6 on the causes of earthquakes on the occasion of the...

6

On the causes of earthquakes on theoccasion of the calamity that befell

the western countries of Europe towardsthe end of last year

editor’s introductionA major earthquake struck off the coast of Lisbon, Portugal, on 1 Novem-ber 1755, killing tens of thousands of the city’s citizens and, compoundedby flooding and fires, destroying over two-thirds of its buildings. Themagnitude of the disaster shocked the collective consciousness of Euro-peans. In Candide, Voltaire used the event to criticize Leibniz’s doctrineof optimism, that ours is the best of all possible worlds, along with vari-ous other, more implicit targets. Others, taking note of the fact that thetragedy occurred on All Saints’ Day and annihilated most of the majorchurches in Lisbon, claimed that it was divine punishment for corruptionand sin. Though Konigsberg was not itself directly affected, Kant wrote,in quick succession, three essays that attempted to reassure its citizensthat the events attending the earthquake were not to be viewed as anunspeakable evil inconsistent with God’s existence and the perfection ofthe world or as an act of divine vengeance for the decadent behaviour ofLisboans. Instead, he endeavoured to show that earthquakes have purelyphysical causes and that they should therefore incite not fear, which is, inany case, a very weak motive for virtuous behaviour in his view, but rathercareful thought about how best to control their effects (by engaging in,for example, appropriate urban planning).

Kant published the first essay, “On the causes of earthquakes on theoccasion of the calamity that befell the western countries of Europetowards the end of last year”, in two instalments, in the 24 and 31January issues of the Wochentliche Konigsbergische Frag- und Anzeigungs-Nachrichten of 1756. His main contention in this essay is that earth-quakes are caused by the conflagration of a mixture of iron filings,sulphur, or vitriolic acid, and water that has been compressed in extensivecaverns lying below the Earth’s surface (both under land and under theocean floor). He also argues that earthquakes are connected with volcanicactivity, which have the same cause. He denies that they are caused by

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electricity, but allows for a connection with magnetic materials and atmo-spheric changes. Further, he argues that the frequency and direction ofearthquakes in mountainous regions is consistent with his view of thecause of earthquakes.

In its most general features, Kant’s views were not particularly novel,displaying similarities with the views of Nicholas Lemery, ChristianWolff, Georg Erhard Hamberger, Pierre Bouguer, and Johann HeinrichWinkler. It contrasts in both content and style, however, with, for exam-ple, Johann Gottfried Kruger’s Gedancken von den Ursachen des Erdbebens,nebst einer moralischen Betrachtung [Thoughts on the Causes of the Earth-quake, along with a Moral Observation], also published in 1756, whichconsists of thirty-five pages of explanation of earthquakes on the basis ofelectricity and 170 pages, consisting mostly of moralizing reflections.

further readingBraun T. E. D. and J. B. Radner (eds.). The Lisbon Earthquake of 1755: Represen-

tations and Reactions (Oxford: The Voltaire Foundation, 2005).Kendrick, T. D. The Lisbon Earthquake (London: Methuen & Co., 1956).Kozak, Jan T., Victor S. Moreira, and David R. Oldroyd. Iconography of the Lisbon

Earthquake (Prague: The Geophysical Institute of the Academy of Sciences ofthe Czech Republic, 2005).

Oldroyd, David, Filomena Amador, Jan Kozak, Ana Carneiro, and Manuel Pinto.“The Study of Earthquakes in the hundred years following the Lisbon Earth-quake of 1755”, Earth Sciences History 26 (2007): 321−370.

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Causes of Earthquakeson the Occasion of the Calamity

that

befell

the Western Countries of Europetowards the end of last year.

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Great eventsv that affect the fate of all mankind rightly arouse that com-1:419mendable curiosity, which is stimulated by all that is extraordinary andtypically looks into the causes of such events. In such cases, the natu-ral philosopher’sw obligation to the public is to give an account of theinsights yielded by observation and investigation. I do not [however] pro-pose to satisfy this obligation in its entirety, and leave it to that person,if such a one should arise, who can claim to have observed the Earth’sinterior with exactness. My account will only be an outline.x To makeclear what I propose, it will contain almost everything that can, as yet, besaid with any probability about this [subject], but not enough, of course,to satisfy that strict judgement which tests everything with the touch-stone of mathematical certainty. We dwell peacefully on ground whosefoundations are shaken from time to time. Without concern, we buildover cavitiesy whose supports sometimes sway and threaten to collapse.Unperturbed by the fate that is perhaps not [so] distant from us, we giveway to pity rather than fear when we observe the devastation caused inneighbouring places by the destruction lying hidden beneath our feet.It is doubtless the goodness of Providence that lets us be unaffected byfear of such fates, which cannot be prevented in the slightest by anyamount of worry, and that we should not increase our actual suffering[unnecessarily] by fear of what we recognize as possible.

The first thing to be observed is that the ground under us is hollow and1:420its caverns extend very widely, almost in a single interconnected system,even under the floor of the sea. I quote no historical examples in thisconnection; it is not my intention to write a history of earthquakes. Theterrible noise heard in association with many earthquakes, like the ragingof a subterranean storm or the driving of heavy carts over cobblestones,the continued effect [felt] simultaneously in widely separated places, ofwhich Iceland and Lisbon, which are separated by more than four-and-a-half hundred German miles1 of sea and were set in motion on thesame day, deliver irrefutable testimony, all these phenomena agree inconfirming the interconnections of these subterranean caverns.

I should have to go back to the history of the Earth [at the time]of the original chaos to say anything intelligible about the causes thatproduced these caverns when the Earth was formed. Such explanationswill seem too much like fabrications if they cannot be presented with allthe arguments that would make them credible. Whatever their cause,one thing is certain, namely that the direction of the caverns is parallelto the mountain ranges, and, by a natural connection, to the great riversalso. For these occupy the lowest parts of long valleys bounded on bothsides by parallel mountains. This is also precisely the direction in which

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earthquakes usually extend. In the earthquakes that have affected thegreater part of Italy, an almost exactly north–south motion has beenobserved in the lanterns in the churches, and the recent earthquake wasfrom west to east, which is also the main direction of the mountainsrunning through the highest part[s] of Europe.

If human beings are permitted to use foresight in [the face of] suchterrible catastrophes, and if it is not regarded as a foolhardy and futileeffort to oppose general misfortune with some precautions suggestedby common sense, then should not the unhappy survivorsz of Lisbonhesitate to rebuild along the length of the same river that indicates thedirection along which earthquakes must naturally occur in that country? 1:421Gentil∗,2 asserts that if a city is shattered along its longer axis by anearthquake running in the same direction, all the houses are knockeddown, but if the direction is transverse, only a few fall over. The reasonis obvious. The swaying of the ground moves the buildings out of theirvertical positions. Now if a row of buildings is shaken in this way fromeast to west, then not only does each one have to carry its own weight, butthose on the west also press simultaneously on those on the east, and thusinevitably destroy them. But if they are moved transversely, where eachhas to maintain only its own balance, less damage will be caused under thesame circumstances. The catastrophe at Lisbon thus seems to have beenexacerbated by its position along the banks of the Tagus. And for thisreason, any town in a country where earthquakes have been experiencedseveral times, and where their direction can be known from [previous]experiences, should not be laid out in a direction that is the same asthat of the earthquakes. However, in such cases most people are of quitea different opinion. Since fear robs them of [the capacity for rational]thought, they believe they can see in such widespread misfortunes akind of evil quite different from those [calamities] against which one isjustified in taking precautions. They imagine that they may [help to]mitigate the severity of their fate by the blind submission with whichthey yield unconditionally to it.

The main line of earthquakes follows the direction of the highestmountains, and thus the countries that are chiefly affected are closeto these, especially if they are enclosed by two mountain ranges, inwhich case the tremors combine from both sides. In a flat region, uncon-nected to any mountains, tremors are less common and weak[er]. Thisis why Peru and Chile are more subject to frequent tremors than anyother countries in the world. In these countries, one may observe the

∗ Gentil’s Journey Around the World, as quoted by Buffon. He also confirms that thedirection of the earthquakes almost always runs parallel to the direction of large rivers.

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precaution of building houses of two storeys, of which only the loweris made of stonework while the upper is built of reeds and light timber1:422so that no one will be crushed under it. Italy and indeed the island ofIceland, part of which is in the Arctic, and other high regions of Europe,confirm this. The earthquake that spread from west to east last Decem-ber through France, Switzerland, Swabia, the Tyrol, and Bavaria, largelyfollowed the line of the highest regions in this continent. But it is alsoknown that all the main mountain ranges send out subsidiary branchesin a crosswise direction. In these, the subterranean conflagration alsospreads gradually outwards and consequently, having reached the highregions of the Swiss mountains, it also ran through the caverns that runparallel to the River Rhine, right into Lower Germany. What can be thecause of this law whereby nature has linked earthquakes with the highregions in particular? If it is agreed that a subterranean conflagrationcauses these tremors, then one can easily see that because the caverns inmountainous regions are more extensive, the emission of inflammablevapoura there is less restricted, and the association with the air trappedin the subterranean regions, which is always necessary for combustion,will be freer. In addition, our knowledge of the interior composition ofthe surface of the Earth, insofar as human beings are able to discoverit, teaches that the layers in the mountainous regions are not nearly sothick as those in flat lands and the resistance to tremors is much less inthe former than the latter. If, therefore, one were to ask whether ourFatherland has cause to be afraid of such catastrophes, then, if it weremy vocation to preach the improvement of morals, I would let the fearof them stand in view of the general possibility [of such events] whichcannot, of course, be ruled out. But since, among the [various] motivesfor piety, those that originate in [the fear of] earthquakes are doubtless[among] the weakest, and it is my intention to adduce only physical rea-sons for supposing that earthquakes may occur, then one can easily seefrom what I have said so far that, since Prussia is not only a land withoutmountains, but must also be considered as a continuation of an almostentirely flat land, the measures of Providence give us more cause forhope than otherwise.

It is now time to say something about the cause of earthquakes. It iseasy for a natural philosopherb to reproduce their manifestations. Onetakes twenty-five pounds of iron filings, an equal amount of sulphur,1:423and mixes it with ordinary water, buries this paste one or one-and-a-half feet underground and compresses the earth firmly above it. Afterseveral hours, a dense vapour is seen rising; the earth trembles, andflames break forth from the soil.3 There can be no doubt that the firsttwo materials are frequently found in the interior of the Earth, and

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water seeping through cracks and crevices can bring them into a state offermentation. Another experiment produces spontaneously inflammablevapours from the combination of cold materials. Two drams of oil ofvitriol combined with eight drams of water, when poured onto two dramsof iron filings, bring forth a violent effervescence and vapours, whichignite spontaneously. Who can doubt that vitriolic acid and iron particlesare contained in sufficient quantity in the interior of the Earth? Now ifwater is added and occasions their reciprocal action, they give off vapoursthat endeavour to expand, make the ground shake, and break out in flamesat the orifices of the volcanoes.

It has long been observed that a country is relieved of its violent earth-quakes if a volcano has broken out in the vicinity, for it is by this meansthat the enclosed vapours find an exit. And it is known that around Naplesthe earthquakes are much more frequent and terrible when Vesuvius hasbeen dormant for a long time. In this manner, what frightens is oftenbeneficial, so that if a volcano were to open up in the mountains ofPortugal, it could herald the gradual departure of the misfortune.

The violent motion of water that was felt on so many coasts on thatunfortunate All Saints’ Day, is the most remarkable object of interest andenquiry in relation to this event. It is well known that earthquakes extendbeneath the sea and cause ships to shake as violently as if they were in anearthquake on dry land. However, in the areas where the water surgedup there were no signs of earthquakes; at least none could be felt at amoderate distance from the coast. Nonetheless, this motion of water isnot entirely without precedent. In 1692, something similar was observed 1:424on the coasts of Holland, England, and Germany at the time of an almostuniversal earthquake. I gather that many are inclined to believe, and notwithout reason, that the surging of the waters [near Lisbon] arose froma continued shaking that the sea received off the Portuguese coast, fromthe direct impact of an earthquake. [However,] this explanation appearsto be subject to some initial difficulties. I can understand very well that ina liquid any pressure must be felt throughout the whole mass,c but howcould the pressure of the water of the Portuguese sea still raise the waterat Gluckstadt and Husum4 by several feet, and that after spreading forseveral hundred [German] miles? Does it not seem that mountain-highwaves would have to occur there [i.e., near Portugal] to create hardlydiscernible waves here [i.e., on the Schleswig-Holstein coast, etc.]? Ianswer that there are two ways in which a liquid might be set in motionthroughout its mass by a cause acting locally: either through the swayingmotion of rising and falling, that is, in a wave-like manner; or through asudden pressure that gives an impulse to the mass of water in its interior,and repulses it as if it were a solid body without giving it time to evade the

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pressure by means of a wave-like surge and [thereby] dissipate its motiongradually. The first alternative is undoubtedly insufficient to account forthe event referred to. But as far as the latter is concerned, if one considershow water resists a sudden violent pressure as if it were a solid body, andthis lateral pressure spreads out with such violence as not to allow theadjacent water to rise above the horizontal, [and] if one considers, forexample, the experiment of Herr Carre in the second part of the PhysicalTransactions of the Academy of Sciences, page 549, where a musket ball wasshot into a box made of two-inch boards filled with water, and the waterwas so compressed that the box was quite blown apart,5 [then] this givesone an idea of the way in which the water is caused to move duringan earthquake. If one imagines, for example, that the whole west coastof Portugal and Spain from Cape St Vincent to Cape Finistere, about100 German miles, were shaken, and if one supposes that this quakeextended an equal distance westward into the sea, then 10,000 squareGerman miles of the bottom of the sea were raised by a sudden quakewhose speed we do not exaggerate if we equate it with that producedby a powder mine that throws a body lying on it fifteen feet into the1:425air, and is thus capable (according to the principles of mechanics) oftravelling 30 feet per second. The overlying water resisted this suddenshock to such an extent that it did not, as happens in slow motions,yield and rise in waves, but received its whole pressure and drove thesurrounding water, which is to be regarded as a solid body when thereis such a rapid compression,d to the side with the same force [as thatwhich it received from the earthquake]. Consequently, the extremitiesmove with the same speed as that [water] which is directly affected [bythe impulse]. Thus in every baulke of liquid, if I may use this expression,regardless of whether it is two or three hundred miles long, there is nodiminution of motion, if it is regarded as being enclosed in a canal withequal openings at each end. But if the far end is larger, then conversely,the motion through it will be correspondingly reduced. Now one mustthink of the continuation of the water’s motion around itself as extendingin a circle, the circumference of which increases with the distance fromthe centre. So at the periphery the flow of water is decreased in thesame measure. Thus it will be found to be six times less at the Holsteincoast, which is three hundred German miles from the assumed centre ofthe earthquake, than on the Portuguese coast, which according to ourassumption is fifty miles from that [central] point. The motion on theHolstein and Danish coast will therefore still be great enough to traversefive feet per second, equal to the forcef of a very fast river. Against this,

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it might be objected that the transmission of the pressure to the watersof the North Sea can only occur through the channel at Calais so that itsagitation must diminish markedly through being dissipated into a widesea. However, if one considers that the pressure of water between theFrench and English coasts before it reaches the channel must, as a resultof being compressed between these two countries, increase to the sameextent as it is subsequently diminished by expansion, then there is nosignificant loss of the effects of the earthquake on the aforementionedHolstein coast.

The most extraordinary thing about this compression of water is thatit was felt even in lakes with no visible connection with the sea, as atTemplin6 and in Norway. This seems to be almost the strongest evi- 1:426dence ever advanced to show that there are subterranean connectionsbetween land-locked lakes and the sea. In order to avoid the counter-argument based on the equipoise [of the waters], one would have toimagine that the water of a lake constantly flowed downwards throughchannels connecting it with the sea, but because these channels arenarrow and because the water that they lose in this way is sufficientlyreplaced by inflowing streams and rivers, the out-flow is not discernible.

Nonetheless, one should not form an over-hasty conclusion concern-ing so strange an occurrence. For it is not impossible that the disturbanceof the inland lakes might result from other causes. The subterranean air,set in motion by the raging fire, could well force its way through cracksin the Earth’s strata that are normally blocked except on such occasionsof violent eruption. Nature reveals herself but gradually. One should notseek impatiently to discover by fabrication what she conceals from us,but wait until she reveals her secrets in distinct activities.

The cause of earthquakes seems to extend its effect into the atmos-phere. Some hours before an earthquake occurs, a red sky and otherindications of altered atmospheric conditions have been observed. Ani-mals become terrified shortly beforehand. Birds take refuge in houses.Rats and mice scurry out of their holes. At this moment, there can be nodoubt that the heated vapour, which is on the point of ignition, breaksthrough the upper vault of the Earth’s crust. I would not venture to sayexactly what effects are to be expected. But at least [we can say that]they are not pleasing to the natural philosopher,g for what hopes doeshe have of ascertaining the laws according to which changes occur in theair when a subterranean atmosphere is interfering with their effects, andcan one doubt that this must take place frequently, for how else may weexplain the fact that there is no regularity in the changes in the weather,because the causes of these changes are partly constant and partlyperiodic?

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Note. In the previous issue7 the date of the earthquake in Iceland is1:427to be corrected from 1 November to 11 September, in accordance withthe report in the 199th issue of the Hamburger Correspondent.

The present observations are to be regarded as a small preliminaryexercise on the memorable natural event that occurred in our time. Itsimportance and various peculiarities move me to communicate to thepublic a detailed history of this earthquake, its spread over the countriesof Europe, the noteworthy things that happened during its course, andthe observations to which they can give rise, in a more detailed treatise,which will be published in a few days by the Royal Court and AcademicPress.

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7

History and natural description of the mostnoteworthy occurrences of the earthquake

that struck a large part of the Earth at theend of the year 1755

editor’s introductionThis essay is the second and most detailed of Kant’s writings on earth-quakes in response to the Lisbon disaster. It was published as an inde-pendent piece by Johann Heinrich Hartung’s press in Konigsberg. Theimprimatur was dated 21 February 1756, and it was advertised in the11 March issue of the weekly Konigsbergische Frag- und Anzeigungs-Nachrichten.

In this essay Kant intends to give a more detailed description andexplanation of the Lisbon earthquake and the events surrounding it.He reports that the earthquake was preceded by a vapour rising intothe air that turned red in the atmosphere and made the torrential rainsthat ensued blood-red as well. He explains these atmospheric phenom-ena on the basis of the iron compounds contained in the mixture ofsubstances that, through fermenting and being heated, led to the subter-ranean conflagration that caused the main earthquake. He then describesthe tsunami caused by the earthquake, its effects in distant places, itsspeed of transmission and extent as well as its influence on springs,and the mode of transmission of these effects (through the compressionof the water), distinguishing, to the extent possible, what effects are due tothe subterranean explosions and what to those of the tsunami. Kant alsodescribes the series of aftershocks on 18 November, 9 December, and26 December as well as patterns in the intervals between these tremors.He then theorizes about what geographical features are most conduciveto earthquakes and the directions of motion of an earthquake. He alsospeculates, somewhat freely, about the connection between earthquakesand the seasons and the influence of earthquakes on atmospheric con-ditions as well as their potential uses. Kant concludes this essay with asketch of a theodicy, according to which man often inappropriately viewshimself rather than nature as a whole as the object of God’s actions, and,

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in addition, man is in no position to know God’s intentions in any spe-cific case. Instead, one must assume that God’s wisdom will subordinatelower purposes to higher ones in accordance with the noblest of aims. Inthis way, there are, Kant suggests, no theologically unacceptable moralimplications of the disaster that befell Lisbon in 1755.

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History and Natural Description 1:429

of the Most Noteworthy

Occurrences of the EarthquakeThat struck a

Large Part of the Earth

at the End of the Year 1755

by

Immanuel Kant, M.A.

Natural Science

It is not in vain that nature has spread out a treasury of curiosities every-1:431where for our observation and admiration. Man, to whom the husbandryof the Earth’s surface has been entrusted, has the capacity and the desireto familiarize himself with them, and praises the Creator through hisinsights. Even the terrible instruments by which disaster is visited onmankind, the shattering of countries, the fury of the sea shaken to itsfoundations, the fire-spewing mountains, invite man’s contemplation,and are planted in nature by God as a proper consequence of fixed lawsno less than other accustomed causes of discomfort which are thoughtto be more natural merely because they are more familiar.

The contemplation of such terrible occurrences is instructive. It givesman a sense of humility by making him see that he has no right, or at leastthat he has lost any right, to expect only pleasant consequences from thelaws of nature that God has ordained, and perhaps he will learn therebyto realize how fitting it is that this [present] arenah of his desires shouldnot contain the goal of all his aspirations.i

P R E F A C E . j

concerning the nature of the interior ofthe earth.

So far as its extent is concerned, we know the surface of the Earthfairly completely. However, we have another world beneath our feetwith which we are at present but little acquainted. The fissures in themountains that open up unfathomable depths to our plumb bobs, the1:432caves that we discover inside mountains, the deepest mine-shafts, whichwe have extended for centuries, are utterly inadequate to give us anydistinct familiarity with the internal structurek of the huge globel weinhabit.

The greatest depth to which people have reached from the uppersurface of the ground is less than 500 fathoms, that is, not even one sixthousandth part of the distance to the centre of the Earth. Yet thesecavities occur up in the mountains although the whole of dry land is [ina sense] a mountain, for to reach even the bottom of the sea one wouldhave to descend at least three times deeper.

But those things which nature conceals from view and from our directinvestigation she reveals by their effects.m The [recent] earthquakes haverevealed to us that the surface of the Earth is full of vaults and cavities,and that mines with manifold labyrinths running everywhere are hidden

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History and description of the earthquake of 1755

beneath our feet. What follows in the history of the earthquake will placethis beyond doubt. We must ascribe the same origin to these caves as thatwhich gave rise to the sea-bed. For it is certain that even if one is onlymoderately well informed about the relics left behind throughout the dryland by the ocean after its former presence there, of the immeasurableheaps of shells that are found even in the insides of mountains, of petrifiedsea animals that are unearthed from the deepest [mine] shafts, then itcan readily be seen: first, that long ago the sea covered the entire landfor a long period; [second,] that this inundation lasted a long time andpredated the Great Flood; and finally that the waters could not havereceded by any other means than that the sea-floor sank from time to timeinto deep cavities and formed deep basins into which the water flowedand between the shores of which it is still confined. Meanwhile, theraised areas of this sunken crust have become dry land [but] everywhereundermined by caverns. This [dry land] is covered with steep peaks,which we call mountains. The peaks run along the greatest heights ofthe dry land in those directions in which it extends for some considerabledistance.

All these caverns contain a blazing fire, or at least an inflammable 1:433material requiring only a slight excitationn to rage violently and shatteror even split the overlying ground asunder.

If the whole extent of this subterranean fire is considered, then wehave to admit that there are few countries on Earth that have not felt itseffects occasionally. In the furthest north, the island of Iceland is subjectto the most violent and frequent earthquakes. There have been somemild tremors in England and even in Sweden. Nonetheless, they are tobe found more frequently and violently in the southern lands, [by which] Imean [those] near the Equator. Italy, and the islands in all the seas closeto the Equator, especially those in the Indian Ocean, are frequentlysubject to this disturbance of their foundations. Among the latter, thereis hardly one that does not have a mountain which spews forth fire, eitherat present or at least in the past; and they are just as frequently subject toearthquakes. It is for this reason that the Dutch employ a nice precaution,if we can believe Hubner’s report.1 In order to avoid the risk of [thesource of] the valuable spices, nutmegs, and cloves being destroyed byan earthquake, they maintain a nursery for the plants on an island farremoved from the islands of Banda and Amboina, which are otherwise theonly places where they permit the cultivation of these species [and] whichmight be totally destroyed by an earthquake. Peru and Chile, which areclose to the Equator, are troubled by this evil more frequently than anyother countries. In the former country, hardly a day passes without someslight tremors being felt. It should not [however] be supposed that this

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is a consequence of the far greater heat of the Sun that affects the soilof these lands. In a cellar barely forty feet deep, there is hardly anydifference felt between summer and winter. So little [therefore] is theheat of the Sun able to penetrate the soil to great depths, and to attractthe inflammable [matter] and set it in motion. Rather, the earthquakesare determined by the nature of the subterranean caverns. And thesefollow the law according to which the collapses of the upper crust musthave occurred in the beginning, in such a manner that the closer they are1:434to the Equator the deeper and more numerous are the indentations theyhave made, and as a result of which these mines containing the tindero

for the earthquakes have become enlarged and are consequently bettersuited to ignition.

This formationp of subterranean passages is of no small importancefor understanding that which follows concerning the wide extent of theearthquakes in large countries, of the lines they follow, the places wherethey occur most frequently, and where they originate.

I now begin with the history of the latest earthquake itself. By thisI mean not a history of the instances of misfortune that people havesuffered as a result of it, nor a list of the cities and their inhabitantsdestroyed under its debris. All the terrible things the imagination canconceive have to be taken together to understand even to a small extentthe horror people must experience when the Earth moves under theirfeet, when everything around them crashes to the ground, when a bodyof water moved in its foundations completes their misfortune throughflooding, when the fear of death, the despair at having lost all one’searthly goods, and finally the sight of other people in misery must dis-hearten even the most courageous. A narrative of such events would bemoving, and it would, since it has such an effect on the heart, perhapsalso have the effect of improving the latter. But I shall leave this storyto more skilful hands. Here I shall only describe the work of nature,and the remarkable natural circumstances that accompanied the terribleevent together with its causes.

concerning the harbingers of the lateearthquake.

The prelude to the subterranean conflagration that proved to be so ter-rible subsequently I see in the atmospheric phenomena that were per-ceived in Locarno in Switzerland on 14th October last year [i.e., 1755] at8 o’clock in the morning. A vapour as warm as if it were coming out of an

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oven spread [over the area] and within two hours turned into a red mistwhich developed into a blood-red rain towards the evening, which, afterit had been collected, deposited 1/9th of [its volume as] a reddish, stickysediment. The six-foot deep snow was similarly dyed red. This red rainwas seen for 40 hours, over an area of about 20 German miles square, 1:435indeed as far away as Swabia. Upon this atmospheric phenomenon fol-lowed unnatural torrents of rain, which yielded up to 23 inches of waterin 3 days, which is more than is deposited in a country of moderate rain-fall in a whole year. This rain lasted for more than 14 days, although notwith the same intensity for the entire period. The rivers in Lombardythat have their source in the Swiss mountains, and the Rhone as well,swelled as a result of this water and burst their banks. Thereafter, terriblehurricanes prevailed in the atmosphere and these raged everywhere withcruel force. As late as in the middle of November, a similar red rain fellin Ulm, and the disorder in the atmosphere, the whirlwinds in Italy, andthe exceedingly wet weather continued.

If one wishes to get some idea of the causes of this phenomenon and itsconsequences, one should consider the nature of the ground over whichit took place. All the Swiss mountains have extensive caverns beneaththem, which are undoubtedly connected to the deepest subterraneanpassages. Scheuchzer2 has counted nearly twenty chasms that blow outwinds at certain times. Now if we assume that the minerals hidden inthese caves have come to be mixed with the liquids that cause themto effervesce and thus start to ferment inwardly, thereby preparing thecombustible materials for that conflagration which was to break out fullywithin a few days; if, for example, we imagine the acid contained inspirit of saltpetre, and which is necessarily prepared by nature herself,attacking the ferruginous earth upon which it fell, having been set inmotion either by the influx of water or by some other cause, then thesematerials will have been heated when they were mixed and will haveemitted warm, red warm vapours from the chasms in the mountains; inthe violence of the effervescence, particles of the red ferruginous earthwere both mixed with and carried up by these vapours, and this causedthe aforementioned sticky blood-red rain. The nature of such vapourstends to lessen the tensionq of the air and thus to make the water vapourssuspended therein coalesce; also, the concentration of all the moist cloudshovering in the surrounding atmosphere as a result of the natural fall ofthe land in the direction where the height of the column of air had beenreduced, caused the heavy and continuous downpours observed in theareas mentioned.

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Thus, by means of expelled vapours, the subterranean fermentationgave forewarning of the disaster it was preparing in the hidden depths.∗1:436Fate then took its full course in gradual steps. Fermentation does notbreak out into a conflagration immediately. The fermenting and heatedmaterials have to meet with combustible oils, sulphur, bitumen or some-thing similar in order to ignite. The heating process spread to and froin the subterranean passages until the dissolved flammable materials inthe mixture, and the other [materials], had been heated to the point ofcombustion, and then the vaults of the earth were shattered and thecatastrophe reached its conclusion.

the earthquake and the motion of water of1st november, 1755.

The moment at which this shock occurred seems to be most accu-rately fixed at 9:50 a.m. in Lisbon; this time accords exactly with thatobserved in Madrid, namely 10:17 to 10:18 a.m., if one converts the lon-gitude of both cities into a time difference. At the same time, the waterswere shaken over an astonishing area, [not only] those that have a visibleconnection with the ocean but also those where the connection may behidden. From Abo in Finland to the West Indian archipelago few if anycoasts escaped the quake. It affected an area of 1,500 miles in almost thesame space of time. If one could be sure that the time at which it wasfelt at Gluckstadt on the Elbe could be fixed, as reported in the publicnews, at precisely 11:30 a.m., then one would conclude that the motionof water took 15 minutes to travel from Lisbon to the coasts of Hol-stein. It was also felt within precisely this time on all the coasts of theMediterranean, and its full extent is not yet known.

Waters on the mainland that seem to be cut off from all communica-tion with the ocean, [such as] wells [and] lakes, were set in extraordinarymotion simultaneously in countries far distant from each other. Most of1:437the lakes in Switzerland, the lake at Templin in Brandenburg and somelakes in Norway and Sweden took on a surging motion, much more vio-lent and chaotic than in a storm, yet the air was still at the time. If thenews may be relied on, the lake at Neuchatel flowed [away] into hid-den clefts, and the lake at Meiningen3 did likewise but soon returned.In these same [few] minutes, the mineral water at Toplitz4 in Bohemiasuddenly ceased to flow and then returned blood-red. The forcer with

∗ Eight days before the earthquake, the ground at Cadiz was covered by a great manyworms that had crawled out of the earth. These had been driven out by the cause justmentioned. In the case of several other earthquakes, violent lightning in the air and theapprehension observed in animals have been harbingers.

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which the water was pushed through enlarged its former passages, andthus it gained a stronger inflow. The inhabitants of that town had goodcause to sing Te Deum laudamus, while those in Lisbon began to sing inquite different tones. Such is the nature of the accidents that affect thehuman race. The joy of one group and the misery of another often havea common cause. In the Kingdom of Fez in Africa, a subterranean forces

split open a mountain, which poured blood-red streams from its depths.At Angouleme in France a subterranean roar was heard, and a deepchasm opened on the plain, containing bottomless water. In Gemenosin Provence, a well suddenly became turbid and then poured forth ina red colour. The surrounding areas reported similar changes in theirwells. All this occurred in the same [few] minutes when the earthquakewas devastating the coasts of Portugal. In just this same short period oftime several earthquakes were felt in far distant countries. But nearly allof them took place near the sea coasts. In Cork in Ireland, as in Gluckstadtand several other places situated on the sea, there were slight tremors.Milan is probably the place furthest from the sea to have experienced anearthquake on that day. On the very same morning at 8 o’clock, MountVesuvius near Naples erupted, and then became quiet around the timewhen the earthquake occurred in Portugal.

observation on the cause of thismotion of water.

History has no precedent for so widespread a disturbance of water and alarge part of the Earth observed in the space of a few minutes. One shouldtherefore be cautious in inferring its causes from what was a uniqueevent. [Nevertheless,] one can have particular regard to the following 1:438causes that may have brought about the aforementioned event; [namely]a general quaking of the sea-floor directly under those areas where thesea was disturbed. But then one would have to indicate why the vein offire responsible for these earthquakes ran only under the bottom of theseas, without extending to the lands that are in close connection withthe latter and are often interposed between them. It would be difficultto explain why this disturbance of the ground, which extended fromGluckstadt on the North Sea to Lubeck on the Baltic, and along thecoast of Mecklenburg, was not felt in Holstein, which lies between thesetwo seas, and where only a very slight tremor was felt on the coast butnone was felt inland. Even so, the most convincing thing is the surging ofthe waters far from the ocean, such as occurred at the lakes at Templin,in Switzerland and elsewhere. It is easy to see that, in order to bringa body of water into such violent agitation, the shock must be quite

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considerable. But why was this mighty quake not felt in the surroundinglands under which the vein of fire must needs have run? It is easy to seethat all the evidence is against this opinion. It is extremely unlikely thatan earthquake impressed itself upon the surrounding solid mass of theEarth itself by a violent convulsion at one point, as the ground is shakenfor some distance around when a powder magazine explodes, and bothfor the reason already mentioned and because the awesome extent [ofthe catastrophe] when compared with the circumference of the Earth,constitutes such a large proportion of the latter that its shaking wouldhave had to produce a shaking of the whole globe. Now one can learnfrom Buffon5 that an eruption of subterranean fire capable of throwinga mountain range of seventeen hundred miles long and forty wide a mileinto the air would not move the globe one inch from its position.

Thus we shall have to look for [the cause of] the spread of this motionof water in some medium that is more suited to transmit a disturbance1:439for great distances, namely in the water of the seas themselves, which is in[direct] connection with that which was suddenly and violently disturbedby a direct motion of the sea-bed.

In the weekly Konigsberger Anzeigen, I have tried to calculate the forcet

with which the whole sea was repulsed by the shock of the tremor on itsfloor. I assumed the affected area of the sea-floor to be merely a square,one side of which was equal to the distance from Cape St Vincent to CapeFinistere, that is, the length of the western coast of Portugal and Spain,and I regarded the poweru of the rising sea-bed as equivalent to a powdermine capable of raising the bodies over it by fifteen feet, and accordingto the laws by which motion is transmitted in liquids, I found it to bestronger on the Holstein coast than the impact of the fastest runningstream. Let us here consider from a different perspective the power thatit can exercise as a result of these causes. By means of a plumb line,Count Marsigli6 found the greatest depth of the Mediterranean to beover eight thousand feet, and it is certain that the ocean is much deeperat an appropriate distance from the land, but we will here assume it tobe only six thousand feet, that is, one thousand fathoms. We know thatthe pressure which so high a column of water exerts on the bottom of thesea must exceed the pressure of the atmosphere by nearly two hundredtimes, and that it must far exceed the power behind a ball hurled froma heavy cannon over a distance of one hundred fathoms in the space ofa pulse beat. This enormous load could not withstand the power withwhich the subterranean fire pushed the sea-floor rapidly upwards, andtherefore this [upward] motive powerv was greater. With what pressure,then, was the water impelled for it to shoot suddenly in all directions?

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And is it surprising if the shock was felt a few minutes later in Finlandand simultaneously in the West Indies? It cannot be determined howlarge the area of the direct quake may actually have been. Perhaps itwas much greater than we have supposed; but it was certainly not to befound on the sea-floor under the seas where the motion of water was feltwithout any earthquake, on the Dutch, English, and Norwegian coasts, 1:440and in the Baltic. For otherwise the dry land would undoubtedly alsohave been shaken in its interior, which, however, was not observed.

In ascribing the violent quaking of all the connected parts of the oceanto a single impact,w acting on the sea-bed in a particular area, I do not wishto deny the actual spreading of the subterranean fire under the dry landof almost the whole of Europe. In all probability, the two events occurredsimultaneously and both had a share in the ensuing phenomena, so thatneither individually was the sole cause of the effects as a whole. Thedisturbance of the water in the North Sea, which was felt as a suddenshock, was not the effect of a subterranean earthquake. Disturbanceswould have to be very violent to bring about such effects and wouldnecessarily have been readily detectable on dry land. However, I do notwish to deny that even the dry land as a whole was slightly shaken by aweak forcex of ignited subterranean vapours, or for other causes. Thisis evident from Milan, which on that day [i.e., 1st November, 1755]was threatened by the acute danger of total collapse. Let us suppose,then, that a feeble tremor there set the Earth in motion, which tremorwas sufficient to rock the ground back and forth by one inch over adistance of one hundred Rhineland rods.7 This motion would have beenso imperceptible that a building of four rods in height would not havebeen displaced from the vertical by half a grain [sic], that is, by halfthe [thickness of the] back of a knife. This would scarcely have beenperceptible on even the highest towers. However, the lakes would havemade this imperceptible motion very evident. For if a lake is only twoGerman miles long, then its water will be set into a fairly strong rockingmotion by this slight motion of its floor; for the water then has a fall ofroughly one inch in fourteen thousand inches, and a speedy only slightlyless than that of a fairly fast river, such as the Seine in Paris, whichcould teach us what, after some rocking to and fro, could have caused anextraordinary disturbance in the water. But we can assume that the earth 1:441tremor was as great again as that assumed [above] without its being felton dry land; and so the motion of the inland lakes appears all the moreintelligible.

Thus, it is no longer surprising if all the inland lakes in Switzerland,Sweden, Norway, and Germany were seen to be agitated without any

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disturbance of the ground being felt. It is, however, rather more extraor-dinary that certain lakes disappeared altogether during this disturbance,such as the lake at Neuchatel, that at Como, and that at Meiningen,although some of those have already filled up with water once again. Butthis event is not without parallel. There are some lakes in the Earth thatdisappear at certain times through hidden channels, and return at regularintervals. A notable example is Lake Zirknitz in the Duchy of Carniola.8There are some openings in its floor through which the water suddenlyruns out, complete with all its fish, but not before St James’s Day.9 Andafter it has served as good arable land for three months, the water sud-denly reappears about November. This natural phenomenon is plausiblyexplained by comparison with the siphon in hydraulics. However, for thecases under consideration it can easily be seen that many lakes are fedby underlying springs that have their source in the surrounding higherground. When the effects of subterranean heating and the vapours itcreates have consumed the air in the caverns that hold the water for thesprings, the springs will be sucked back, thereby creating a powerful suc-tion that drains the lake. And after the balance of the air [in the caverns]has been restored, the lake seeks its natural exit once again. For that alake should maintain its level by means of a subterranean connectionwith the sea because it has no external inflow from rivers, as the publicreports of Lake Meiningen have endeavoured to suggest, is obviouslyabsurd, for the laws of equilibrium as well as the salinity of the sea waterspeak against [such a view].

A common feature of earthquakes is that they cause the disturbanceof springs. I could quote a whole list of springs being blocked up andnew ones being opened up elsewhere, of spring water shooting quite1:442high out of the ground, and similar occurrences from the records ofother earthquakes, but I shall keep to my subject. It was reported fromsome places in France that some springs were blocked while others pro-duced excessive amounts of water. The spring at Toplitz [in Bohemia]stopped and the inhabitants were worried; but then the water returned,at first slimy, and then blood-red, and finally in its natural condition andstronger than before. The discoloration of water in so many places, evenin the Kingdom of Fez and in France, is in my view to be ascribed tothe intermingling of sulphur and small particles of iron, with the fer-menting vapours forcing their way through the strata through which thesprings also pass. When these vapours reach the inside of the cisternscontaining the source of the spring, they either push it out again withgreater force,z or they change its outflow by pushing the water into othercavities.

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These are the chief noteworthy events of the history of 1st Novemberand of the motion of water, which was the most remarkable of the con-comitant occurrences. It is entirely credible to me that the earthquakesthat occurred near the ocean, or the shores of any water connected tothe ocean, in Cork in Ireland, in Gluckstadt, and in several places inSpain, should be attributed chiefly to the pressure of the compressedsea water, the powera of which must be unbelievably great if one mul-tiplies the forceb with which it strikes by the area on which it strikes,and I am of the opinion that the disaster in Lisbon, like that of mostof the cities on the western coast of Europe, is to be attributed to theposition it had in relation to the disturbed area of the ocean, since itswhole force, magnified in the mouth of the Tagus by the narrowing ofthe bay, must in addition have shaken the ground to an extraordinarydegree. From this, one may judge as to whether the earthquake wouldhave been felt distinctly only in the coastal towns and not in the interior[as in fact happened], if the pressure of water had not played some partin it.

One last phenomenonc of this great event is worth noting, where aconsiderable time, one to one-and-a-half hours, after the earthquake[there arose] a fearful upsurge of water in the ocean and a rise of theTagus six feet higher than the highest tide; and soon afterwards a fall toan equal distance below the lowest tide was observed. This motion of theocean, which occurred a considerable time after the earthquake and after 1:443the first terrible pressure of the waters, completed the destruction of thetown of Setubal by overwhelming the ruins and completely destroyingeverything that the earthquake had spared. If a proper conception hasalready been formed of the violenced of the sea water’s retreat occasionedby the motion of the sea-floor, it will be easy to imagine that it must alsoreturn with great violencee after its pressure has been spread into thehuge surrounding areas, and the time of its return depends on the areathat it has affected. The fearsome extent of the tidal wave on the coastsis also dependent on the area covered.∗

the earthquake of 18th november.From 17th to the 18th of this month the public news bulletins reporteda significant earthquake on the coasts of Portugal and Spain, as wellas in Africa. It was felt at noon on the 17th in Gibraltar at the mouth

∗ In the harbour in Husum, this tidal wave was also observed between 12 and 1, that is,an hour later than the first shock in the waters of the North Sea.

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of the Mediterranean, and in the evening at Whitehaven in Yorkshirein England. [During the night] of the 17th to the 18th it was alreadyfelt in the English colonies in America. On the same 18th, it wasalso strongly felt in the region of Aquapendente and della Grotta inItaly.∗

the earthquake of 9th december.According to news reports, Lisbon has not suffered any such violentearthquakes since the 1st November as that on 9th December. Thiswas felt on the southern coasts of Spain and of France, throughout theSwiss mountains, in Swabia, and the Tyrol all the way to Bavaria. Ittravelled some 300 German miles from south-west to north-east, and,while its direction followed the range of mountains that runs along the1:444length of the highest regions of continental Europe, it did not spreadvery far sideways. The most careful geographers, Varenius,10 Buffon,and Lulof,11 note that, just as any land that extends more in lengththan in breadth, has a main range running along its length, so that theprincipal line of mountains in Europe extends from a main stem, namelythe Alps, westwards through the southern French provinces, throughcentral Spain and to the most western shore of Europe, although onthe way it sends out considerable lateral branches, and equally eastwardsthrough the Tyrolean and other less impressive mountains until it finallymeets the Carpathian range.

It was this direction that the earthquake followed that day. If the timeof the tremor had been accurately noted at each place, it would be possibleto give some estimate of its speed, and probably one could determinethe area of the initial outbreak; but the reports are so little in agreementthat they cannot be relied upon.

I have stated elsewhere that when they spread, earthquakes usually fol-low the line of the highest mountain range, and for their whole lengthat that, even though they become lower the more they approach theocean shore. The direction of long rivers is a very good indicator of thedirection of the mountain ranges, since they flow between the parallelrows of mountains as in the lowest part of a long valley. This law of thespreading of earthquakes is not a matter of speculation or judgementbut something that has become known through the observation of manyearthquakes. For this reason we ought to keep to the evidence of Ray,12

Buffon, Gentil,13 etc. But this law has so much inherent probability that itmust readily gain our approval by itself. If one considers that the openings

∗ Similarly in Glowson in the county of Hertford, where with a great noise, an abysscontaining very deep water opened.14

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through which the subterranean fire seeks a way out are only ever on thepeaks of mountains, that fire-spewing mouths have never been found onplains, that in countries where earthquakes are violent and frequent, mostof the mountains contain broad abysses that serve to throw out the fire,and that, as far as our European mountains are concerned, nowhere butin them are spacious caves found that are undoubtedly interconnected;if, in addition, one applies to all these subterranean cavities the idea 1:445of their origin discussed above, then one will find no difficulty withthe idea that the conflagration can find open and free passages princi-pally under the range of mountains that run the length of Europe, fastertherein than in other regions.

Even the continuation of the earthquake of 18th November fromEurope to America under the floor of a broad ocean can be found inthe links between mountain ranges, which, though their continuation isso low that they are covered by the sea, nonetheless remain mountainsthere, since, as we know, there are as many mountains to be found on thefloor of the sea as there are on land; and in this way, the Azores Islands,which are encountered half-way between Portugal and North America,must be connected with these [mountains].

the earthquake of 26th december.After the heating of the mineral matter had penetrated the main stemof the highest mountains in Europe, that is the Alps, it also openedfor itself the narrower passages under the row of mountains that runoutwards from it at right angles from south to north, and extended inthe direction of the Rhine, which, like all rivers, occupies a long valleybetween two rows of mountains from Switzerland to the North Sea.On the western side of the river, [the earthquake] shook the regions ofAlsace, Lorraine, the Electorate of Cologne, Brabant and Picardy, andon the eastern side, Cleve, part of Westphalia, and presumably someother countries situated on this side of the Rhine about which the newshas not reported anything specific. Evidently, it maintained a directionparallel to this great river and extended a short distance on either side.

One may ask how the foregoing can be reconciled with the fact thatit penetrated into the Netherlands, which are without any significantmountains. But it is sufficient that a country be in direct contact withcertain ranges of mountains and may be thought of as a continuation ofthese for the subterranean conflagrations to continue under the other-wise low ground, for it is certain that the chain of caverns will extendunderneath it just as, as already explained, it continues even under thefloor of the sea.

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on the intervals between successive1:446earthquakes.

If the succession of earthquakes is considered carefully, then, if onewere prepared to speculate, one might work out an interval after theconflagration broke out anew after an interim period without activity.After 1st November, we find another very violent tremor in Portugalon the 9th, similarly on the 18th, since it extended to England, Italy,Africa, and even to America; on the 27th a strong earthquake on thesouth coast of Spain, principally in Malaga. From this time onward, ittook 13 days, until on 9th December it struck the entire region fromPortugal to Bavaria, moving from south-west to north-east, and afterthis one, after another 18 days, namely on the night of 26th to 27thDecember, it shook the breadth of Europe from south to north,∗ so thata fairly accurate period of 9 or two times 9 days passed between therepeated conflagrations, if one excepts that time it took to penetrate theinnermost part of the mountains of our continent and to move the Alpsand the entire chain of its extension on 9th December. I cite this notwith the aim of concluding anything from it, but rather to provide anoccasion for observations and reflection when similar cases occur.

I intend to make only a few remarks here on those earthquakes thatalternately diminish and then begin again. Herr Bouguer,15 one of therepresentatives of the Paris Royal Academy of Sciences who visited Peru,had the discomfort in that country of residing next to a volcano, whosethundering noise allowed him no rest. But the observation he made of this1:447phenomenon offered him some compensation, in that he noticed that themountain always became quiet at regular intervals, and that its violencealternated regularly with quiet periods. The observation of Mariotte16

made with a lime kiln, which when heated up expelled air through anopen window and soon after drew it in again, thus to some extent emulat-ing the respiration of animals, is very similar to this phenomenon. Bothhave the following causes in common. When the subterranean fire isignited, it expels all the air from the surrounding caverns. When this air,filled with fiery particles, finds an opening, for example in the mouth ofa volcano, it rushes out and the mountain belches fire. But as soon as theair has been driven out from the seat of combustionf the combustion dies

∗ On the 21st it was very violent in Lisbon, on the 23rd in the mountains around Roussil-lon, and it continued there until the 27th. It can be seen from this that it began from thesouth-west once again and required much longer to spread. If we assume the place oforigin to be in the ocean to the west of Portugal, as is clear from the entire course of theearthquake, then its beginning is fairly closely connected with the interval mentioned.

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down; for without a supply of air any fire goes out; then the displaced airreturns to its place since the cause that drove it out has ceased to operateand the air rekindles the extinguished fire. In this way, the eruptions ofa volcano alternate at certain regular intervals. It is the same with thesubterranean conflagrations, even where the expanded air can find noway out through the clefts of the mountains. For, if the conflagrationbegins at one place in the caverns of the earth, it repels the air violentlyand in large quantities into all the passages of the subterranean vaultswith which it is connected. At this moment the fire is stifled by the lackof air. And as soon as this expanding force of the air diminishes, the airthat was disseminated throughout the caverns returns with great forceg

and fans the dead fire to [cause] a new earthquake. It is noteworthyh

that Vesuvius, which had been activated and ignited by the outflow ofair expelled through its mouth when the fermentations in the interiorof the Earth got properly under way, suddenly subsided a short timelater, when the earthquake had occurred in Lisbon; for at that momentall the air that was in connection with these vaults, even that above thepeak of Vesuvius, rushed through all channels to the seat [or epicentre]of the conflagration, where the reduction of the elasticity of the air gaveit access. What an amazing object! Imagine a chimney which derives itsdraught from air vents 200 [German] miles away!

Exactly the same cause must create subterranean storm winds in theEarth’s cavities, the forcei of which must far exceed anything we expe-rience on the surface, when the position and connection of the caverns 1:448lends itself to disseminating the winds. Presumably the commotion thatis felt under foot during the course of an earthquake can only be ascribedto this cause.

From this we can probably assume that not all earthquakes are causedby a conflagration immediately under the ground that is being shaken;rather, the fury of these subterranean storms can set the vaults abovethem in motion, which cannot be doubted if one considers that the air,which is far denser than that on the surface of the Earth, is set in motionby far more sudden causes, and, increased by passages that prevent itsexpansion, can exercise an untold force.j It is thus probable that theslight motion of the ground that took place in the greater part of Europeduring the violent conflagration of 1st November, was perhaps caused bynothing other than this violently agitated subterranean air, which gentlyshook the ground that was resisting its expansion in the form of a strongstorm wind.

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on the seat of the subterranean conflagrationand the places subject to the most frequent

and most dangerous earthquakes.By comparing the time[s], we see that the place at which the earthquakeof 1st November began was on the sea-bed. The Tagus, which hadalready swelled before the earthquake, the sulphur brought up by sailorsfrom the shaken sea-bed with their plumb lines, and the violence ofthe shocks they felt [all] confirm this. The history of earlier earthquakesalso makes it clear that the most terrifying earthquakes have always takenplace at the bottom of the sea and next to this, in places at or not far fromthe shores of the sea. To prove the former, I cite the raging fury withwhich a subterranean conflagration has often raised new islands fromthe sea-floor and, for example, in the year 1720 near the Azores island ofSt Michael, the expulsion of matter from the bottom of the sea at a depthof 60 fathoms, threw up an island one mile long rising to several fathomsabove sea level. The island at Santorini in the Mediterranean, which1:449emerged in our century from the depths of the sea as witnessed by manypeople, and many other examples that I will pass over for the sake ofbrevity, are indisputable proofs of this.

How often do sailors suffer a seaquake! And in some regions, espe-cially in the neighbourhood of certain islands, the seas are profuselycovered with pumice stones and other varieties of ejecta from a fire thathas broken through the ocean bed. The observation of the frequency ofearthquakes on the sea-floor is naturally related to the following ques-tion: Why is it that, of all the places on land, none are subject tomore violent and frequent earthquakes than those situated not farfrom the shores of the sea? This last statement is undoubtedly correct:if we consider the history of earthquakes we find an infinite number ofdisasters that earthquakes have brought upon cities or countries near thesea shore whereas those felt in the middle of a land mass are very fewand then of less significance. Ancient history already records the terribledevastation this [kind of] disaster has wrought on the sea coasts of AsiaMinor or Africa. But neither with them nor with more recent ones dowe find significant earthquakes in the centre of large land masses. Italy,which is a peninsula, most oceanic islands, and coastal Peru suffer thegreatest incidence of this evil. And even in our own time, all the west-ern and southern coasts of Portugal and Spain have been much moreseverely shaken than the interior of the mainland. To both questions Ipropose the following solution.

Of all the interconnected caverns under the uppermost crust of theearth, there is no doubt that those running under the bottom ofthe sea must be the narrowest, because there the continuing base ofthe solid ground has sunk to the greatest depth, and must rest far lower

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on its deepest foundation than places in the centre of the land. But it iswell known that an ignited, expanding matter must have a more violenteffect in narrow cavities than where it can expand [freely]. In addition, itis natural to suppose that, since there can be no doubt that the seethingmineral and inflammable materials will very often have become liquidwhen subterranean heating occurs, as is demonstrated by the sulphur 1:450streams and lava which often pour out of volcanoes, and, on account ofthe natural slope of the floor of the subterranean caverns, will always haveflowed to the lowest caves of the bottom of the sea, more frequent andmore violent tremors must take place there on account of the plentifulsupply of combustible material.

Herr Bouguer correctly supposes that the penetration of sea water bythe opening of some cracks in the sea-floor must bring the mineral matterthat is naturally inclined to heating into the most vigorous calefaction.For we know that nothing can stimulate the fire of heated minerals intogreater fury than the ingress of water, which increases its activity tothe point where its violence,k expanding in all directions, prevents anyfurther inflow of water by expelling all earthy matters and blocking theopening.

In my opinion, the great violencel that shakes land situated close to asea shore is partly the perfectly natural result of the weight with whichthe sea water burdens its floor which adjoins this land. For everybody willeasily recognize that the force with which the subterranean fire attemptsto raise this vault, on which such an astonishing weight rests, must bevery much restrained, and, since it cannot find any space for expansion,must turn its entire force against the base of the dry land which is mostclosely connected to it.

on the direction in which the ground isshaken by an earthquake.

The direction in which an earthquake spreads over large areas is differentfrom that in which the ground on which it exerts its forcem is shaken.If the uppermost covering of the hidden cavern in which the burningmatter is expanding has a horizontal direction, then the ground mustbe alternately raised and lowered in a vertical direction because thereis nothing that might direct the motion more to one side than to theother. But if the layer of earth that constitutes the vault is tilted, thenthe disruptive force of the subterranean fire will also push it upwardsat an oblique angle to the horizon, and one could deduce the directionin which the oscillation of the ground must occur on each occasion, if 1:451

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one had definite knowledge of the direction of slope of the layer underwhich the vault of fire is situated. The slope of the topmost surface ofthe shaken ground is no certain indication of the angle of the vault in itsentire thickness; for the layers of earth lying on top can form manifolddeclivities and hills, which the lowest layers do not follow at all. Buffonbelieves that all the different layers found on Earth have a commonbasement rock that covers all enclosed cavities below it and that someparts of it are usually exposed on the peaks of high mountains whererain and storm winds have completely eroded the loose material. Thisopinion is given strong support by the evidence of earthquakes. For aforcen so furious as that exercised by earthquakes would, by its repeatedonslaughts, long ago have shattered and eroded any vaulting other thanone made of rock.

On the coast, the slope of this vault is undoubtedly inclined towardsthe sea and thus slopes down in its direction from the place in question.On the banks of a great river, it must slope in the direction of the flowof the stream; for if one considers the very long stretches, often exceed-ing several hundred [German] miles, that the rivers run through on dryland without creating permanent pools or lakes, then there is proba-bly no other explanation for this uniform slope than the extremely firmfoundation, which, by sloping uniformly towards the bottom of the seawithout many depressions, provides the river with an inclined surface fordraining the water. For this reason, we can suppose that during an earth-quake, the motion of the ground of a city situated on a large river willbe in the same direction as that river, as in [the case of] the Tagus fromwest to east,∗ while the [motion] of a city on the sea shore will be in thedirection in which the shore slopes towards the sea. Elsewhere,17 I haveindicated what the lie of the land may contribute to the total destruc-1:452tion by an earthquake of a city in which the main streets follow theslope. This note is not merely a supposition; it is a matter of experience.Gentil, who personally had the opportunity to gather accurate informa-tion about numerous earthquakes, reports this as an observation con-firmed by many examples: that, if the direction in which the ground isshaken is the same as that in which the city has been built, it will bedemolished completely, while less damage will occur if it crosses thisdirection at right angles.

The Histoire de l’Academie Royale des Sciences in Paris reports that whenSmyrna, which lies on the eastern coast of the Mediterranean, was rocked

∗ Just as a river has a slope towards the sea, the lands on its sides have a slope towards itsbed. If this last applies to the whole layer of earth, and this has just such a slope at itsgreatest depth, then the direction of the earthquake will also be determined by this.

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in 1688, all the walls having a direction from east to west collapsed andthose that were built from north to south remained standing.

The fact is that the shaken ground makes repeated motions and movesthose things that are built lengthwise in the direction of the motion tothe greatest extent. All bodies that have great freedom of motion, e.g.,chandeliers in churches, usually show the direction in which the tremorsoccur and are much more reliable indicators for a city to determine thedirection in which it should build than the somewhat more doubtfulfactors previously mentioned.

on the connection of earthquakeswith the seasons.

Herr Bouguer, the French Academician already referred to on severaloccasions, reports in [the account of] his journey to Peru, that, eventhough earthquakes occur in this country fairly often and at all seasons,the most terrible and most frequent ones are felt in the months of autumntowards the end of the year. This observation is confirmed not only bynumerous cases in America, for apart from the destruction of the cityof Lima ten years ago, and that of another equally populous city inthe previous century, very many examples have been noted, but also inour part of the world we find, apart from the latest earthquake, manyother historical instances of earthquakes and volcanic eruptions that haveoccurred more frequently in autumn than at any other time of the year.Is there a common cause for this agreement, and to which cause can 1:453one more properly attribute the supposition than to the rains which,in the long valley between the Cordillera Mountains in Peru, last fromSeptember until April, and are also most frequent in autumn in our owncountry? We know that all that is necessary to cause a subterranean fireis to bring the mineral matter in the caverns of the Earth into a state offermentation. But this is done by the water when it has seeped throughthe clefts in the mountains and has run away through the deep passages.The rains first stimulated the fermentation that expelled so many strangevapours from the interior of the Earth in the middle of October. It wasprecisely these, however, which drew forth even more humid influencesfrom the atmosphere, and the water, which penetrated into the deepestcavities through cracks in the rock, completed the heating, which hadalready begun.

on the influence of earthquakeson the atmosphere.

We have seen above an example of the effects of earthquakes on ouratmosphere. It is probable that more natural phenomena are dependent

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on the eruptions of the subterranean heated vapours than is generallysupposed. It would hardly be possible for there to be such great irregu-larity and so little consistency in the weather if external causes did notoccasionally enter our atmosphere and bring disorder into its properchanges. Can one imagine a likely reason why the sequence of meteoro-logical changes is almost always different even in a sample of many years,whereas the course of the Sun and the Moon is bound by laws that arealways the same and water and earth, taken generally, always remain con-stant? Since the unfortunate earthquake and shortly before it, we havehad such abnormal weather over our entire continent that one mightbe forgiven for suspecting that the earthquakes were responsible. It is truethat there has been warm winter weather before without any earthquakehaving preceded it; but can one be sure that there was not a fermenta-tion in the interior of the Earth that frequently drove vapours throughclefts in rocks, through the cracks in the layers of the earth and eventhrough its loose substance, and that these might have caused significant1:454changes in the atmosphere? After observing that in the present centuryalone, and indeed only since 1716, very bright Northern Lights havebeen seen in Europe all the way to its southern lands, Muschenbroeck18

regards the most probable cause of this change in the atmosphere tobe the volcanoes and the earthquakes, which had frequently been activesome years previously, and had emitted flammable and volatile vapours;and because of the natural northward flow of the upper atmosphere,the vapours had accumulated there and brought about the fiery atmo-spheric phenomena which have been seen so frequently since that time,and these will presumably be gradually consumed until new exhalationsreplace what has been used up.

In accordance with these principles, let us examine whether it is notin keeping with nature that changing weather such as we have had is aresult of that catastrophe. The bright winter weather and the accompa-nying cold is not merely a consequence of the greater distance of theSun from our zenith at this time of the year, for we often perceive thatdespite this the air can be very temperate; rather, the draught of air fromthe north, which sometimes can also turn into an east wind, brings uscooled air from as far away as the Arctic Circle that covers our waterswith ice and makes us feel some of the winter of the North Pole. Thismotion of air from north to south is so natural in the autumn and wintermonths if external causes do not interrupt it, that this north or north-eastwind is encountered continually throughout this period in the [Atlantic]Ocean at a considerable distance from any dry land. It originates quitenaturally from the effect of the Sun, which at that time is making theair less dense over the southern hemisphere and thus causes it to flowfrom the northern hemisphere: so that this must be considered to be auniform law which, though it might be altered to some extent by the

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features of the various countries, cannot be reversed. Now if subter-ranean fermentations eject heated vapours somewhere in the countriesto the south, then these will initially reduce the atmospheric pressureo

in the region where they rise by weakening the elasticity [of the air] andcausing cloudbursts, hurricanes, and so on. Subsequently, however, thispart of the atmosphere, since it is weighed down with so many vapours,will move the neighbouring air by its density and cause a flow of air fromsouth to north. But since the motion of the atmosphere from north tosouth is natural in our region at this time of the year, these two mutually 1:455opposed motions will act against one another and result initially in dull,rainy air because of the concentrated vapours, and at the same time ina high level of barometric pressure,∗ because the air, which has beenpressed together by the conflict of two winds, must form a high column;and for this reason, people will learn to accept the apparent error ofthe barometer, when there is rainy weather even though the barometeris high, because then this same humidity of the air is an effect of twoconflicting winds which drive the vapours together and can nonethelessmake the air significantly denser and heavier.

I cannot pass over in silence the fact that on that terrible All Saints’Day the magnets in Augsburg cast off their burden and the compasseswere disoriented. Boyle19 has previously reported that something similaronce occurred after an earthquake in Naples. We do not know enoughabout the hidden nature of the magnet for us to be able to give a reasonfor this phenomenon.

on the uses of earthquakes.People will be shocked to find such a terrible scourge of humanity praisedfrom the point of view of utility. I am sure that people would gladly dowithout it in order to be relieved of the fear and the associated dan-gers. Such is our nature as human beings. Once we have laid an illegiti-mate claim to all the pleasant things in life, we are not prepared to paythe cost of any advantages. We demand that the Earth’s surface shouldbe so constituted that one might wish to live on it forever. In addition,we imagine that we would better regulate everything to our advantage,if fate had asked for our vote on this matter. Thus we wish to havee.g. the rain in our power so that we could distribute it over the whole yearin accordance with our convenience and so could always enjoy pleasantdays between the dull ones. But we forget the wells, which we cannot dowithout and which would not be maintained under this system. Equally

∗ This has been observed almost constantly in this wet winter weather.

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we do not know the use which is brought to us by the same causes that1:456frighten us in the case of earthquakes, and yet we should like to see thelatter abolished.

As human beings, who were born to die, we cannot tolerate the factthat some died in the earthquake, and as strangers here who possess nogoods we are inconsolable that goods were lost which in the generalnature of things would soon have been left behind anyway.

It is easy to guess that, if people build on ground that is filled withflammable matters, then sooner or later the whole glory of their build-ings could be destroyed by earthquakes; but must we therefore becomeimpatient with the ways of providence? Would it not be better to con-clude that it was necessary for earthquakes to occur occasionally on theEarth, but it was not necessary for us to erect splendid houses on it? Theinhabitants of Peru live in houses that are built with mortar only up toa low height and the rest consists of reeds. Man must learn to adapt tonature, but he wants nature to adapt to him.

Whatever damage earthquakes may, on the one hand, ever have causedfor man, they can, on the other hand, easily replace with interest. Weknow that the warm baths, which over the course of time may have beenuseful to a significant proportion of mankind in promoting health, derivetheir mineral properties and their heat from just the same causes that areat work in the heating of the Earth’s interior, which set these [waters] inmotion.

It has long been suspected that the veins of ore in the mountains are aslow effect of the subterranean heat, which brings the metals to maturitythrough a gradual process of shaping and boiling them by means ofpenetrating vapours in the rock’s interior.

In addition to the coarse and dead matters it contains, our atmospherealso needs a certain active principle, volatile salts and parts that enterinto the composition of plants, to move and developp them. Is it notlikely that the natural forms that continually expend a large part of it,and the changes that all matter ultimately undergoes through dissolutionand composition, would in time entirely use up the most active parti-cles if there were not a fresh influx from time to time? The soil at least1:457becomes less and less potent when it feeds strong plants, but rest andrain restore it again. But where, finally, would the potent material thatis used without replacement come from if there were no other sourceto maintain its supply? And this source is presumably the store of thesemost active and volatile substances which the subterranean caverns con-tain, some of which they distribute from time to time over the surfaceof the Earth. I also note that Hales20 has had great success in purifying

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gaols and indeed all other places affected by animal exhalations by fumi-gating them with sulphur. Volcanoes expel an immeasurable amountof sulphurous vapours into the atmosphere, [so] who knows whetherthe animal exhalations with which the air is laden would not eventuallybecome harmful if the volcanoes did not provide a powerful antidote tothem?

Finally, it seems to me that the heat in the interior of the Earth pro-vides a powerful proof of the effectiveness and great utility of the heatingthat takes place in the deep caverns. Daily experience shows that in thegreat, indeed the greatest depths that men have reached in the inte-rior of mountains, there is a permanent heat which cannot possibly beascribed to the effect of the Sun. Boyle cites a good deal of evidence whichshows that, in all the deepest shafts, the upper region is found to bemuch cooler than the outside air in the summer, but that the deeperone descends, the warmer the region, so that at the greatest depths, theworkers are obliged to take off their clothing while they work. Everyonewill easily grasp that, since the warmth of the Sun penetrates the Earth toonly a very slight depth, it cannot have the slightest effect in the very low-est caverns, and the fact that the warmth encountered there is the resultof a cause that prevails only in the greatest depths can also be seen fromthe reduced warmth that is experienced the more one ascends even inthe summer. After carefully comparing and examining the experimentscarried out, Boyle concludes very reasonably that, in the lowest caverns,which are inaccessible, there must be constant heating processes and aninextinguishable fire maintained thereby which transmits its warmth tothe uppermost crust.

If this is indeed the case, as one cannot but concede, will we not be ableto expect the most beneficial effects from this subterranean fire, whichalways maintains a gentle warmth for the Earth at the time when the 1:458Sun withdraws its warmth from us, and which is able to encourage thegrowth of plants and the economy of the natural realms? Since so muchutility is apparent, can the disadvantage that accrues to the human racethrough one or other eruption, exempt us from the gratitude we owe toProvidence for all the measures it employs?

The reasons I have cited to encourage [such gratitude] are naturallynot of a kind to furnish the greatest conviction and certainty. However,even suppositions are acceptable if the aim is to move mankind to a desirefor gratitude towards that supreme being that is worthy of respect andlove even when it chastises [us].

note.I mentioned above that earthquakes force sulphurous exhalationsthrough Earth’s cavities. The latest information from the mining shafts

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in the mountains of Saxony confirms this by means of a new example.They are now so full of sulphurous vapours that the workers have hadto abandon them. The occurrence at Tuam in Ireland, when a shiningatmospheric phenomenon appeared in the shape of pennants and flagsover the sea, changed colour gradually, and finally spread a bright light,whereupon a violent earth tremor ensued, is a new confirmation of this.The change of colour from the darkest blue to red and finally into abright white light can be attributed to the exhalation that was initiallyvery thin when it erupted and then gradually increased by the more fre-quent influx of further vapours; as is well known to science, these vapoursmust go through all degrees of light from blue to red and finally to a shin-ing white. All this occurred before the tremor. It was also proof that theseat of the conflagration was at the bottom of the sea, as the earthquakeitself was mainly felt on the coast.

If one were to extend the list of places on the Earth that have alwaysexperienced the most frequent and most violent tremors, one might addthat the western coasts have always suffered far more incidents than the1:459eastern coasts. In Italy, Portugal, in South America, and even recently inIreland, experience has confirmed this correspondence. Peru, which issituated on the western coast of the New World has almost daily tremors,while Brazil, which has the Atlantic Ocean to its east, experiences nothingof this. If one were to conclude any causes from this curious analogy,then one might well forgive one Gautier,21 a painter, when he seeksthe cause of all earthquakes in the rays of the sun, the source of hiscolours and his art, and imagines that it is precisely these that drive ourgreat sphere around from west to east by striking the western coastsmore strongly, which is allegedly the reason why those coasts are upsetby so many tremors. In a healthy natural science, however, such an ideascarcely merits refutation. The reason for this law seems to me to beconnected with another one, for which there is no sufficient explanationas yet: namely that the western and southern coasts of nearly all countriesare steeper than the eastern and northern coasts, which is confirmed bya glance at the map as well as the reports of Dampier,22 who, on all hismaritime journeys found this to be almost universal. If one derives thedepressions on dry land from subsidences, then in the regions with thegreatest declivity, deeper and more numerous caves must be encounteredthan in places where the Earth’s crust has only a gentle slope. But thishas a natural connection with earthquakes, as we saw above.

concluding observation.The sight of so many wretched people as the latest catastrophe causedamong our fellow citizens ought to arouse our philanthropy and makeus feel some of the misfortune that afflicted them with such cruelty. But

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we go against this very much if we always regard this sort of destiny asa punishment meted out, which afflicts the destroyed cities on accountof their evil deeds, and if we regard these unfortunates as the target ofGod’s vengeance over whom his justice pours out all its wrath. Thiskind of judgement is a culpable impertinence that arrogates to itselfthe ability to understand the intentions behind divine decisions and tointerpret them according to its own opinions.

Man is so opinionated that he sees only himself as the object of God’s 1:460activities, just as if the latter had only him to take account of in devisingthe appropriate measures for the ruling of the world. We know thatthe whole essenceq of nature is a worthy object of divine wisdom andits activities. We are a part of this and try to be all of it. The rules ofperfection in nature at large are regarded as irrelevant, and everythingis to be seen merely in relation to ourselves. All the things in the worldthat provide comfort and pleasure, people imagine to be there only forour sakes, and nature supposedly does not undertake any changes thatmight be any sort of cause for discomfort for mankind except to punishus, threaten us, or to wreak vengeance on us.

Nonetheless, we see that an infinite number of evildoers sleep in peace,the earthquakes have shattered certain countries since time immemorialwith total indifference to the old and new inhabitants, that ChristianPeru is shaken just as much as the heathen part, and that many citieshave been spared this devastation from the beginning, cities that couldnot presume to be any less punishable than others [that were destroyed].

Thus man is in the dark when he tries to guess the intentions that Godenvisages in the ruling of the world. We are, however, in no doubt whenit is a question of applying these ways of providence in accordance withits purpose. Man is not born to build everlasting dwellings on this stageof vanity. Since his entire life has a far nobler aim, how well does thisharmonize with all the destruction fit into this which allows us to see thetransience of the world in even those things that seem to us the greatestand most important and to remind us that the goods of this world cannotprovide any satisfaction for our desire for happiness!

I am in no way implying that man is subject to an unchanging fateof natural laws without respect to his particular virtues.r That samesupreme wisdom from which the course of nature derives that accuracythat requires no correction, has subordinated lower purposes to higherones, and in just those intentions in which the former has often madethe most significant exceptions to the general rules of nature in orderto attain those infinitely higher aims that far surpass all the resources 1:461of nature, in those intentions the leaders of the human race will alsoprescribe laws in their government of the world to regulate even the

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course of natural things. When a city or country perceives the disasterwith which divine providence terrifies it or its neighbours, can therebe any doubt as to the party it should support in order to prevent thethreatened destruction, and will the signs still be ambiguous that makethose comprehensible intentions to whose implementation all the pathsof providence unanimously either invite or drive mankind?

A prince who, activated by a noble heart, allows himself to be moved bythese hardships of the human race to avert the miseries of war from thosewho are threatened on all sides by serious misfortune, is a beneficent toolin the gracious hand of God, and a divine gift to the peoples of the earthwho can never assess its worth in keeping with its magnitude.

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8

Continued observations on the earthquakesthat have been experienced for some time

editor’s introductionKant’s third and final essay on earthquakes was published in the 10 and17 April issues of the Wochentliche Konigsbergische Frag- und Anzeigungs-Nachrichten and continues the reflections presented in the previous twoessays. Kant’s primary concern in this essay is to refute various compet-ing opinions about earthquakes, specifically, those by Gottfried Profeand Pierre Bouguer. His main objection to Profe, who claims that thealignment of the planets was responsible for the Lisbon earthquake, andto Bouguer, who agrees with an unnamed Peruvian author that the Mooncould bear some responsibility for this event, is that if one calculates theactual gravitational effect that either the planets, fully aligned, or theMoon by itself would have, the effect would be minuscule and certainlymuch too small to be a significant cause of such a large effect. Moreover,Kant notes, a report by Gassendi suggested that a rare conjunction of thethree outer planets, which had occurred in 1604, resulted in no signifi-cant earthquakes, thus contradicting Profe’s theory. Kant concludes histreatment of earthquakes with a brief reiteration of the main contoursof his theory.

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Magister Immanuel Kant’s 1:463

Continued Observations

on the

Earthquakesthat have been experienced for some time.

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The fire of the subterranean vaults has not yet subsided. The tremors1:465continued until recently and terrified countries where this evil was previ-ously unknown. The disorder in the atmosphere has altered the seasonsin half of the world. Those who know least claim to have guessed thecause. Some can be heard to declare without reflection or understandingthat the Earth has shifted its position and come closer to the Sun by Idon’t know how many degrees; a judgement worthy of a Kindermann,1were he to arise again to peddle the dreams of a deranged mind as obser-vations. In the same category are those who bring comets back into playsince Whiston2 has taught even the philosophers to fear them. It is acommon extravagance to import the source of an evil from several thou-sand miles away when it can be found in the neighbourhood. This is whatthe Turks do with the plague; this is what people did with the locusts,with the livestock disease, and with God only knows what other evils.People are reluctant to perceive something that is merely close at hand.To detect causes at an infinite distance is the only proper proof of anastute understanding.

Among all the conjectures that, by differing significantly from therules of proper science, can easily deceive people who do not know howto test them, is the notion attributed in the press to Herr Professor Profeof Altona.3 It is admittedly a long time since the observation of majorevents on Earth caused suspicion to be thrown on the planets. The listsof harsh accusations our revered ancestors, the astrologers, have madeagainst these bodies have been filed in the archive of antiquated fantasiesalong with the true story of fairies, the sympathetic miracles of Digby41:466and Vallemont,5 and the nocturnal events on the Blocksberg.6 But sincenatural science has been purged of these foolish ideas, a Newton hasdiscovered and confirmed empirically a real force which even the mostdistant planets exercise on each other and on our Earth. However, tothe great misfortune of those who wish to make extravagant use of thisnoteworthy property, the magnitude of this force and the manner of itsoperation are defined, with the assistance of geometry, by the very sameobservation[s] to which we owe its [original] discovery. Now no one canany longer make us believe whatever they like about its effects. We havethe balance in our hand by which we can weigh up the effects against thegiven cause.

If someone, who had been told that the Moon attracts the waters of theEarth and in this way causes that rising and falling of the ocean that wecall the tides, and further that all the planets are endowed with a similargravitational force, and, when they are close to a straight line drawnthrough the Earth and the Sun7 combine their gravitational forces withthat of the Moon, if, I say, such a person, with no ambition to examine thematter more closely, were to suppose that these combined forces were

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Continued observations on the earthquakes

able not only to bring the waters on the Earth into the violents motion weobserved on 1 November, but also to ignite the hidden tinder by meansof some influence on the subterranean air so as to cause an earthquake,then no more can be asked of such a person. But one expects more froma student of nature.t It is not sufficient to have stumbled upon a causethat has some similarity with the effect; it must also be proportional inits magnitude. I shall quote an example. Dr Lister,8 an otherwise ablemember of the Royal Society of London, had observed that the marineplant called sea lentil has an unusually strong scent. He noticed that itis frequently found on the tropical coasts. Now, since a strong scent canprobably move the air a little, he concluded that the prevailing east windthat blows constantly in these seas and extends more than a thousandmiles from the land, stems from this cause, especially since this plantturns with the Sun. The absurdity of this opinion is simply that the cause 1:467is out of all proportion to the effect. The same applies to the force of theplanets when compared to the effect that is supposed to derive from it,namely that of moving the seas and causing earthquakes. Perhaps peoplewill say: do we know the strength of the force with which these celestialbodies can act upon the Earth? I shall reply to this question shortly.

Herr Bouguer,9 a celebrated member of the French Academy, relatesthat during his stay in Peru, a learned man who wished to become Pro-fessor of Mathematics at the University of Lima had written a bookentitled An Astronomical Clock of Earthquakes, in which he undertook topredict earthquakes from the orbit of the Moon. It is easy to guess thatit is all very well for a prophet in Peru to predict earthquakes, as theyoccur there almost daily and differ only in their strength. Herr Bougueradds that anyone who, without much thought, bandies about ideas con-cerning the rising and falling node of the Moon, proximity and distanceto the Earth, conjunction and opposition, might happen at times to saysomething that is confirmed by events, and he [Bouguer] admits thathe [the Peruvian author] has not always predicted incorrectly. He him-self conjectures that it is not altogether unlikely that the Moon, whichmoves the waters of the ocean so strongly, may have some influence onearthquakes, either by carrying the water, which it raises to extraordinarylevels, into cracks in the Earth that it would otherwise not reach, and thatthis causes the raging motion in the deep caves, or by some other kind ofconnection.

If one considers that the gravitational forces of the celestial bodiescan act on the innermost parts of matter and thus move the air in thedeepest and most inaccessible passages of the Earth, then one can hardlydeny the Moon some influence on earthquakes. But this force would at

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most merely stimulate the flammable matter within the Earth, and theremainder, the tremors, the motion of the water, will only be an effectof this latter.

If one ascends from the Moon to the sphere of the planets, this capacitygradually disappears as the distances increase, and the combined forcesu

of all the planets produce only an infinitely small fraction of the effect1:468produced by the single Moon which is so close to us.

Newton, who discovered the admirable law of gravity, which mustbe regarded as the most fortunate attempt the human intellect has yetmade in understanding nature, teaches us how to calculate the gravi-tational force of the planets that have moons around them and he hasestablished that of Jupiter, the largest of all the planets, to be somewhatless than one thousandth part of the gravitational pull of the Sun. Theability to bring about changes on our Earth through this force decreasesin inverse proportion to the cube10 of the distance and is thus, in thecase of Jupiter, which is more than five times further from the Earththan is the Sun, and if one takes the ratio of its gravitational force intoaccount, 130,000 times smaller than what the gravitational force of theSun alone can effect on our Earth. Now, on the other hand, the attrac-tion of the Sun can raise the level of the water in the ocean by abouttwo feet, as we know from experience combined with calculations; thusthe attraction of Jupiter, when combined with that of the Sun, wouldadd one 65th of a decimal scruple11 to this level, which would amountto approximately one thirtieth of a hair’s breadth. If one considers thatMars and Venus are much smaller bodies than Jupiter and that theirgravitational forces are proportional to their masses,v then one is stillgoing too far if one attributes to both together approximately twice asmuch capacity to affect our Earth by their gravity as Jupiter, becausethey are roughly three times closer, even though they have many hun-dred times less bodily content and hence gravitational force. But evenif I were generous enough to make their force ten times greater, theycould not, even combined, raise the level of the sea water by one third ofa hair’s breadth. If one adds the remaining planets, Mercury and Saturn,and considers them all in conjunction, then it becomes clear that theycould not nearly increase the rise in the water brought about by the Sunand the Moon together by one half of a hair’s breadth. Is it not ridicu-lous to fear frightening motions of water resulting from the attractionof the Moon and the Sun, when the level to which they raise the waterhas been increased by one half of a hair’s breadth, whereas without thesethere would [supposedly] be no danger to worry about? All other circum-stances completely contradict the alleged cause. Just as the Moon causes1:469

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the highest tides not merely at the moment when it is closest to the[imaginary] straight line drawn through the Sun and the Earth, but doesso for some days before and afterwards, so also the combined [force ofthe] planets should have caused motions of water and earthquakes onseveral successive days and for several hours at each of them, if they hadhad any part in it.

I must beg my readers’ pardon for having led them so far aroundthe firmament to enable them to judge correctly events that have takenplace on our Earth. The effort one applies to stop up the sources oferrors also provides us with purified cognition. In the following piece,I shall consider the most noteworthy appearances of the great naturalevent that have occurred since those which I attempted to explain in aseparate article.

The planets have been acquitted before the tribunal of reason of havinghad any part in the devastation that befalls us in earthquakes. From nowon let no one suspect them again in this connection. There have prob-ably been several planets in conjunction on previous occasions withoutany earthquake being felt. According to Gassendi,12 in 1604 Peiresc13

observed the rare conjunction of the three outer planets, which occursonly once every eight hundred years, but the Earth remained safe. Ifthe Moon, upon which alone such suspicion might fall with some plau-sibility, did have a part in it, then the contributing causes would haveto be present in such full measure that even the smallest external influ-ence could provide the impetus for the change. For the Moon frequentlycomes into the position in which it exercises a maximum effect on thesurface of the Earth, but it does not produce earthquakes nearly so often.The quake of 1 November occurred soon after the last quarter, but atthat time the Moon’s influence is at a minimum, as Newton’s theoryand observation show. Let us therefore look for the cause in our placeof habitation itself, for we have the cause beneath our feet.

Since the earthquakes mentioned previously, none have occurred thathave extended further afield than that of 18 February. This was feltin France, England, Germany, and the Netherlands. As reported fromnumerous places such as Westphalia and the regions of Hanover and 1:470Magdeburg, it was also more like a gentle rocking of ground movedby violent subterranean storms than the explosions of burning material.Only those in the top floors of buildings felt the rocking; it was hardlynoticed on the ground below. Already on the preceding 13th and 14th,tremors were felt in the Netherlands and neighbouring places, and onthose days, especially from the 16th to the 18th, widespread hurricanesraged in Germany, Poland, and England, and lightning and tempestsoccurred; in short, the atmosphere had been brought into a kind offermentation, which may serve to confirm what we have already notedelsewhere, namely that earthquakes or the subterranean conflagrations

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that are their cause, alter our atmosphere by injecting foreign vapoursinto it.

From time to time subsidences have occurred in the soil. Pieces of rockhave broken loose from the mountains and have rolled into the valleyswith terrible force. Besides, such events often take place without any pre-ceding earthquakes. Continuous rain often causes the channels supplyingthe wells,w filled with water, to undermine the base of an area of land bywashing out the soil, and likewise to tear pieces of rock from the tops ofmountains, especially when the effects of frost and water are combined.The great crevasses and clefts that have opened up and usually closed overagain in Switzerland and other places are clearer proofs of an expansivesubterranean powerx as a result of which the layers of somewhat lesserdensity have fractured. If we consider this fragility of the ground we standon, the store of subterranean heat that might everywhere maintain thecombustible materials, seams of coal, resins and sulphur in a constantlyblazing fire (just as coal mines, when they have ignited spontaneously inthe air, will often smoulder and burn outwards for centuries), if, I say,we consider this constitution of the subterranean caverns, would not a[mere] nod be enough to plunge our vaults into whole seas of glowingsulphur and to devastate our inhabited places with streams of burningmaterial, just as the ejected lava destroyed the villages that were builtat the foot of Mount Etna in undisturbed tranquillity? Herr Dr Pollis right, when, in a short treatise on earthquakes, he demands nothing1:471more than water to set the ever-glowing embers beneath the earth inmotion by means of expanding water vapours and cause the earth totremble; when, however, he tries to invalidate Lemery’s experiment14

(which explains the tremors by adding water to a mixture of sulphur andiron filings) by saying that no pure iron is encountered in the earth butonly iron ore, which does not produce the required result in this exper-iment, then I would ask him to consider whether the manifold causeof the heating, e.g., the weathering of iron pyrites, the fermentationsthrough the admixture of water, as is detected in ejected lava after rainand likewise in the permanent fire of Pietra Mala, after it has meltedthe deep-seated iron ore to granulated iron, or even magnetite, which isvery like pure iron and which is doubtless to be encountered plentifullyin the depths, is not able to provide sufficient material for carrying outthis experiment on a large scale. The most curious observation reportedfrom Switzerland that a magnet, together with the thread from which itwas hanging, deviated several degrees from its vertical direction duringan earthquake, seems to confirm the involvement of magnetic materialsin earthquakes.

w Quelladern x Gewalt

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It would take a large volume to cite and examine all the hypothesesthat have been proposed in order to forge new paths of research, andthat often succeed each other like the waves of the sea. There is alsoa certain good taste in the natural sciences which knows at once howto distinguish the unbridled excesses of a craving for novelty from thesecure and careful judgements that have the evidence of experience andof rational credibility on their side. Father Bina,15 and only recentlyHerr Professor Kruger,16 have ascribed earthquakes and electricity tothe same causes. There is an even greater temerity in the suggestion ofHerr Prof. Hollmann,17 who, having demonstrated the usefulness of airvents in soil ignited by inflamed materials by the example of volcanoes,without which the Kingdoms of Naples and Sicily would no longer exist,then maintains that the uppermost crust of the Earth ought to be dugthrough, down into the deepest burning clefts, so as to provide a way 1:472out for the fire. The great thickness, together with the hardness of theinterior layers, without which such cruel attacks of earthquakes wouldhave destroyed such a country long ago, and likewise the water thatsoon puts an end to all digging operations, and finally the incapacityof human beings, make this suggestion [no more than] a fine dream.From the Prometheus of modern times, Herr Franklin,18 who soughtto disarm the thunder, to that man who sought to extinguish the firein Vulcan’s workshop, all such endeavours are proofs of the boldness ofman, allied with a capacity which stands in a very modest relationshipto it, and ultimately they lead him to the humbling reminder, which iswhere he ought properly to start, that he is never anything more than ahuman being.

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9

New notes to explain the theory of thewinds, in which, at the same time, he

invites attendance at his lectures

editor’s introductionThis set of notes was published on 25 April 1756 as part of Kant’s adver-tisement for the lectures he was planning to give at the university in thesummer semester of that year. For this reason, it is appropriate that at theend of these notes he announced the textbooks that he would be using forhis lectures on physics, logic, and metaphysics. Kant used no textbook forhis lectures on physical geography, since none was approved to that end,and he always used Wolff for mathematics, most likely Wolff ’s Auszugaus den Anfangsgrunde aller mathematischen Wissenschaften [Excerpt fromthe First Principles of All Mathematical Sciences].1

Kant does not present a comprehensive theory of winds in this essay.Instead, over the course of five notes, he attempts to explain a series ofspecific meteorological phenomena, sometimes in novel ways. (In eachcase, he cites independent experience to confirm the principle that iscentral to each explanation.) Accordingly, he claims that the directionof coastal winds – onshore or offshore – depends on the expansion andcontraction of air that is caused by differences in the rate of heating andcooling of the land and the water at sea during the day and at night(first and second notes). He also explains the difference in (east–west)direction arising for winds moving from the Equator towards either ofthe Poles and vice versa that is due to the rotation of the earth (thirdnote) – a phenomenon that was later described in terms of the Corioliseffect– as well as the easterly direction of the trade winds (fourth note).Finally, Kant provides an account of monsoon winds (fifth note).2

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6 on the causes of earthquakes on the occasion of the...

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