by a very small quantity of gun-powder; and no vapour could be so subtle, that produc'd such effects, and not be very obvious to our senses.
Even in vulcano's, it is the opinion of the learned Italian philosopher Borelli, and of other great naturalists, that they are kindled first from the surface, where there is a possibility of ventilation from the air. They imagine, it begins at the top of the mountains; not by any fancied fermentation of the pyrites and sulphureous vapours arising from subterraneous caverns, in the lower parts of mountains.
There is another consideration, which utterly overthrows these suppositions, of earthquakes being caused by any thing under-ground; and that is a due consideration of springs, and fountains perpetually flowing; and that from the creation of the world to this day. If we would form any tolerable idea of their nature, we must needs conceive, that God Almighty has laid their pipes, and canals in the earth, from a great depth, even to the surface; like as he has planted the veins, arteries, and glands in an animal body. And likewise that they are more and more ramify'd, as they nearer approach the outward shell of the earth; just so our veins, and arteries, as they come nearer the skin.
The workmen in coal-mines, and those of metals, minerals, and stone-quarries, never fail to