Occasional Papers on the Theory of Glaciers Now First Collected and Chronologically Arranged: With a Prefatory Note on the Recent Progress and Present Aspect of the TheoryA. and C. Black, 1859 - 278 páginas |
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Alps analogy angle annual motion appears Arveiron August bands Bishop of Annecy breadth cause centre compact congelation considerable continuity convex Courmayeur crevasses curve curved bands daily motion direction dirt-bands Edinburgh effect Elie de Beaumont Etna evidence experiment explained fact feet fissures fluid fluidity friction frontal dip Glace of Chamouni Glacier des Bois glacier motion glacier moves glacier of Bossons Grindelwald hydrostatic hydrostatic pressure inches inclination internal July lava stream less Letter on Glaciers longitudinal lower marked mass measurement Mer de Glace millimetres Mont Blanc Montanvert moraine Motion of Glaciers movement nearly névé observations origin parallel particles Philosophical Journal plane plastic Plate portion pressure produce rock Saussure SAUSSURE'S THEORY season sides sliding slope snow solid station summer surface temperature thawing theodolite theory of glaciers tion transverse Travels valley veined structure velocity vertical Vesuvius viscous theory volume whilst winter
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Página 228 - Faraday's chief fact, to which the term 'regelation ' has been more lately applied, is this : that pieces of ice, in a medium above 32°, when closely applied, freeze together, and flannel adheres apparently by congelation to ice under the same circumstances. "1. These observations I have confirmed. But I have also found that metals become frozen to ice when they are surrounded by it, or when they are otherwise prevented from transmitting heat too abundantly. Thus, a pile of shillings being laid...
Página 29 - This is a fact which, though generally enough admitted, has not yet excited sufficient attention.' — p. 78. ' Every year, and year after year, the water- courses follow the same lines of direction ; their streams are precipitated into the heart of the glacier by vertical funnels called " moulins," at the very same points ; the fissures, though forming very different angles with the axis or sides of the glacier at different points of its length, opposite the same point, are always similarly disposed...
Página 9 - They appear to me only resolvable, on the supposition that crystalline or polar forces acted on the whole mass simultaneously, in given directions, and with adequate power.
Página 229 - I conclude that the effect of pressure in assisting ' regelation' is principally or solely due to the larger surfaces of contact obtained by the moulding of the surfaces to one another. " 3. Masses of strong ice, which had already for a long time been floating in unfrozen water-casks, or kept for days in a thawing state, being rapidly -pounded, showed a temperature...
Página 231 - ... surface cannot afford warmth enough to keep the water liquid. " This effect is well seen by the instant freezing of a piece of ice to a worsted glove even when on a warm hand. But metals may act so, provided they are prevented from conveying heat by surrounding them with ice. Thus, as has been shown, metals adhere to melting ice.
Página 65 - Over the first of these the theodolite was regularly centered, in order to observe the relative motions of the others which were respectively 30, 60, 90, 120, and 180 feet distant. Finding that, even in the course of a single day, the acceleration of the more central parts was evident, and the six points in question formed a portion of a continuous curve, I subdivided the first 90 feet from the theodolite into 45 spaces of 2 feet, each of which was marked by a perforation in the ice into which short...
Página 251 - A GLACIER is AN IMPERFECT FLUID, OR A VISCOUS BODY. WHICH IS URGED DOWN SLOPES OF A CERTAIN INCLINATION BY THE MUTUAL PRESSURE OF ITS PARTS.
Página 231 - This waste has yet to be proved ; but I have little doubt of it ; and it is confirmed by the wasting action of superficial streams on the ice of glaciers, though other circumstances may also contribute to this effect. III. The theory explains ' regelation.' For let a second plane surface of ice A'B' be brought up to nearly physical contact with the first surface AB.
Página xvi - ... that the reconsolidation of the bruised glacial substance into a coherent whole may be effected by pressure alone acting upon granular snow or upon ice softened by imminent thaw into a condition more plastic than ice of low temperature, and that the terms ' bruising and re-attachment,' ' incipient fissures reunited by time and cohesion...
Página 268 - May we venture to suppose that, in the felspathic lavas with horizontal laminae, we see an analogous case ? All geologists •who have examined trachytic regions have come to the conclusion, that the lavas of this series have possessed an exceedingly imperfect fluidity ; and as it is evident that only matter thus characterized would be subject to become fissured, and to be formed into zones of different tensions, in the manner here supposed, we probably see the reason why augitic lavas, which appear,...