ble substances, and actual fires, in the bowels of the earth; and that there may be some caverns under ground, as well at 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
