Dr. _Parsons_ took pains to find out the way of the motion of the earthquake, from the different position of people's beds; but from the contradictory answers given, he cou'd not obtain any satisfaction, as to that point. All this, and what was observ'd from _Northampton_, of the motion being thought by some, to be upward and downward; by others rather horizontal, or lateral: the counting the pulses, and the like, only points out to us the prodigious celerity, and the vibratory species of the motion of an earthquake. But far, very far is this from being owing to the tumultuous ebullition, the irregular hurry of subterraneous explosions. 12ly, How the atmosphere, and earth, are put into that electric and vibratory state, which prepares them to give, or receive the snap, and the shock, which we call an earthquake; what it is, that immediately produces it, we cannot say: any more than we can define, what is the cause of magnetism, or of gravitation; or how muscular motion is perform'd, or a thousand other secrets in nature. We seem to know, that the author of the world has disseminated ethereal fire, thro' all matter, by which these great operations are brought about. This is the subtil fluid of Sir _Isaac Newton_, pervading all things: the occult fire diffused thro' the universe, according to _Marsilius Ficinus_ the platonic philosopher, on the _Timeus_ of his master. All the Platonists insist on an occult fire passing thro', and agitating all substance, by its vigorous and expansive motion. Before them, _Hippocrates_ writes in the same sense, _I. de victûs ratione_, that this fire moves all in all. This ethereal fire is one of the four elements of the ancients. It lies latent, and dispersed thro' all the other three, and quiescent: till collected into a quantity, that over-balances the circumjacent; like the air crouded into a tempest: or till it is excited, by any proper motion.