eleven the next morning, mostly melted 

 away on the surface of the earth, except in several places in Bushy Park, 

 where there were drains dug and covered with earth, on which the snow 

 continued to lie, whether those drains were full of water or dry ; as also 

 where elm-pipes lay under ground ; a plain proof this, that those drains 

 intercepted the warmth of the earth from ascending from greater depths 

 below them : for the snow lay where the drain had more than four feet 

 depth of earth over it. It continued also to lie on thatch, tiles, and the 

 tops of walls." See Hales's H&mastatics, p. 360. Quere, Might not such 

 observations be reduced to domestic use, by promoting the discovery of 

 old obliterated drains and wells about houses ; and, in Roman stations 

 and camps, lead to the finding of pavements, baths, and graves, and other 

 hidden relics of curious antiquity ? 



[Some additional instances evidencing the ascent of warmth from beneath 

 the surface, are given by the author in his letter to Daines Barrington, 

 numbered LXI ; in which he describes the effects of the short but intense 

 frost of 1768. E. T. B.] 



3 A more recent instance of the occurrence of a log of the bog-oak is 

 recorded by Gilbert White in Letter LIX. to Daines Barrington : and the 

 stock is yet by no means exhausted, although fifty years have elapsed 

 since the time at which he wrote. The sides of the peat-moor to the 

 north-east of Wolmer pond show many heaps of chumps and stumps of 

 trees dug by the labourers, in the prosecution of their cuttings, from the 

 bog and the turf above it. Oak, and fir, and birch are certainly included 

 among them. They are in various stages of carbonization, dependent 

 on their position, or, in other words, on the length of time during which 

 they have been subjected to the action of moisture and pressure. Those 

 which occur among the peat are converted throughout their entire substance 

 into a charcoal, which is generally rather brown than black : of this 

 kind all the pieces that I observed were of small diameter, not exceeding 



