rmation of, 284.

Mount Vesuvius, 263-285, 288, 289, 293, 302, 381;
description of the eruption of, in A.D. 79, 277-280;
diagrammatic sections through, showing changes in the form
of the cone, 283;
eruption of, in 1056, 281;
in 1882-'83, 264, 266;
eruption of, in 1872, 282;
eruptions of, increased since 1636, 282;
flow of lava from, 285;
likely to enter on a period of inaction, 282, 283;
outbreak of, in 1882-'83, 264, 266.

Naples, prosperity of the city, 289.

Nebular hypothesis, 34, 35, 39, 52.

Neptune, 70.

_Neve_, the, 214;
no ice-cutting in the region of the, 224.

Newcomb's (Prof.) belief regarding the heat of the sun, 52.

Niagara Falls, 191, 192, 204;
cutting back of, 204.

North America,
changes in the form of, 91, 92;
triangular form of, 90.

Ocean,
average depth of the, 89;
climatal effect of the, 147;
currents, 145;
effect of, on migration, 156;
effect of, on organic life, 154;
floor, 85, 93;
hot and cold currents of the, 102;
sinking of the, 93, 94;
the laboratory of sedimentary deposits, 351;
depth of the, 89, 126.

Oceanic circulation, effect of, on the temperature, 152.

Oceans and continents, 83.

Orbit,
alterations of the, and the seasons, 60, 61;
changing of the, 59-63;
shape of the, 61-63.

Organic life, 315, 317, 321, 352, 353, 363;
action of, on the soil, 317, 321;
advantages of the shore belt to, 363;
development of in the sea, 352, 353;
effect of ocean currents on, 154;
processes of, in the soil, 315;
decay of, in the earth, 321.

Orion, 46.

Oscillations of the shores of the Bay of Naples, 287.

Oxbow of a river, 182, 183.

Oxbows and cut-off, 182.

Pebbles,
action of seaweeds on, 143;
action of the waves on, 142, 144.

Photosphere, 74.

Plains, 86;
alluvial, 91, 179, 182, 184-186, 325;
history of, 91;
sand, 325.

Planets, 38;
attended by satellites, 57;
comparative sizes of the, 68;
experiments illustrating consolidation of disseminated
materials of the sun and, 40;
gaseous wraps of, 97;
important observations by the ancients of fixed stars
and planets, 43;
movements