Luigi Palmieri

“ Hitherto no one appears to have formed any clear notion as to what an Earthquake is—that is to say, any clear idea of what is the nature of the movement constituting the shock, no matter what may be the nature or origin of the movement itself. ”

“ The light and fragile butterfly, whose glorious garb irradiates the summer zephyr in which it floats, has had its power of flight—which is its power to live—determined by results of that same chain of causes that lifted from the depths the mountain on whose sunny side he floats, that has determined the seasons and the colour of the flower whose nectar he sucks, and that discharges or dissipates the storm above, that may crush the insect and the blossom in which it basked. ”

“ The crust of our earth, then, as it now is, must crush, to follow down after the shrinking nucleus—if so be that the globe be still cooling, and constituted as it is; even to the limited extent to which we know anything of its nature—it must crush unequally, both regarded superficially and as to depth; generally the crushing lines being confined to the planes or places of greatest weakness ”

“ I have no space for discussing these views further than to assert that, in the existing state of our globe, and even admitting a solid crust of only 60,000 metres thick, dislocation of the crust by tension is not possible. The solid crust of our globe, as I hope we shall see further on, is not in a state of tension, and has not been so since it was extremely thin, a mere pellicle as compared with the liquid nucleus, but is, on the contrary, in a state of tangential compression. ”

“ The main mischief of all eruptions is effected in two ways: by the deposit of dust and ashes, lapilli, etc., to the injury or destruction of fertile land, and by the streams of lava which overwhelm it, as well as buildings, etc. But what information of any value can seismographic observation afford as to the course that either of these may take in any eruption? The volume of pulverulent material that may be ejected cannot be foreseen; its distribution depends mainly upon its nature and upon the direction and force of the wind at the time ”

“ To the popular mind, Volcanoes and Earthquakes are only isolated items of curiosity amongst "the wonders of the world:" few geologists even appear to realise how great and important are the relations of Vulcanicity to their science, viewed as a whole. Yet of Vulcanicity it is not too much to say, that in proportion as its nature and doctrines come to be known and understood as parts of the Cosmos, the nearer will it be seen to lie at the basis of all Physical Geology. ”

“ Were the contraction, lineal or cubical, for equal decrements or losses of heat, or in equal times—equal both in the material of the solidified crust and in that of the hotter nucleus—there could be no such tangential pressures as are here referred to, at any epoch of the earth's cooling. But in accordance with the facts of experimental physics, we know that the co-efficient of contraction for all bodies is greater as their actual temperature is higher, and this both in their solid and liquid states. ”

“ Earthquake and the Volcano is not destructive but, preservative. But we now see that: that the preservative scope of this function, as respects our earth, is far wider than what has been previously attributed to it. The Volcano does not merely throw up new fertile soil, and tend, in some small degree, to restore to the dry land the waste for ever going on by rain and sea; it fulfils a far weightier and more imperative task ”

“ The definition given by me in that Paper is that an earthquake is "The transit of a wave or waves of elastic compression in any direction, from vertically upwards to horizontally, in any azimuth, through the crust and surface of the earth, from any centre of impulse or from more than one, and which may be attended with sound and tidal waves dependent upon the impulse and upon circumstances of position as to sea and land." ”

“ Germany has shown more desire to cultivate this branch of science. Although, as yet, the distinct enunciation of its fundamental principles has but sparsely found its way into her text-books, several able monographs, such as those of Schmidt and of Höttinger, prove how completely some of her philosophers have mastered and how well applied them. The men of science of Northern Italy, amongst whom so many glorious names are to be found on the roll of discovery, have shown themselves quite alive to the importance of Seismology ”

“ The general term, Vulcanicity, properly comprehends all that we see or know of actions taking place upon and modifying the surface of our globe, which are referable not to forces of origin above the surface, and acting superficially, but to causes that have been or are in operation beneath it. It embraces all that Humboldt has somewhat vaguely called "the reactions of the interior of a planet upon its exterior." ”

“ When the observer is near the source of the lava, he sees matter in a state of fusion, which, like a torrent of liquid fire, runs along, with more or less impetuosity, between two banks formed by itself. ”

“ No geological system can be well founded, or can completely explain the working of the world's system as we now see it, that does not start from Vulcanicity as thus defined; and this is equally true, whether, as do most geologists, we include within the term Geology everything we can know about our world as a whole, exclusive of what Astronomy teaches as to it, dividing Geology in general into Physical Geology—the boundaries of which are very indistinct—and Stratigraphical Geology, whose limits are equally so. ”

“ I have said that if we can find a true cause in Nature for the origination of volcanic heat, all the other known phenomena, at and about volcanic vents, become simple. Lavas and all other solid ejecta of Volcanoes, from all parts of the earth's surface, as well as basalts, present in chemical and physical constitution close resemblance, and may be all referred to the melting of more or less fusible mixtures of siliceous crystalloid rocks with aluminous (slates, etc.) ”

“ Without denying the probability that a part of the positive electricity depends upon the elevation of the smoke, as in the case of every other conductor we raise aloft, or with a jet of water sent from a vessel by compressed air, I think that the greater part of the electricity proceeds from the rapid condensation of vapours, which are changed from the gaseous condition into dense clouds; for even when the smoke issues tranquilly and does not rise, because carried away horizontally by the wind, it gives signs of positive electricity. ”

“ We have seen that, on the whole, both Earthquakes and Volcanoes follow along the great lines of elevation of our surface. Any true solution of the play of forces which has produced any one of those three classes of phenomena must connect itself with them all, and be adequate to account for all. And this would have earlier been seen, had geologists generally framed for themselves any correct notions of the mechanism of elevation itself, and seen its real relation with the secular cooling of our planet. ”

“ When, after the great Calabrian Earthquake of 1783, the Royal Academy of Naples sent forth its commission of its learned members to examine into the effects, they had spread around them in sad profusion all that was necessary to have enabled them to arrive at a true notion of the nature of the shock, and thence a sound explanation of the varied and great secondary effects they witnessed, and of which they have left us the records in their Report, and the engravings illustrative of it. But we look in vain for any light ”

“ Hopkins, based upon precession and nutation, it appears to me, on various other grounds, some of which have been urged by Sir William Thompson, that the earth's solid crust is not a thin one, at least not thin enough to render it conceivable that water can ever gain admission to a fluid nucleus, if any such still exist, situated at so great a depth; and without such access we can have no Volcano. ”

“ There is, therefore, no need for the hypothesis of those who have supposed all the huge volumes of steam blown off from Volcanoes in eruption to come from vesicular water pre-existent in the minute cavities of crystalline or other rocks before their fusion into lava: a fact not proved for many classes of rock, and for none in sufficient quantity to account for the vast volume of steam required and for the irregularity of its issue. ”

“ After the great eruption of 1850, Vesuvius remained in apparent repose until the end of May, 1855, when there was an eccentric eruption and a great flow of lava lasting twenty-seven days. But for a year before the fumaroles on the top of the mountain had acquired great activity, their temperature increased, and hydrochloric and sulphuric acid became more abundant, and generated the usual coloured products on the adjacent scoriæ. Finally, in the month of January, a crater was formed by falling in of the ground, and although it did not discharge fire, yet it poured forth dense smoke. ”

“ I have applied this method of calculation to test the adequacy of the source I have assigned for volcanic heat, in two ways, viz.: 1. To the phenomena presented during the last two thousand years by Vesuvius, the best known Volcano in the world; and 2. To the whole of the four hundred and odd volcanic cones observed so far upon our globe, of which not more than one-half have ever been known in activity. ”

“ I am enabled, however, to prove thus how enormously more than needful has been the store of energy dissipated since our globe was wholly a melted mass, for the production, through the contraction of its volume, of all the phenomena of elevation and of Vulcanicity which its surface presents. And how very small is the amount of that energy in a unit of time as now operative, when compared with the same at very remote epochs in our planet's history. ”

“ I believe I have on other occasions shown that a fumarole is nothing but a communication between the more or less cooled and hardened surface of the lava and the interior, which is still incandescent. Some fumaroles last but a day, others preserve their activity for weeks, months or years, according to the depth of lava through which they penetrate; and when they cease to be active, that is, when the sublimations are formed, or smoke or other æriform matters issue from them, they still retain a rather elevated temperature. ”

“ Quickly raising the conductor by pulling the cord, f, the index of the electrometer will describe a more or less large impulsive arc, and, after two oscillations, will stop at the definite arc. Having thus measured the electric tension of the air, and having lowered the conductor, I next place the wire, i, in communication with the electroscope, B, and by again raising the conductor, I ascertain whether the electricity be positive or negative. It is scarcely necessary to say that the conductor, when raised, gives electricity of the same nature as that prevailing at the moment in the atmosphere ”

“ We see, moreover, that the geological doctrine of absolute uniformity cannot be true as to Vulcanicity, any more than it can for any other energy in play in our world. Its development was greatest at its earliest stages, when the great masses of the mountain chains were elevated. It is even now—though as compared to men's experience, and even to all historic time, apparently uniform and always the same—a decaying energy. ”

“ The chloride and sulphate of copper are formed from the oxide, directly contrary to general belief. I do not think that the chloride of calcium, which I found on this occasion in almost all the deliquescent sublimations, is a product peculiar to this eruption only, in which alone, however, I found it. I was, therefore, induced to look for it in other sublimates, in which I might possibly have overlooked it, as, without doubt, my predecessors have done, owing to the deliquescence of the chloride of iron with which it was constantly combined. ”

“ But were we to take the extreme case, and suppose it possible that all the heat the globe loses annually resulted from the transformation of the work of internal crushing of its shell, we shall find that the total volume of rock needed to be crushed in order to produce the required amount of lost heat is perfectly insignificant as compared with the volume of the globe itself, or that of its shell. ”