A Third Cause is ascribed to Mineral Eruptions and subterraneous Exhalations. _Pestilences_ from this Cause are more infrequent than from several others; because such Eruptions hardly ever happen but upon Earthquakes, or Breaking into the Bowels of the Earth by Mines, Pits, Wells, and the like; and then too, in Order to produce a _Pestilence_, it is necessary that whatsoever exhales and mixes with the ambient Air, must be of such a Nature, as to render it unrespirable; or to communicate by it such Particles to the Animal Juices as will pervert their natural Crasis, and disturb their due Secretions; which does not often happen, for there are frequent Shocks of the Earth from intestine Fermentations, which are not followed by any such Mischiefs, as they happen only from the Struggle of such Principles, as when they have got Vent, neither of themselves, or by any Thing emitted with them, are of that disagreeable Nature, as to give any Disturbance to the Animal OEconomy. _CAROLUS de la Font_,[17] indeed, as well as several others, lays great Stress upon Causes of this kind, and charges _Pestilential Diseases_ chiefly to Mineral Exhalations of divers kinds; as _Arsenical_, _Mercurial_, _Sulphurous_, &c. which he imagines the ambient Air often to be overcharged with, either from the Heat of the Sun, Earthquakes, or subterraneous Fires. To all this, Persons of different Opinion object, the Infrequency of Plagues in _Calabria_, _Naples_, and several Parts of _Sicily_, where there are manifestly very great subterraneous Fires, such as occasion violent Earthquakes, and many furious and plentiful Eruptions of metallick and mineral Fumes. A very distinct Relation of which, from his own Knowledge, may be met with from Dr. _Bernard Connor_,[18] who has been very curious in his Enquiries hereinto. BUT however Authors differ upon this Head, several very odd Relations are to be met with in History of malignant and deadly Sicknesses from these Causes. That Story is very strange which is related by _Ammianus Marcellinus_,[19] and taken Notice of by _Cardan_ and _Riolanus_, that a most grievous Pestilence broke out in _Seleucia_, which, from thence to _Parthia_, _Greece_, and _Italy_, spread it self thro’ a great part of the World, from the Opening an ancient Vault in the Temple of _Apollo_, and that it raged with so much Fury, as to sweep away a third part of the Inhabitants of those Countries it visited. IT is needless to trouble the Reader with many Relations of the sudden and strange Effects of some Steams arising from Mines and Pits, which are generally termed by our Colliers _Damps_, because almost every Body has already been acquainted with such Accounts.