the Calotte; the Summit; wind and snow-dust; Balmat frostbitten; halt on the Calotte; descent to Chamouni; good conduct of porters

26. 192

Hostility of Chief Guide; Procès Verbal; the British Association; application to the Sardinian authorities; President's Letter; Royal Society; Testimonial to Balmat

27.—Winter Expedition to the Mer de Glace, 1859. 195

First defeat and fresh attempt; Geneva to Chamouni; deep snow; Desolation; slow progress; a horse in the snow; a struggle; Chamouni on Christmas night; mountains hidden; Climb to the Montanvert; Snow on the Pines; débris of avalanches; Breaking of snow; Atmospheric Changes; the mountains concealed and revealed; colour of the snow; the Montanvert in Winter; footprints in the snow; wonderful frost figures; Crystal Curtain; the Mer de Glace in Winter; the first night; "a rose of dawn;" Crimson Banners of the Aiguilles; the stakes fixed; a Hurricane on the glacier; the second night; Wild Snow-storm; a man in a crevasse; calm; Magnificent Snow Crystals; Sound through the falling snow; swift descent; Source of the Arveiron; Crystal Cave; appearance of water; westward from the vault; Majestic Scene; Farewell

PART II.

1.—Light and Heat. 223

What is Light?—notion of the ancients; requires Time to pass through Space; Römer, Bradley, Fizeau; Emission Theory supported by Newton, opposed by Huyghens; the Wave Theory established by Young and Fresnel; Theory explained; nature of Sound; of Music; of Pitch; nature of Light; of Colour; two sounds may produce silence; two rays of light may produce darkness; two rays of heat may produce cold; Length and Number of waves of light; Liquid Waves; Interference; Diffraction; Colours of Thin Plates; applications of the foregoing to cloud iridescences, luminous trees, twinkling of stars, the Spirit of the Brocken, &c.

2.—Radiant Heat. 239

The Sun emits a multitude of Non-luminous Rays; Rays of Heat differ from rays of Light as one colour differs from another; the same ray may produce the sensations of light and heat

3.—Qualities of Heat.241

Heat a kind of Motion; system of exchanges; Luminous and Obscure Heat; Absorption by Gases; gases may be transparent to light, but opaque to heat; Heat selected from luminous sources; the Atmosphere acts the part of a Ratchet-wheel; possible heat of a Distant Planet; causes of Cold in the upper strata of the Earth's Atmosphere

4.—Origin of Glaciers. 248

Application of principles; the Snow-line; its meaning; waters piled annually in a solid form on the summits of the hills; the Glaciers furnish the chief means of escape; superior and inferior snow-line

5.249

Whiteness of snow; whiteness of ice; Round air-bubbles; melting and freezing; Conversion of snow into ice by Pressure

6.—Colour of Water and Ice.253

Waves of Ether not entangled; they are separated in the prism; they are differently absorbed; Colour due to this; Water and Ice blue; water and ice opaque to radiant heat; Long Waves shivered on the molecules; Experiment; Grotto of Capri; the Laugs of Iceland

7.—Colours of the Sky. 257

Newton's idea; Goethe's Theory; Clausius and Brücke; Suspended Particles; singular effect on a painting explained by Goethe; Light separated without Absorption; Reflected and Transmitted light; blueness of milk and juices; the Sun through London smoke; Experiments; Blue of the Eye; Colours of Steam; the Lake of Geneva

8.—The Moraines. 263

Glacier loaded along its edges by the ruins of the mountains; Lateral Moraines; Medial Moraines; their number one less than the number of Tributaries; Moraines of the Mer de Glace; successive shrinkings; Glacier Tables explained; 'Dip' of stones upon the glacier enables us to draw the Meridian Line; type 'Table;' Sand Cones; moraines engulfed and disgorged; transparency of ice under the moraines

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