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more probable hypothesis may be formed out of them both.

“ Suppose (says he) the electric matter to be accumulated in cuepart of the surface of the earth, and on account of the dryness cfthe season cannot easily diffuse itself; it may force its way into thehigher regions of the air, forming clouds in its passage out of thevapours which float in the atmosphere, and occasion a suddenshow er, which may further promote the passage of the fluid. Thewhole surface, thus unloaded, w ill receive a concussion, like anyother conducting suhstae.ee, on parting with, or receiving a quan-tity of the electric fluid. The rushing noise will likewise sweepoyer the whole extent of the country. And upon this supposi-tion also the fluid in its discharge from the country, will naturallyfollow the course of the rivers, and also take the advantage of anveminences t q facilitate its ascent into the higher regions ot the uir. ! ’The three last hypotheses, though somewhat dim-ring, yet agreein the main ; but if a particular solution of the phenomena is re-quired, every one of them will be found deficient. The editorsof tile Encyclopaedia Britannica, urge the following objections tothem, and offer a much more plausible theory, a part of whichwe shall here quote. “ If, according to Dr. Stukely’s hypothesis,the electric matter is lodged only on the surface of the eartii, orbut a small depth below, how are we to account for those violenteil'eets which often take place in the bowels of the tarlh? In theearthquake at Lisbon , a large quay sunk to any unfathomable depth.M'e are certain that the cause of the earthquake mu-i have beenbelow tills depth, how ever great it was, and have opened the earthfor an immense way downwards. At the saihe tune a hill in Bar-barv clave asunder, and the two halves of it le;l different ways.This shews, that the cause of the earthquake opeiated not on thesurface of the hill, but on the solid foundation and contents of it ;nor can it lie explained by any supeificial action whatever. TV'in what the miners at Eyam bridge in Derbyshire ob-erved, it is alsoevident, that the shock was felt at the depth of 39(3 Let below thesurface of the ground, more than at the surface itself ; ami conse-quently there is all tiie reason in the world to think, that the cati-clay at a depth vastly greater. Again, though the earthquake atLondon was supposed to begin with a black cloud and shower;yet in that of 1753, the effects of which were incomparably greater,the air was calm and serene almost in every place where it w as felt.It does not appear, that there is at any time a considerable dif-ference between the electricity of the atmosphere and that of theearth, or indeed that there can be so. Eor if the earth is electrifiedplus, and the atmosphere minus, there are innumerable points onthe surface of the earth, w hich must he imperceptibly drawing offthe superfluous electric matter into the air. The vapours also,with jwhich the atmosphere abounds, would always be ready in the sameservice: and thus thunder and lightning might indeed sometimesbe produced, but not earthquakes. But lastly neither the air northe earth do always shew any remarkable signs of electricity be-fore earthquakes happen. Eor, the summer before the earthquakeat Manchester in 1777, there had scarce been any thunder, light-ning, or other signs of elei tricity in the atmosphere, and vegeta-tion had been extremely backward; and, according to the bestaccounts, the weather continued remarkably fine. Eor these rea-sons, Dr. Stnkely’s hypothesis seems not to be satisfactory. ThatofSignior Beccaria is not indeed liable to the above-mentionedobjections; but seems highly improbable on another account.The atmosphere is know n to be a substance through which theelectric matter makes its way with the utmost difficulty. It is avastly worse conductor than water or than moist earth. If there-fore the equilibrium of this fluid is lost in the bowels of the earth,it is impossible to give a reason, why it should not rather go to theplaces where it is wanted through the earth itself, than through theatmosphere. Besides, if this were the case, the shock of an earth-quake could only be felt at those places where the electric fluidissued,from the earth, and where it entered. All the intermediateplaces, ought to be free from anv shock, and to be sensible only ofa violent concussion in the atmosphere; but of this we have no ex-ample in any history of earthquakes whatever. Dr. Priestley’s hy-pothesis is liable to the same objections with that of Dr. Slukely ;for any superficial operation w ill never account for those effectsabove-mentioned, which take place at great depths below the sur-face. Ilis experiment cannot he admitted as any way conclusivewith regard to the cause of earthquakes, because no' quantity ofelectr.c tire L seen to pass over the earth and sea, like the flash at-tending the explosion of an electric battery ; and the force of his

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earthquake (being but just able to throw down a stick that couldhardly stand by itself) seems by far too little. 'To give an ex-planation of the phenomena of earthquakes, which shall be freeIrom the objections above-mentioned, and from all others, it willbe necessary in the first place, to consider those parts of the systemof nature, which seem to be be mo.-1 -affected (luring the terriblephamotnena we treat of. These are, the air, the solid earth, andthe water. Oflhc.-e the two former are electrics per so ; die latteris a conductor, though a bad one. (See Kiectricity.) lieneeit follows, 1. '1 hat in proportion to the quantity of earth which ismixed with any quantity of water, that mixture will approachnearer to the nature ot an electric per sc, and vice versa. 2. Thatwhatever quantity of electricity is communicated to the solideai th,will be quickly taken off from it by the water which is mixedwith it, in the same manner that the electric matter is carried offfrom an excited globe by a metallic conductor. 3. The wholeearth is moist, and therefore in some degree a conductor. Mever-thelcss, as earth of all kinds, when perfectly dry, is tound to he anelectric capable ot receiving a charge like glass, it is therefore pos-sible, that ihe ilcctric power of the earth may be excited to sucha degree, that the moisture of the solid pari.- cannot easily containthe quanfiiv of electricity communicated. 4. In this case, theearth must cither give undoubted signs of its being excited in thesame maimer that other excited electrics arc, or the electricitymust be discharged somewhere else. 5. To receive any super-fluous quantity of electric matter, that may be communicated tothe solid t-;nth, the waters of the ocean are alway s iea;ly. These,being a nail'll heller conductor than earth, must be a principalmean of preserving the equilibrium ot electricity in ihe diflerentparts of the earth ; and lienee \ve see a natural reasen why thewaters of the on .-.n should cover so large a proportion of theglobe, as l hey are know n to do. See Ocean. (1. Eire is also aconductor ot ilcctiii ity. Then-fore, wherever a quantity of elec-tric matter is collected in any parted the solid earth, if it (an nei-ther he ccnvcnh ntly received by the moisture which the earth na-turally contams, in-r by the ocean in its neighbourhood, it willdi-charge itself hv rnv volcano dial happens to be in . ii at live statenear the pi ce wiren-tiiat collection oi electric matter is. 7. r l lieelectric lniid be ng violently resisted by tne supt rineuinbent at-mosphere, has always a tendency to (list barge itseh in those placeswhere that resistance is least. ’1 he tops ol high mountains, there-fore, w lu re the weight of the atmo-pliere is greatly diminished,will also afford a ready passage n r tl:e electric fluid, when it iscollected in very great qu. ntity in the bowels of the earth. 8.

] If, from some natural cause-, the electric matter sliali happen tobe collected in the bowels ol the earth many particular place, andat the same time such obstacles are thrown in its wayg that it canneither discharge itself into the ocean, nor into the atmosphere by,the tops of high mountains, nor by the more open passages of vol-canoes ; the most terrible consequences must ensue : the matterbeing pent up, and the cause by winch it is collected continuingstill to ad, its impulse becomes at last irresistible. It then flicsagainst every obstacle with inconceivable violence. 11 breaks outin all those places wlterb there is llit* least resistance, and thereforethe shock is directed a great number of different ways at once.Houses, steeples, trees, &c. by their height take off somewhat ofthe pressure ot the atmosphere ; and therefore the electric matterflies against them very violently. ’1 lie houses and other build-ings being had conductors, are thrown down ; the trees affording areadier passage to the fluid are not hurt, though even they also aresometimes split. '1 lie height of the mountains renders them theobjects of the destructive force of this fluid much more than anybuildings whatever. Hence they arc often rent, and rocks thrownfrom them. 'The water contained in the solid parts of the earth,being a conductor of electricity, becomes overloaded with it ; amiwhen it can receive no more, is forced to yield to the impulse ofthe rest, and therefore is thrown out of the earth in great quanti-ties. Eor the same reason, the waters on the surface of the earthare most violently agitated. The small quantities contained inwells are thrown out at the tops of them : the rivers and lakes,which contain too great a quantity of water to be thrown otf fromthe earth, rise in billows: the ocean itself, receiving more electricmatter than can be immediately dispersed through the whole bodyof water, or evaporated into the atmosphere, retreats trom the land,and is raised in vast mountains. 'The solid earth being unable eitherto conduct the fluid quietly to those parts where it is wanted, or to

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