To a very preponderant class in the civilised world no knowledge is of much interest or value that does not point to what is called a "practical result," one measurable into utility or coin. I do not stop to remark as to the bad or as to certain good results of this tendency of mind; but I may venture to point out to all, that the exact knowledge of the nature of earthquake motion, even during the short time that it has become known, has not been barren in results absolutely practical and utilitarian. The minute investigation of the destruction of buildings, etc., and the deductions that have been made as to the relations between the form, height, materials, methods of building, combination of timber and of masonry, and many other architectural or constructive conditions, have made it certain now that earthquake-proof houses and other edifices can be constructed with facility, and at no great increase, if any at all, of cost. I can affirm that there is no physical necessity why in frequently and violently shaken countries, such as Southern Italy or the Oriental end generally of the Mediterranean, victims should hereafter continue by thousands to be sacrificed by the fall of their ill-designed and badly built houses.
Were a "Building Act" properly framed, put in force by the Italian Government in the Basilicatas and Capitanata, etc., so that new houses or existing ones, when rebuilt, should be so in accordance with certain simple rules, a not very distant time can be foreseen when Earthquakes, passing through these rich and fertile but now frequently sorely afflicted regions, should come and go, having left but little trace of ruin or death behind. Some disasters there must always be, for we cannot make the flanks of mountains, nor the beds of torrents, etc., always secure; but the main mortality of all Earthquakes is in the houses or other inhabited buildings. Make these proof, and the wholesale slaughter is at an end.
The principles we have established have been thus practically applied in another direction. The Japanese Government, with the keen and rapid perception of the powers inherent in European science which characterises now that wonderful people, has commenced to illuminate its coasts by lighthouses constructed after the best European models. But Japan is greatly convulsed by earthquakes, and lighthouses, as being lofty buildings, are peculiarly liable to be destroyed by them.
The engineer of the Japanese Government for these lights, Mr. Thomas Stevenson, C.E. (one of the engineers to the Commissioners of Northern Lights), was instructed to have regard, in the design of those lighthouses, to their exposure to shock. I was consulted by Mr. Stevenson as to the general principles to be observed; and those edifices have been constructed so that they are presumedly proof against the most violent shocks likely to visit Japan; not, perhaps, upon the best possible plan, but upon such as is truly based upon the principles I have developed. Mr. Stevenson has published some account of their construction.
The earthquake regions of South America might with incalculable benefit apply those ideas; and, indeed, they have been, to some extent, already applied by my friend, Mr. William Lloyd, Member of the Institution of Civil Engineers, to the New Custom Houses constructed from his designs at Valparaiso.
As one of these utilitarian views, and an important one, it will occur to many to ask—Can the moment of the occurrence or the degree of intensity of earthquake shock be predicted, or is it probable that at a future day we may be able to predict them? At present, any prediction, either of the one or the other, is impossible; and those few who have professed themselves in possession of sufficient grounds for such prediction are deceivers or deceived. Nor is it likely that, for very many years to come, if ever, science shall have advanced so as to render any such prediction possible; but it is neither impossible nor improbable that the time shall arrive when, within certain, perhaps wide, limits as to space, previous time, and instant of occurrence, such forewarnings may be obtainable.
Earthquakes, like storms and tempests, and nearly all changes of weather, are not periodic phenomena, nor yet absolutely uncertain or, so to say, accidental as to recurrence.
They are quasi-periodic, that is to say, some of their conditions as to causation rest upon a really periodic basis, as, for example, the recurrence of storms upon the periodic march of the earth, and sun and moon, etc., and the recurrence of Earthquakes upon the secular cooling of our earth; but the conditions in both are so numerous and complicated with particulars, that we cannot fully analyse them—hence, cannot reduce the phenomena to law, and so cannot predict recurrence. Yet storms and tempests—which were, along with pestilences and Earthquakes, amongst the natural phenomena which Bishop Butler deemed in his own day impossible of human prediction—have already, through the persistent and systematised efforts of meteorological observers, become to a certain extent foreseeable; and medical science assures us that it has rendered that, though to a much less degree of probability, true of pestilences.
We may, therefore, give the utilitarian some hope, that if he will help us along—who value our accessions of knowledge primarily upon a different standard to his—in our talk of discovery, our posterity, in a century or two hence, may not improbably possess the advantage of being able, in some degree, to predict their Earthquakes. I fear the inducement will go but a small way with the utilitarian generation, whose bent tends much towards asking, "What has posterity ever done for them?"
But though we cannot as yet predict the time when an Earthquake may take place in any locality, we can, on mixed statistic and dynamic grounds, in many cases state the limits of probable violence of the next that may recur. For example, the three shafts of marble columns of the Temple of Serapis, at Pozzuoli, each of about 411/2 feet in height, and 4 feet 10 inches in diameter at the base, remain standing alone, since they were uncovered, in the year 1750.