11 
series of rude diagrams, lie sought to prove that the “ country 
of Etruria hath been tw ice fluid, twice plane and dry, and twice 
scabrous and craggy.” Stracliey also had a faint knowledge 
of this fact as exhibited in his diagrams of the unconformity 
of the coal measures and new red sandstone of Somersetshire.* 
Our illustrious Hutton was, however, the first geologist who 
clearly expounded the laws of unconformity, and proved their 
universal application. 
IIow, then, do these truths bear on the question, when, as 
in the instance recorded by Smith, sinkings were begun in the 
Oxford clay, the dark coal measure colour of which deceived 
the speculators and prompted the experiment ? In the first 
place it is perfectly known, that excepting in the coal measures 
no coal occurs in any other formation in this and the sur- 
rounding districts. The sinkers knew this, for when they 
reached the oolitic limestones they abandoned the attempt. At 
what depth, then, had they persevered, might the true coal 
measures have been found ? There is little reason to doubt that 
it would have been necessary to have sunk through oolitic and 
other rocks, (too thick to permit of such a speculation being 
profitable,) at the very least from 1,500 to 1,800 feet. 
But even then there would have been no certainty of reaching 
the coal measures, for the newer rocks rest unconformably 
upon the older strata, and it is not improbable that owing to 
earlier disturbances other beds beneath the coal may rise 
towards their base at the point beneath the shaft. 
It is forty years since this incident occurred. There are now 
sparsely scattered throughout England mining engineers of high 
attainments, well versed in the principles of geology ; and the 
science is reaching a point when problems in economics may be 
solved far more obscure than those that tasked the knowledge 
of Smith ; but you must not therefore suppose, that, as a general 
rule, many of our proprietors and speculators are guided by a 
higher knowledge than then prevailed. Such is not the case. 
Throughout the length and breadth of the land, down to this 
very day (as I have already stated), equally fruitless and still 
* Philosophical Transactions, vol. 33. p. 395. 
