In an age when electricity has been so much our entertainment, and our amazement; when we are become so well acquainted with its stupendous powers and properties, its velocity, and instantaneous operation through any given distance; when we see, upon a touch, or an approach, between a non-electric and an electrified body, what a wonderful vibration is produc'd! what a snap it gives! how an innocuous flame breaks forth! how violent a shock! Is it to be wonder'd at, that hither we turn our thoughts, for the solution of the prodigious appearance of an earthquake?
Here is at once an assemblage of all those properties and circumstances which we so often see in courses of electricity. Electricity may be call'd a sort of soul to matter, thought to be an ethereal fire pervading all things; and acting instantaneously, where, and as far as it is excited. 'Tis every body's observation, that there never was a winter, like the last past, in any one's memory, so extremely remarkable for warmth and driness, abounding with thunder and lightning, very uncommon in winter; coruscations in the air frequent, justly thought electrical by all philosophers; particularly, twice we had the extraordinary appearance of that called aurora australis, with colours altogether unusual; and this just before the first earthquake: All the while the wind constantly south and south-west, and that without rain, which is unusual with these winds.
This state of the atmosphere had continued five months before the first earthquake. Is it not hence reasonable to conclude, that the earth, especially in our region, must be brought into an unusual state of electricity; into that vibratory condition wherein electricity consists; and, consequently, nothing was wanting but the approach of a non-electric body, to produce that snap, and that shock, which we call an earthquake; a vibration of the superficies of the earth.
That the earth was in that vibratory and electric state we have further reason to conclude, from the very extraordinary forwardness of all the vegetable world with us. Every one knows, that, at the end of February, all sorts of garden-stuff, trees, fruits, and flowers, were as forward as in other years, by the middle of April. Conformable to which, experiments abundantly show, that electrifying of plants quickens their growth, equally as in animals it quickens the pulse. Nor will the unusual driness and warmth of the weather solely account for such a precipitate vegetation: because a necessary supply of rain was wanting, as in the natural Spring-season.
A very long dry frost will produce the same electrical state of the earth, as it equally favours electrical experiments. Thus, March 27, 1076, a frost from the 1st of November to the middle of April, a general earthquake in England succeeded. Matt. Paris. That of Oxford, 17th of September 1683, was after a frost. Jan. 4, 1680, An earthquake in Somersetshire: The air was very calm; a frosty night.
Mr. Flamsted concurs with us, in our first position, That earthquakes always happen in calm seasons. He adds, "That Keckerman, a learned author, who wrote on the subject, affirms, and backs it from the authority of Aristotle and Pliny."
The 8th of September 1601 was a very calm day but cloudy: And the Smyrna merchants observe the earthquakes there happen in calm, still weather. The remarkable clearness and calmness of the morning was observed in that of Oxford 17th of September 1683, and the air continued so for five or six days after: Therefore we may infer, that it is not impossible, what has been abundantly related, that some foreigners from Italy here in England, some from the West-Indies (in both which countries earthquakes are more frequent than with us) did seem to apprehend our first earthquakes from the apparent temper of the weather; and observations of this kind are as old as Aristotle. It is observed in Jamaica, when the air is extraordinary calm, an earthquake is always apprehended.
We had lately read at the Royal Society, a very curious discourse, from Mr. Franklin of Philadelphia, concerning thundergusts, lightning, the northern lights, and meteors. All which he rightly solves from the doctrine of electricity. For, if a cloud raised from the sea, which is a non-electric, happens to touch a cloud raised from exhalations of the land, when electrified, it must immediately cause thunder and lightning. The electrical fire flowing from the touch of perhaps a thousand miles compass of clouds, makes that appearance, which we call lightning. The snap which we hear in our electrical experiments, when re-echoed from cloud to cloud, the extent of the firmament, makes that affrightning sound of thunder.
From the same principle I infer, that, if a non-electric cloud discharges its contents upon any part of the earth, when in a high electrified state, an earthquake must necessarily ensue. The ship made upon the contact of many miles compass of solid earth is that horrible uncouth noise, which we hear upon an earthquake; and the shock is the earthquake itself.
In the relation received from Portsmouth, and the Isle of Wight, concerning the last shock there, on the 18th of March, the writer observes, the Day was warm and serene; but, upon a gentle shower falling in the evening, the earthquake came. Here we have reason to apprehend the electrified state of the earth, and the touch of the non-electric: which caused the earthquake.