Chapter IX: The Rocks and Their Order (3)

With almost all students a difficulty is encountered which hinders them in acquiring any large views as to the world about them. This is due to the fact that they can not make and retain in memory clear pictures of the things they see. They remember words rather than things--in fact, the training in language, which is so large a part of an education, tends ever to diminish the element of visual memory. The first task of the student who would become a naturalist is to take his knowledge from the thing, and to remember it by the mental picture of the thing. In all education in Nature, whether the student is guided by his own understanding or that of the teacher, a first and very continuous aim should be to enforce the habit of recalling very distinct images of all objects which it is desired to remember. To this end the student should practise himself by looking intently upon a landscape or any other object; then, turning away, he should try to recall what he has beheld. After a moment the impression by the sight should be repeated, and the study of the memory renewed. The writer knows by his own experience that even in middle-aged people, where it is hard to breed new habits, such deliberate training can greatly increase the capacity of the memory for taking in and reproducing images which are deemed of importance. Practice of this kind should form a part of every naturalist's daily routine. After a certain time, it need not be consciously done. The movements of thought and action will, indeed, become as automatic as those which the trained fencer makes with his foil.

Along with the habit of visualizing memories, and of storing them without the use of words, the student should undertake to enlarge his powers of conceiving spaces and directions as they exist in the field about him. Among savages and animals below the grade of man, this understanding of spacial relations is very clear and strong. It enables the primitive man to find his way through the trackless forest, and the carrier pigeon to recover his mate and dwelling place from the distance of hundreds of miles away. In civilized men, however, the habit of the home and street and the disuse of the ancient freedom has dulled, and in some instances almost destroyed, all sense of this shape of the external world. The best training to recover this precious capacity will now be set forth.

The student should begin by drawing a map on a true scale, however roughly the work may be done, of those features of the earth about him with which he is necessarily most familiar. The task may well be begun with his own dwelling or his schoolroom. Thence it may be extended so as to include the plan of the neighbouring streets or fields. At first, only directions and distances should be platted. After a time to these indications should be added on the map lines indicating in a general way contours or the lines formed by horizontal planes intersecting the area subject to delineation. After attaining certain rude skill in such work, the student may advantageously make excursions to districts which he can see only in a hurried way. As he goes, he should endeavour to note on a sketch map the positions of the hills and streams and the directions of the roads. A year of holiday practice in such work will, if the tasks occupy somewhere about a hundred hours of his time, serve greatly to extend or reawaken what may be called the topographic sense, and enable him to place in terms of space the observations of Nature which he may make.

In his more detailed work the student should select some particular field for his inquiry. If he be specially interested in geologic phenomena, he will best begin by noting two classes of facts--those exhibited in the rocks as they actually appear in the state of repose as shown in the outcrops of his neighbourhood, and those shown in the active manifestations of geological work, the decay of the rocks and the transportation of their waste, or, if the conditions favour, the complicated phenomena of the seashores.

As soon as the student begins to observe, he should begin to make a record of his studies. To the novice in any science written, and particularly sketched, notes are of the utmost importance. These, whether in words or in drawings, should be made in face of the facts; they should, indeed, be set down at the close of an observation, though not until the observer feels that the object he is studying has yielded to him all which it can at that time give. It is well to remark that where a record is made at the outset of a study the student is apt to feel that he is in some way pledged to shape all he may see to fit that which he has first written. In his early experience as a teacher, the writer was accustomed to have students compare their work of observation and delineation with that done by trained men on the same ground. It now seems to him best for the beginner at first to avoid all such reference of his own work to that of others. So great is the need of developing independent motive that it is better at the outset to make many blunders than to secure accuracy by trust in a leader. The skilful teacher can give fitting words of caution which may help a student to find the true way, but any reference of his undertakings to masterpieces is sure to breed a servile habit. Therefore such comparisons are fitting only after the habit of free work has been well formed. The student who can afford the help of a master, or, better, the assistance of many, such as some of our universities offer, should by all means avail himself of this resource. More than any other science, geology, because of the complexity of the considerations with which it has to deal, depends upon methods of labour which are to a great extent traditional, and which can not, indeed, be well transmitted except in the personal way. In the distinctly limited sciences, such as mathematics, physics, or even those which deal with organic bodies, the methods of work can be so far set forth in printed directions that the student may to a great extent acquire sound ways of work without the help of a teacher.

Although there is a vast and important literature concerning geology, the greater part of it is of a very special nature, and will convey to the beginner no substantial information whatever. It is not until he has become familiar with the field with which he is enabled to deal in the actual way that he can transfer experience thus acquired to other grounds. Therefore beyond the pleasing views which he may obtain by reading certain general works on the science, the student should at the outset of his inquiry limit his work as far as possible to his field of practice, using a good text-book, such as Dana's Manual of Geology, as a source of suggestions as to the problems which his field may afford.

The main aim of the student in this, as in other branches of inquiry, is to gain practice in following out the natural series of actions. To the primitive man the phenomenal world presents itself as a mere phantasmagoria, a vast show in which the things seen are only related to each other by the fact that they come at once into view. The end of science is to divine the order of this host, and the ways in which it is marshalled in its onward movement and the ends to which its march appears to be directed. So far as the student observes well, and thus gains a clear notion of separated facts, he is in a fair way to gather the data of knowledge which may be useful; but the real value of these discernments is not gained until the observations go together, so as to make something with a perspective. Until the store of separate facts is thus arranged, it is merely crude material for thought; it is not in the true meaning science, any more than a store of stone and mortar is architecture. When the student has developed an appetite for the appreciation of order and sources of energy in phenomena, he has passed his novitiate, and becomes one of that happy body of men who not only see what is perceived by the mass of their fellows, but are enabled to look through those chains of action which, when comprehended, serve to rationalize and ennoble all that the senses of man, aided by the instruments which he has devised, tell us concerning the visible world.

INDEX.

Ætna, Mount, 381.

Agriculture,
American, 346;
in England, winning swamp lands for, 335;
recent developments of, 345.

Alaska, changes on the coast of, 96.

Ants taking food underground, 319;
work of the, on the soil, 318.

Apsides, revolution of the, 61, 62.

Arabians, chemical experiments of the, 13.

Arches, natural, in cavern districts, 258.

Artesian wells, 258, 259.

Arts, advance of Italian fine, 19.

Asteroids, 53;
motions of, about their centres and about the sun, 53.

Astronomers, the solar system and the early, 79.

Astronomy, 31-80;
growth of, since the time of Galileo, 33, 34;
the first science, 10.

Atmosphere, 97-206;
along the tropical belt, 102;
as a medium of communication between different regions, 99;
deprived of water, containing little heat, 105;
beginning of the science of the, 117;
counter-trade movements of the, 105;
envelope of the earth, 98;
expansion of, in a hollow wall during the passage of a storm, 114;
heat-carrying power of the, 105;
heights to which it extends, 99;
in water, 99;
movements no direct influence on the surface of the earth, 122;
movements of the, qualified by the condition which
it encounters, 118;
of mountains, 98;
of the seashore, 98;
of the earth, 98;
of the sun, 73;
snow as an evidence of, 65;
supplying needs of underground creatures, 331;
uprushes of, 101, 102;
upward strain of the, next the earth, 107;
weight and motion of the, 120, 121.

Atmospheric circulation of the soil, 330, 331;
envelopes, 97.

Aurora borealis, 168.

Avalanches, 210-213;
dreaded, in the Alpine regions, 212;
great, in the Swiss Oberland, 211, 212;
rocky, 175-177.

Axis,
imaginary changes in the earth's, 59;
of the earth's rotation, 58;
polar, inclined position of, 58;
polar, nodding movement of the axes, 54;
rotations of the planetary spheres on their axes, 56.

Barometer, causes of changes in the, 117, 118.

Basalts, 309.

Beaches, 93, 142, 144;
boulder, 142, 143;
pebbly, 142;
sand, 144.

Beetles, work of, on the soil, 318, 319.

Belief of the early astronomers about the solar system, 79.

_Bergschrund_, the, 214.

Birds and mammals contributing to the fertility of the soil, 319.

"Blanketing," 269.

Bogs,
climbing, 331-334;
lake, 331-333;
peat, 334, 335;
quaking, 334.

Botany, rapid advance in, 14, 15.

Boulders, 217, 220.

Breakers, 135, 137, 139.

Bridges, natural, 257, 258.

Canals of Mars, 67.

Cañon, newly formed river cutting a, 195.

Cataracts, 193.

Caves, 253-258, 261;
architecture of, 255-258;
hot-water, 261;
mammoth cave, 258;
stalactites and stalagmites on the roof and floor of, 257.

Chasms, 140, 141.

Chemistry, 6, 12, 14;
advance of, 12;
modern, evolving from the studies of alchemists, 13, 14.

Chromosphere, 73.

Civilization of the Icelanders, 384.

Cliffs, sea-beaten, 132, 141, 142.

Climate,
changes of, due to modifications of the ocean streams, 153;
effect of the ocean on the, 147;
of the Gulf Stream, 149, 150.

Clouds, 159;
formation of, 162, 163;
shape of, 163;
water of, usually frozen, 207;
cloud-making, laws of, 161, 162.

Coast,
changes on the Scandinavian, 96;
line, effect of tide on the, 145;
of Greenland, 226;
of New Jersey sinking, 95;
marine, changes in, 95.

Cold in Siberia, 243.

Comets, 47, 50;
collisions of, 50;
kinship of meteorites and, 48;
omens of calamity to the ancients, 50;
the great, of 1811, 49, 50.

Cones. See under VOLCANOES.

Conflict between religion and science, 20, 22;
between the Protestant countries and the followers of science, 20.

Continental shelves, 125.

Continents and oceans, 83;
changes in position of, 91;
cyclones of the, 111;
forms of, 90;
proofs that they have endured for many years, 92;
shape of, 84, 96.

Coral reefs, 153, 353.

Corona, realm of the, 73.

Craters. See under VOLCANOES.

Crevasse, a barrier to the explorer, 218.

Crevice water, 250.

Curds, 214.

Currents,
coral reefs in Florida affecting the velocity of, 153;
equatorial, 150;
of the Gulf Stream, 147-149;
hot and cold, of the sea, 102;
ocean, 145;
oceanic action of trade winds on, 145;
effect on migration of, 157;
icebergs indicating, 243;
surface, history of, 172;
uprushing, near the equator, 106.

Cyclones, 111;
cause of, 111;
of North America, 111;
secondary storms of, 112.

Deltas, 173, 187.

Deposits, vein, 260, 261.

Deserts, interior, 158.

Dew, 159, 160;
a concomitant of cloudless skies, 160,
and vegetation, 160;
formation of, 159-161.

Diablerets, 174.

Diagram of a vein, 260;
showing development of swamp, 335;
how a portion of the earth's surface may be sunk by faulting, 374;
growth of mangroves, 340;
the effect of the position of the fulcrum point
in the movement of the land masses, 94.

Diameter of our sphere at the equator, 62;
of the earth, 82.

Dikes, 192, 293; 305-310;
abounding in volcanic cones, 305;
cutting through coal, 306;
driven upward, 307;
formation of, 305, 310;
material of, 307, 308;
representing movements of softened rock, 309;
their relation to volcanic cones, 307;
variations of the materials of, 307, 308;
waterfalls produced by, 192;
zone of, 306.

Dismal Swamp, 95, 333.

Distances,
general idea of, 27;
good way to study, 27, 28;
training soldiers to measure, 28.

Doldrums, 104, 109;
doldrum of the equator, 109;
of the hurricane, 109.

Drainage, imperfect, of a country affected by glaciers, 242.

Dunes, 123, 124, 325, 326, 387;
moulded, 387.

Duration of geological time, 389.

Dust accumulations from wind, in China, 122.

Earth,
a flattened sphere, 82;
air envelope of the, 98;
amount of heat falling from the sun on the, 41;
antiquity of the, 391;
atmosphere of the, 98;
attracting power of the, 127;
axis of the rotation of the, 58;
composition of the atmosphere of the, 98;
crust of the, affected by weight, 93;
deviation of the path of the, varied, 61;
diameter of the, 82;
of the, affected by loss of heat, 131;
difference in altitude of the surface of the, 83;
discovery that it was globular, 31, 32;
effect of imaginary changes in the relations of sun and, 59;
effect of the interior heat of the, 309, 310;
effect of the sun on the, 60, 61;
formerly in a fluid state, 82;
imaginary view of the, from the moon, 81;
important feature of the surface of the, 83;
jarring caused by faults, 367;
surface of the, determined by heat and light from the sun, 57;
most important feature of the surface of the, 83;
motion of the, affecting the direction of trade winds, 103;
movements, 366;
natural architecture of the, 377;
no part of the, exempt from movement, 384;
parting of the moon and, 396;
path of the, around the sun, 55, 56, 59, 60;
revolving from east to west, 103;
shrinking of the, from daily escape of heat, 89;
soil-covering of the, 343;
study of the, 81-96;
swaying, 385;
tensions, problem of, 371;
tremors, caused by chemical changes in the rocks, 385;
tropical belt of the, 74;
viewed from the surface of the moon, 311, 312;
water store of the, 125.

Earthquakes, 277, 278, 280, 356, 358, 370-384, 388-390;
accidents of, 358;
action of, 356;
agents of degradation, 383, 384;
basis of, 367;
certain limitations to, 380, 381;
Charleston, of 1883, 374, 375;
countries, architecture in, 381;
echoes, 369, 370;
damages of, 377, 390;
effect of,
on the soil, 375;
the surface of the earth, 371;
formed by riving of fissures, 382;
great, occurring where rocks have been
disturbed by mountain-building, 381, 382;
Herculaneum and Pompeii destroyed by an, 277, 280;
Italian, in 1783, 371, 372;
important, not connected with volcanic explosions, 381;
Jamaica, in 1692, 372, 376;
Lisbon, in 1755, 368, 369, 373, 374, 381;
maximum swing of, 369;
measuring the liability to, 386, 387;
mechanism of, 370, 371;
method of the study of, followed by Mr. Charles Mallet, 382, 383;
Mississippi, in 1811, 373, 374, 380, 381;
movement of the earth during, 377;
originating from a fault plane, 367, 369, 370;
originating from the seas, 358, 375;
oscillation of, 376;
poised rocks indicating a long exemption from strong, 388;
Riobamba, in 1797, 375;
shocks of, and their effect upon people, 383;
the direct calamities of Nature, 386;
waves of, 389.

Earthworms, 317-319;
taking food underground, 319.

Eclipses, record of ancient, 130.

Electrical action in the formation of rain and snow, 164.

Elevations of seas and lands, 83.

Energy indestructible, 23.

Envelope, lower, of the sun, 74.

Equator,
diameter of our sphere at the, 62;
doldrum of the, 109;
updraught under the, 102;
uprushing current near the, 106.

Equinoxes, precession of the, 61, 62.

_Eskers_, 221.

Expansion of air contained in a hollow wall during the
passage of the storm, 114.

Experiment, illustrating consolidation of disseminated
materials of the sun and planets, 40.

Falls. See WATERFALLS.

Fault planes, 382.

Feldspar, 324.

Floods, 180, 197;
rarity of, in New England, 121;
river, frequent east of Rocky Mountains, 198.

Föhns, 121.

Forests, salicified, 124.

Fossilization, 354-356.

Fulcrum point, 95.

Galactic plane, 45.

Galongoon, eruption of, 294.

Geological work of water, 168-206.

Glacial action in the valleys of Switzerland, 224;
periods, 63, 243, 246;
in the northern hemisphere, 246;
waste, 324.

Glaciation,
effect of,
in North America, 241;
in Central America, 234;
South America, 234.

Glaciers, 207-249;
action of ice in forming, 230-232;
Alaskan, 216;
continental, 225, 239, 240;
discharge of, 220;
exploring, 220;
extensive, in Greenland and Scandinavia, 244;
former, of North America, 232, 234;
map of, and moraines near Mont Blanc, 217;
motions of, 213;
retreat of the, 228, 230, 235;
secrets of the under ice of, 221;
speed of a, 224;
study of, in the Swiss valleys, 222;
testimony of the rocks regarding, 228;
when covered with winter snows, 216;
valley, 216.

Gombridge, 1830, 74.

Gravitation, law of, 4.

Greeks' idea of the heavens, 31;
not mechanically inventive, 22.

Gulf Stream, current of the, 147.

Heat,
amount of, daily escaping from the earth, 89;
amount of, falling from the sun on the earth, 41;
belief of the ancients regarding, 42;
dominating effect on air currents of tropical, 104;
energy with which it leaves the sun, 41;
internal,
of the earth, 88, 89;
of the earth's interior, 309, 310;
sun, effect on the atmosphere of the, 100;
Prof. Newcomb's belief regarding the, of the sun, 52;
radiation of the earth's, causing winds, 101;
solar, 41;
tropical, and air currents, 104.

Hills, sand, 123.

Horizontal pendulum, 384.

Horse latitudes, 104.

"Horses," 261.

Hurricanes, 107, 110, 317;
commencement of, 107;
doldrum of, 109;
felt near the sea, 110;
in the tropics, 110.

Hypothesis,
nebular, 34, 35, 39, 52, 56;
working, 4, 5.

Ice action,
effect of intense, 222, 223;
in forming glaciers, 230, 232;
recent studies in Greenland of, 239;
depth of, in Greenland, 227;
effect of, on river channels, 196;
effect of, on stream beds, 196;
expanding when freezing, 237;
epoch, 92, 93, 246;
floating, 242;
made soils rarely fertile, 241;
mass, greatest, in Greenland, 226, 227;
moulded by pressure, 215;
streams,
continental, 225, 226;
of the mountains, 225;
of the Himalayan Mountains, 234.

Icebergs, 242, 243;
indicating oceanic currents, 243.

Iceland, volcanic eruptions in, 297, 298.

Instruments, first, astronomical, 10, 11.

Inventions, mechanical, aiding science, 22.

Islands, 84, 272;
continental, 84;
in the deeper seas made up of volcanic ejections, 272;
volcanic, 272.

Jack-o'-lantern, 167.

Jupiter,
gaseous wraps of, 97;
path of the earth affected by, 59, 60;
the largest planet of the sun, 69.

Kames, 325.

Kant, Immanuel, and nebular hypothesis, 34.

Kaolin, 324.

Klondike district, cold in, 243, 244.

Krakatoa,
eruption of, 298-300;
effect of, on the sea, 299;
effect of, on the sun, 300.

Lacolites, 306.

Lacustrine beds, 351.

Lagoons, salt deposits found in, 200.

Lake basins,
formation of, 200, 201;
bogs, 331, 333, 334;
deposits, 350, 351.

Lakes, 199-206;
effect of, on the river system, 205;
fresh-water, 145;
formed from caverns, 202;
great, changing their outlets, 205;
of extinct volcanoes, 203;
temporary features of the land, 203;
volcanic, 203.

Lands,
great, relatively unchangeable, 96;
table, 91;
movements resulting in change of coast line, 351, 352;
shape of the seas and, 83, 84;
accounting for the changes in the attitude of the, 95;
and water, divisions of, 84;
dry, surface of, 85;
general statement as to the division of the, 83, 84;
surface, shape of the, 85;
triangular forms of great, 90.

Latitudes, horse, troublesome to mariners, 104.

Laplace and nebular hypothesis, 34.

Lava, 266-268, 270, 271, 292, 293, 295, 296, 303, 304;
flow of, invading a forest, 268;
from Vesuvius, 293;
of 1669, 295, 296;
temperature of, 295, 296;
incipient, 304;
outbreaks of, 292, 303;
stream eaves, 292, 293.

Law, natural,
Aristotle and, 3;
of gravitation, 4;
of the conservation of energy, 23.

Leaves, radiation of, 160.

Length of days affected by tidal action, 131.

Level surfaces, 91.

Life, organic, evolution of, 15, 16.

Light, belief of the ancients regarding, 42.

Lightning, 24, 164-168;
noise from, 166;
proceeding from the earth to the clouds, 165;
protection of buildings from, 165;
stroke, wearing-out effect of, 165.

Limestones, 353, 357, 358, 360, 364;
formation of, 357, 360.

Lisbon, earthquake of, 1755, 368, 369.

Lowell, Mr. Percival, observations on Venus, 64.

Lunar mountains near the Gulf of Iris, 397.

Mackerel sky, 35.

Mallet, Mr. Charles, and the study of earthquakes, 382, 383.

Man as an inventor of tools, 10.

Mangroves, 340;
diagram showing mode of growth, 340;
marshes of, 339.

Map of glaciers and moraines near Mont Blanc, 217;
of Ipswich marshes, 338.

Mapping with contour lines, 27.

Maps,
desirable, for the study of celestial geography, 77;
geographic sketch, 26, 27.

Marching sands jeopardizing agriculture, 123.

Marine animals, sustenance of, 361-363;
deposits, 325-327, 349, 356;
marshes, 336-340;
waves caused by earthquakes, 387.

Mars, 65-67, 84, 97;
belief that it has an atmosphere, 65;
canals of, 67;
gaseous wraps of, 97;
more efficient telescopes required for the study of, 67;
nearer to the earth than other planets, 65.

Marshes,
mangrove, 339;
map of Ipswich, 338;
marine, 336-340;
deposits found in, 336;
of North America, 337;
on the coast of New England, 339;
phenomena of, 167, 168;
tidal, good earth for tillage, 337;
tidal, of North America, 340.

Mercury, 55, 63, 78;
nearest to the sun, 63;
time in which it completes the circle of its year, 55.

Meteorites, 47, 48;
kinship of comets and, 48.

Meteors, 47;
falling, 47;
composition of, 48;
flashing, 39, 40, 47;
speed of, 47;
inflamed by friction with air, 99.

Methods in studying geology, 400.

Milky Way, 45;
voyage along the path of the, 44, 45.

Mineral crusts, 328, 329;
deposits, 308.

Moon, 38, 395-400;
absence of air and water on the, 399;
attended by satellites, 57;
attraction which it exercises on the earth, 62;
curious feature of the, 397;
destitute of gaseous or aqueous envelope, 397;
diameter of the, 399;
imaginary view of the earth from the, 81;
"libration" of the, 398;
made up of circular depressions, 396, 397;
movements of the, 78;
no atmosphere in the, 97;
parting of the earth and, 396;
position of the, in relation to the earth, 62;
tidal action and the, 131;
tides of the, 126, 127;
why does the sun not act in the same manner as the, 78.

Moraines, 216, 218, 229, 230;
map of glaciers and, near Mont Blanc, 217;
movements of the, 216-218;
terminal, 228.

_Moulin_, 219.

Mount Ætna, 288-310;
lava yielding, 290, 293, 294;
lava stream caves of, 292, 293;
more powerful than Vesuvius, 297;
peculiarities of, 291, 292;
size of, 289-291;
turning of the torrents of, 295.

Mountain-building, 90-93, 304;
folding, 86, 87, 90, 365;
attributed to cooling of the earth, 88;
growth, 392;
Swiss falls, 174;
torrents, energy of, 177.

Mountains, 85, 86, 89, 90-93; 174-178;
form and structure of, 86;
partly caused by escape of heat from the earth, 89;
sections of, 87.

Mount Nuova, formation 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.

_Névé_, 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 of, 57-61;
outer, 78;
table of relative masses of sun and, 77.

Plant life in the Sargassum basins, 156.

Plants and animals,
protection of,
by mechanical contrivances, 364;
and trees, work of the roots of, on the soil, 316, 317;
water-loving, 181;
forming climbing bogs, 332.

Polar axes, nodding movement of, 54.

Polar snow cap, 66.

Polyps, 155, 353.

Pools, circular, 203.

Prairies, 340, 342.

Radiation of heat, 159.

Rain, 152, 156, 164, 168, 170, 328, 330;
circuit of the, 156-168;
drops, force of, 169, 170;
spheroidal form of, 170;
electrical action in the formation of snow and, 164;
work of the, 171.

Realm, unseen solar, 75.

Reeds, 332.

Religion,
conflict between science and, 20, 22;
struggle between paganism and, 21.

Rivers and _débris_, 183;
changes in the course of, in alluvial plain, 182;
deposition of, accelerated by tree-planting, 181;
great, always clear, 205;
inundation of the Mississippi, eating away land, 182;
muds, 222;
newly formed, cutting a cañon, 195;
of snow-ice, 211;
origin of a normal, 173;
oxbow of a, 182,183;
sinking of, 199;
swinging movement of, 179-181;
river-valleys, 193, 194;
diversity in the form of 188-191.

Rocks, 145;
accidents from falling, 174;
cut away by sandstones, 188;
divided by crevices, 252;
duration of events recorded in, 389, 390,
ejection of, material, 311;
falling of, 174-176;
formation of, 262, 263;
from the present day to the strata of the Laurentian, 390;
migration of, 291;
poised, indicating a long exemption from strong earthquakes, 388;
rents in, 252, 253;
stratification of, 349, 350, 352, 365, 390;
testimony of the, in regard to glaciers, 228;
under volcanoes, 303;
variable elasticity of, 366;
vibration of, 367, 368;
rock-waste, march of the, 343;
water, 250, 267.

Rotation of the earth affected by tides, 130;
of the planetary spheres on their axes, 56.

Salicified forests, 124.

Salt deposits formed in lagoons, 200;
found in lakes, 199-200.

Sand bars, 183;
endurance of, against the waves, 145;
hills, travelling of, 123;
marching, 123;
silicious stones cutting away rooks, 188.

Satellites, 53, 54;
motions of, about their centres and about the sun, 53, 54.

Saturn, 38, 53, 57, 396;
cloud bands of, 70;
gaseous wraps of, 97;
path of the earth affected by, 59, 60.

Savages, primitive, students of Nature, 1.

Scandinavia, changes on the coasts of, 96.

Science,
advance of, due to mechanical inventions, 22;
astronomy beginning with, 10;
chemical, characteristics of, 14;
conflict between religion and, 20, 22;
conflict between the Roman faith and, 20;
mechanical inventions as aids to, 22, 23;
modern and ancient, 4;
natural, 5, 6;
of botany in Aristotle's time, 14;
of physiology, 15;
of zoölogy in Aristotle's time, 14;
resting practically on sight, 10.

Scientific development,
historic outlines of, 17;
tools used in measuring and weighing, as an aid to vision, 12.

Sea,
battering action of the, 140;
coast ever changing, 385, 386;
effect of volcanic eruptions on the, 299;
floor deposits of the, affected by volcanoes, 360, 361;
in receipt of organic and mineral matter, 359;
hot and cold currents of the, 102;
littoral zone of the, 351, 352;
puss, 142;
rich in organic life, 352, 353;
solvent action of the, 361;
strata, formation of, 354;
water, minerals in, 185;
weeds, 155, 156.

Seas, dead,
originally living lakes, 200;
water of, buoyant, 199;
eventually the seat of salt deposits, 199-201;
general statement as to division of, 83, 84;
shape of the, 83, 84.

Seashore, air of the, 98.

Seasons, changing the character of the, 61, 62.

Sense of hearing, 9,10;
of sight, 10;
of smell, 9, 10;
of taste, 9, 10;
of touch, 9, 10.

_Seracs_, 214.

Shocks, earthquake. See under EARTHQUAKES.

Shore lines, variation of, 83, 84.

Shores, cliff, 138-142.

Sink holes, 202;
in limestone districts, 253, 254.

Skaptar,
eruption of, 297, 298;
lava from the eruption of, 298.

Sky, mackerel, 35.

Snow, 207-225, 244;
as an evidence of atmosphere, 65;
blankets, early flowers beginning to blossom under, 208;
covering, difference between an annual and perennial, 210;
effect of, on plants, 208;
electrical action in the formation of rain and, 164;
flakes, formation of, 164;
red, 210;
slides, 210;
slides, phenomena of, 210, 211.

Soil,
alluvial, 321, 322;
atmospheric circulation of, 330, 331;
conditions leading to formation of, 313, 331;
continuous motion of the, 314;
covering of the earth, 343;
decay of the, 314, 315;
degradation of the, 344-348;
means for correcting, 346-348;
destruction in grain fields greater than the accumulation, 344;
developing on lava and ashes an interesting study, 343;
development of, in desert regions, 340;
effect of animals and plants on the, 317-320;
effect of earthquakes on the, 375;
fertility of the, distinguished from the coating, 344, 345;
fertility of, affected by rain, 327;
formation of, 314-321;
glacial, characteristics of, 324;
glaciated, 323, 324;
irrigation of the, 328-330;
local variation of, 327;
mineral, 321;
of arid regions fertile when subjected to irrigation, 341;
of dust or blown sand, 321;
of immediate derivation, 321, 322;
phenomena, 313;
processes of organic life in the, 315;
variation in, 321-331;
vegetation protecting the, 316, 317;
washing away of the, 346, 347;
winning, from the sea, 337;
work of ants on the, 318;
tiller, duty of the, 348.

Solar bodies,
general conditions of the, 63-71;
forces, action of, on the earth, 349;
system, 52, 56;
independent from the fixed stars system, 43;
original vapour of, 52, 53;
singular features of our, 68;
tide, 127.

Spheres,
difference in magnitude of, 51;
motions of the, 50, 51;
planetary, rotation of, on their axes, 56.

Spots, sun, 72.

Spouting horn, 141.

Springs, formation of small, 252.

Stalactitization, 256.

Stalagmites and stalactites on the roof and floor of a cavern, 257.

Stars as dark bodies in the heavens, 47;
discovery of Fraunhofer and others on, 23, 38;
double, 39;
and tidal action, 131;
earliest study of, 10;
fixed, important observations by the ancients of planets and, 43;
not isolated suns, 38, 39;
variation in the light of, 46;
limit of, seen by the naked eye, 11;
revolution of one star about another, 46, 47;
shooting, 47;
speed of certain, 51;
study of, 31-80;
sudden flashing forth of, due to catastrophe, 46;
voyage through the, 44, 45;
star, wandering, 74.

Stellar realm, 31-80.

Storms,
circular, 111;
desert, 121, 122;
expansion of air contained in a hollow wall during
the passage of, 114;
great principle of, 105, 106;
in the Sahara, 121;
lightning, more frequent in summer, 167;
paths of, 115;
secondary, of cyclones, 112;
spinning, 115;
thunder, 165-167;
whirling, 106, 124;
whirling peculiarity of, 108, 109.

Strabo, writings of, 18.

Sun,
atmosphere of the, 73;
constitution of the, 72;
distance of the earth from the, 29;
effect from changes in the, and earth, 59;
envelope of the, 73, 74, 97;
experiments illustrating consolidation of disseminated
materials of planets and, 40;
finally, dark and cold, 42;
formation of the eight planets of the, 53;
heat leaving the, 41;
heat of the, 76;
imaginary journey from the, into space, 44;
mass of the, 76, 77;
path of the earth around the, 55;
physical condition of the, 71;
Prof. Newcomb's belief regarding the heat of the, 52;
spots, 75;
abundant at certain intervals, 72;
difficulty in revealing cause of, 75;
structure of the, a problem before the use of the telescope, 72;
table of relative masses of, and planets, 77;
three stages in the history of the, 71;
tides, 126;
why does it not act in the same manner as the moon? 78.

Surfaces, level, 90.

Surf belt, swayings of the, 137.

Swamps,
diagram showing remains of, 335;
Dismal Swamp, 95, 333;
drainage of, 334, 335;
fresh-water, 334, 335;
phenomena of, 167, 168.

Table-lands, 91.

Table of relative masses of sun and planets, 77.

Telescopes, 11, 12, 45;
first results of, 72;
power of, 11;
revelations of, 45.

Temperature,
effects of, produced by vibration, 42;
in the doldrum belt, 118;
of North America, 118;
of the Atlantic Ocean, 118.

Tempests, rate of, 99, 100.

Thunder, 166;
more pronounced in the mountains, 166.

Thunderstorms, 165, 166;
distribution of, 166, 167.

Tidal action,
recent studies of, 131, 132;
marshes of North America, 340.

Tides,
carving channels, 129;
effecting the earth's rotation, 130;
effect of, on marine life, 130;
height of, 128, 129;
moon and sun, 126, 127;
normal run of the, 127;
production of, 131;
of the trade winds, 150;
solar, 127;
travelling of, 127, 128.

Tillage introducing air into the pores of the soil, 331.

Tornadoes, 112, 113, 317;
development of, 113;
effect of, on buildings, 113;
fiercest in North America, 113;
length of, 115;
resemblance of, to hurricanes, 115;
upsucking action of, 114, 115.

Torrents, 177-179, 204.

Trade winds. See under WINDS.

Training in language,
diminishing visual memory, 401;
soldiers to measure distances, 28;
to measure intervals of time, 28;
for a naturalist, 25-29.

Tunnels, natural, 257.

Uranus, 70.

Valley of Val del Bove formed from disturbances of Mount Ætna, 294.

Valleys,
diversity in the form of river, 188-191;
river, 193.

Vapour, 156, 157, 159, 163;
gravitative attraction of, 34, 35;
nebular theory of, 52, 53;
original, of the solar system, 52, 53.

Vegetation,
and dew, 160;
in a measure, independent of rain, 160;
protecting the soil, 316, 317.

Vein, diagram of a, 260.

Venus, 64, 78;
recent observations of, by Mr. Percival Lowell, 64.

Vesuvian system, study of the, 285.

Vesuvius. See MOUNT VESUVIUS.

Visualizing memories, 402, 403.

Volcanic action, 268-276.

Volcanic eruption of A.D. 79, 288;
important facts concerning, 276-279;
islands, 272;
lava a primary feature in, 266;
observations of, made from a balloon, 301;
peaks along the floor of the sea, 272, 273;
possibility of throwing matter beyond control of gravitative
energy, 300.

Volcanoes, 125, 203, 263;
abounding on the sea floor, 302;
accidents from eruptions of, 288;
along the Pacific coast, 271;
ash showers of, maintaining fertility of the soil, 289;
distribution of, 271;
eruption of, 286-294, 368;
explosions from, coming from a supposed liquid interior
of the earth, 275;
exporting earth material, 310;
little water, 375;
Italian, considered collectively, 296, 297;
Neapolitan eruptions of and the history of civilization, 288;
subsidence of the earth after eruption of, 287, 291;
origin of, 263-274;
phenomena of, 263-267;
submarine, 301;
travelling of ejections from, 287, 288.

Waters,
crevice, 250;
of the earth, 250, 251;
cutting action of, 117, 192;
drift, from the poles, 151;
journey of, from the Arctic Circle to the tropics, 151, 152;
dynamic value of, 171;
expansion of, in rocks, 270;
geological work of, 168-206;
in air, 99;
of the clouds usually frozen, 207;
pure, no power for cutting rocks, 204;
rock, 250, 263;
sea, minerals in, 185;
store of the earth, 125;
system of, 125, 156;
tropical, 151;
velocity of the, under the equator, 150;
wearing away rocks, 178, 179;
underground, carrying mineral matter to the sea, 193;
chemical changes of, leading to changes in rock material, 262, 263;
effect of carbonic-acid gas on, 251;
operations of the, 126;
wearing away rocks, 178, 179;
work of, 250.

Waterfalls, 189-193;
cause of, 191;
the Yosemite, 192;
Niagara, 191, 192;
numerous in the torrent district of rivers, 192;
produced by dikes, 192;
valuable to manufactures, 192, 193.

Waterspouts, 115, 116;
atmospheric cause of, 116;
firing at, 116;
life of a, 116;
picturesqueness of, 116;
the water of fresh, 117.

Waves, 128, 129, 132, 145;
action of friction on, 135, 136;
break of the, 136;
endurance of sand against the, 145;
force of, 133, 136, 139;
marine, caused by earthquakes, 387;
of earthquakes, 389;
peculiar features in the action of, 137;
size of, 137, 138;
stroke of the, 144;
surf, 135;
tidal height of, 132;
undulations of, 132;
wind, 132;
wind influence of, on the sea, 134, 135;
wind-made, 128.

Ways and means of studying Nature, 9.

Weeds of the sea, 155.

Well, artesian, 258, 259.

Whirling of fluids and gas, 36, 37.

Whirlwinds in Sahara, 121.

Will-o'-the-wisp, 167.

Winds, 101, 110, 122, 317;
effect of sand, 122;
hurricane, 110;
illustration of how they are produced, 101;
in Martha's Vineyard, 120;
of the forests, work of the, 317;
of tornadoes, effect of, 113;
on the island of Jamaica, 119, 120;
regimen of the, 119;
variable falling away in the nighttime, 100;
trade, 102-105; 145, 146, 150;
action of, on ocean currents, 145:
affected by motion of the earth, 103;
belt, motion of the ocean in, 146;
flow and counter-flow of the, 150;
tide of the, 150;
uniform condition of the, 102;
waves, work of, 132, 134, 135.

Witchcraft, belief of, in the early ages, 21.

Zoölogy, rapid advance in, 14, 15.