iv.] THE COAL IN THE FIBE. 101 



which they grew sank below the water-line ; the trees 

 were killed ; and the mud and sand which were brought 

 down the streams enveloped their trunks ? As for the 

 inside being full of sandstone, have we not all seen 

 hollow trees ? Do we not all know that when a tree 

 dies its wood decays first, its bark last? It is so, 

 especially in the Tropics. There one may see huge 

 dead trees with their bark seemingly sound, and their 

 inside a mere cavern with touchwood at the bottom ; 

 into which caverns one used to peep with some caution. 

 For though one might have found inside only a pair of 

 toucans, or parrots, or a whole party of jolly little 

 monkeys, one was quite as likely to find a poisonous 

 snake four or five feet long, whose bite would have 

 very certainly prevented me having the pleasure of 

 writing this book. 



Now is it not plain that if such trees as that sunk, 

 their bark would be turned into lignite, and at last into 

 coal, while their insides would be silted up with mud 

 and sand ? Thus a core or pillar of hard sandstone 

 would be formed, which might do to the collier of the 

 future what they are too apt to do now in the Newcastle 

 and Bristol collieries. For there, when the coal is 

 worked out below, the sandstone stems " coal-pipes " 

 as the colliers call them in the roof of the seam, 

 having no branches, and nothing to hold them up 

 but their friable bark of coal, are but too apt to drop 

 out suddenly, killing or wounding the hapless men 

 below. 



Or again, if we find as we very often find as was 

 found at Parkfield Colliery, near Wolverhampton, in 

 the year 1844 a quarter of an acre of coal-seam filled 

 with stumps of trees as they grew, their trunks broken 



