extraordinary Effects of Lightning. 295 
Mr. Watt fuggefted to me, that the hollows had been 
occafioned by the expanfion of moifture whilft the fufion 
exifted. 
I (hall conclude with obferving, that judging from the da- 
mage done to the oak tree, the ftroke was not very great ; and 
that having now an inducement to dig where the earth has 
been perforated by lightning, we may probably hereafter find 
foffil fubftances melted by it to a confiderably greater extent. 
