We cannot pretend to deny that there may be such vapours, and fermentations, inflammable substances, and actual fires, in the bowels of the earth; and that there may be some caverns under-ground, as well as we find some few above ground: such as _Pool_'s-_Hole_, _The Devil_'s-_Arse in the Peak_ of _Derbyshire_, and _Okey-Hole_ in _Somersetshire_. These, I believe, to have been so from the creation, never were made by earthquakes. We know, there are hot springs running continually: There are some vulcano's frequently belching out flames and smoke, and to these perhaps some earthquakes may be owing, tho' not according to the vulgar notion; as we shall see, by and by. But these matters are very rare, much rarer than earthquakes, both as to time and place. _Vesuvius_ in _Italy_, and in that part of it abounding with mines of sulphur: _Ætna_ in _Sicily_, and _Heckla_ in _Iceland_; these are all we know of, in the old world. In the _Andes_ mountains of _America_, there are some. The scarcity of these appears to me a strong argument against the common deductions made therefrom, as to their being the cause of earthquakes. Nor can I enter into the sentiments of those that hold the cavernous state of the earth, so as to contribute to the forming an earthquake by vapours running from place to place under ground. How many thousand acres of coal-mines do they daily work in _England_, and have done for ages? I have been myself 2 or 300 feet deep in a solid rock of native salt: I have walked a mile lengthwise directly into the earth, and descending all the way, in the proportion of one yard in five, 'till we came under the bed of the very ocean, where ships were sailing over our heads. This was at Sir _James Lowther_'s coal-pit, at _Whitehaven_. We were at this time deeper under ground by the perpendicular, than any part of the ocean, between _England_ and _Ireland_.