Chapter I: Part 1

Transcriber Note: Text emphasis is denoted as _Italics_.

THE

PHILOSOPHY

OF

EARTHQUAKES,

Natural and Religious.

OR

An Inquiry into their Cause, and their
Purpose.

_O Vita philosophia dux, virtutum indagatrix, expultrixque vitii!_

Cicero.

By _WILLIAM STUKELEY_, M.D. Rector
of St. _George_'s, _Queen-Square_: Fellow of the
College of Physicians and Royal Society:

The SECOND EDITION.
To which is added, PART II. on the same Subject.

_LONDON_:
Printed for C. Corbet over-against St. _Dunstan_'s
Church, _Fleetstreet_.

MDCCL.

To the Reader.

_The substance of the philosophical part of this discourse was delivered at twice to the Royal Society, on_ March 15, _and_ 22: _The theological, in my own church. I could not refuse the solicitation of my friends, hearers in both places, to print it. I wish my intention, in the compliance, may any ways prove successful; to show, how vain, and unmeaning, are all our philosophical inquiries, when destitute of their true view; to lead us into the more engaging paths of religion. That, from speculation of material causes, we may become adepts in that wisdom which is from above. Otherwise, like_ Epicurus, _and the ancient heathen philosophers, we barter away our immortal part, for a curiosity, that amuses us to no good purpose. Mean are these objects of our senses to be accounted, in comparison of our spiritual natures, to which our principal regard is due! For we must rightly say with_ Job: Lo, these are parts of God's ways, but how little a portion is heard of him? and the thunder of his power, who can understand?

TO

_Martin Folkes_, Esq; LL.D.

President of the Royal Society.

_March 26, 1750._

When so great and unusual a _phenomenon_, as an earthquake, and that repeated, happens among us; it will naturally excite a serious reflection in everyone that is capable of thinking. And we cannot help considering it, both in a philosophical and a religious view. Any mind will take the alarm when we perceive a motion that affects the earth, that bears the whole city of _London_, and some miles round it. And at the same time while it gives us so sensible a shake, so gently sets us down again; without damage to any buildings, and without a life lost.

'Tis hard to say, which is the greater wonder. But alas in the works of nature, there are no degrees of great, and little; comparisons are incompatible. We indeed are more affected with what seems great in our own apprehensions: I would rather say, what is rare and unusual. An omnipotent power admits of no distinctions. And when prodigious effects are produc'd from causes imperceptible, it rightly claims our most serious attention, as well as wonder. Nor need we lose sight of the theological purpose of these amazing alarms; whilst we endeavor to find out the philosophy of them.

Among all the appearances of nature, which are the subject of the inquiries of the Royal Society, none more deserves the regard of a contemplative mind. And among the very numerous accounts received there, from all quarters, being only Observations upon the manner of it, and its extent: I judg'd, it became us to inquire into the _cause_ of so extraordinary a motion: of which we could not form a proper idea; had we not repeatedly seen, and felt it.

The moderns have not improv'd upon the opinions of the ancients, in this matter; any further than by the fancied analogy of some chymical experiments. But these chymical experiments, and all sorts of explosions by gun-powder, and the like, are to me a very unsatisfactory solution they are merely artificial compositions, which can have nothing similar in the bowels of the earth, and they produce their effects by violence, by rending and tearing, by a _solutio continui_. This is indeed too often the case of earthquakes, but _that_ is a partial degree, not at all equivalent to the compass of the shock; and is very far from being the constant concomitant of an earthquake. Quite the contrary. Innumerable such happen, when there is no breach of the surface; and of these three or four which we have now felt, nothing of it has appear'd. But the immensity of the vibration of the earth which shook every house in _London_, with impunity, and for twenty miles round, can never, in my apprehension, be owing to so unbridled a cause, as any subterraneous vapours, fermentations, rarefactions, and the like; the vulgar solution. Nor does the kind of motion, which I discern in an earthquake, in any sort agree with what we should expect from explosions.

In order then to proceed with some degree of certainty, in our inquiry after the cause of earthquakes, it will be useful, in the first place, to set in one view, the general appearances remarkable therein; the most usual concomitants: As we can collect them from our own observation, or from the relations and writings of others.

Circumstances.

I. That earthquakes always happen in calm seasons, in warm, dry, sultry weather; or after a dry, frosty air.

II. That they are felt at sea, as well as land, even in the main ocean; and at that time, the sea is calm.

III. That earthquakes differ very much in magnitude. Some shake a very large tract of country, at the same instant of time; nay, sometime extend to very many countries, separated by mountains, seas, lakes, the ocean.

IV. That earthquakes differ very much in the quantity, of their vibratory motion: Whence in some, tho' largely extended, they are innocuous; in others, both small and great, they lay all in ruin and destruction.

V. That a hollow, thundering, unusual noise accompanies them, or rather seems to preceed the shock; which rolls in the air like the noise of cannon.

VI. That they are felt more sensibly in the upper story of houses than in the lower.

VII. That the shock is more violent upon more solid buildings, churches, castles, and stone-houses, than upon those of slighter materials.

VIII. That many people find themselves sick at stomach, with headake, and pains in their joints, and the like, which sometime lasts for the day after, or longer.

IX. That earthquakes generally happen to great towns, and cities, and more particularly to those that are situate on the sea.

X. That earthquakes do not cause any damage to springs and fountains; but the water in wells becomes foul for a short time.

XI. That they are more frequent in the neighboring countries of a vulcano.

This last circumstance, in my opinion, has led all inquirers in this question, out of the true path; therefore I propose in the ensuing paper.

I. To shew what it is not; the insufficiency of the vulgar opinion, of subterraneous fires and vapours.

II. To shew what it is in reality, as it appears to me.

III. I shall conclude with the moral use we ought to make of these prodigies of nature.

I. The struggles of subterraneous winds and fires, that should heave up the ground like animal convulsions, seem to me impossible: Their powers, and manner of acting (if such there be) is quite incapable of producing the appearance of an earthquake. That these should operate instantaneously, in one minute, thro' a circle of 30 or 40 miles diameter, or more, I could not conceive. Nor that there should be any possible, much less ready passage thro' the solid earth, for such nimble agents, as every one is apt to imagine that speak of this appearance; without sufficiently reflecting on the insuperable difficulties in that _hypothesis_.

We cannot pretend to deny that there may be such vapours, and fermentations, inflammable substances, and actual fires, in the bowels of the earth; and that there may be some caverns under-ground, as well as 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 all the way, in the proportion of one yard in five, 'till we came under the bed of the very ocean, where ships were sailing over our heads. This was at Sir _James Lowther_'s coal-pit, at _Whitehaven_. We were at this time deeper under ground by the perpendicular, than any part of the ocean, between _England_ and _Ireland_.

We never hear, from the many hundreds of thousands of workmen in this kind, at _Newcastle_, _Nottinghamshire_, _Yorkshire_, _Derbyshire_, _Staffordshire_, _Somersetshire_, and _Wales_: from the infinite numbers of workmen in the mines of lead, tin, and the like, of the cavernous state of the earth, so as to give any colour for this _hypothesis_ of earthquakes. The earth is generally of solid rock; in which there must be now, and then, some clefts, and vacuities, small in compass, as naturally so many heterogeneous _strata_ of the earth consolidate together. But there can be no imagination of vapours breaking through, uniting, traversing so suddenly, a large space of earth, so as to produce those earthquakes, we have seen, and felt; much less such as we read of. The workmen in all sorts of mines confess by their hard labor, that the earth is not cavernous; nor are there mines of sulphur, nitre, and the like inflammable materials in _England_. Or if there were, could they burn, and cause convulsions of the earth, without proper cavities, pipes, and conveyances of air; as vulcano's, and coal-pits, when set on fire. But even from these coal-pits, when fired, do we ever find any thing like an earthquake produced. Nor do we find earthquakes frequent in those countries, that abound with coal-mines, as certainly would be the case, if that _hypothesis_ was just. How easy would it be, on the slightest occasion for earthquakes to happen in the countries abounding with coal-mines, which are so full of artificial cavities communicating with one another, for many miles together: The very thing supposed, by those who hold the old opinion, of vapours traversing the earth for that purpose.

In the coal-pits, some small natural cavities now and then are found; which when opened, send forth a pestiferous vapor and a fire-damp which runs for a long time together. And tho' there are many substances that may generate air, within the bowels of the earth; yet these matters are infinitely unable to produce an earthquake: Never would have force to open a passage for themselves thro' the solid rock, of perhaps many hundred feet in thickness. Nor did we observe in these last earthquakes any fire, vapour, smoke, or smell, any kind of eruption, in the least; as must certainly have been, in so great a struggle of the superfice, as affected a circle of so large a diameter. Were there such, we could scarce hope any otherwise, than that they would be too sensibly felt; to the destruction of many thousands, by their pestiferous qualities.

Indeed this consideration alone, of the extent of that surface, is sufficient to overthrow any supposition, of earthquakes being chiefly owing to subterraneous vapours: They cannot momentarily fly under so large a tract of ground, if they were near the outward shell of the earth. They could not do it without breaking ground, and discovering themselves to the sight, or smell; and that for a long time after. It cannot possibly be imagin'd, they could have so immense a force, as to lift up the city of _London_, and never be perceived by our organs, and outward senses. We have frequent accounts of a little fire-ball bursting in the air, at a distance; yet it instantly propagates a sulphureous smell around.

If the movement of a superficies of 30 miles diameter was owing to fumes, and vapours; we ought reasonably to find some great discharges of them, belching out smoke and fire, for a long time after, like vulcano's, and coal-pits fir'd. The operation of the shock ought to be of hours continuance, not instantaneous; and the evaporation of so vast a quantity of matter, must darken the whole region of the air for a long time after; or require a long time, if gradually it discharges itself. We see how immense a volume of smoke is produc'd 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 anything 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 meet with springs, and currents of water, every where. Often they ruin, and divert springs another way, only by digging into the earth for foxes, and the like. Whenever they dig for wells, in any kind of earth, they commonly find springs. The colliers, and workers of mines, are oblig'd to drain the waters off with very great expence.

These are circumstances not favorable to subterraneous fires being in the earth in abundance; much less to their being the cause of earthquakes. And further, we cannot possibly think of earthquakes doing their work that way, without absolutely ruining the whole system of springs, and fountains, throughout the whole country, where they pass. But all this is quite contrary to fact; even where an earthquake has been repeatedly. For an instance from home.

On _Wednesday, April_ 6, 1580, about six in the evening, just such another earthquake was felt in _London_ and around it, as these two we have seen. Another exactly similar 1692. In all these four, no houses thrown down, no springs disturb'd thereby, no sensible eruptions nor smells.

These considerations I apply only to this little inconsiderable space, of a circle 30 miles diameter; as with us. But what is that to the earthquakes we read of in history? In the year of our Lord 17, no less than thirteen great and noble cities in _Asia minor_, were destroyed in one night. _Tacitus_, _Pliny_, and many other authors mention it. The fact is so notorious, that some persons here present, have seen a vast block of white marble now standing near _Naples_; being the pedestal of a coloss statue of _Tiberius_ the emperor; having carv'd on it the _genius's_, or pictures of all those cities, with their names. The accurate _Bulifon_ and others have wrote treatises upon it. These cities were rebuilt by that emperor. But without going so far, we may see another evidence of it, a coin of that emperor struck upon the occasion, with this inscription,

CIVITATIBUS ASIAE RESTITUTIS.

I have one of them, in large brass, which was found at _Colchester_.

The compass of this earthquake may be reckon'd to take up 300 miles diameter, as a circle. Now, we cannot conceive, how any subterraneous vapour can produce such an effect, as instantaneously to demolish all these cities; and that such an accident should never happen after. That the whole country of _Asia minor_ should not at the same time be destroy'd, its mountains be renversed, its fountains, springs, and rivers broken up and ruin'd for ever. Instead whereof we find nothing suffered, but those cities; no kind of alteration in the surface of the country; it remains the same as it were in the beginning of time. In 1586 an earthquake in _Peru_, that extended 900 miles.

From these considerations, I cannot persuade myself, to enter into the opinion of vapours, and eruptions being the cause sought for; and, after we have treated the argument in a superficial view, we must go a little deeper.

If we would consider things like philosophers, let us propose to ourselves this problem: Where is the power to be plac'd, that is requir'd to move a surface of earth 30 miles in diameter?

To answer this, consult the ingineers, and those that make mines in the sieges of towns; they will acquaint us, that the effect of mines is produced in form of an inverted cone. And that a diameter of 30 miles, in the base, will require an _axis_ of 15 or 20 miles to operate upon that base, so as to shake it, at least. Now the vapours, or whatever power we propose to operate, according to the foregoing requisite, in order to form the appearance of an earthquake, must be 15 or 20 miles deep in the earth. But what mind can conceive, that any natural power is able to move an inverted cone of solid earth, whose base is 30 miles diameter, whose axis 20? or was it possible; would not the whole texture of that body of earth be quite disturb'd and shatter'd, especially in regard to its springs and fountains? but nothing like this is ever found to be the consequence of an earthquake, tho' fatal to cities.

Apply this reasoning to the earthquake of _Asia minor_, and this vigorous principle at the _apex_ of the cone must lie, at least, 200 Miles deep in the ground. Enough to show the absurdity of any moving power plac'd under the Earth! A cone of 300 miles diameter at base, 200 miles _axis_: I dare be bold to say, that all the gun-powder made since its invention, if put together and fired, would not be able to move it; how much less pent up vapours? what must we say of a circle of 900 miles diameter?

But, could that be admitted as possible, would any one be persuaded, that such a subterraneous tumult, of so vast an extent, will be no ways injurious to the internal system of springs and fountains, and that this shall often be repeated without the least damage? We may as well imagine, that we can stab a man 100 times and never touch vein or artery.

Since I gave in my two papers to the Royal Society, a letter of Mr. _Flamsted_'s has been printed, which abundantly confirms my sentiments. The whole drift of it is, to show how invalid is the vulgar idea conceiv'd, of earthquakes arising from subterraneous vapours and eruptions: That the earth itself is not moved to any depth, and that the shock must arise from the atmosphere. The circumstances which he has judiciously collected, are extremely agreeable to mine; many of them the very same, strongly confirming my _hypothesis_: And had that great man known the properties of electricity, which we are now masters of, he would have prevented me in this affair.

"Considering (says he) what variety of substances, sand, gravel, stones, rock, minerals, clay, and mold, our earth is compounded of, and how little nitre, or explosive matter, a large quantity thereof will afford; I cannot think, where we can find matter enough to move so vast a bulk of earth, as all the South parts of _England_, all the _Netherlands_, with part of _Germany_, all _France_, and perhaps _Italy_, (which were shock'd at once the 8th of _September_ last 1692;) or part of _Asia_, and near all _Europe_, which trembled together the same day, 91 years before.

"But, allowing there may have been sufficient matter prepared for these purposes, I can hardly think, there are continued cavities, at any reasonable depth, all under _Europe_, wherein an explosion being made, might shake the whole at once, and yet make no clefts, or separations, in those parts where the minerals and mountainous rocks part from the light mold and clay. If an hundred barrels of gun-powder could be fixed in some cave, a thousand yards under ground; allowing the force of the explosion sufficient to raise all the weight of earth incumbent on the cavern; it would certainly break the loose mold from any large solid rock we may conceive adjacent, and leave at least some clefts behind it. But we seldom or never hear of such clefts, made in such places, when earthquakes happen."

Again, he writes thus: "I cannot apprehend, (if all earthquakes must be made by explosions in subterraneous caverns) why sometimes a large country, or whole continent, should be thereby shook all at once; why there should be no eruptions in the neighbourhood?"

From all circumstances consider'd, he concludes, that the abstruse, effective cause of them comes from the air; and that a calm is necessary before an earthquake. And these two particulars are likewise Dr. _Hales_'s positions: "The earth-lightning, as he calls it, is first kindled on the surface, and not at great depths, as has been thought; whose explosion is the immediate cause of an earthquake. He says, long, dry, hot seasons, are usually the preparatory forerunners of earthquakes." From all these considerations I conclude; earthquakes are not caus'd by subterraneous vapors.

II. We are to inquire, what is the cause of earthquakes.

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.

The learned Dr. _Childrey_ observes, treating on this subject, that earthquakes happen upon rain; a sudden shower of rain in the time of a great drought.

'Tis objected, that, if this was the case, nothing would be more frequent than earthquakes; but these two circumstances concurring, a shower and dry weather, must not necessarily cause it, any more than touching a tube before it is electrified causes a snap. The earth must be in a proper electrified state to produce it; and electricity has its fits; is remitted, intended, ceased and recommenced. It has its bounds. All causes must concur. And now, with us, all necessary causes did so apparently. Tho' a shower of rain falling upon the earth when electrified, may cause an earthquake, yet too much rain before, will prevent that state of electricity, necessary.

The day before the catastrophe of _Port-Royal_, the weather was remarkably serene and clear. In that most dreadful earthquake, 1692, of _Sicily_, where 54 cities and towns, beside a great number of villages were destroy'd; but especially the whole city of _Catania_: It was preceded by a most agreeable, serene and warm season, which was the more observable on account of its being unusual at that time of the year.

I have been inform'd, that in the morning of both earthquakes last past with us, the air was serene and calm; on the morning before that 8th of _February_, the air was observ'd to be remarkably calm; and that a little before, a black cloud appear'd over great part of the horizon. Dr. _Hales_, in his relation, says, the Centinels in _St. James's Park_, and others who were abroad in the morning of the last earthquake, observ'd a large black cloud, and some coruscations, just before the shock, and that it was very calm weather: And that, in the history of earthquakes, they generally begin in calm weather, with a black cloud.

This observation precludes the suspicion of earthquakes arising from tumults and commotions in the upper, or under region of the air. The remarkable clearness of the air before earthquakes, observ'd by all, shows evidently how free it is from vapours and the like.

Agreeable to our _fifth_ position, Mr. _Flamsted_ writes, "A hollow noise in the air always precedes an earthquake, so near that it rather seems to accompany them. He refers us to _Philosophical Transactions_, N^o 151. p. 311. The noise was heard by many that liv'd in the out-streets, and alleys of _London_, remote from the noise and tumult of the greater streets."

This he speaks of that felt in _London_ 1692; but now the whole city heard the noise, on both these earthquakes of ours.

The gardener, who gave a relation to the Royal Society of what he observed in the _Temple_-garden, took notice, that first he heard the most dreadful noise imaginable, which he thought to be a great discharge of ship-guns, on the river: and that the noise rolled from the water-side towards _Temple-bar_, rather before the nodding of the houses.

The gentleman who observed it about _Hartingfordbury_, says, the noise preceded the shock. And this is a common observation, which at once both strengthens our opinion of electricity, and confutes that of subterraneous vapours; for, in the latter case, the concussion must precede the noise.

Agreeable to out _second_ position, Mr. _Flamsted_ writes, "That earthquakes are felt at sea, equally as on land. Our merchants say, that, tho' the water in the bay of _Smyrna_ lies level and smooth as a pond; yet ships riding there feel the shocks very sensibly, but in a very different manner from the houses at land: For they heave not, but tremble; their masts shiver, as if they would fall to pieces and their guns start in their carriages, though the surface of the sea lies all the time calm and unmoved." In Dr. _Hook_'s _Philosophical Collections_, N^o 6. p. 185. we are told, "That a ship felt a shock in the main ocean; that the passengers, who had been asleep in their cabins, came upon deck in a fright, fearing the ship had struck upon some rock; but, on heaving the lead, found themselves out of soundings."

All this is extremely agreeable to our assumption. The water receives the electrical touch, and vibratory intestine motion of its parts, as well as land. And the impression may be made solely on the writer a non-electric, by the touch of an electric fire-ball, or the like; and that seems to have been often the care. The proper vibratory motion is impress'd on the water without ruffling its surface; and so communicated to all the parts of the ship, gives the sense of a shock to the bottom, the shivering to the mast, and the rest of the symptoms: which sufficiently proclaim the cause of it to be an electrical impression upon the water. The president mentioned a relation of a waterman, that felt it in his boat upon the river; he thought it like a great thump at the bottom of the boat. And so the ships at sea fancy, they strike upon a rock.

This makes us apprehend, the reason of the fishes leaping up out of the canal in _Southwark_, of which we had an account. So in that of _Oxford_, 1683, one fishing in the _Charwell_ felt his boat tremble under him, and the lesser fishes seem'd affrighted by an unusual skipping. That electricity is the cause sought for, seems deducible from this consideration. Several writers on earthquakes assimilate these vibrations of the earth to those of a musical string. Experiments have shown, that fishes in water may be killed by the particular tone of a musical string; and 'tis known, that electricity will kill animals. They assuredly felt the vibratory motion in the water, which they were absolutely strangers to before. No doubt it made them sick; as those of weak nerves on land. And this circumstance alone precludes any suspicion of subterraneous fires under the ocean. Or, if we were to admit of it, would the boiling of the water exhibit any appearance, like what we are speaking of, either to the water, or to the ship?

Mr. _Flamsted_ likewise concurs in our _eighth_ position, "That many people found themselves suddenly sick at stomach, and their heads dizzy and light; so that those that had formerly fits of apoplexies, dreaded their return; particularly, one gentleman, a surgeon, feeling himself so affected, and fearing a return of his apoplexy, resolved to be let blood, without suspecting the earthquake."

After these two shocks which we felt, many people had pains in their joints and back, as after electrifying; many had sickness, headakes, hysteric and nervous disorders, and colicks, for the whole day after, and some much longer, especially people of weak nerves, weak constitutions; some women miscarry'd upon it; to some it has prov'd fatal.

To this we must attribute, that relation we had, of the dog lying asleep before the fire; but upon the earthquake, he suddenly rose up, run about the room, whining, and endeavouring to get out.

Any solid matter is capable of being put into a state or electricity, such as iron guns; and the more so, by reason of their solidity. And in proportion to it, is the greatness of the snap, and of the shock; and a kind of lambent flame issues from the point of contact; and likewise somewhat of a sulphureous smell: So that if both flame and smell were discernible in an earthquake; 'tis to be found, without going to the bowels of the earth.

Dr. _Hales_ mentions, that solid bodies are the best conductors of aereal lightning; whence oaks are rent, and iron melted. And in our earthquakes in _London_, the loudest noise was heard near such large stone buildings, as churches, with lofty steeples. From the top of these we must apprehend, that the electrical explosion goes off into the open air; as in our experiments, from the point of swords, and the like.

The electrical shock is proportionate to the solid electrified, agreeable to our _seventh_ position. This fully accounts for earthquakes in general, and for many in particular. What can be imagin'd greater than a shock of the body of the earth? 'Tis greater, or less in proportion to the state of electrification. And now we can account for several appearances. In the first earthquake, the Lord Chancellor, Masters in Chancery, and several Judges, were sitting in _Westminster-Hall_, with their backs to the wall of the upper-end, which is of a vast thickness. They all relate the severity of the shock, from the wall seeming to push towards them with great violence.

And thus in the earthquake of 1692, _Deal_ castle is one of them built by _Henry_ VIII. the walls are of immense thickness, and strength; yet they shook so sensibly, that the people living in it, expected it was falling on their heads. And this is the case in all earthquakes: the more substantial the building, the more violent is the shock: exactly the mode of electrical vibration. And this Dr. _Hales_ takes notice of and others; that an earthquake shatters rocks of marble, more easily than the _strata_ of sand, earth, or gravel. In the earthquake here of 1692, a great cliff fell down near _Dover_; and part of _Saltwood_-castle wall.

'Tis from hence we account for that observation, that when we electrify any person; upon a touch, the pain and blow of the shock is felt at the joints, the wrist, elbow, and shoulder, for instance, more than in the intermediate parts; because _there_ is the greatest quantity of solid.

At the same time, that the force of electricity in solids, is as the quantity of matter: we see most evidently, by innumerable experiments, that water is equally assistant in strengthening, and conveying the force of electricity; and _that_ in proportion too to its quantity. And hence is to be deduc'd the reason of my observation; that the most frequent and dreadful earthquakes have fallen upon maritime places. And I find the same is taken notice of in some degree, by _Acosta_, by _Dolittle_, who wrote on that in 1692, and others.

In the dreadful catastrophe at _Port-Royal_ then, 'tis notorious, that its violence was chiefly near the sea. So _Lima_ could not suffer without its port of _Callao_. Even in those so lately felt by us, they were sensibly more violent towards the river, than farther from it.

In that earthquake which was felt in _England_, in the year 1692, (which was very much like these with us) there were no houses thrown down, nor persons kill'd: but it reach'd more particularly _Sheerness_, _Sandwich_, _Deal_, _Dover_, _Portsmouth_, and the maritime parts of _Holland_, _Flanders_, and _Normandy_.

In this that happened on _Sunday_ the 18th of _March_ last, at _Bath_; it was felt particularly and strongly at _Portsmouth_, seven miles above and below it, on the sea-side; all round the isle of _Wight_, at _Southampton_, the sea-coast of _Selsey_, south of _Chichester_, _Arundel_, and the whole coast of _Sussex_, without going up the land; and across the sea to the islands of _Jersey_ and _Guernsey_.

On _Monday_ night, the 2d of this instant _April_, 1750, at ten o'clock, at _Leverpool_, a shock of an earthquake. And felt in several other places in the neighbourhood; but particularly at _Chester_, and _Warington_.

If we look into ancient history, we find 197 years before Christ, an earthquake shook terribly the isle of _Rhodes_, damag'd many cities: and some quite swallow'd up.

Seventeen years before Christ, many cities in the isle of _Cyprus_ destroy'd.

Six years before Christ, the isle of _Coos_ vehemently afflicted.

During the _Peloponnesian_ war among the _Greeks_, the isle of _Delos_ shaken, and the most beautiful temple of _Apollo_ thrown down.

Soon after, the city of _Lacedæmon_ totally destroy'd.

_A. D._ 79. Three cities in _Cyprus_ overthrown.

_A. D._ 82. The city of _Smyrna_ ruined.

In the time of _Valens_ the emperor, a terrible earthquake in _Crete_, whereby 100 cities were destroy'd.

_Feb._ 13, 1247, An earthquake, chiefly felt in the _Thames_. _Matt. Paris._

_May_, 1382, A general earthquake, which did much mischief; the _Friday_ following one less; the _Saturday_ following, one felt mostly by water. _Henry de Knyhton._ _Holinshed._

_A. D._ 1456, In the city of _Naples_, 40,000 people lost.

_Constantinople_ has often suffer'd; particularly in 1509, 13,000 people overwhelm'd.

1531, At _Lisbon_, 1400 houses thrown down; as many shatter'd.

_April_, 1690, The _Leeward-Islands_, _Montserat_, _Nevis_, and _Antigua_: At _Martinico_, and the _French_ islands, at St. _Lucia_, &c. a violent earthquake.

_Dec._ 8, 1703, An earthquake at _Hull_, a perfect calm.

1702, At _Stroution_, in _Argyleshire_, which extended all along the west coast of _Great-Britain_; but to no breadth on land.

_Oct._ 25, 1734, At _Havant_, in _Sussex_, considerable, the air perfectly calm.

But instances enough, to show what I aim'd at, that maritime places are most subject; which is a strong argument in favour of electricity; when both the solid of the earth, and the quantity of the water concur, to make the shock; exactly as in electrical experiments; when the bottle of water is held in the hand.

Thus when our mind is discharged of the prejudices of former notions, we discern, that every appearance favours the principle we go upon. That, agreeable to Mr. _Flamsted_, subterraneous explosions, could they pervade, and traverse the earth at pleasure, must at last burst, and disperse every thing in their way. Yet 'tis not possible for us to imagine, such a kind of vibration should follow, either by sea or land, as that we are treating of. But electricity compleatly answers it. This accounts for that superficial movement of the earth, that universal instantaneous shock, which made every house in _London_ to tremble, none to fall: That quivering, tremulous, horizontal vibration, highly different from any motion we must conceive, to be produc'd from subterraneous evaporations. Hence authors tell us, _Dec._ 30, 1739, describing an earthquake in the west-riding of _Yorkshire_: It seem'd as if the earth mov'd backward and forward horizontally; a quivering, with reciprocal vibrations.

Mr. _Flamsted_ rightly accounts the motion of earthquakes to be undulatory; and by being continued, causes a like motion to a great distance. As when you strike a long stretch'd string of wire at one end, the motion is immediately continued to the other. So far he entered into the nature of electricity.

Tho' he be in the right, thinking the cause comes from the air, yet what follows, contradicts his own hypothesis. For if a calm be necessary before an earthquake; then 'tis not produc'd by any turbulence in the air. Nor can we imagine that any aerial commotion, tho' it may shake windows, chimneys, and the like, shall reach 500 miles distance, split the solid earth, destroy whole cities, and cause those dire desolations we hear of.

Mr. _Flamsted_ mentions a circumstance, that the earthquake here in 1692, was not felt in the north of _England_, nor in all _Scotland_: for rain fell that day in both. We may very readily conceive, the earth there was not in an electrified state; and the rain would sufficiently prevent it. We hence understand, how the southern regions should be more subject to them, than our northern; where the warmth, and driness of the air, so necessary to electricity, is more frequent than with us.

From electric vibration only can we account for our _tenth_ position, of springs, and fountains being no ways damag'd by earthquakes: The motion goes no deeper into the earth, than the force and quantity of the shock reaches; which generally is not far; yet it proceeds lower down when the ready passage of a well offers, and _there_ affects the water contained in it; puts it into an intestine vibration, as to foul it, and raise mud from the bottom.

It may seem difficult to conceive, how a large portion of the earth's surface should be thus capable of electrification. This difficulty is lessened by reflecting on the nature of electricity, and of the electrical, ethereal fluid pervading all things: how it is excited by the little motion of a small revolving glass globe. By this we electrify the most solid bodies, to the greatest distance, and with a velocity equal to that of lightning.

Dr. _Hales_ observes, that the usual explosion of the cannon on great days, in St. _James_'s-_Park_, is observ'd to electrify the glass, in the windows of the Treasury.

We must conceive, that when the electric shock is communicated to one part of the earth, it extends itself proportionably to the force of the shock, and to the quantity of electrified surface; and to the quality of the matter more or less susceptible of it, more or less apt to propagate it.

Set 1000 men in a row; let every one communicate with those next him by an iron-wire held in their hands: on an electrical shock they all feel it alike, at the same instant; and this gives us a very good idea of the earthquake.

When the earth is broken up in any large degree, 'tis by the sea-side; where sometimes on a bold shore, whole streets tumble into the sea, or into the gaping earth, now falling toward the sea. Sometimes on a flat and sandy shore, whole streets are rolled along the level into the sea.

I am not sensible of any real objection against our _hypothesis_, but this, being the _eleventh_ of my positions, or circumstances. It seems true, that earthquakes are more frequent in _Italy_, near _Vesuvius_, and by _Ætna_, in _Sicily_. And the cause seems apparently owing to these vulcano's. At first sight, every one would think so, but not from the true reason. This has given the great prejudice to the judgments of the curious, even at this day. But consider the matter impartially, and it will appear, so far from being a strong argument in favour of subterraneous eruptions, that it ought to be esteem'd a convincing proof to the contrary, and most cogent in favour of my principle. In strictest logic, there is no inference to be made from particulars to generals. Quite the contrary. We have but these two or three vulcano's on one quarter of the globe, and two of them toward the warmer climate of it; whereas earthquakes are innumerable, especially in those of a warmer clime. That there are no vulcano's, no discharges of fire and smoke for a continuance, and abundance, after earthquakes; no suspicion of it either from sight or smell, as we know by innumerable examples, as well as in our own country, and experience: is demonstration, that this is not the cause. If the vulcano's were the real cause of earthquakes, we ought assuredly to expect, that in the countries thereabouts, the earthquakes ought to be far more extensive than those in other countries, where are no vulcano's; but this is altogether contrary to experience. For, as the celebrated naturalist _Buffon_ observes, such are not extensive, as are near _Ætna_ and _Vesuvius_. He further adds: _Histoire naturelle_, tom. I. p. 508. speaking, among many others, of a _vulcano_ in the island of _Ternate_, he remarks, "That this burning gulph is less agitated when the air is calm, and the season mild, than in storms and hurricanes;" and says, "This confirms what I have said in my foregoing discourse, and seems evidently to prove, that the fire which makes _vulcano's_ comes not from the bottom of mountains, but from the tops, or at least from a very little depth; and that the hearth (or floor) of the fire is not far from the summit of the _vulcano's_; for, if this was not the case, great winds could not contribute to their conflagration." And this, in general, is a corroborative proof of my whole hypothesis. For there can be no great fire in the earth, where there is no great conveyance of air.

We have one vulcano in the cold region of _Iceland_, and there is sometimes an earthquake there; but, in the countries of that northern latitude, and those of lesser, 'tis obvious in all history, that earthquakes are less frequent than in the more southern. Therefore 'tis easy, and very natural to conclude, from all considerations weighed together, that these vulcano's help to put the earth about them, into that vibratory state and condition of electricity, which is the requisite in my _hypothesis_, and by that means only, promote a frequency of earthquakes there.

I have only one circumstance to add, which may seem not inconsiderable; probably perceived by many, tho' not taken notice of. For a whole week before the first earthquake, the partition wainscot of my house (between the forward and backward rooms) made an odd kind of tremulous, crackling noise continually, as if the wainscot would split; or as if some damage was apprehended to the house. This was observ'd by the family, with a good deal of concern. _That_ in the chamber crackled more than that below. We never perceiv'd it before, nor since; and apparently, it shows the vibratory state of the surface of the earth, at that time.

But whether our conjectures upon this important subject be well founded or no, it certainly becomes a christian philosopher, whilst he is investigating material causes, to look up, and regard the moral use of them. For in reality, every thing, the whole world, was ultimately for that purpose made. When we see such a kind of spirituality impress'd on mere matter, as this amazing property of electricity, it should kindle in us a high ambition of asserting, and exerting the infinitely superior value, and powers, and excellency of the spiritual part of us, destin'd to an immortal duration. And of all the great and public calamities, which affect us mortals, earthquakes claim the first title to the name of warnings and judgments. None so proper to threaten, or to execute vengeance upon a guilty people. Nor has any other, those annexed terrors, so much of the unusual, the unavoidable, the sudden and the horrible apprehension of being crush'd to death, or buried alive. And when in our own sight, these rare and extraordinary _phænomena_ appear, it cannot but be a lesson to us, to do our duty toward that great Being, who, by a drop of water, can produce effects so prodigious.

That earthquakes proclaim themselves to mankind in this light, is further deducible from this observation, the _ninth_ in our recapitulation of circumstances; that they are peculiarly directed to great cities, and maritime towns, those nurseries of wealth, luxury, and of all the evils naturally flowing therefrom. It would be childish to rehearse from old history, or modern, a proof of it. We have no other notices of them. Look upon these two shocks we have here felt. We own that _Hampsted-heath_, and _Finchley-forest_, and _Kennington-common_ were affected with it; yet it is notorious, that _London_ was the center, the place to which the finger of God was pointed.

And this leads us in the _third_ place, to consider the moral use and purpose of these _magnalia naturæ_, and prodigies of the agency of material causes. For nothing sure, but an electrical shock, and that from a divine hand, could have been so well adjusted, as twice, nay four times, so sensibly to shake every house in _London_, and not throw one down. This duty we will endeavour to execute, from the words of that great man, king _David_.

PSALM xviii. 7.

_Then the earth shook, and trembled; the foundations also of the
hills moved, and were shaken; because he was wroth._

This Psalm is a triumphal song, which _David_ deliver'd publickly before God, in thankful remembrance of the great mercies he had receiv'd; being firmly established on his throne: and all his enemies, foreign or domestick, subdued.

He does not attribute this happy situation of his affairs to his own prudence and courage; but, like a consummate politician, absolutely to the mediation of the divine providence. He draws up a most grand and magnificent description of the advent of the deity, such as words never before expressed. All the heathen pictures of the appearance of their gods, are cold and lame, compar'd to this; which is deservedly so much admir'd by all criticks that have any taste for religion, as well as language.

This verse, in our text, is the first movement in the scene, which was to represent the appearance of _Jehovah_, without whose interposition _David_ hoped for nothing fortunate. After describing all the pomp of light, and darkness, celestial; hailstones, thunder, lightning, and the like instances of majesty and terror, in the skies; he still keeps his eye on the ground, and concludes with the earthquake, where he began.

_Then the channels of waters were seen; and the foundations of the earth were discovered; at thy rebuke, O Lord; at the blast of the breath of thy nostrils._

Our holy psalmist, at other times, has exhibited the same images, in different coloring; as a great master varies his works, to strike out all the beauties.

Psal. lxviii. 7. _O God, when thou wentest forth before thy people; when thou didst march thro' the wilderness; the earth shook, the heavens also dropped, at the presence of God. Even Sinai itself was moved, at the presence of God; the God of Israel._

By this he means, the giving the law. _Exod._ xix. 8. _And mount Sinai was altogether on a smoke; because the Lord descended on it in fire: and the smoke ascended as the smoke of a furnace, and the whole mount quaked greatly._