In the second earthquake, not only this country was affected again, but likewise a much larger space of the same sort of fenny ground, rather worse than the former: all Donnington-fen, Deeping-fen, Croyland-fen, Thorney-fen, Whitlesea-fen, Bedford level, and the whole extent of Ely-fen, under various denominations. This country, under the turf, abounds with subterraneous timber of all sorts; fir, oak, and brush-wood: and stags horns. Now and then they find a quantity of hazel nuts, crouded together on an heap. I have some of them. This is a matter common to all boggy ground over the whole globe, Such things are the ruins of the antediluvian world, washed down from the high country where they grew, were here lodg'd upon the subsiding of the waters, and by time are o'ergrown with the present turf. They that seek for any other solution of this affair, than the universal Noachian deluge, want to account for a general effect, by a partial cause: and shut their eyes, both to the plain history of this matter; and to the infinite, notorious demonstrations of it, from fossil appearances.
5ly, All this country, tho' underneath 'tis a watry bog, yet thro' this whole summer, and autumnal season (as they can have no natural springs in such a level) the drought has been so great on the superficies, that the inhabitants were oblig'd every day, to drive their cattle several miles, for watering. The drought was greater, than has been known in the memory of any one living. This shows how fit the dry surface was, for an electrical vibration. And we learn from hence, this important particular, that it reaches but very little below the earth's surface.
Mr. Johnson, in another letter which he wrote to me concerning the second earthquake observ'd at Spalding; says upon this occasion, he was obliged to scour his canal, and deepen it: that they came to a white, quicksand; which afforded to all the neighbourhood, excellent water in plenty.
In the gravelly soil of London; and where the two shocks were felt by us, in the beginning of the year; we know, there is not a house in the whole extent of this vast city, and all around it, but a spring of water is ready, upon digging a well, Whence we have much reason to believe, that the interior of the earth, is like a sponge soak'd in water. So that the only dry part is the superficies, which is the object, and the subject of that electric vibration; wherein, according to my sentiments, an earthquake consists.
This shews the mistake of the ancients, who fancying that earthquakes proceeded from subterraneous eruptions, built their prodigious temple of Diana at Ephesus, upon a boggy ground, to prevent such a disaster, The marshy part of Lincolnshire, being my native country, the adjacent fen, together with that in the isle of Ely, I have been perfectly acquainted with; from one end to the other, ever since I knew any thing. This vast extent of fenny level, from near Cambridge in the south, to near Horncastle in the north, is 70 miles in length. And when I perceiv'd, that it was, in whole, or in part, shaken by both the last earthquakes: I could not but see, that it was no less than a demonstration against the old notion of their cause.
6ly, Earthquakes are truly most violent, in a rocky country: because the shock is proportionate to the solidity of the matter electrify'd. So that rocks, cliffs, quarries, old castle walls, and strong buildings, are most obnoxious to the concussion. The isle of Cerigo was more liable, and more rudely handled by the late earthquake; both because it was an isle, and because it was rocky. So we must say of the late earthquake in Switzerland, that split the mountain, and the old castle wall. Whence Mr. Johnson in his second letter, says, it cracked a very strong brick-house in Gosberton by Spalding. Dr. Doderidge observes from Northampton that Dr. Stonehouse's dwelling being a very strong one, was most sensibly shaken. And throughout the whole compass of this great earthquake, we find, both the noise, the shock, and the terror was greatest at the churches, whose walls and bulk made more resistance than houses. And generally speaking, the churches throughout this whole extent have very fair, and large towers, and very many remarkable spires all of good stone, which no doubt quiver'd very much at top, if we could have discern'd it. This same vibration impressed on the water, meeting with the solid of the bottom of ships, and lighters, gives that thump felt thereon; just as in common electrifying, we feel the stroke upon the joints of our limbs chiefly. Yet of the millions of ordinary houses, over which it passed, not one fell. A consideration which sufficiently points out to us, what sort of a motion this was not, what sort of a motion it was, and whence deriv'd; not a convulsion of the bowels of the earth, but an uniform vibration or undulation of its surface, aptly thought like that of a musical string: or what we put a drinking glass into, by rubbing one's finger over the edge; which yet brought to a certain pitch, breaks the glass; undoubtedly an electric repulsion of parts. And from this remarkable similarity in the appearance of earthquakes we gather an invincible argument against the old opinion of their cause; for the tumult of subterraneous eruptions can have no possible place herein.
7ly, We find from all accounts, ancient and modern, that the weather preceding these shocks, was mild, warm, dry, serene, clear, frosty: what notoriously favours all our electrical experiments. This is particularly observ'd by Mr. Johnson and Mr. Smith, and other accounts. In the extensive shock of sunday march 18, along the Sussex coast, they take notice from Portsmouth, that the day was serene, warm, and dry, and that a shower of rain fell immediately before the shock. Mr. Bowman of Moulsey observ'd a shock there on may 24 last, and says, the air was perfectly serene, and clear. We very well know, that generally, all last winter spring, summer, and autumn, have been most remarkably of this kind of weather; more so, than has been observ'd in our memory; and have had all those requisites, appearances, and preparations, that notoriously cause electricity, that promote it, or that are the effects of it.
8ly, We find the blood-red australis aurora preceding at Spalding, as with us at London. At the time of the earthquake at Manchester this year, it accompanied it. And this year has been more remarkable than any for fire-balls, storms, wind, thunder, lightnings, and coruscations, almost throughout all England. A large ball of fire, with a long fiery tail on july 22, that passed over great part of England northward. Another seen over London, passing from west to east, in october. Coruscations were seen just before that extensive shock of 70 miles long felt from Lancaster to Wrexham, on april 2, last. Fire-balls more than one were seen in Rutland, and Lincolnshire: and particularly observ'd. And Mr. Smith from Peterborough writes, that a fire-ball was seen the morning of the earthquake, in the upper part of Northamptonshire. All these kind of meteors are rightly judg'd to proceed from a state of electricity in the earth and atmosphere: and how far they are actually concerned in causing earthquakes, time, and accurate observation must inform us.