On the Gaseous Products of the Krakatoa Eruption, and Those of Great Eruptions in General

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Royal Dublin society, 1886 - 14 pages
 

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Page 33 - Cadaster trilobatus, M'Coy. Lateral view, natural size. ,, 4. — Do. do. var. acutus, M'Coy. Lateral view, natural size. ,, 4A. — Do. do. do. Ventral surface of same, showing pentagonal mouth and ovate anal aperture, natural size. ,, 4s. — Do. do. do. One of the ambulacral areas of same, showing perforated plates, and intermediate jointed ridges, enlarged four diameters. ,, 5. — Do. do. do. Small ovate specimen, natural size.
Page 27 - ... account must be taken of the porosity of the surface rocks and soil, and of the ocean, which can absorb and retain quantities of gases, variable relatively to temperature and pressure. Thus supposing the volume of the atmosphere to be actually doubled by volcanic emission at a given moment, it does not at all follow that the barometer would show that increase of volume in totality and at once, since the pressure on the surface of the earth would cause a certain portion to be taken up by the soil...
Page 20 - ... or less degree, and frequently to the point which brought into play chemical affinities ; and that thus the whole series of phenomena, which have tended and are tending to modify the form of the earth's surface, are intimately bound up with the existence and action of gases in the interior and at the surface thereof? Thus, from the very earliest period, we are called upon to recognize the continuous presence of gases as essential constituents of the earth's mass, and, so far as analogy allows...
Page 22 - ... been periods or phases of marked contraction, and therefore of very active vulcanism and accompanying emission of gases, during or about these periods. Such geological data as we already possess certainly do point to periods of great volcanic activity, manifested by outbursts of lava and alterations of the earth's surface, and corresponding changes in the relations of land and ocean. The tertiary period may be cited as an example in this respect. Turning now from what may, perhaps, be considered...
Page 31 - Blastoid is remarkable for its size and elongated shape, as compared with others of the genus. Its general outline is that of a lanceolate body (calyx), with a pentagonal summit, its greatest diameter being at the termination of the ambulacra eight-tenths of an inch from the summit, decreasing regularly towards the base and terminating obtusely, without any trace of stem. The basal plates, conical in shape, extend upwards to about one-third of its length, measuring nine-tenths by seven-tenths of...
Page 30 - ... years." The Japanese journals, working on records relative to the period included between the dates AD 628 and AD 886, have divided it into 26 periods of 10 years, between which the following intervals occur : — 40 years between the 2nd and 6th, 60 „ „ 6th „ 12th, 40 „ „ 12th „ 16th, 40 „ „ 16th „ 20th, 40 „ „ 20th „ 23rd; and from "the author's explanatory notes a still more correct table can be deduced, by means of which the cycle of earthquake intensity is finally...
Page 31 - ... obtusely, without any trace of stem. The basal plates, conical in shape, extend upwards to about one-third of its length, measuring nine-tenths by seven-tenths of au inch ; the radial plates are oblong, one inch and a-half by threequarters of an inch at the widest part ; the deltoid plates are small and triangular, extending only to about three-tenths of an inch from the summit, the five plates forming a pentagon when viewed from above. The ambulacra are narrower than in 0. inflatus; the small...
Page 28 - ... (to use the expression) of the explosion was felt at or near the antipod of that point, as observed by Monsieur Forel in Nature, March 26, 1885. He states that underground noises were heard at Caiman-Brae, in the Caribbean Sea, in August, 1883, contemporaneously with the eruption, the exact antipod of Krakatoa being the middle of the State of Colombia, on the Magdalena river, between the towns of Antigua and Tunja. Another fact which would lead one to infer that the seat of the explosion lay...
Page 20 - ... globe ? Is it not reasonable to suppose that, in the slow and continuous process of contraction, very great masses of gases became retained or occulted by the cooling matter, and that these occulted gases have been the essential agents in balancing tensions in the continually contracting sphere ? — that this continuous contraction led to the pressure of masses of these gases until heat was liberated in more or less degree, and frequently to the point which brought into play chemical affinities...

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