Natural Questions Chapter 26

Poteram ad hoc probandum abuti auctoritate magnorum uirorum, qui Aegyptum numquam tremuisse tradunt. Rationem autem huius rei hanc reddunt, quod ex limo tota concreuerit. Tantum enim, si Homero fides est, aberat a continenti Pharos quantum nauis diurno cursu metiri plenis lata uelis potest; sed continenti ammota est: turbidus enim defluens Nilus multumque secum caeni trahens et id subinde apponens prioribus terris Aegyptum annuo incremento semper ultra tulit. Inde pinguis et limosi soli est nec ulla interualla in se habet sed creuit in solidum arescente limo; cuius pressa erat et sedens structura, cum partes glutinarentur, nec quicquam inane interuenire poterat, cum solido liquidum ac molle semper accederet. Sed mouetur et Aegyptus et Delos, quam Uergilius stare iussit: "immotamque coli dedit et contemnere uentos"; hanc philosophi quoque, credula natio, dixerunt non moueri auctore Pindaro. Thucydides ait antea quidem immotam fuisse sed circa Peloponnesiacum bellum tremuisse; Callisthenes et alio tempore ait hoc accidisse: "Inter multa", inquit, "prodigia, quibus denuntiata est duarum urbium, Helices et Buris, euersio, fuere maxime notabilia columna ignis immensi et Delos agitata"; quam ideo stabilem uideri uult, quia mari imposita sit habeatque concauas rupes et saxa peruia, quae dent deprehenso aeri reditum: ob hoc et insulas esse certioris soli urbesque eo tutiores quo propius ad mare accesserint. Falsa haec esse Pompei et Herculaneum sensere. Adice nunc quod omnis ora maris obnoxia est motibus: sic Paphos non semel corruit; sic mobilis et huic iam familiaris malo Nicopolis; Cyprum ambit altum mare et agitatur; Tyros et ipsa tam mouetur quam diluitur. Hae fere causae redduntur propter quas tremat terra.

Je pourrais ici m’appuyer fort au long de grandes autorités, lesquelles nous disent que jamais le sol de l’Égypte n’a tremblé. La raison qu’elles en donnent, c’est qu’il est tout entier formé de limon. En effet, s’il faut en croire Homère, Pharos était éloignée du continent de tout l’espace que peut franchir en un jour un vaisseau voguant à pleines voiles ; elle fait maintenant partie de ce continent. En effet, les eaux bourbeuses du Nil, chargées d’une vase épaisse qu’elles déposent incessamment sur le sol primitif, l’ont toujours reculé par ces alluvions annuelles. Aussi ce terrain, gras et limoneux, n’offre-t-il aucun interstice ; enrichi d’une croûte solide à mesure que se desséchait la vase, d’une couche concrète et cohérente par l’agglutination de ses molécules, aucun vide ne s’y put former, puisque toujours aux parties sèches venaient s’ajouter des matières liquides et molles. Cependant et l’Égypte tremble et aussi Délos, que de son chef Virgile déclare Immobile, sacrée, inébranlable aux vents . Les philosophes aussi, race crédule, en avaient dit autant, sur la foi de Pindare. Thucydide prétend que, jusque-là toujours immobile, elle trembla vers le temps de la guerre du Péloponnèse. Callisthène parle d’une autre secousse à une époque différente. « Parmi les nombreux prodiges, dit-il, qui annoncèrent la destruction d’Hélice et de Buris, les plus frappants furent une immense colonne de feu, et la secousse que ressentit Délos. » Selon lui, cette île demeure ferme, parce que, sur la mer où elle est assise, elle a pour bases des roches poreuses et des pierres perméables où l’air s’engage et d’où il peut sortir ; qu’ainsi encore le sol des îles est mieux assuré, et les villes d’autant plus à l’abri des secousses, qu’elles sont plus voisines de la mer. Assertion fausse, comme ont pu le sentir Herculanum et Pompeï. Toutes les côtes, au reste, sont sujettes aux tremblements de terre. Témoin Paphos, renversée plus d’une fois, et la fameuse Nicopolis, pour qui c’était un fléau familier. Cypre, qu’environne une mer profonde, n’en est pas exempte, non plus que Tyr elle-même, quoique baignée par les flots. Telles sont à peu près toutes les causes que l’on assigne aux tremblements de terre.

To prove my point I might have used, somewhat unfairly perhaps, the authority of the great writers who relate that Egypt never experienced an earthquake shock, the reason they allege for it being that it is all composed of mud. If one may believe Homer, Pharos used to be as far from the mainland as a ship under full sail could reach in a day’s voyage; but it has now become attached to the mainland. The Nile’s swollen stream brings down great quantities of mud, and by adding it from time to time to the existing land it has by an annual increase constantly carried forward the coast of Egypt. The country thus is composed of rich loamy soil without interstices, as it has become solid just by the drying up of the mud. The composition of the mud was close and firm, the particles of it being stuck together; no vacant space could intervene, since the solid was always being added to by the liquid and soft slime. But Egypt is, as a matter of fact, subject to earthquake; and Delos, too, though Virgil bade it stand fast, And granted that it should be a settled land of tillage, and should laugh the winds to scorn. The philosophers, too, a credulous set of people, relying on Pindar’s authority, said that it did not experience movement. Thucydides asserts that in former times it was unshaken, but sustained a shock about the time of the Peloponnesian War. Callisthenes asserts that the same thing happened on another occasion also. Among the numerous portents--these are his words--by which warning was given of the overthrow of the two cities Helice and Buris, the most remarkable were the appearance of a huge pillar of fire and the earthquake shock in Delos. Yet he will have it that the island is comparatively firm for the reason that it is placed on the sea and has hollow crags and porous rocks, which afford a way of escape to air imprisoned in them. For this reason, too, islands have, he thinks, a firmer soil, and cities are safer in proportion to their proximity to the sea. The falsity of such an opinion surely Pompeii and Herculaneum learned to their cost. Add now the fact that every sea-coast is particularly subject to earthquakes. Paphos, for instance, was more than once ruined, and the famous Nicopolis is already intimately acquainted with this mischief. Cyprus is surrounded by a deep sea, but is subject to shocks. Tyre is as regularly shaken by earthquake as it is washed by the waves. Such, then, are for the most part the explanations that have been suggested for the trembling of the earth.