Page:Cyclopaedia, Chambers - Volume 1.djvu/633

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Mark that ever Tree, or Plant, had been thereon. Above 12 Miles from the Sea, the Earth gaped and fpouted out, with a prodigious Force, vaft Quantities of Water into the Air : Tet the greateft Violences were among the Mountains and Rocks ; and 'tis a general Opinion, that the nearer the Mountains, the greater the Shake ; and that the Caufe thereof lay there. Molt of the Rivers were flop'd up for 34 Hours, by the falling of the Mountains ; till fwclling up, they found thamfelves new Tracks and Channels ; tearing up in their Paffage Trees, tSi. After the great Shake, thofe People who efcaped, got on board Ships in the Harbour, where many continued" above two Months ; the Shakes all that Time being fo violent, and coming fo thick, fometimes two or three in an Hour, accompanied with frightful Noifes like a ruffling Wind, or a hollow rumbling Thunder, with Brimftone Blafts, that they durft not come a Shore. The Confequences of the Earthquake was a general Sicknefs, from the noifomc Vapours belched forth, which fwtpt away above 5000 Perfons. Ibid.

After the Detail of thefe horrible Convulfions, the Reader will have but little Curiofity left, for the 'left confidcrable Phenomena of the Earthquake at Lima, in 1S87, de r cribed by Fa. Alvarez de 'Toledo, wherein above ;ooo Perfons were deftroy'd ; this being of the Vitratory Kind, fo that the Bells in the Church rung of themfelvcs : Or that at fiatavia in 10-99, by Witzen : That in the North of England m 1703, by Mr. Thoresby : Or, laftly, thole in New-Eigland in 1661 and 10-70, by Dr. Mather. We will therefore relieve him with fome Attempts towards a Theory of Earthquakes.

Caufes 0/ Earthquakes.

Naturalifts are here divided. Some afcribc Earthquakes to Water, others to Tire, and others to Air ; and all of 'em with fome Reafon. To conceive which, it is to be ob- ferved, that the Earth every where abounds in huge fub- terrancous Caverns, Veins and Canals; particularly about the Roots of Mountains : That of thefe Cavities, Veins, ZSc. fome are full of Water, whence -arc compofed Gulphs, 'Abjffes, Springs, Rivulets; and others full of Exhalations : And that ibme Parts of the Earth are replete with Nitre, Sulphur, Bitumen, Vitriol, iSc. Sec Abyss, Stratum, iSc.

This premi/ed, 1. The Earth it felf may be the Caufe of its own fliaking ; when the Roots, or Balis, of fome large Mafs being didblved, or wore away by a Fluid un- derneath, it finks into the fame; and with its Weight, oc- cafions a Tremor of the adjacent Parts; produces a Nofe; and frequently an Inundation of Water.

2. The fubterraneous Waters may occafion Earthquakes, by their overflowing, cutting out new Courfes, HSc. Add, that rhe Water being heated, and rarified by the fubter- raneous Fires, may emit .Fumes, Blafts, &c. which by their Action, either on the Water, or immediately on the Earth it felf, may occafion great SuccufJions.

3. The Air may be the Caufe of Earthquakes : For Air, being a Collection of Fumes, and Vapours rais'd from the Earth and Water ; if it be pent up in the too narrow Vifcera of the Earth, the fubterraneous, or its own native Heat, rarifying and expanding it, the Force wherewith it endeavours to efcape, may ftiake the Earth : Hence there arife divers Species of Earthquakes, according to the dif- ferent Pofition, Quantity, &c. of the imprifon'd Aura.

Lajfly, Fire is a principal Caufe of Earthquakes ; both as it produces the aforefaid fubterraneous Aura, or Vapours ; and as this Aura, or Spirit, from the different Matter and Compofition whereof arife Sulphur, Bitumen, and other inflammable Matters, takes Fire cither from fome other Fire it meets withal, or from its Colliiion againft hard Bodies, or its Intermixture with other Fluids ; by which Means burfting out into a greater Compafs, the Place becomes too narrow for it ; fo that preffing againft it on all Sides, the adjoyning Parts are fhaken 5 till having made it felf a Paf- fage, it fpends it felf in a Volcano, or burning Mountain. See Volcano, Eruption, &c.

But to come nearer to the Point : Dr. Lifier, in *Phi- lofo/h. TranfaB. N. 157. is of Opinion, that the material Caufe of Thunder, Lightning, and Earthquakes, is one and the fame, viz. the inflammable Breath of the Pyrites, which is a fubffantial Sulphur, and takes Fire of it {df. See Pyrites, T htjnder, Z5c.

The Difference between thefe three terrible Phenomena, he takes only to confift in this ; that this Sulphur, in the former, is fired in the Air ; and in the latter, under Ground. Which is a Notion that 'Pliny had long before him : £Ht'til cni',/1, fays he, aliud eft m Terra Tremor, quam in Tyube Tonitru ?

This he thinks abundantly indicated by the fame ful- phureous Smell being found in any Thing burnt with Light- ning ; and in the Waters, efc. call up in Earthquakes, and even in the Air before and after them.

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Add, that they agree m the Manner of the Noife; which is earned on, as ma Tram, fired. the one rowlina and ratling through the Air, takes Fire as the Vapours c°hance to drive; as the other hred under Ground, in like Manner, moves with defultory Noife.

Thunder, which is the Effefl of the Tremblino of the Air, caufed by the fame Vapours difperfed through it has Force enough to /hake our Houfes ; and why" may not there be Thunder and Lightning under Ground, in fome raft Repositories there, I fee no Reafon. Efpecially if we reflect, that the Matter which compotes the noify Vapour above us, is i n much larger Quantities under Ground; Tbtlofopj. TranfaB. No. 202.

That the Earth abounds in Cavities, every Body allows ; and that thefe fubterraneous Cavities are, at certain Times and in certain Seafons, full of inflammable Vapours, the Damps in our Mines fufficiently Witnefs, which fired, do eVe Z>j g as in an Ear 'bjuake, fave in a leffcr Degree, that the Pyrites alone, of all the known Minerals,
 * - :_n r 1 ... _ '

Add,

yields this inflammable Vapour, is highly probable : For that no Mineral, or Ore whatfocver, is fulphureous, but as it is wholly, or in Part, a 'Pyrites ; and that there is but one Species of Brimftone, at leafl with us in England, w.uch the "Pyrites naturally, and only yields. Tiie Sulphur Vive, of natural Brimftone, which is found in and about the burning Mountains, is certainly the Eftefls of Sublima- tion ; and thofe great Quantities of it faid to be found about the Skirts of Volcano's, is only an Argument of the long Duration and Vehemence of thofe Fires : Poffibly, the Pyrites of the Volcano's, or burning Mountains, may be more fulphureous than ours : And, indeed it is plain, that fome of ours in England are very lean, and hold but little Sulphur ; others again very much : Which may be one Reafon, why England is fo little troubied with Earthquakes; and Italy, and almoft round the Mediter- ranean Sea, fo very much : tho' another Reafon is, the Paucity t^f 'Pyrites in England.

Comparing our Earthquakes, Thunder and Lightning, with theirs, it is obferved, that there it lightens almoft daily, efpecially in Summer Time, here feldom ; there Thunder and Lightning is of long Duration, here it is foon over ; there the Earthquakes are frequent, long, and terrible, with many Paroxyfms in a Day, and that for^many Days ; here very fhort, a few Minutes, and fcarce perceptible. To this Purpofe, the Subterraneous Cavities in England are fmall, and few, compared to the vaft Vaults in thofe Parts of the World ; which is evident, from the fudden Difappearance of whole Mountains and Iflands.

Dr. Woodward gives us another Theory of Earthquakes* He endeavours to fliew, that the fubtereaneous Heat, or Fire, (which is continually elevating Water out of the Abyfs, to furniOi the Earth with Rain, Dew, Springs and Rivers) being flopped in any Part of the Earth, and fo diverted from its ordinary Courfe, by fome accidental Glut, or Ob- ftruction, in the Pores or Paffages, through which it u r ed to afcend to the Surface ; becomes, by fuch Means, preter- naturally aflemblcd, in a greater Quantity than ufual, into one Place ; and therefore caufeth a great Rarefaction, and Intumcfcence of the Water of the Abyfs ; putting it into great Commotions, and Diforders, and at the fame Time making the like Effort on the Earth ; Which bein<» ex- panded upon the Face of the Abyfs, occafions that Agita- tion and Concuflion we call an Earthquake.

This Effort, in fome Earthquakes, he obferves, is fo ve- hement, that it fplits and tears the Earth, making Cracks and Chafms in it, fome Miles in length, which open at the Inftant of the Shock, and clofe again in the Intervals betwixt them ; nay, it is fometimes fo violent, that it forces the fuper-incum- bent Strata, breaks them all throughout, and thereby perfectly undermines, and ruins the Foundation of them ; fo that thefe failing, the whole Tract, as foon as the' Shock is over, finks down into the Abyfs, and is fwallow'd up by it ; the Water thereof immediately rifing up, and forming a Lake in the Place, where the faid 'Tracf before was. That this Effort being made in all Directions indifferently, the Fire dilating and expanding on all Hands, and endeavouring to get room, and make its Way through all Obftaclcs, falls as foul on the Water of the Abyfs beneath, as on the Earth above, forcing it forth, which Way foever it can find Vent, or Paffage, as well through its ordinary Exits, Wells, Springs, and the Outlets of Rivers, as through the Chafms then newly open'd ; through the Caraini, or Spiracles of JEtna, or other neighbouring Vulcano's ; and thofe Hiatus's at the Bottom of the Sea, whereby the Abyfs below opens into it, and communicates with it. That as the Water, refident in the Abyfs, is, in all Parts of it, ftored with a confide- rable Quantity of Heat, and more efpecially in thofe, where thefe extraordinary Aggregations of this Fire happen ; fo likewife is the Water, which is thus forced out of it ; in- fomuch, that when thrown forth, and mixed with the

Waters