# Great Neapolitan Earthquake of 1857

Great Neapolitan Earthquake of 1857.
LONDON—PRINTED BY WILLIAM CLOWES AND SONS, STAMFORD STREET AND CHARING CROSS.
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GREAT NEAPOLITAN EARTHQUAKE OF 1857.
THE FIRST PRINCIPLES
OF
OBSERVATIONAL SEISMOLOGY
AS DEVELOPED IN THE
REPORT TO THE ROYAL SOCIETY OF LONDON OF THE EXPEDITION MADE BY COMMAND OF THE SOCIETY INTO THE INTERIOR OF THE KINGDOM OF NAPLES,
TO INVESTIGATE THE CIRCUMSTANCES OF THE GREAT EARTHQUAKE OF DECEMBER 1857.
BY
ROBERT MALLET, C.E., F.R.S., F.G.S., M.R.I.A.,
&c., &c.
"Non fingendum aut excogitandum sed inveniendum quid natura faciat aut ferat."
PUBLISHED BY THE AUTHORITY AND WITH THE AID OF THE ROYAL SOCIETY OF LONDON.
IN TWO VOLUMES.—VOL. I.
CHAPMAN AND HALL, LONDON.
1862.
The Right of Translation is reserved.
DEDICATION.
To the Rev$^d$. T. R. Robinson, D.D., F.R.S., &c., Astron. Dir. Armagh.
My dear Sir,
Friendship, unbroken since my boyhood, and the many occasions upon which you have encouraged or assisted such attempts as I have made to advance knowledge, alone would induce me, with affectionate regard, to dignify these Volumes by connecting them with your own distinguished name; but to whom else could I so properly inscribe them, for to your early recognition of those truths which I had enunciated as the foundations of the science of Seismology, and to your prompt and weighty advocacy, of the importance to science, of seizing the opportunity of the great Neapolitan shock to apply those principles to nature, these Volumes probably owe their existence.
Ever, with much esteem, I am yours,
Robert Mallet.
    London, 1st October, 1862.
PREFACE.
Some explanation seems desirable of how it is that the following Report to the Royal Society of London appears in form of the present volumes, and why not at an earlier period.
The earthquake of December, 1857, by almost the first notices that reached England, revealed itself as the third greatest in extent and severity of which there is any record as having occurred in Europe.
Impressed with its observational value to science, the Author at once addressed the following letter to the then President of the Royal Society:—
"Delville, Glasnevin, Co. Dublin,
"28th December, 1857.
"My Lord,
"The very recent occurrence of a great earthquake in the Neopolitan territory presents an opportunity of the highest interest and value for the advancement of this branch of Terrestrial Physics.
"Within the last ten years only Seismology has taken its place in cosmic science—and up to this time no earthquake has had its secondary or resultant phenomena—sought ​for, observed, and discussed by a competent investigator—by one conversant with the dynamic laws of the hidden forces we are called upon to ascertain by means of the more or less permanent traces they have left, as Phenomena, upon the shaken territory.
"Observed without such guiding light, or often passed by unnoticed and undiscovered for want of it—the facts hitherto recorded are in great part valueless—but with this guide such investigation is capable of results of high importance. Thus it was that Dolomieu's elaborate record of the effects of the great Calabrian Earthquake is of so much less value than it might have been.
"Earthquake observations are of two classes—those which must be made before and at the moment of shock (time and space measurements chiefly) and those which may be made at a recent period after it. To the latter belong those numerous and instructive facts treated of under the heads of Secondary and Accidental Phenomena in my First Report on the Facts of Earthquakes ('Reports Brit. Ass. 1850'), and also in the 'Admiralty Manual'—as well as many questions treated of under heads 15' to 24' of the former. In those papers I have stated some of the methods of observation—of shattered buildings—altered water courses and springs—changed relations of level and position—localities of maximum and minimum disturbance—their relations to origin—to formation, &c., &c., and the inferences deducible. I need not, therefore, dilate upon them here.
"I have long looked for the occurrence of an opportunity so favourable for inquiry as that which has been ​just presented. It is one so rare, and in so peculiar and suggestive a region, that I venture to urge, through your Lordship, the Royal Society, that it should not be permitted to be lost to Science. To avoid this, however, the examination must be made with all possible promptitude, as every hour alters or removes the characters of the terrible inscription which we are to decipher, and renders circumstantial, local, and oral evidence less trustworthy.
"I respectfully offer, my Lord, if such be the will of the Royal Society, to proceed at once to Naples and the shaken regions, to collect, discuss, and report the facts. I am prepared to devote a month or five weeks to the inquiry, which, allowing ten days to the journey, to and from the city of Naples, I deem sufficient, if energetically and well employed.
"Were I a wealthy man I should proceed instantly, and on my own responsibility; but, although willing to give one-twelfth of my professional time and income for 1858 to it, private duties make it unsuitable that I should also be at the necessary expenditure for the journey and local inquiry.
"For this a sum of about One Hundred and Fifty Pounds would, I consider, be required, as the aid of local assistants, interpreters, with the peasantry, and the means of rapidly moving in remote and little frequented places (such as Basilicata), with other accessory charges, must be provided for. The best maps and all requisite instruments I am prepared with.
"In the humble but earnest confidence that I can in this do good service to Science, I submit to the Royal ​Society whether it see fit to make such a grant, and to entrust the work to me; if so, I should be prepared to set out by the middle of next month.
"I have the honour to be, My Lord,
"Your very obedient Servant,
"Robert Mallet.
"The Lord Wrottesley, President,
    "Royal Society, London"
The writer's views were promptly laid by the President before the Council of the Royal Society, where they were supported by the advocacy of Doctor Robinson, General Sabine, Sir Charles Lyell, Sir Roderick I. Murchison, and others. In result the Author was requested to proceed with the inquiry, and a grant made of the entire sum asked for. This amount proved, in the end, inadequate, as did also the period of time which it was proposed to devote to the investigation; so that the Author himself defrayed about two-fifths of the entire cost of the expedition, and found it necessary to devote to it more than double the time he intended beforehand. A further sum of Fifty Pounds toward procuring the Photographs, from which many of the Illustrations of these volumes have been reproduced, was voted by the Royal Society after the Author's departure, and the fact was communicated to him by telegraph.
A comparatively small proportion of the large collection of scientifically valuable Photographs made in the convulsed regions have been now reproduced, the ​limitation having been due to cost of production. The whole, however, are referred to by number in the text, those omitted with the addition (Coll. Roy. Soc.); and the originals may be consulted by Seismologists in the Library of the Royal Society, where the entire collection made, is now preserved along with the original sketches, maps, and manuscript.
Within a week of the Author's return to England in April, 1858, he addressed a preliminary Report to the President and Council of the Royal Society, the nature of which may be seen by the following extract from its introductory sentences:—
"On my return from the expedition of observation in the earthquake-shaken provinces of Naples, entrusted to me by the Royal Society, it becomes my duty to report briefly to your Lordship as President, and to the Council, where I have been, what I have done, and what of value to science, I may conceive myself to have accomplished; reserving scientific details and deductions to a separate and more systematic communication, which I hope ere long to have the honour of laying before the Royal Society, and which will embrace the results of my inquiries."
Two years nearly elapsed before the Author, interrupted frequently through necessity of professional avocation, and by other events, was enabled to complete the laborious work of reducing his observations, involving much tedious calculation, expanding and writing out his field notes, colligating his results, and finally bringing ​his Report into the form in which it was presented and read to the Royal Society on the 24th May, 1860, and which is substantially that in which it now appears in the following pages.
A brief abstract of the Report was published in the 'Proceedings Roy. Soc. Lon.,' vol. x. p. 486, &c., and the document itself, with its accompanying maps, diagrams, sketches, and photographs, ordered to be referred for publication.
As to the mode of this, some difficulty arose. The Report, although in a great degree dealing with dynamical and other rigid questions, is partly an inductive argument; and hence, being necessarily of the nature of a pièce justicatif, requires the sufficient statement of a number of directly employed facts; besides and related to which were, many observations made en passant, upon the physical features, geology, and other collateral subjects, which, referring to a country so little explored as the interior of the Neapolitan kingdom, it was not desirable to suppress.
Its bulk thus became such that if published by the Royal Society in what might seem its natural place, it would have occupied an entire volume of the 'Philosophical Transactions,' to the exclusion, for the time, of all other papers, however valuable. Some suggestions were made to divide the Report, publishing in the 'Philosophical Transactions' only its rigid mechanical portions in result, leaving the remainder for publication there ​in future years; but to this the Author felt much objection.
Finally, the Council of the Royal Society, in the exercise of a wise discretion, and in a very liberal spirit, decided to devote a sum of three hundred pounds towards the cost of illustration, and proposed to the Author that he should publish, in extenso, his Report as a distinct and independent work.
In pursuance of this, the Author arranged with Messrs. Chapman and Hall for publication in the form in which the work now appears, the Publishers having undertaken to defray the entire expense over and above the grant made by the Royal Society. Liberal as the amount of that was, it was not nearly sufficient for its object, owing to the great expenditure involved in the production of volumes illustrated as these are. The Author can but hope that the spirit with which the Publishers have thus shown themselves ready substantially to aid in promoting science, may not be to them profitless.
It was midsummer last, before all these preliminaries admitted of the work being placed in the hands of the printer, and the illustrations in those of Mr. V. Brooks for lithographing. Practically, the whole was ready for publication early this year. For trade reasons the Publishers requested that it might be postponed to the present time, to which the Author, though conscious of the long delay that circumstances had already imposed, readily assented. ​These volumes, as they now appear, will probably be perused by two distinct classes . To the first, the really scientific reader, the Author will venture, though perhaps at the risk of some undeserved suspicion of egotism or vanity, to commend the subject and the method which they evolve, as pregnant with the power of future knowledge, of the cosmical conditions of the interior of our own and of other planets; that will be hereafter recognized as having first shown the way to any true intelligence from the viewless and unmeasured miles of matter beneath our feet; and that will ere long give us up the key to the hitherto undeciphered enigma of vulcanicity.
To the general reader, earthquake narratives have long shared in some degree, the charm that belongs to tales of shipwreck, of battle, or wild adventure, and "perilous hair-breadth 'scapes'" amidst natural phenomena the most tremendous: something of this he here will find; and though sobered to a reality not always found in earthquake stories, the events by which such multitudes perished, in which so many cities were overthrown, will be found by him who shall have even generally understood the principles here unfolded, to yield more intelligent pleasure, than the exaggerated and often fabulous phantasmagoria, of the older earthquake narratives, in the maze of which he wandered without any rational clue.
He will here trace with interest the successive steps by which finally the depth of the focus, whence the impulse that produced the earthquake has been for the ​first time ascertained, and measured in miles and yards with the certainty that belongs to an ordinary geodetic operation.
It is of the nature of all science, to be but the portal to greater and higher truth beyond. Such is peculiarly the case with Seismology. The exact knowledge of earthquakes, of their distribution in time and space, of their movements result and proximate cause however interesting in themselves, are yet but means to an end.
As palæontology—itself dependent upon natural history—lithology, and many other cognate knowledges, are but instruments of geology, so is seismology chiefly to be viewed and valued, as the instrument by which a knowledge of the deep interior of our planet will be attained; the only instrument yet discovered to this end, yet one possessed of vastly greater power and directness of aim, than any of those that physical geology has previously called to its aid.
Though the youngest branch of cosmical science, it is to be regretted, that it has not been already better understood, and more applied by observational geologists, many of whom, had they mastered even its rudiments, might ere now have come laden with fruit from various regions.
Physical geology, much as it owes to the labours, of the topographical and field geologist, to the patient observer and comparer of nature's superficial phenomena, can no longer rest satisfied with such modes of investigation ​alone. The time has more than come, when it must devise new methods and new problems, and appropriate to their solution, all the aids that theoretical mechanics, including those of undulations, physics, and chemistry can afford; and the geologist of the coming time, who shrinks from mastering these, though he may continue a labourer, shall be no “light bearer” in the rising palace of cosmical truth. More or less, it is the Author’s hope that these volumes may be ancillary to promoting and giving direction to such a result.
London, October, 1862.
Part I
* Chapter I
* Chapter II
* Chapter III
* Chapter IV
* Chapter V
* Chapter VI
* Chapter VII
* Chapter VIII
* Chapter IX
* Chapter X
* Chapter XI
* Chapter XII
* Chapter XIII
* Chapter XIV
* Chapter XV
* Chapter XVI
* Chapter XVII
* Chapter XVIII
* Chapter XIX
* Appendix to Part I
Part II
* Chapter I
* Chapter II
* Chapter III
* Chapter IV
* Chapter V
* Chapter VI
* Chapter VII
* Chapter VIII
* Chapter IX
* Chapter X
* Chapter XI
* Chapter XII
* Chapter XIII
* Chapter XIV
* Chapter XV
* Chapter XVI
* Chapter XVII
* Chapter XVIII
* Chapter XIX
* Chapter XX
* Chapter XXI
* Chapter XXII
LIST OF ILLUSTRATIONS
USED OR REFERRED TO
IN THE FIRST VOLUME.
Note.—In the following List of Illustrations, and in the text, wherever the reference is made in the words, "Collection of the Royal Society," or "Coll. Roy. Soc.," it is to be understood that such Illustrations have been necessarily omitted from this work, in order to limit the expense of reproducing so great a number of Photographs or Sketches, and that the originals of all such as are so omitted are to be found in the possession of the Royal Society of London.
⁂ For List of Maps see Illustrations to Vol. II.
City of Polla after the Earthquake.—See No. 161 Frontispiece.