Part 27

490. As long as it is sound the laminated glacier ice resists cleavage. Regelation, as I have said, makes the severed attachments good. But when such ice is exposed to the weather the structure is revealed, and the ice can then be cloven into tablets a square foot, or even a square yard in area.

§ 67. Conclusion.

491. Here, my friend, our labours close. It has been a true pleasure to me to have you at my side so long. In the sweat of our brows we have often reached the heights where our work lay, but you have been steadfast and industrious throughout, using in all possible cases your own muscles instead of relying upon mine. Here and there I have stretched an arm and helped you to a ledge, but the work of climbing has been almost exclusively your own. It is thus that I should like to teach you all things; showing you the way to profitable exertion, but leaving the exertion to you more anxious to bring out your manliness in the presence of difficulty than to make your way smooth by toning difficulties down.

492. Steadfast, prudent, without terror, though not at all times without awe, I have found you on rock and ice, and you have shown the still rarer quality of steadfastness in intellectual effort. As here set forth, our task seems plain enough, but you and I know how often we have had to wrangle resolutely with the facts to bring out their meaning. The work, however, is now done, and you are master of a fragment of that sure and certain knowledge which is founded on the faithful study of nature. Is it not worth the price paid for it? Or rather, was not the paying of the price the healthful, if sometimes hard, exercise of mind and body, upon alp and glacier--a portion of our delight?

493. Here then we part. And should we not meet again, the memory of these days will still unite us. Give me your hand. Good bye.

INDEX.

Accurate measurements of the motions of glaciers, by Agassiz and Forbes, 60-62. Æggischhorn, view from the, 137. Agassiz's measurements, 60; conclusions, 107; discovery by, 150; observations made by, 187. Aiguille du Dru, pyramid of, 43; cloud-banner of, 90. ---- des Charmoz, 43; clouds about, 90. ---- Noire, 51. ---- Verte, height of, 53 ---- du Midi, stone avalanches of, 56. Air, its expansion, 24; a chilling process, 25; experiments illustrating, 25, 26. Aletsch glacier, 136; length of, 136; arm of, 137. Alpine ice, origin in the sun's heat, 7. Ancient glaciers of England, Ireland, Scotland, and Wales, 150, 151. Architecture of snow, 29-34, 91; of lake-ice, 35, 169. Arveiron, vault of, 66; description and cause of, 92.

Bel Alp, description of the, 139, 140. Bergschrund, formation of the, 102, 103, 179. Blue veins of glaciers, 176; whiteness of snow, 176; whiteness of ice, 177; freezing of lake-ice, 177; explanation of cause of whiteness of glaciers, 178; translucency converted into transparency, 178; vertical veins, 179; structure and bedding on glaciers, 181, 182; stratification theory, 183; observations, 187. Bodies of guides found on Glacier des Bossons, 57, 144. Boulders, size of, 148, 149.

Changes of volume resulting from heat and cold, 118-122; illustrations of, 119, 120; consequences from, 122; opinions of Count Rumford, 12, 124. Chapeau, refreshment at, 41. Cleavage and glacier lamination, 187; analogy between, 188, 189; planes of, 188; observations of Prof. Sedgwick, 188; discovery by Daniel Sharp, 188; additional evidence of Mr. Sorby, 189; association of pressure and cleavage established, 189: relation of cause and effect, 189; artificial conditions of Nature combined, 189, 190. Clouds, their formation, 3-6; in tropical regions, 25; illustration of the formation of, 26. Col du Géant, snows and ice-cascade of the, 46, 47; snow-fall on the plateau of, 48, 49; cracks on, 179. Conclusion, 191, 192. Condensers needed, 154. Conditions necessary for the production of natural phenomena, 99. Conscience, scientific, 180. Crevasses, 41; work among the, 52; widening of, 54; drifting of bodies buried in, 57; birth of, 98; features of, 100; characteristic, 102; transverse, 103; stalactites of Alpine, 100; marginal, 105-107; longitudinal, 109; curvature of glacier related to number of, 110-112. Crystallization of metals, 29; of sugar, 30; of saltpetre, 30; of alum, 30; of chalk, 30; of carbon, 30; reversal of the process of, 36.

De Saussure's theory of glacier-motion, 156. Dilatation theory, 155, 156. Dirt-bands of Mer de Glace, observed by Prof. Forbes, 130; description and explanation of, 131, 132. Distillation, oceanic, 18; ordinary, 21. Dôme du Goûté, broken crags of, 50. Drifting of huts on ice, 59, 60. Dr. William Hopkins's conclusions regarding the obliquity of the lateral crevasses, 107.

Égralets, passage through the, 53. Electric light, dark waves of, 14. Equivalent points, comparison of velocities of, 75, 76, 107. Erratic blocks, 147-150. Evaporation, caused by the heat-rays of the sun, 13. Expansion of water, 121, 155. Experiments to show the heat-power of the dark rays, 14-19; illustrative, 22, 23, 25, 20; Dr. Franklin's experiment, 112. Extract from Bordier's book, 157, 162.

Faraday's theory regarding regelation, 171; special solidifying power exerted by substances upon their own molecules, 172, 173; opinion of Prof. James Thomson, 174, 175; experiments illustrating the subject, 174; quotation from Faraday, 175. Fog, its formation in ball-rooms, 5. Forces, of crystallization, 30; of gravitation, 30; of Nature, 31; attractive and repulsive, 127. Freezing mixture, 120, 168.

Glacier, the source of the Rhone, 7; fed by mountain-snow, 7, 21; melted by the sun's dark rays, 13; terminal moraines of, 38; questions regarding motions of, 54-58; action of the ends of, 58; motion at top and bottom of, 80, 81; lateral compression of, 81, 82; longitudinal compression of, 84, 85; slow movement in winter of, 87; motion of Grindelwald, 94; motion of Great Aletsch, 94; motion of Morteratsch, 95; crevasses at the side of, 106; action, 146, 147; ice, 155; veined or ribboned structure of, 178; blue veins of, 170; tables, 113, 114; mills, 116-118; theory of Scheuchzer regarding, 155; ancient, 145-147; impurities thrust out by, 144; whiteness of a clean, 43, 170; measurements by Hugi and Agassiz of, 59, 60; epoch, 152-167. Glacier des Bois, description of, 38-43. ---- des Bossons, 56; mass of ice upon, 134. ---- of Aletsch, sand-cones of, 116. ---- des Périades, 51. ---- du Talèfre, boundary of, 53; width of, 92; chasms of the, 98. ---- de Léchaud, motion of, 80; width of, 82; compression of, 190. ---- du Géant, névé of the, 49; motion of, 79; width of, 82; cracks above the ice-falls of, 119; honey-combing of, 115; shortening of, 190. ---- Unteraar, movement of, 61; appearance of Prof. Forbes on, 161; measurements by Agassiz on, 162. ---- Görner, sand-cones of, 116; description of, 140-144; moraines of, 143; advance and retreat of, 144; objects of interest on, 144; structure and bedding on, 181. Grand Plateau, crevasse on, 57, 118. Greenland's icy mountains, 21. Growth of knowledge, 59. Guesses in science, 74.

Harmony of life and its conditions, 125. Heat, waves of, 12; invisible, 14; office of the invisible waves of, 36; absorption of solar, 100; demanded for the liquefaction of ice, 131; latent, 153. Hoar-frost, 5, 6; not melted by light-waves, 13, 18. Hôtel des Neuchâtelois, movements of, at Riffelberg, 141.

Ice, structure of, 35, 36, 119; towers of, 104; sea, 132-134; retreat of, 145; development in the Alps of, 150; freezing of pieces of, 164; liquefaction by pressure of, 108, 160; translucent, 177; difference between hard and soft, 87. Icebergs, of arctic seas, 133; described by Sir Leopold McClintock, 133, 134; drifting of, 134; origin of, 134; of Switzerland, 136-138; colors of, 138; formation of chains of, 165. Ice-lens, concentration of sun's rays by means of, 37. Ice-river through the vale of Hasli, 146. Icicles, 99; how produced, 100; a theory of, 100-102 Imagination, scientific use of, 34. Impurities thrust out by glaciers, 144. Infinite Wisdom, designs of, 124.

Jardin, description of, 53. Jungfrau, 136, 137.

Killarney, luxuriant vegetation of, 27, 151.

La Grande Jorasse, crests of, 43; roses of cloud about, 90. Lake of Geneva, an expansion of the river Rhone, 6. Latent heat, 153, 167. Lateral moraines, origin of, 54. Light, wave-theory of, 10, 11; inference from the phenomena of, 11; length of wave of, 12. Likeness of glacier-motion to river-motion, 72-76. Liquefaction of ice, 168, 169; experiment by Mr. Bottomley, 170; experiment by Mr. Boussingault, 170, 171. Locus of the point of swiftest motion, 76. Longitudinal crevasses, how formed, 109; examples of, 110.

Magillicuddy's Reeks, 27, 150, 151. Magnet, poles of, 32; repelling corners and ends of, 126. Märgelin See, 138; icebergs in the, 138. Marginal crevasses, explanation of, 106-109. Mauvais Pas, 41. Measurements of glaciers by Hugi and Agassiz, 59, 60. Medial moraines, how accounted for, 55. Mer de Glace, 41; its sources, 43-45; view of the, 44; branching of the, 45; medial moraines of the, 51, 52; triangulation of, 62; motion of, 66, 70; daily motion of, 67; unequal motion of the two sides of, 70-72; motion of axes of, 78; summer condition of, 87; winter on, 88-92; dirt-bands of, 127; dimensions of, 145; winter motion of, 93; greater number of crevasses on eastern side of, 112; glacier tables of, 113; grand moulin of, 117, 118; approximate weight of, 154. Molecules, of water, 31, 34; expansion of, 125; forces acting upon, 127; exclusiveness of water, 132, 133. Montanvert, auberge of the, 41, 43; appearance in winter, 89. Moraine, lateral, 41; medial moraines of the Mer de Glace, 51, 112; cedars of Lebanon growing on ancient, 150; explanation of the cause of ridges on, 112, 113. Morteratsch glacier, cause of the widening of the medial moraine of, 97; motion of, 95, 96; sand-cones of, 116. Motion, of Mer de Glace, 93; of Grindelwald, 94; of Great Aletsch glacier, 94; of Morteratsch glacier, 95; sand-cones of, 116. Moulins, description of, 116; dangers from, 117; sounding of, 118. Mountain condensers, 27, 150.

Névé, explanation of term, 49; stratification of the, 179.

Obliquity of the lateral crevasses, 167; illustration, 107, 108.

Petit Plateau, 56. Piz Bernina, route to, 95. Place de la Concorde of Nature, 136. Plastic theory, 156; advocated by Bordier, 157; advocated by Rendu, 158. Poles, atomic, 32, 126; attractive and repellent, 30. Pontresina, village of, 95. Precious stones, examples of crystallizing power, 30. Precipitation, 23, 25; atmospheric, 27. Promontory of Trélaporte, 44; of Tacul, 51. Proofs of glacier-motions, 58. Pyramid of Aiguille du Dru, 43; of Aiguille des Charmoz, 43.

Quotation from Rendu, 158.

Rain, its source, 3; tropical, 23, 25. Rainfall, observations on amount of, 28. Regulation, theory, 163-167; observations made by Mr. Faraday, 164; formation of chain of icebergs by, 165; cause of, 167; Faraday's view of, 171-176. Relation of structure to pressure, 183; veined structure described by Guyot, 183-185; illustration, 186; connection established, 187. Retina, how excited, 8; theory of Sir Isaac Newton, 9. Riffelberg Hotel, location of, 144. Rivers, their sources, 1, 7, 19.

Sand-cones, 116. Scientific tacts, connection of, 72. Siedelhorn, view from the summit of, 146. Snow, its conversion into ice, 156; consolidation in Alpine regions, 156; line, 49; its formation in Russian ball-rooms, 5; in subterranean stables, 5, 14; in polar regions, 21; its architecture, 29-32, 34, 91; absorbs solar heat, 100. Solidifying power of camphor and metals, 17. Source of the Severn, 2; the Thames, 2; the Danube, 2; the Rhine, 2; the Rhone, 2; the Gauges, 2; the Euphrates, 2; the Garonne, 2; the Elbe, 2; the Missouri, 2; the Amazon, 2; Albula, 2; the Arveiron, 38; the Aar, 50. Stalactites of Alpine crevasses, 100. Steam, its condensation, 3, 4. Sunbeams, office of, 10-21. Sun, its heat the source of Alpine ice, 7; vibratory motion of the atoms of the, 11; position of, 19; indirect heat, of the, 28. Switzerland, ancient glaciers of, 145-147.

Theodolite, description of, 63; use of, 64, 65. Theory, of Dilatation, 155; developed by De Charpentier, 156; sliding, 156; plastic, 156-160; viscous, 161-103; regulation, 163-167; of glacial epoch, 155-167. Trade-winds, 20. Transverse crevasses, formation of, 104, 105. Trélaporte, promontory of, 44; motion of the water through the narrows of, 79.

Universe, order of the, 32.

Valley, of Hasli, 146, 147; Black, 151. Vapor, in the atmosphere, 5. Viscous theory, advocated by Prof. Forbes, 161; rejected by M. Agassiz, 162.