fig. 85
— section of volcanic cone in, 116, fig. 35
— section in, 129
— shifting of centre of eruption in, 196
Vulcanello, craters of, 197, fig. 86
Vulcanology, origin of the science, 4
— earliest treatise on, 5

WALFERDIN, M., cited, 340
Water in lavas, 353
— penetration through rocks, 358
— presence of in lavas, 102
— and saline solutions in cavities of crystals, 63
Werner, cited, 201
Western Isles of Scotland, 103, 139, 142
— — volcanoes of, 212
Whymper, Mr., 69
Woodward, Mr., experiments of, 119
Wrekin, ancient volcanic rocks of, 259

YOUNG, Professor, cited, 365

ZEOLITES, formation of, 150