Law of Motion sought; the glacier moves through a Sinuous Valley; effect of Flexure; Western half of glacier moves quickest; Point of Maximum Motion crosses axis; Eastern half moves quickest; Locus of Point of Maximum Motion; New Law; Motion of the Géant; motion of the Léchaud; Squeezing of the Tributaries through the Neck of the valley at Trélaporte; the Léchaud a Driblet
11.—Ice Wall at the Tacul—Velocities of Top and Bottom.289
First attempt by Mr. Hirst; second attempt, stakes fixed at Top, Bottom, and Centre; dense fog; the stakes lost; process repeated; Velocities determined
12.—Winter Motion of the Mer de Glace. 294
First line, Above the Montanvert; second line, Below the Montanvert; Ratio of winter to summer motion
13.—Cause of Glacier Motion—De Saussure's Theory. 296
First attempt at a Theory by Scheuchzer in 1705; Charpentier's theory, or the Theory of Dilatation; Agassiz's theory; Altmann and Grüner; theory of De Saussure, or the Sliding Theory; in part true; strained interpretation of this theory
Character of Rendu; his Essay entitled 'Théorie des Glaciers de la Savoie;' extracts from the essay; he ascribes "circulation" to natural forces; classifies glaciers; assigns the cause of the conversion of snow into ice; notices Veined Structure; "time and affinity;" notices Regelation; diminution of glaciers réservoirs; Remarkable Passage; announces Swifter Motion of Centre; North British Review; Discrepancies explained by Rendu; Liquid Motion ascribed to glacier; all the phenomena of a River reproduced upon the Mer de Glace; Ratio of Side and Central velocities; Errors removed
15. 308
Anticipations of Rendu confirmed by Agassiz and Forbes; analogies with Liquid Motion established by Forbes; his Measurements in 1842; measurements in 1844 and 1846; Measurements of Agassiz and Wild in 1842, 1843, 1844, and 1845; Agassiz notices the "migration" of the Point of Swiftest Motion; true meaning of this observation; Summary of contributions on this part of the question
Discussions as to its meaning; Facts and Principles; definition of theory; Some Experiments on the Mer de Glace to test the Viscosity of the Ice
Caused by the Motion; Ice Sculpture; Fantastic Figures; beauty of the crevasses of the highest glaciers; Birth of a crevasse; Mechanical Origin; line of greatest strain; Marginal Crevasses; Transverse Crevasses; Longitudinal Crevasses; Bergschrunds; Influence of Flexure; why the Convex Sides of glaciers are most crevassed
18. 325
Further considerations on Viscosity; Numerical Test; formation of crevasses opposed to viscosity
Connexion of Natural Forces; Equivalence of Heat and Work; heat produced by Mechanical Action; heat consumed in producing work; Chemical Attractions; Attraction of Gravitation; amount of heat which would be produced by the stoppage of the Earth in its Orbit; amount produced by the falling of the Earth into the Sun; shifting of Atoms; heat consumed in Molecular Work; Specific Heat; Latent Heat; 'friability' of ice near its melting point; Rotten Ice and softened Wax
20. 334
Papers presented to the Royal Society by Professor Forbes in 1846; Capillary Hypothesis of glacier motion; hypothesis examined
Statement of theory; influence of Pressure on the Melting Point of Ice; difficulties of theory; Calculation of requisite Pressure; Actual pressure insufficient
Pressure and Tension; possible experiments; Ice may be moulded into Vases and Statuettes or coiled into Knots; this no proof of Viscosity; Actual Experiments; a sphere of ice moulded to a lens; a lens moulded to a cylinder; a lump of ice moulded to a cup; straight bars of ice bent; ice thus moulded incapable of being sensibly stretched; when Tension is substituted for Pressure, analogy with viscous body breaks down
Faraday's first experiments; Freezing together of pieces of ice at 32°; Freezing in Hot Water; Faraday's recent experiments; Regelation not due to Pressure nor to Capillary Attraction; it takes place in vacuo; fracture and regelation; no viscidity discovered
24.—Crystallization and Internal Liquefaction. 353
How crystals are 'nursed;' Snow-Crystals; Crystal Stars formed in Water; Arrangement of Atoms of Lake Ice; dissection of ice by a sunbeam; Liquid Flowers formed in ice; associated Vacuous Spots; curious sounds; their explanation; Cohesion of water when free from air; liquid snaps like a broken spring; Ebullition converted into Explosion; noise of crepitation; Water-cells in glacier ice; Vacuous Spots mistaken for Bubbles; not Flattened by Pressure; experiments; Cause of Regelation
Their character; Depth of Moulin on Grindelwald Glacier; Explanation the Grand Moulin of the Mer de Glace; Motion of moulins
26.—Dirt-Bands of the Mer de Glace.367
Their discovery by Professor Forbes; view of Bands from a point near the Flégère; Bands as seen from Les Charmoz; Skew Surface of glacier; aspect of Bands from the Cleft Station; Origin of bands; tendency to become straight; differences between observers
