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Outlines of Forestry;

OR,

THE ELEMENTARY PRINCIPLES

UNDERLYING THE SCIENCE

OF FORESTRY.

BEING A SERIES OF PRIMERS OF FORESTRY.

BY

EDWIN J. HOUSTON, A.M.,

MEMBER OF THE PENNSYLVANIA FORESTRY ASSOCIATION, PROFESSOR OF PHYSICS
IN THE FRANKLIN INSTITUTE OF THE STATE OF PENNSYLVANIA, PRO-
FESSOR OF NATURAL PHILOSOPHY AND PHYSICAL GEOGRAPHY IN
THE CENTRAL HIGH SCHOOL OF PHILADELPHIA, ETC., ETC.

PHILADELPHIA:

J. B. LIPPINCOTT COMPANY.
1893..

Copyright, 1893,

BY

J. B. LipPiNcoTT Company.

Printed by J. B. Lippincott Company, Philadelphia.

PREFACE.

"When from any cause a necessity exists in any
country for the removal of its forests from ex-
tended areas, unless care be taken as to the man-
ner in which such removal is made, and some
parts are left wooded, irreparable injuries will
inevitably follow.

In the United States, where the enormous in-
crease in population has resulted in the removal
of the forests from extended areas, such intelli-
gence and care have unfortunately, in most cases,
not been exercised. The timber lands have gen-
erally been purchased at figures based almost
entirely on the value of the standing wood. The
trees have been cut down in a reckless manner,
and fires, carelessly started, have often been left
indifierently to burn themselves out. l!^o attempts
have been made to protect the soil that has been
denuded of its natural protective covering by the
axe or the fire. Before the forest has been
made to yield its entire harvest, the greed of the

4 PREFACE.

speculator has too often led him to ahandon to the
destructive action of the elements the area he has
thus despoiled, in order to seek another, as yet
unbroken, forest area.

Instead of carefully removing some of the trees
from the forest, and leaving the area in such a
condition as to enable it to produce a new growth,
in the United States it has too frequently been
the case that the virgin forest is thoughtlessly
attacked, its best trees cut down in so careless a
manner that the harvested crop amounts to, per-
haps, but a third, or even less, of the total growth,
and the remaining part abandoned to certain
destruction by the elements.

The irreparable loss caused by such greed should
be prevented by the enactment of judicious penal
laws.

It is often very difficult to persuade the general
public that evil results following any course of
action, which do not come immediately, are not
thereby prevented from coming eventually. Be-
cause the evil day draws not nigh quickly, there
is a tendency to believe that it will never come at
all.

An attempt has been made in the " Outlines of
Forestry'' to point out to the general public, in

PREFACE. 5

simple, non-technical language, the character of
the effects, both on the general climate of a coun-
try and on the distribution of its rainfall, which
inexorably follow the unsystematic removal of its
forests.

It is only necessary to give the public some little
insight into the effects produced by the destruction
of the forest to arouse it to a conviction of the
necessity for the existence of "Forestry Associa-
tions," for the enactment of laws regulating the
manner in which the forests shall be removed,
and for the setting aside of certain districts on
which forests shall be perpetually maintained.

In order to enable the readers of this little book
to carry their reading beyond the elementary prin-
ciples which it discloses, appropriate extracts, taken
from standard authors, and published by permis-
sion of the authors or publishers, have been added
at the end of each primer. In all cases the exact
title of the book has been given, as well as the
names of its publishers.

For general aid in remembering the princi-
ples discussed in each primer, a concise review
has been given at the close of the book in the
form of a primer of primers.

The author has not hesitated to consult freely

1*

6 PREFACE.

all standard authorities in matters pertaining to
the general subject of forestry.

There have been added to the book, in the shape
of an appendix, lists of trees suitable for planting
in different sections of the United States, as fur-
nished by eminent authorities on the subject.

The author desires to express his thanks to the
gentlemen who have responded to his circular
letter of inquiry as to lists of trees suitable for
replanting in various sections of the United States,
and to his friend Professor Charles S. Dolley for
revision of the manuscript of this book.

Edwin J. Houston.

Central High School, Philadelphia, Pa.,
January, 1893.

CONTENTS.

PAGB

I. — Forestry 9

II. — Conditions Necessary for the Growth of

Plants 20

III. — The Wide Distribution of Plant Germs . 32
IV. — Conditions Necessary for the Growth of

Trees 42

V. — The Formation of Soil 50

VI. — The Inanimate Enemies of the Forest . . 61

VII. — The Animate Enemies of the Forest ... 71

VIII. — The Destruction of the Forest 81

IX. — The Earth's Ocean of Vapor 90

X.— Rain 100

XI.— Drainage 109

XII.— Climate 119

XIII. — Climate as Influenced by the Presence of

THE Forest 127

XIV. — Purification of the Atmosphere 140

XV.— Hail 147

XVI. — Reforestation and Tree-Planting .... 155

XVII. — The Balance of Nature 164

XVIII.— Primer of Primers 177

Appendix 209

Index 245

7

OUTLINES OF FORESTRY.

I. FORESTRY.

The science of forestry not only treats of the
care and preservation of those parts of the earth
that are covered with trees, but also of the means
best suited to the replanting of the areas from
which the trees have been removed.

If nature is let alone she will cover any por-
tion of the earth where vegetable life is possible
with the particular kind of vegetation best fitted
to grow under the existing conditions of soil, heat,
light, and moisture.

l^ature will, therefore, cover with forest all por-
tions of the earth where forests are best fitted to
exist.

It may then be asked, on what does the science
of forestry rest ? Why not leave nature alone ?
Such questions arise from a misunderstanding of
what forestry endeavors to accomplish. Forestry

10 OUTLINES OF FORESTRY.

does not aim to oppose nature, but simply to aid
her. It endeavors to make use of the conditions
naturally existing in any locality that are favorable
to the continued growth of trees, and to oppose
or hold in check conditions unfavorable to such
growth.

The following considerations will suffice to show
the necessity for the existence of Forestry Associa-
tions, and the enactment of strict laws for the care
and preservation of the rapidly decreasing forest
areas of the earth. The !N'orth Temperate zone,
the cradle of the human race, possesses the densest
civilized population. This zone was originally
covered by extensive forests, and is still heavily
wooded over extended areas.

Civilized man, however, cannot continue a
dweller in the forest. It is true that in sparsely
settled districts no necessity exists for the removal
of the entire forest ; but, as the density of popula-
tion increases, the demands made on the forest
increase. Such demiinds will, therefore, increase
rather than decrease in the near future. Hence
the necessity for the existence of Forestry Associa-
tions and the enactment of Forestry Laws.

The demands made on the forest by civilized
man are either —

FORESTRY.

11

1. For the area on which the forest stands, or

2. For some of the products of the forest, such
as wood for building purposes or fuel, or bark for
the tannery.

The demands for the areas on which the forests
stand are made either for the purpose of increas-
ing the extent of the agricultural areas, or for the
building of ordinary roads or railroads.

"We may tabulate these demands as follows :

Encroachment

on the forest

for —

1. Area on
which it -
stands.

1. For land to he cultivated for
ordinary farm products.

2. For the construction of ordi-
nary roads or railroads.

' 1.

Fuel.

2.

Charcoal.

2. For its
products.

3.
4.

5.
6.

Building purposes generally.
Fences.
Kailroad ties.
Telegraph poles.

7.
8.

Mining purposes.
Bark for tanneries.

. 9.

Turpentine, rosin.

When the forests are removed for the area on
which the trees stand, the destruction is necessarily
complete.

Where the removal is for agricultural purposes,

12 OUTLINES OF FORESTRY.

the destruction should not be complete. The prin-
ciples of forestry teach that the truest economy
will permit certain tracts to remain covered with
trees; for the ultimate gain to the farmer from
such a course will be greatly in excess of the
sums paid for rental, or the interest-charges on
the land that is not directly productive in ordi-
nary farm products.

The areas required to be taken from the forests
for agricultural purposes necessarily greatly ex-
ceed those required for the location of ordinary
roads or railroads. The damage done indirectly
to the forest, however, by the location of new
roads, especially railroads, is often greater than by
the location of new farming-lands, since the loca-
tion of new roads greatly increases the liability to
destructive fires, and also opens up extensive tracts
of yet unmolested forest to the greed of the lum-
berman, or to the indifference of the railroad
authorities or of the travelling public.

Besides this, an area taken for agricultural pur-
poses is, to a certain extent, protected from the
loss of its soil by a covering of vegetation. Dur-
ing the construction and operation of a road-bed,
much of the adjoining land is often needlessly
destroyed by being thoughtlessly left for floods

")

FORESTRY. 13

to work irreparable damage by the removal of
the soil.

It is for the purpose of regulating the necessary
removal of the forest, and for pointing out the
manner in which the products of the forest can
be most advantageously harvested, that Forestry
Associations and Forestry Laws are so imperatively
demanded.

In order to intelligently protect forest areas,
and thus aid rather than oppose nature in main-
taining them, the principles underlying the growth
of trees, the conditions of heat, light, and moisture,
or, in general, the conditions of climate best suited
to continue such growth, must be carefully studied.
The natural influences or conditions which oppose
the growth of trees must be ascertained, and,
where possible, checked ; the enemies of the forest
recognized, and the best means taken to hold them
in check. In other words, forestry must assume the
position of an exact science, in order to call intelli-
gently for the passage of laws intended for insuring
the growth and reproduction of the earth's forests.

It is a mistaken idea that forestry endeavors to
preserve intact the virgin forests of the earth.
This is by no means the intent of intelligent for-
estry.

2

14 OUTLINES OF FORESTRY.

The wood and other products of the forest
form an important part of the resources of a
country. Man is as much entitled to the harvests
of the woods as to the harvests of the fields.
Forestry endeavors to point out the best ways in
which forest crops maybe harvested without detri-
ment to the subsequent crops, and without causing
the ultimate destruction of the forest.

Since it is manifestly impossible to preserve
forests on all parts of the earth's surface where
forests can naturally grow, it should be the duty
and care of every community to set aside certain
portions where forests shall be perpetually main-
tained ; or, if already deforested, shall be replanted
or reforested. Such preserves were originally
maintained by the arbitrary will of the sovereign
lord of the country, for the good of a few, in
order to insure royal hunting-grounds. They
should now be maintained, by the will of the
people, for the good of the many.

The parts best suited for the perpetual mainte-
nance of forests will necessarily vary in different
regions.

In agricultural districts, certain areas should
invariably be set aside on which trees shall be
perpetually preserved; for true economy requires

FORESTRY. 15

the maintenance of some timber on nearly all
farm-land.

These areas will, perhaps, in the majority of
cases be found as follows, — viz. :

1. On poor or thin soils where no other crops
will thrive.

2. In damp places where no other crops will
thrive.

3. On the borders of rivers or other streams.

4. On mountain slopes, hill-tops, or other
elevations.

It can be shown, generally, that the areas which
can be most profitably set aside for the mainte-
nance of perpetual forests are situated, for the
greater part, in the mountainous districts of the
earth, the natural home of the forest.

As will hereafter be shown, the forests should
especially be preserved on mountain slopes, for the
following reasons :

1. Because the rain falls more frequently and
in greater quantity in the mountainous districts
of the earth than elsewhere. The cold mountain
slopes, chilling the air, cause it to deposit its sur-
plus moisture, in no matter from what direction
the winds may come.

2. Because the principal rivers of the earth

16 OUTLINES OF FORESTRY.

are born in the mountainous districts, and, if the
forests are removed, the rain which falls drains so
rapidly from the earth's surface that the soil
that took a long time to form by the gradual
disintegration of the igneous rocks, and slowly
accumulated its vegetable mould from the growth
and subsequent decay of thousands of generations
of plants, is lost to the highlands, only to become
a source of damage to the lowlands.

3. Because the rapid drainage of the mountain
slopes on the removal of their forests will result in
dangerous floods during times of rain.

4. Because the failure of so great a part of
the rain-water to sink into the ground and fill the
reservoirs of the springs will cause such springs
to more readily dry up shortly after the appear-
ance of drought.

5. Because the mountain slopes, when de-
prived of their forests, become excessively hot
during the day, and excessively cold during the
night, and thus tend to sensibly alter the climate
of the country.

6. Because such marked differences in tem-
perature tend to increase the number and severity
of destructive hail-storms.

7. Because the removal of the forests tends to

FORESTRY. 17

increase the liability of occurrence of early frosts
in the neighboring agricultural districts.

8. Because the removal of the forests will be
attended by marked changes in the relative quan-
tity of moisture in the air at different times of the
year.

B. E. Fernow, Chief of the Department of For-
estry in the United States Department of Agricul-
ture, in a paper entitled "What is Forestry ?''*
says, on page 15 :

" Forestry in a wooded country means harvesting the wood
crop in such a manner that the forest will produce itself in
the same, if not in superior, composition of kinds. Keproduc-
tion, then, is the aim of the forest manager, and the difference
between the work of the lumberman and that of the forester
consists mainly in this : that the forester cuts his trees with a
view of securing valuable reproduction, while the lumber-
man cuts without this view, or at least without the knowledge
as to how this reproduction can be secured and directed at
will. The efficient forest manager requires no tool other than
the axe and the saw, — the planing-tools being only needed to
correct his mistakes, — ^but he sees them differently from the
lumberman."

* Reprinted, by permission, from " What is Forestry ?" by
B. E. Fernow, Washington, Government Printing-Office, 1891.
b 2*

18 OUTLINES OF FORESTRY.

The true position which forestry takes in the
United States is thus forcibly expressed in the
Annual Report of the I^ew York Forest Commis-
sion, for the year ending December 31, 1890,* on
page 91, as follows :

"A misunderstanding has prevailed to some extent with
regard to the attitude of forestry towards the lumber interests
of private owners. It is, however, generally misunderstood,
now, that the true interests of the lumbermen are not incom-
patible with forest preservation, and it has been declared to
be one of the objects of the forestry movement in this country
*To harmonize the interests of the lumberman and the for-
ester, and to devise for the lumbering interest such protection
as is not given at the cost of the forests.' Forestry is not
opposed to having trees cut down in the proper way. They
must be cut to supply the world with timber. They furnish
the material for shelter to mankind, and contribute to render
the houses of men comfortable and beautiful by providing
fiiel and decorations. It is needless to point out here the
manifold purposes for which wood is needed, and how largely
it enters into our industries and arts, contributes to our con-
venience and pleasure, and becomes a necessity of our daily
lives. Civilization could hardly exist without it. It is from
trees, and from trees only, that our needs for wood are supplied

* Reprinted, by permission, from Annual Report of the
New York Forest Commission, for the year ending Decem-
ber 31, 1890. Albany : James B. Lyon, State Printer, 1891.
Pp. 317.

FORESTRY. 19

through the timber-dealer and lumberman. It is not the ex-
ercise of their vocation, but their frequent abuse of it, that
calls for criticism, — a distinction that has not always been
made by the critics. Estimates show that thirty billion feet
are required annually in this country for building and manu-
facturing purposes alone, leaving the fiiel question out of con-
sideration. It is the unwise, improvident, stupid method, or
want of method, by which the cutting has heretofore too often
been done, that is deplored. Under the old practice the
forests have rapidly disappeared, and, if it continues, in a few
years none will be left. The lumberman will have ruined his
own business, as there will be no forests to fiirnish him with
his stock in trade. It is the purpose of forestry to point out
to the lumberman the true methods of exercising his own
profession, which will provide him material for the future, as
well as the present, by maintaining permanent forests through
a succession of crops."

20 OUTLINES OF FORESTRY.

II. CONDITIONS NECESSARY FOR THE
GROWTH OF PLANTS.

Extended scientific researcli has established the
fact that all forms of life, whether of the animal
or the plant, can, at their earliest stages, be traced
to a minute germ-cell filled with a more or less
transparent substance called protoplasm, and con-
taining a dark, opaque spot called the nucleus.
Unless this germ-cell exists, plant or animal life is
impossible.

Although cases exist where there has been no
apparent evidence of the presence of a germ or
seed, yet such germ or seed must have existed,
and was derived from a plant of exactly the same
character as that which such seed will produce
when called into active and matured growth.

Under peculiar circumstances, plant or animal
germs possess wonderful vitality, and may remain
in a dormant state for a very long time, only
beginning to grow when exposed to the conditions
necessary for growth.

In order that any form of plant life may exist

CONDITIONS FOR THE GROWTH OF PLANTS. 21

on the earth, the following conditions are neces-
sary :

1. The germ or seed from which the plant
grows.

The germ or seed in all cases comes directly
from a plant similar to that which is produced
when the seed sprouts or germinates, and attains
its full growth.

2. The cradle where the plant is born.

The plant's cradle is the soil. In the soil the
plant spreads its roots, and from it obtains, in
great part, the materials necessary for nourish-
ment and growth.

Cases exist where the plant finds its cradle in
the air or in the water. These need not, however,
be considered in this connection.

3. The sunshine and the heatshine, which awaken
the sleeping germ and call it into activity ; or, in
other words, the light and heat which are so
essential to a plant's growth.

4. The nourishment, or the food which the
plant takes into its structure and assimilates, and
thus causes it to become a part of itself.

The processes by which a plant causes different
materials taken from the soil in which it grows,
or from the air around it, to become a part of

22 OUTLINES OF FORESTRY.

itself, is called assimilation. At the commence-
ment of its life the plant gets its nourishment
from the protoplasm surrounding the nucleus. It
is not long, however, before it exhausts this stock
of food, and it must then get all its nourishment
either from the soil or from the atmosphere ; or,
in other words, from outside the seed.

This latter nourishment of the plant comes
from a variety of materials, derived either from
the air or from the ground, the most important
of which are as follows :

1. Moisture.

This moisture is mainly taken up by the roots
of the plant from the soil; but it is, in some
cases, absorbed directly from the air by the leaves.

2. Carbonic acid.

Carbonic acid is a gaseous substance, formed of
carbon combined with an invisible gas called oxy-
gen. The carbonic acid is absorbed by the leaves
of the plant, and, in the presence of sunshine, is
broken up into carbon and oxygen. The oxygen
is given oft' from the surfaces of the leaves, and
the carbon is retained by the plant to form its
woody fibre. In the case of large vegetable forms
like forest-trees, the amount of carbonic acid taken
from the air and converted into woody fibre must

CONDITIONS FOR THE GROWTH OF PLANTS. 23

be very great. A certain amount of oxygen, how-
ever, must be present in the air, to permit the
continued growth of the plant ; for most plants will
not grow in an atmosphere of pure carbonic acid gas.

The hydrogen needed for the plant's growth is
derived from the decomposition of the water asso-
ciated with the carbonic acid; the result is that
the plant retains the carbon and the hydrogen, and
throws out the oxygen into the atmosphere.

3. Mineral matters taken from the soil.

The tissues of the plant contain various kinds
of mineral substances which are taken directly
from the soil. For the proper growth of the
plant, the soil must contain these particular min-
eral substances in the condition or state in which
they can be readily taken up or assimilated by the
plant.

The above conditions — viz., the germ, the cradle,
the sun's light and heat, and some form of solid
and liquid food — are not of equal importance to
the growth of the plant.

The presence of the germ or seed is, of course,
of the greatest importance, since without it no
plant can grow.

The sunshine and the heat may, perhaps, be
considered as next in importance to the growth

24 OUTLINES OF FORESTRY.

of the plant. Heat and light are to be found in
practically all parts of the earth. They differ,
however, in amount, in different regions of the
earth, and such differences cause the differences
that are noticed in the plants that grow in dif-
ferent regions.

Even in the same region, differences in the light
and heat cause differences in the plant's growth,
as may be noticed in almost any forest region.

The plants that form the undergrowth of those
portions of the forest where the light is more
thoroughly shut out are markedly different from
those appearing in the clearings, where the light
and heat have full access to the soil.

The nourishment of the plant comes next in
importance. The quantity of carbonic acid found
in the air is practically the same in all parts of the
earth. The quantity of moisture in the air differs
very greatly in different parts of the earth, and
on this difference, together with the difference of
temperature, depends the differences observed in
the plants of various regions.

The liquid nourishment of the plant in the
shape of water is of so great importance to the
growth of the plant, that the character of the
rain-fall in any country will, to a marked ex-

CONDITIONS FOR THE GROWTH OF PLANTS. 25

tent, determine the character of the flora of that
country.

The soil is, perhaps, the least important of the
conditions required for plant growth.

This statement is at first thous^ht so much at
variance with the generally received opinion as to
need an explanation.

Where a particular kind of plant is to be grown,
the character of the soil, probably, stands next in
importance to the presence of the germ or seed ;
for each plant thrives best in a particular kind of
soil. The variety of plants that exist, however,
is so great that, given almost any kind of soil,
together with certain conditions of heat, light,
and moisture, such soil will be found to be best
suited for the growth of some particular kind of
plant. In other words, if the proper conditions
of moisture, heat, and light are present, and the
germ is present, vegetation will appear in almost
any region.

E"ature has generously scattered the germs of
various forms of plant life nearly all over the
earth's surface. Therefore, if unmolested by man,
she will, in most cases, maintain on such surfaces
the kind of plant forms or plant growths best
suited to grow naturally.

26 OUTLINES OF FORESTRY.

There, therefore, will be found in every section
of country a plant growth or plant life peculiar
to, or naturally belonging to, such a section of
country. Each section of country possesses, so
to speak, a nationality in its plants, or, in other
words, there lives in each section of country a
particular nation of plants. Such a nation of
plants, or the plants peculiar to a particular sec-
tion of country, is called its flora.

Since heat, light, and moisture are, next to the
presence of the plant germ, the most important
things for plant growth, there will necessarily
exist in different parts of the earth a flora that will
vary according to the differences that exist in the
distribution of heat, light, and moisture over such
part of the earth's surface.

The heat, light, and moisture are greater in
amount at the equator than at any other portion
of the earth's surface. Therefore, the vegetation
is more luxuriant, or possesses a greater diversity
of forms, here than at any other part of the sur-
face. As we pass from the equator towards the
poles, the decrease in the heat, light, and moisture
causes a corresponding decrease in the variety and
luxuriance of vegetable life.

In passing from the base to the summit of a

CONDITIONS FOR THE GROWTH OF PLANTS. 27

high tropical mountain, the same differences in
the variety and luxuriance of plant life are noticed
that are seen in going from the equator to the
poles. This is due mainly to the distribution of
the heat and moisture.

The planting of a germ or seed in any soil will
not result in its continued growth, unless the con-
ditions of heat, light, and moisture are practically
the same as those in which the plant from which
such germ or seed was derived required for its
existence.

Trees planted in a particular locality may, there-
fore, fail to grow in such locality, from want of
the proper conditions of heat, light, and moisture.

In all regions where forests can grow naturally,
wherever practicable, they should be permitted to
grow, since, as will be shown, the continued ex-
istence of forests on certain portions of the earth
is necessary for insuring that balance of nature on
which the comfortable existence of man depends.

Guyot, on page 188 in his " Earth and Man," *

* " The Earth and Man," lecture on Comparative Physi-
cal Geography in its Eelation to the History of Mankind, by
Arnold Guyot, Professor of Physical Geography and History
at Neufchatel, Switzerland. Boston : Gould, Kendall & Lin-
coln, 1849.

28 OUTLINES OF FORESTRY.

thus refers to the conditions favorable to luxuriant
vegetable growth :

"The warm and the moist — these are the most favorable
conditions for the production of an exuberant vegetation.
Now, the vegetable covering is nowhere so general, the vege-
tation so predominant, as in the two Americas. Behold,
under the same parallel where Africa presents only parched
table-lands, those boundless virgin forests of the basin of the
Amazon, those selvas, almost unbroken over a length of more
than fifteen hundred miles, forming the most gigantic wilder-
ness of this kind that exists in any continent. And what
vigor, what luxuriance of vegetation I The palm-trees, with
their slender forms, calling to mind that of America itself,
boldly uplifted their heads one hundred and fifty or two hun-
dred feet above the ground, and domineer over all the other
trees of these wilds, by their height, by their number, and by
the majesty of their foliage. Innumerable shrubs and trees
of smaller height fill up the space that separates their trunks ;
climbing plants, woody- stemmed, twining lianos, infinitely
varied, surround them both with their flexible branches, dis-
play their own flowers upon the foliage, and combine them in
a solid mass of vegetation, impenetrable to man, which the
axe alone can break through with success. On the bosom of
their peacefiil waters swims the Victoria, the elegant rival of
the Rafflesia, that odorous and gigantic water-lily, whose white
and rosy corolla, fifteen inches in diameter, rises with a daz-
zling brilliancy from the midst of a train of immense leaves,
softly spread upon the waves, a single one covering a space of
six feet in width. The rivers, rolling their tranquil waters

CONDITIOXS FOR THE GROWTH OF PLANTS. 29

under verdurous domes, in the bosom of these vast wilds, are
the only paths that nature has opened to the scattered inhabi-
tants of these rich solitudes. Elsewhere, in Mexico and Yu-
catan, an invading vegetation permits not even the works of
man to exist ; and the monuments of a civilization compara-
tively ancient, which the antiquary goes to investigate with
care, are soon changed into a mountain of verdure, or demol-
ished, stone after stone, by the plants piercing into their
chinks, pushing aside with vigor, and breaking with irresisti-
ble force, all the obstacles that oppose their rapid growth."

The author, in his " Elements of Physical Geog-
raphy," * page 119, thus refers to the growth of
living matter :

" All life, whether vegetable or animal, consists of various
groupings of cells, or approximately spherical masses, con-
sisting of a peculiar form of a jelly-like matter called proto-
plasm, composed of various complex combinations of carbon,
hydrogen, oxygen, and sulphur, called proteids. At its begin-
ning all life consists of a minute germ- cell, filled with more
or less transparent protoplasm, and containing a darker
opaque spot called the nucleus. Examined by a sufiiciently
powerfal glass, all living protoplasm is seen to be in constant
motion, currents passing through the different parts in some-
what definite directions.

* Reprinted, by permission, from " The Elements of Physical
Geography, for the Use of Schools, Academies, and Colleges."
By Edwin J. Houston, A.M. Eldredge & Brother, No. 17
North Seventh Street, Philadelphia. 1891. Pp. 272.

3*

30 OUTLINES OF FORESTRY.

"As the germ-cell develops in all the higher forms of life, it
multiplies, and various organs appear, peculiar to the form of
life from which the germ-cell was derived. All living bodies
contain organs, and living matter is therefore sometimes called
organic matter, to distinguish it from non-living or inorganic
matter.

"Science has not yet disclosed the nature of the change
whereby non-living matter is converted into living protoplasm.
To produce living matter, the intervention of already living
matter is, so far as is known, absolutely necessary."

Concerning the influence of climate on plant
growth, Elisee Reclus, in his work, *' The Ocean," *
on page 361, says :

" Each plant has its special domain, determined not only
by the nature of the soil, but also by the various conditions
of climate, temperature, light, moisture, the direction and
force of winds, and of oceanic currents. During the course
of ages the extent of this domain changes incessantly, accord-
ing to the modifications which are produced in the world of
air, and the limits of the region inhabited by the various
species are dovetailed into one another in the most compli-
cated manner. The flora indicates the climate ; but what is
the climate itself, in the apparently confused mixture of
phenomena which compose it ? The preponderating influence

* Reprinted, by permission, from " The Ocean, Atmosphere,
and Life," by Elisee Reclus. New York : Harper & Brothers,
Publishers, Franklin Square. 1874. Pp. 534.

CONDITIONS FOR THE GROWTH OF PLANTS. 31

is naturally that of temperature ; nevertheless, we must not
think, as many botanists did till very recently, that the limits
of the zone of vegetation of each plant are marked on the
continents by the insinuosities of the isothermal lines. In fact,
as Charles Martins and Alphonse de CandoUe remark, each
plant requires for its germination and development a certain
amount of temperature, differing according to the species.
With some, life resumes its activity after the sleep of winter,
when the thermometer marks three or five degrees above the
freezing-point ; others need a heat of eighteen, twenty, and
even twenty-five and thirty-five degrees, before taking the first
step in their career of the year. Each species has, so to say,
its particular thermometer, the zero of which corresponds to
the degrees of temperature when the vegetating force awakens
its germs. It is, therefore, impossible to indicate by such
general climatal lines the limits of habitation for such or such
species, since each one of them has for the commencement of
its vital period a different starting-point."

32 OUTLINES OF FORESTRY.

III. THE WIDE DISTRIBUTION OF
PLANT GERMS.

In order that seed-time and harvest shall not
fail on the earth, nature has distributed the seeds
or germs of plant life with a liberal hand over
all parts of the surface. Even amid the burning
sands of the deserts and the eternal snows of the
polar regions, myriad forms of plant germs exist.

Mature has provided numerous ways for insuring
the thorough scattering of these plant germs or
seeds.

Many forms of seeds are provided with delicate
hair-like projections, or with wings, by means of
which they are carried by the winds to great
distances. Others are provided with projecting
hooks or bristles, by means of which they catch
in the fur of animals, or in the plumage of birds,
and are thus carried into distant regions.

Perhaps one of the most important of the
means provided by nature for the distribution of
plant germs, is that the seeds, which are swallowed
whole by birds or other animals, subsequently pass

THE WIDE DISTRIBUTION OF PLANT-GERMS. 33

out of the animal uninjured by the process of
digestion. By such means seeds are carried to
distant parts of the earth.

Man, either purposely or accidentally, scatters
plants, germs, or seeds in far-distant countries.
!N'ot unfrequently some of the plants thus brought
from one country to another find the conditions
of soil and climate in their new home so favorable
to growth as to completely drive out and exter-
minate domestic species.

Besides the means just mentioned for the scatter-
ing of germs or seeds of plants, there are possibly
others that have not yet been recognized.

The germs or seeds of plants possess a singular
vitality under certain conditions. The grains of
corn or wheat found in the Egyptian mummies, in
many cases, grew and bore fruit notwithstanding
their centuries of rest. Such instances of the
preservation of vitality are, perhaps, less wonder-
ful when viewed in the light of the exceedingly
dry climate in which the mummies were preserved.
More curious instances are found in which the
germs existed for a long time in the presence of
an abundance of moisture, and did not grow as
long as the heat and light alone were absent.

The truth of the above statements is denied by

34 OUTLINES OF FORESTRY.

some, but that such experiments succeeded in
some cases is undoubtedly true.

For example, in denselj-wooded countries, where
the ground is thickly covered with trees, the light
and heat of the sun are so thoroughly expended
in maintaining such growtfc^t*bat no other forms
of plant life occur. Let, however, some of the
trees be removed, so that the light and heat of
the sun may reach the ground, and the seeds that
were there, possibly during the centuries that the
forest covered it, at once spring into active life.
Here all the conditions except sufficient li^rht and
heat were present, and yet the germs slumbered.

That the Sahara desert was once, in certain
portions, if not in all parts, well watered, is
attested by the presence of the wadys, or deserted
river- valleys. That the soil of the desert contains
a liberal supply of numerous plant germs, is shown
by the fact that, on the successful sinking of an
artesian well, the appearance of the water is in-
variably attended by the appearance of a flora
often containing peculiar species of plants. Here
the light, heat, and soil were all present, and yet
the germs slumbered for want of moisture.

The boring of artesian springs, or the digging
of cellars or other excavations, by bringing to the

THE WIDE DISTRIBUTION OF PLANT-GERMS. 35

sun's light and heat soil which has been deprived
of such sunlight and heat for unknown ages, in
many — indeed, in most — cases is followed by the
appearance of vegetation often containing species
quite strange to that particular section of country.

A curious story of such a case is told, which, if
true, shows in a striking manner the wonderful
vitality of certain seeds. In a given section of
country, let us say in England, a farmer com-
menced to dig a well. This act, so common in
an agricultural district, attracted no particular
attention until the depth of the still dry hole far
exceeded that of most wells in the locality. The
neighbors then began to speculate as to whether
the farmer would eventually strike water, but
when he continued without success, many of his
neighbors began to quietly laugh at him. The
farmer, however, persisted, and at last his per-
sistency or stubbornness, whichever it may have
been, was rewarded.

After having dug through a considerable deposit
of sand, which appeared very much like the sand
of an ancient sea-beach, a water-logged stratum
was reached from which gushed forth a copious
supply of excellent water. So pleased was the
farmer with the result of his labors, that he ar-

36 OUTLINES OF FORESTRY.

ranged the sand and other materials brought up
from below in a form of a garden-plot around the
mouth of the well. Strange plants soon appeared,
and among them a tree, which, when sufficiently
matured, proved to be an ancient form of beech-
plum. !N^ow, since it is universally recognized that
no form of plant life appears without the presence
of a germ similar to that which the plant will it-
self produce, the germ of this ancient beech-plum
was presumably preserved in the deep-seated strata
for untold centuries, awaiting to be called into life
by the genial warmth and light of the sun.

The virgin soil of the prairies, where turned up
by the plough of the settler, generally produces a
vegetation different from that of the undisturbed
soil. Even the tracks of the settlers' wagons dis-
turb the soil sufficiently to be afterwards marked
by a growth of plants quite distinct from those
which cover the undisturbed portions. The seeds
must have lain a long time below the surface,
only springing into active life on exposure to the
light and heat of the sun.

The burning of a pine forest in the ITorth Tem-
perate Zone is almost invariably followed by a
growth of scrub oak. What was the origin of
the germs of these oaks ? They presumably ex-

THE WIDE DISTRIBUTION OF PLANT-GERMS. 37

isted in the ground, and, in some as yet unex-
plained manner, were aroused into active life by
the presence of the fire.

In some parts of the United States the burning
over of a region is almost invariably followed by
a growth of what is very appropriately called fire-
weed, the seeds of which appear to have been
called into active life in some as yet unexplained
manner, either by something added to the soil by
the heat, or possibly by the heat of the fire itself.

Cases are on record where earthquakes have
brought up to the surface, soil which had probably
been buried for ages, but which, on exposure to
the light and heat of the sun, gave birth to strange
forms of plant life.

Possibly, in some of the cases mentioned, the
germs of plant life have been carried to the locali-
ties by one or another of the agencies already
mentioned. In other cases, however, the germs
appear to have existed in the soil, waiting to be
called into life by the sun's light and heat.

IS'ature, therefore, has taken care that the earth
shall be covered with a vegetable carpet wherever
man does not oppose her action. If left to work
out her own course, she will cover the earth with
a dress of such vegetable forms as are best suited

38 OUTLINES OF FORESTRY.

to exist there naturally. If interfered with, to
even a comparatively trifling degree, such changes
may be produced in the soil, climate, or other
conditions as will bring wide-spread destruction
to widely separated sections of the country.

Speaking of the vitality of seeds, Marsh, in his
work entitled " The Earth as Modified by Human
Action," * page 295, says :

" When newly-cleared ground is burnt over in the United
States, the ashes are hardly cold before they are covered with
a crop of fire-weed, Senecio hieracifolius, a tall, herbaceous
plant, very seldom seen growing under other circumstances,
and often not to be found for a distance of many miles from
the clearing. Its seeds, whether the fruit of an ancient vegeta-
tion or newly sown by winds or birds, require either a quicken-
ing by a heat which raises to a high point the temperature of
the stratum where they lie buried, or a special pabulum fur-
nished only by the combustion of the vegetable remains that
cover the ground in the woods.

"Earth brought up from wells or other excavations soon
produces a harvest of plants often very unlike those of local
flora, and Hayden informs us that on our great Western desert
plains, wherever the earth is broken up, the wild sunflower
(Helianthus) and others of the taller-growing plants, though

* Reprinted, by permission, from " The Earth as Modified by
Human Action," by George P. Marsh. New York : Scribner,
Armstrong & Co., No. 654 Broadway, 1874. Pp. 656.

THE WIDE DISTRIBUTION OF PLANT-GERMS. 39

previously unknown in the vicinity, at once spring up, almost
as if spontaneous generation had taken place."

The wonderful vitality of certain seeds is thus
referred to by Lindley in his " Botany," * on page
358:

" The action of seeds is confined to that phenomenon which
occurs when the embryo which the seed contains is first called
into life, and which is named germination.

" If seeds are sown as soon as they are gathered, they gener-
ally vegetate, at the latest, in the ensuing spring ; but, if they
are dried first, it often happens that they will lie a whole year
or more in the ground without altering. This character varies
extremely in different species. The power of preserving their
vitality is also variable : some will retain their germinating
powers many years, in any latitude, and under almost any
circumstances. Melon-seeds have been known to grow when
forty-one years old, maize thirty years, rye forty years, the
sensitive plant sixty years, kidney-beans one hundred years.
Clover will come up from soil newly brought to the surface of
the earth, in places in which no clover had been previously
known to grow in the memory of man, and I have at this mo-
ment three plants of raspberries before me, which have been
raised in the garden of the Horticultural Society from seeds
taken from the stomach of a man whose skeleton was found

^"An Introduction to Botany," by John Lindley, Ph.D.
London : Longman, Orme, Brown, Green, and Longmans.
Third Edition, 1839. Pp. 594.

40 OUTLINES OF FORESTRY.

thirty feet below the surface of the earth, at the bottom of a
barrow which was opened near Dorchester. He had been
buried with some coins of the Emperor Hadrian, and it is
therefore probable that the seeds were sixteen or seventeen
hundred years old."

" It has already been seen that under certain circumstances,
the vitality of seeds may be preserved for a very considerable
length of time ; but it is difficult to say what are the exact
conditions under which this is effected. We learn from ex-
periment that seeds will not germinate if placed in vacuo, or
in an atmosphere of hydrogen, nitrogen, or carbonic acid ; but
no such conditions exist in nature, and, therefore, it cannot
be they which have occasionally preserved vegetable vitality
in the embryo plant for many years. Perhaps the following
remarks, in a work lately published by the Society for the
Diffusion of Useful Knowledge, may throw some light on the
subject :

" It may, upon the whole, be inferred from the duration of
seeds buried in the earth, and from other circumstances that
the principal conditions are, 1, uniform temperature ; 2, mod-
erate dryness ; 3, exclusion of light ; and it will be found
that the success with which seeds are transported from foreign
countries, in a living state, is in proportion to the care and
skill with which these conditions are preserved. For exam-
ple, seeds brought from India, round the Cape of Good Hope,
rarely vegetate freely : in this case the double exposure to the
heat of the equator, and the subsequent arrival of the seeds
in cold latitudes, are probably the causes of their death ; for
seeds brought overland from India, and therefore not exposed
to such fluctuations of temperature, generally succeed. Others,

THE WIDE DISTRIBUTION OF PLANT-GERMS. 41

again, which cannot be conveyed with certainty if exposed to
the air, will travel in safety for many months if buried in
clay rammed hard in boxes: in this manner only can the
seeds of the mango be brought alive from the West Indies ;
and it was thus the principal part of the Araucania pines, now
in England, were transported from Chile. It may therefore
be well worth consideration, whether by some artificial con-
trivance, in which these principles shall be kept in view, it
may not be possible to reduce to something like certainty the
preservation of seeds in long voyages, — such, for instance, as
by surrounding them wdth many layers of non-conducting
matter, as case over case of wood, or by ramming every other
space, in such cases, with clay in a dry state."

4*

42 OUTLINES OF FORESTRY.

IV. CONDITIONS NECESSARY FOR THE
GROWTH OF TREES.

If a soil exists in any locality, and certain con-
ditions of light, heat, and moisture are present,
the character of the vegetation that naturally
grows in such a region will depend more on the
peculiarities of the distribution of the heat, light,
and moisture, than on the character of the soil
itself.

If moisture be entirely absent, or if it exists in
such a form as ice or snow, in which it cannot be
readily appropriated by plants, then that region
must become a desert.

Deserts occur either in dry, arid regions, or in
the regions of perpetual snow of the polar zones,
or on the higher mountain slopes.

If the rainfall is absent during certain seasons of
the year, but occurs during the rest of the year, —
that is, if one part of the year is dry and the rest
is wet, — the vegetable forms, which die or disap-
pear at the beginning of the dry season, reappear
at the beginning of the wet season. Areas of the

CONDITIONS FOR THE GROWTH OF TREES. 43

earth possessing this character of vegetation are
called steppe regions.

"WTien the rainfall is not very great in amount,
but is fairly well distributed throughout the year,
so that the rain is never absent for a very long
time, regions called meadows or prairies occur.

If there is an abundance of moisture at nearly all
times throughout the year, so that such moisture
is absent for no very long time, then the country
may be covered by trees. Such areas are called
forests.

Forests cannot exist in the temperate zones of
the earth in localities where, during the time of
the trees' active growth, a very long interval exists
during which no rain falls. While the active
growth of the trees is temporarily suspended, as
during the winter, this necessity for liquid nour-
ishment, of course, no longer exists.

The reason forests cannot grow except where
moisture is present during nearly all the time the
plants are growing, will be easily understood from
the following considerations :

Suppose a soil exists in any section of country,
and such soil contains germs of practically all
species of plant life. When such a soil is sub-
mitted to the action of light, heat, and moisture,

44 OUTLINES OF FORESTRY.

most of these germs will be called into active
growth, and various forms of plant life will begin
their existence.

Suppose this particular section be a region
where, for several months of the year, no rain
falls, and whose soil, as is generally the case,
rapidly becomes dry. During the dry season all
forms of plant life will die from want of proper
nourishment

On the reappearance of the wet season, only
those forms of plant life will appear that have
been able, during the brief time of the wet season,
to reach their full maturity and produce their fruit
or seeds, and so supply the germs necessary for a
new growth. Such forms as trees, which, as is
well known, require many years to mature their
seed or fruit, will necessarily be unable to continue
to grow naturally in such a region of country.

Of course, it might easily happen that during
the first wet season all the germs might not have
been called into active life by the combined influ-
ence of the light and heat, so that on the next wet
season such forms might again spring up naturally.

But their continued existence, under these cir-
cumstances, would be impossible from the absence
of the new germs.

CONDITIONS FOR THE GROWTH OF TREES. 45

In any section of country where the rainfall is
limited to certain periods of the year, only those
plants can continue to grow that, during the time
the rain continues and water is supplied to them,
or during the time the plant is actually growing,
can reach their maturity and develop their seeds,
and thus supply new germs that shall be ready
for the appearance of the next rainy season.

For the growth of forests, both a certain depth
of soil and, in general, a certain character of soil
are necessary. This soil was slowly formed by the
decomposition of the hard, igneous rocks that origi-
nally formed the entire crust of the earth, and
contains a quantity of vegetable mould or humus
derived from many successive generations of plant.

In the beginning, when the rocks' bare surfaces
emerged from the universal oceans, forests could
not grow even where the proper conditions of
light, heat, and moisture were present, until such
soil had been prepared for them.

Extensive forests can exist naturally only in
regions where suitable soil exists and where the
rainfall during the time of growth is maintained
with a certain approach towards regularity, so
that the trees are then properly and continually
supplied with liquid nourishment.

46 OUTLINES OF FORESTRY.

It is in the temperate regions of the earth and
in some parts of the tropics that the great forest
areas are to be found, since it is in these regions
that the rain may fall at almost any time of day,
and on almost any day of the year.

There are, however, certain regions in the tropics
where forests exist, although there are compara-
tively extended periods during the growth of the
trees when rain does not fall. Here, however, the
air is very moist, and heavy dews take the place
of rain, or the rich vegetable humus absorbs the
vapor directly from the air ; or, in some cases,
though growth is not actually suspended, it is at
least so markedly retarded that the decreased
nourishment of the trees is less injurious.

It is especially on the sides of mountains, where
rain may fall in no matter from what direction the
wind comes, or on the side of an island or conti-
nent that receives the prevalent wind, that forests
are to be found in nearly all portions of the earth's
surface, provided the heat is sufficiently great and
a suitable soil is present. These conditions of soil
and temperature exist on nearly all mountain
slopes outside the polar regions.

The mountains may, therefore, be regarded as
the natural home of the forests. The mountains

CONDITIONS FOR THE GROWTH OF TREES. 47

are also the natural birthplaces of the rivers.
The preservation of the forests on the sides of
mountains is necessary to insure such a drainage
of the rainfall as will best preserve the uniform
flow of the rivers and best prevent them from
overflowing their banks in times of rain, or be-
coming too shallow in times of drought.

The preservation of the forests is necessary in
certain portions of the lowlands to protect the
crops from the direct action of winds that are
either too hot or too cold.

When it is necessary to cut down the forests for
the sake of their timber, the areas on which they
grew in all cases should be replanted, so that
such areas may be able to yield continually suc-
cessive crops of timber so necessary for man's
needs.

As to the necessity for an abundance of water
well distributed throughout the year in order to
insure the growth of trees, Guyot, in his " Earth
and Man," * says, on page 189 :

* " The Earth and Man : Lectures on Comparative Physical
Geography in its Relation to the History of Mankind," by
Arnold Guyot. Boston: Gould, Kendall & Lincoln, 59
Washington Street, 1849.

48 OUTLINES OF FORESTRY.

" North America, in spite of its more continental climate,
shares no less in this character of the New World. The
beauty and the extent of the vast forests that cover its soil,
the variety of the arborescent species composing them, the
strong and lofty size of the trees which grow there, all these
are too well known for me to stop and describe them. It is
because to a more abundant irrigation this continent adds a
soil slightly mountainous, almost everywhere fertile, securing
it always an equal moisture, a more abundant harvest of all
the vegetables useful to man."

Concerning the growth of trees on mountain
slopes, £lisee Reclus, in his work, " The Ocean," *
says on page 383 :

" The stages of vegetation have been studied with care on
the slopes of many other mountains of temperate Europe,
especially on the sides of the Ventoux, by M. Charles Martins ;
but it is in the Alps, above all, that the most celebrated bota-
nists of our country have made their comparative researches
on the floras of the various altitudes. The limits of these
floras vary, so far as we can understand, according to the form,
exposure, and height of the mountains, the nature of the
rocks, the moisture of the soil, and abundance of snow, and
the meteorological conditions of the surrounding atmosphere.
It is, therefore, impossible to give the precise figures on the
whole of the Alpine masses, and the averages obtained by

* Reprinted, by permission, from " The Ocean, Atmosphere,
and Life," by Elisee Eeclus. New York : Harper & Brothers,
Publishers, Franklin Square, 1874. Pp. 534.

CONDITIONS FOR THE GROWTH OF TREES. 49

savants have only a very general value. Without taking ac-
count of the upper limits of cultivation, which varies singu-
larly in the high valleys in proportion to the industry, intelli-
gence, and social condition of the inhabitants, we may say
that the vegetation of the plain hardly exceeds three thousand
feet; above this height the slopes where man has not violently
interfered to change the productions of the soil are naturally
covered by vast forests. Still, the great trees gradually dimin-
ish in height in proportion as we rise into a zone where the
air is rarer and colder ; their wood becomes harder and more
knotted ; and the hardy kinds, which venture not far from the'
region of the snows, end by creeping on the ground, as if to
seek shelter between the stones. To the north of Switzerland,
the beech does not exceed the height of four thousand feet,
and the spruce-fir stops at six thousand feet. In the group of
Monte Rosa, the same forest growth, which approaches most
nearly to the zone of perpetual snow, ascends as far as six
thousand two hundred feet on the northern slope ; while on
the opposite side the larch, still hardier, attains its upper
limit at seven thousand two hundred feet. Higher still w^e
only find the fantastically twisted trunks of a few mugho pines,
rhododendrons, willow-herbs, and juniper-trees; then all vege-
tation becomes more stunted, and is attached to the ground in
order to escape the icy winds, and to allow of its being covered
in winter with a protecting layer of snow up to the very edges
of the glacier and the white surface of the snows."

60 OUTLINES OF FORESTRY.

V. THE FORMATION OF SOIL.

The soil, in which the plant grows and which
forms its cradle, is composed chiefly of mineral
matters derived from the originally crystalline
rocks which were formed by the gradual cooling
of the earth's crust. The soil, however, also con-
tains a small quantity of vegetable mould or
humus, obtained by the growth and subsequent
decay of successive generations of plants.

Before soil can be formed, the hard crystalline
rocks must be broken up, or, as it is technically
called, disintegrated.

This disintegration is effected to some slight
degree by the roots of plants, but it is mainly
brought about by the action, in one way or an-
other, of water.

Soils are divided by Gray into gravelly, sandy,
clayey, calcareous, loamy, and peaty.

Gravelly soils are such as have coarse pebbles
or fragments of quartz, lime, or feldspar spread
through more finely divided mineral matter.

Sandy soils are usually formed of fine particles

THE FORMATION OF SOIL. 51

of quartz, associated witli feldspar. Such soils
generally contain some compound of iron.

Clayey soils are formed from the decomposition
of feldspathic rocks. They are impervious to
water and harden on drying.

Calcareous soils contain carbonate of lime in
large amounts.

Peaty soils are such as contain a large proportion
of partially decayed vegetable matter.

The soil is sometimes found resting in place,
directly on top of the rocks from which it was
derived. In such cases its various mineral ingre-
dients can be traced directly to the decomposition
of the underlying rocks.

A section of such rock and soil will show the
rock gradually passing from the loose soil into the
hard and unchanged rock.

In other cases the soil is found at a considerable
distance from the locality in which it was originally
formed, or in which the plants grew that produced
its vegetable mould.

The soil is carried from the rocks from which
its mineral ingredients were derived either by the
action of the winds or by the waters, though
mainly by the latter, to distances which often reach
thousands of miles.

52 OUTLINES OF FORESTRY.

Where the soil remains directly on the surface of
the rocks from which it was derived, it is interest-
ing to trace the gradual changes that occur in
passing downward from the loose soil to the hard,
unchanged rock below. On top is the loose soil,
with the admixture of vegetable humus so neces-
sary to the growth of the higher forms of vege-
table life. Under this is thoroughly broken-up
rock, which contains less vegetable matter. Under
this is coarser and less broken-up rock. Under
this the rock is intact and merely softened by
the agencies effecting the disintegration. Finally,
lying under all, is the still untouched \drgin rock.

The principal agencies causing the disintegration
of rocks are :

1. The expansive force which sprouting or grow-
ing vegetation exerts on the rock.

2. The alternate expansions and contractions
that attend the freezing and thawing of the water
which flows into the crevices between the rocks,
or sinks into their porous structure.

3. The erosion or cutting power of water charged
with suspended matter or sediment.

4. The erosion or cutting of glaciers or masses
of moving ice.

5. The solvent power of water, especially when

THE FORMATION OF SOIL. 53

aided bj the chemical action of such gases as
oxygen and carbonic acid gas dissolved in the
water.

During the vigorous growth of any form of
plant life the increase in the length and diameter
of the roots will break up or disintegrate even the
hardest of rocks. This action is especially effec-
tive from the fact that in many cases the roots ex-
tend for the greater part through crevices or cracks
where the quantity of moisture is greater than
elsewhere.

The effects of alternate expansion and contrac-
tion are limited to climates where the temperature
occasionally falls below the freezing-point of water.
The water sinking into the porous rocks, and fill-
ing the crevices and cracks between them, expands
on freezing and breaks the rock into fragments.
These fragments are afterwards broken into smaller
fragments, until the pieces are sufficiently small to
be carried by the winds and waters to distant
localities.

The ability of running water charged with sus-
pended mineral matter to cut or wear away hard
rocks is very great. The moving water carries
mechanically suspended in it minute fragments of
such hard minerals as angular fragments of quartz

6*

54 OUTLINES OF FORESTRY,

or pebbles. These act as planes, cutters, or chisels
that gnaw, cut, or wear away even the hardest
rock. This process is technically called erosion,
and is of great aid in the formation of soil.

There collects on the sides of mountains above
the limit of perpetual snow an immense accumula-
tion of snow, which, through gradual pressure, is
converted into hard ice, and forms masses called
glaciers. The glaciers slowly move or slip down
the sides of the mountain. They receive the
drainage of snow from the slopes of the valleys
through which they move, just as rivers receive the
drainage of liquid water. The glaciers carry with
them considerable mineral matter, both in the
shape of small rocks and large boulders. As the
mass moves down the mountains, this mineral
matter is pressed against the sides of the val-
leys, or along the bottom of the bed through
which it is moving, and cuts, grooves, or grinds
the hard rocks, and thus aids in the production
of soil.

From its great solvent power, water is able to
finally sink into what were originally impervious
rocks, by gradually dissolving out the soluble
portions of the rocks. In this way the rock is ren-
dered rotten by the removal of the materials which

THE FORMATION OF SOIL. 55

formerly acted as a cement to bind its different
ingredients together. "When charged with either
oxygen or cabonic acid gas, derived generally
directly from the air, the chemical action of these
dissolved gases greatly aids the water in break-
ing up, and thus rendering partly porous, even the
hardest of the igneous rocks.

Let us take, for example, some of the com-
monest minerals of the igneous rocks, such as
quartz, feldspar, and mica.

IN'one of these ingredients are very soluble in
pure water ; but if the water contains oxygen and
carbonic acid gas in solution, the feldspar will be
gradually broken up, and the hard granites or
gneisses, which form so large a portion of the
igneous rocks, will be gradually disintegrated.
From the feldspar will be derived the kaolins or
clays, and the water percolating through them
will be charged with a small quantity of potash,
so necessary for the growth of plants.

Limestones are readily disintegrated by water
which contains carbonic acid in solution, and from
such rocks are derived the calcareous matter so
necessary to plant-growths.

The carbonic acid dissolved in water sometimes
acts to considerably change the character of the

56 OUTLINES OF FORESTRY.

soil, by effecting new combinations of its mineral
constituents.

Some soils possess the very valuable property of
absorbing water vapor directly from the atmos-
phere and condensing it in their pores. This
property is exceedingly valuable during times of
extended droughts, when a considerable quantity
of vapor may be present in the air. Of all soils,
those containing the greatest quantity of vegetable
mould or humus possess this valuable property in
the greatest degree. Clayey soils also possess it
to a marked degree.

Soils also possess the power of absorbing gases.
Ordinarily, most soils contain of absorbed gases
a smaller proportion of oxygen and more carbonic
acid gas than the atmosphere.

The ability of soils to absorb the sun's heat
varies with their color; as a rule, dark-colored
soils absorb the heat more rapidly than light-
colored soils.

Darwin has shown that in certain localities the
common earthworm greatly aids in the formation
and physical character of the soil by extensive bur-
rowing and tunnelling.

In all cases, however, the process by which the
soil is formed is a gradual one ; and since there is

THE FORMATION OF SOIL. 57

necessarily mingled with such finely broken-up
mineral matters a quantity of vegetable humus
derived from the decay of successive generations
of plants, its formation is rendered still more
gradual.

In wooded districts, where a carpet of decaying
leaves covers a large part of the ground during
most of the year, the water that soaks into such
porous soil naturally contains a larger quantity
of carbonic acid than would water that had not
previously been passed through such matter. This
dissolved carbonic acid, from its chemical action
on the ingredients of the rock, greatly aids the
water in forming new soil.

Speaking of the loss of the vegetable mould,
gained by the patient accumulation of different
generations of plants through passing centuries,
M. de Bouville, a Prefect of the lower Alps, in a
report to the Government, quoted by Marsh on
page 540 of " The Earth as Modified by Human
Action," * writes as follows :

* Reprinted, by permission, from " The Earth as Modified
by Human Action," by George P. Marsh. New York : Scrib-
ner, Armstrong & Co., 654 Broadway, New York, 1874. Pp.
656.

58 OUTLINES OF FORESTRY.

" It is certain that the productive mould of the Alps, swept
off by the increasing violence of that curse of the mountains,
the torrents, is daily diminishing with fearful rapidity. All
our Alps are wholly, or in large proportion, bared of wood.
Their soil, scorched by the sun of Provence, cut up by the
hoofs of the sheep, which, not finding on the surface the grass
they require for their sustenance, gnaw and scratch the ground
in search of roots to satisfy their hunger, is periodically washed
and carried off by melting snows and summer storms.

" I will not dwell on the effects of the torrents. For sixty
years they have been too often depicted to require to be further
discussed, but it is important to show that their ravages are
daily extending the range of devastation. The bed of the
Durance, which now in some places exceeds a mile and a
quarter in width, and, at ordinary times, has a current of
water less than eleven yards wide, shows something of the
extent of the damage. Where, ten years ago, there were
still woods and cultivated grounds to be seen, there is now
but a vast torrent ; there is not one of our mountains which
has not at least one torrent, and new ones are daily forming."

The power of a glacier with its fragments of
rocks to erode the valleys through which it passes
is thus referred to by Le Conte, in his " Elements
of Geology," * on page 51.

* Reprinted, by permission, from the " Elements of Ge-
ology," by Joseph Le Conte, Professor of Geology and Natural
History in the University of California. New York : D.
Appleton & Co., 551 Broadway, 1878. Pp. 588.

THE FORMATION OF SOIL. 59

" When we consider the weight of glaciers and their un-
yielding nature as compared with water, it is easy to see that
their erosive power must be very great. This is increased
immensely by fragments of stone of every conceivable size
carried along between the glacier and its bed. These partly
fall in at the sides and become jammed between the glacier
and the confining rocks, partly fall into the crevasses and work
their way to the bed, and partly are torn from the rocky bed
itself. The effects of glacier erosion differ entirely from those
of water : 1. Water, by virtue of its perfect fluidity, wears away
the softer spots of the rock and leaves the harder standing in
relief; while a glacier, like an unyielding rubber, grinds both
hard and soft to one level. This, however, is not so absolutely
true of glaciers as might be supposed. Glaciers, for reasons to
be discussed hereafter, conform to large and gentle inequalities
of their beds, though not to small ones, acting thus lik-e a very
stiffly viscous body. Thus, their beds are worn into very re-
markable and characteristic smooth and rounded depressions
and elevations called roches moutonees. Sometimes large and
deep hollows are swept out by a glacier at some point where
the rock is softer, or where the slope of the bed changes sud-
denly from a greater to a less angle. If the glacier should
subsequently retire, water accumulates in these excavations
and forms lakelets. Such lakelets are common in old glacier
beds."

Geikie thus describes the formation of soil in
his " Text-Book of Geology," * on page 339 :

* Reprinted, by permission, from " Text-Book of Geology,"
by Archibald Geikie, LL.D., F.R.S, Director of the Geo-

60 OUTLINES OF FORESTRY.

" On level surfaces of rock the weathered crust may remain
with comparatively little rearrangement until plants take root
on it, and by their decay supply organic matter to the de-
composed layer, which eventually becomes what we term
* vegetable soil.' Animals also furnish a smaller proportion
of organic ingredients. Though the character of the soil de-
pends primarily upon the nature of the rock out of which it
has been formed, its fertility arises in no small measure from
the commingling of decayed animal and vegetable matter with
decomposed rock.

" A gradation may be traced from the soil downwards into
what is termed the * subsoil,' and thence into the rock under-
neath. Between the soil and the subsoil a marked difference
in colour is often observable, the former being yellow or brown,
when the latter is blue, gray, red, or other colour of the rock
beneath. This contrast, evidently due to the oxidation and
hydration especially of the iron, extends downwards as far as
the subsoil is opened up by the rootlets and fibres to the
ready descent of rain-water. The yellowing of the soil may
even be occasionally noticed around some stray rootlet which
has struck down farther than the rest, below the general limit
of the soil."

logical Survey of Great Britain and Ireland, etc., etc. London :
Macmillan & Co., 1882. Pp. 971.

THE INANIMATE ENEMIES OF THE FOREST. 61

VI. THE INANIMATE ENEMIES OF
THE FOREST.

Like other forms of animate nature, the forest
is compelled to make a continual struggle for ex-
istence. In order that it may continue to exist,
the conditions requisite for its growth must be
maintained, and the influences that oppose such
growth must be held in check.

The character of the vegetation that covers any
region of the earth is dependent not only on the
character of its soil, but also on the peculiarities
of its climate ; such, for example, as the distribu-
tion of the temperature throughout the year, the
distribution of the moisture, etc.

There is in the vegetable as in the animal world
a veritable struggle for existence. Given a partic-
ular character of soil and climate in any locality,
the plants that will continue to grow in such
locality will be those that are best fitted to exist
there naturally.

At first all forms may appear ; but some partic-
ular form may be so much better suited to the

6

62 OUTLINES OF FORESTRY.

natural conditions of the locality, that it will grow
and multiply so rapidly as to choke out of exist-
ence all other forms. Even such forms, however,
will continue to exist only as long as the condi-
tions continue favorable for their existence.

The dependence of plant life on climatic condi-
tions is, perhaps, more marked in the higher
forms of the vegetable world. Trees may, in a
certain sense, be regarded as of the highest type of
plant life. They rigorously depend on conditions
of soil and climate for their continued existence.
It is true that when a forest is once formed, and its
vigorous growth has almost completely shut out
the light from the soil in which it is growing, that
the numerous forms of vegetable life which lie
ready to spring up, should the sun's rays find free
access to them, are prevented from growing. Even
if they did appear, and the climatic conditions
remained as before, the same struggle for existence
would again occur, 'and the same forest would in
all probability finally be reproduced. If, however,
the character of the soil be altered, or the climatic
or other conditions be changed, the forests would
either disappear or be replaced by trees of another
character.

The forest has many enemies that are ready at

THE INANIMATE ENEMIES OF THE FOREST. 63

all times to resist its growth, and even to sweep it
out of existence.

The soil is continually undergoing a small
change in composition as the different growths of
plants appear and disappear.

The earth's climate is at present undergoing but
very little change. In the geological past such
changes were so far-reaching and severe that they
were followed by pronounced changes in both the
animal and plant life. The comparatively small
changes that have occurred within historical time
are, perhaps, rather to be regarded as some of the
effects produced by the disappearance of certain
forms of plant life, than as the causes of such
disappearance.

The exact balance of conditions that permit the
continued existence of forests is so delicate, that
causes, comparatively insignificant in themselves,
may finally produce marked effects.

The enemies of the forest may be divided into
two classes :

1. Inanimate.

2. Animate.

The principal inanimate enemies of the forest
are:
a. Fire.

64 OUTLINES OF FORESTRY.

b. "Winds.

c. Floods.

d. Avalanches.

The principal animate enemies of the forest are :

a. Plants.

b. Animals.

c. Man.

Limiting our consideration, for the present, to
the inanimate enemies of the forest, we will dis-
cuse the manner in which each of these enemies
tends to destroy the forest.

Mre. — The destruction of the forest by fire
sometimes results finally in a more complete loss
than by any other cause. In case of the intelligent
removal of the forest by the axe of the lumber-
man, only the larger trees are cut down, and the
smaller ones that are left, getting more heat, light,
and nourishment, grow rapidly, and are, in turn,
soon ready for removal by the axe, thus to give
place to others.

Fire, however, generally removes both great and
small.

While a fire may sometimes increase the growth
of forests, as in the case of the pitch pine by the
destruction of the less hardy forms of plant life,
the destruction of the forest by fire, especially on

THE INANIMATE ENEMIES OF THE FOREST. 65

the slopes of mountains, is often so complete that
before a new vegetation can appear, the rapid
drainage of the slopes is attended by such a loss
of the soil as to render such slopes unfit to repro-
duce the forest trees for a period of time much
longer than the life of the average man.

Forest fires are generally kindled during the
drier seasons of the year. Under these conditions
the rain which subsequently falls is apt to carry
off so much of the soil that, even should the trees
again appear, the remaining soil would probably be
insufficient in quantity to bring them to maturity.

The causes of forest fires are to be found in
camp-fires of the lumberman, the burning of
brush, the locomotive spark, the lightning bolt,
and, perhaps, at times, to the heating power of
the sun's rays, concentrated by nodules of gum or
resin, acting as burning-glasses.

In the case of newly-settled countries, fires have
been sometimes purposely started, for the purpose
of readily obtaining an extended pasturage.

The rapidity with which a forest fire spreads
depends, of course, on the character of the trees
and the force of the wind. It is also, however,
dependent largely on the character of the soil. A
rocky or sandy soil permits a fire to spread much

66 OUTLINES OF FORESTRY.

more rapidly than a damp soil. Some forests of
soft and readily ignitible wood have a covering of
moss on the soil, which permits the fire, when once
started, to spread with awful rapidity.

Extensive tracts in South America, capable of
sustaining dense forests, and originally covered by
such, are now prevented from so doing by fires
that are systematically started every year, for the
purpose of obtaining a new growth of grass for
pasturage.

The power of the wind in causing the destruc-
tion of the forest is, to a great extent, limited to
the edges of the forest. In the midst of the forest,
the trees stand so close together that they shield
one another from the force of the wind. If, how-
ever, an opening is made by the axe of the lumber-
man, by fire, or by any other cause, the wind may
cut a wide swath through the forest, and thus
destroy many noble trees.

When rivers overflow their banks, thousands of
acres of forest trees are often swept away, and in
this manner considerable changes may occur in
the general character of such districts.

The timber thus thrown into the river channel
often forms accumulations called rafts, which, be-
coming fixed in certain parts of the stream, tend

TEE INANIMATE ENEMIES OF THE FOREST, 67

to retard the free drainage of the country, and
often result in marked changes in the river chan-
nel. Such rafts are still found in the Mackenzie
Kiver, and formerly existed in parts of the Missis-
sippi and the E-ed Rivers.

The effects of the avalanche in sweeping away
entire forests from the mountain slopes are well
known. Like the influence of the wind, this effect
is at first limited to the edges of the forest. If
the forests are preserved, the further movement of
the avalanche may be checked. In most moun-
tainous countries, forests skirting villages are pre-
served by rigorous penal laws.

The protection from the destructive effects of
avalanches afforded by forests on mountain slopes
is shown in the following statement by Elisee
Reclus in a work entitled, " The Earth," * on page
171:

" The protecting woods of Switzerland and the Tyrol used to
be defended by the national bann, and, as it were, * tabooed.*
They were, and still are, called the Bannwoelder. In the
valley of the Andermatt, at the northern foot of the St. Goth-

* Reprinted, by permission, from " The Earth," by Elisee
Reclus. New York : Harper & Brothers, Publishers, Franklin
Square. Pp. 573.

OUTLINES OF FORESTRY.

penalty of death was once adjudged on any man
guilty of having made an attempt on the life of one of
tnc /trees which shielded the habitations. Added to this, a
sort of mystic curse was thought to hang over this impious
action, and it was told with horror how drops of blood flowed
when the smallest branch was broken off. It was true enough
that the destruction of each tree might perhaps be expatiated
by the death of a man."

" The village and the great establishment of the baths at
Bareges, in the Pyrenees, used to be menaced every year by
avalanches rushing down from an elevation of four thousand
feet, at an angle of thirty-five degrees. The inhabitants,
therefore, were in the habit of leaving vacant spaces between
the two quarters of the Bareges, so as to allow a free passage
to the descending masses. Lately, however, they have en-
deavored to do away with the avalanches by means somewhat
similar to those employed by the Swiss mountaineers. They
have thrown up banks from ten to twelve feet broad on the
sides of the ravines, and have furnished these banks with an
edging of cast-iron piles. Basket-work, and, here and there,
walls of masonry, protect the young growing trees, which are
gradually improving under the protection of these defensive
works. In the mean time, until the real trees are strong
enough to arrest the course of the snow, the artificial trees
have well fulfilled the end they were destined for. In 1860,
the year the defensive works were finished, the only avalanche
which slid into the ravine did not exceed four hundred cubic
yards in bulk ; while the masses which used to fall down upon
the Bareges sometimes attained to more than ninety thousand
yards in volume."

THE INANIMATE ENEMIES OF THE FOREST. 69

Ljell, in his " Principles of Geology," * on page
440, speaks thus of the rafts in the Mississippi :

" One of the most interesting features in the great rivers of
this part of America is the frequent accumulation of what
are termed 'rafts,' or masses of floating trees, which have
been arrested in their progress by snags, islands, shoals, or
other obstructions, and made to accumulate, so as to form
natural bridges across the stream. One of the largest of these
was called the raft of the Atchafalaya, an arm of the Missis-
sippi, which branches ofi" a short distance below its junction
with the Red River. The Atchafalaya, being in a direct line
with the general direction of the Mississippi, catches a large
portion of the timber annually brought down from the north ;
and the drift trees collected in about thirty-eight years previ-
ous to 1816 formed a continuous raft, no less than ten miles in
length, two hundred and twenty yards wide, and eight feet
deep. The whole rose and fell with the water, yet was covered
with green bushes and trees, and its surface enlivened in the
autumn by a variety of beautiful flowers. It went on in-
creasing till about 1835, when some of the trees upon it had
grown to the height of about sixty feet. Steps were then taken
by the State of Louisiana to clear away the whole raft and
open the navigation, which was effected, not without great
labor, in the space of four years."

Dana, in his ^' Manual of Geology," f on page

* " Principles of Geology," by Charles Lyell. London :
Murray, 1872. Pp. 671.
t Reprinted, by permission, from a "Manual of Geology,"

70 OUTLINES OF FORESTRY.

657, gives the following description of tlie raft of
the Ked Eiver ;

"The quantity of wood brought down by some American
rivers is very great. The well-known natural * raft' obstruct-
ing the Ked Eiver had a length, in 1854, of thirteen miles, and
was increasing at the rate of one and a half to two miles a
year, from the annual accessions. The loAver end, which was
then fifty-three miles above Shreveport, had been gradually
moving up stream, from the decay of the logs, and formerly
was at Natchitoches, if not still farther down the stream.
Both this stream and the other carry great numbers of the
logs to the delta."

by James D. Dana. New York : Ivison, Blakeman, Taylor
and Co., Publishers. Triibner & Co., London. Pp. 911.

THE ANIMATE ENEMIES OF THE FOREST. 71

VII. THE ANIMATE ENEMIES OF THE

FOREST.

The animate or living enemies of the forest
are :

1. Plants.

2. Animals.

3. Man.

In classifying the enemies of the forest as ani-
mate and inanimate, it should be borne in mind
that the animate enemies of the forest often call
to their aid the powers of inanimate nature. An
example of this is seen in the case of the destruc-
tion of forests by fire, which are more frequently
started by man than in any other way.

The influence of plants on the destruction of
forests is limited mainly to the natural struggle
which exists between the different forms of plant
life for the possession of the soil. There are,
however, many forms of parasitic plants, which,
growing on the tallest and most vigorous trees,
often in the end cause their destruction.

A disease common in parts of Germany, called

72 OUTLINES OF FORESTRY.

the " scliullkranklieit," often affects the pine for-
ests. Trees attacked by this disease soon present
the appearance of having been burnt over, their
boughs and branches rapidly dying or drying up.
The cause of the disease is not exactly known. It
has, however, been ascribed to the presence of a
fungous growth.

In some parts of Iowa a fungous growth on the
Cottonwood trees has resulted in considerable dam-
age to them. The fungus appears as an orange-
yellow dust on the lower surfaces of the leaves.

The animal enemies of the forest, like the winds,
running water, or the avalanche, produce their
most marked action on the borders or edges of the
forest.

In the deep recesses of the forest the vegetable
kingdom holds almost undisputed sway. The life-
giving power of the sun's light, and, to a great
extent, that of its heat, are dissipated by the dense
foliage that almost completely shuts out the light
from the dank, gloomy ground. Animal life, to
a great extent, is crowded out. Wherever the
sunlight freely enters, animal life appears in
myriad forms, until at length the forest again
chokes it out of existence.

The animal enemies of the forest are too numer-

THE ANIMATE ENEMIES OF THE FOREST. 73

ous to be more than merely mentioned. The
following are among some of the more important :

Domestic animals, which, when allowed to range
freely through the woods, often cause much
damage by gnawing at the bark of trees, or, in
some cases, by the destruction of the foliage.

Among wild animals, the rodents effect the
greatest destruction by devouring the bark, and
often completely girdling the trees. Among the
worst of the rodents may be mentioned rabbits
and mice, which gnaw the bark, or gophers, which
eat the roots. Beavers, too, destroy forests, not
only by the actual cutting down of the trees, but
especially by building dams, and thus, by causing
the overflow of the intervale, destroying all its
growing timber.

Goats and other animals live largely on the
bark of trees. In certain parts of the earth, such,
for example, as Assyria, Greece, Italy, Spain, and
Morocco, the extensive forests which once covered
them have been completely destroyed by the
ravages of goats.

In general, insects damage trees by feeding on
the parts necessary for growth and reproduc-
tion. Some insects damage trees by boring the
trunks and branches in order to deposit their

74 OUTLINES OF FORESTRY.

eggs. In all cases tlie increase in the destruction
produced by insect life can be traced to the indis-
criminate and foolish slaughter of the insectivorous
birds that formerly held such life in check.

Caterpillars often cause considerable destruction
to forest trees.

The caterpillar of the pine bombyx often causes
great ravages in the pine forests. In Germany
these caterpillars are called pine-spinners, from the
great number of cocoons with which they cover
the pine-trees. Such caterpillars have been known
to completely destroy extensive pine forests. The
foresters are often compelled to set fire to portions
of the forests in order to prevent the too rapid
multiplication of this pest.

Another caterpillar, which from its black and
white coating is sometimes called the monk or
nun caterpillar, is equally destructive, not only to
forest trees like the pine, but also the other forest
trees, such as the beech, oak, and birch.

Other caterpillars cause great destruction to the
forest by eating the tender buds or the young
shoots.

Grasshoppers often cause considerable damage
to young trees by devouring the leaves, herbs, and
tender shoots.

THE ANIMATE ENEMIES OF THE FOREST. 75

The larvae of insects do great damage to trees
by boring chambers, or tunnellings, either in
the heart-wood or in the layers of new wood
which lie directly under the bark. The destruc-
tive powers of such larvae are the more marked,
since they work silently and in the dark, and their
presence can scarcely be detected until they have
caused the death of the tree.

A beetle known as the typographer {Bostrychus
typographicus)y from the shape of the galleries it
burrows out in the trees, causes much damage to
the forests, especially to the spruce-firs. Unfortu-
nately, these insects breed very rapidly, and while
in the larva state are capable of withstanding the
most severe frosts.

Some species of willows are severely injured by
the larvae of a species of saw-fly, which strip the
leaves and injure the tree generally.

Perhaps the best remedy for the ravages of
insects in general is to be found in the preserva-
tion of insectivorous birds.

The most powerful enemy of the forest, how-
ever, is civilized man. The products of the forest
are clearly man's right by gift of nature. He is
lord of the forest as of the rest of the earth, and
is, therefore, entitled to the use of the wood thus

76 OUTLINES OF FORESTRY.

grown for liim. It is, however, by the abuse and
not by the use of nature's lavish gifts that man
deranges its economy, and thus brings on himself
so much punishment. If he would only be careful
to select trees of vigorous growth, and in cutting
them down would exercise care that the remaining
trees might live; if he would carefully preserve
the soil, and hold in check the other enemies of
the forest ; if he would wisely set aside large por-
tions of the mountain slopes, the natural home of
the forest, as areas on which trees should be con-
tinually preserved, the earth would yield of her
abundance all the wood required for his use.

Referring to the insect enemies of the forest,
Hough, in a report to the United States Commis-
sioners of Agriculture,* page 263, in citing a
writing of Grandjean, Conservateur des Forets,
says :

" The timber-tree particularly suffering from this cause was
the Abies excelsa (D.C.), or common European spruce-fir, and
the species of insects that did the injury were the Bostrychus
typographicus and the B. chalcographicus, of which the first

* Reprinted, by permission, from the " Report on Forestry,"
submitted to Congress by the Commissioner of Agriculture,
by Franklin B. Hough. Washington : Government Printing-
office, 1882. Pp. 318.

THE ANIMATE ENEMIES OF THE FOREST. 77

attacked the trunk and large branches, and the latter, which
was seldom absent, found a lodgment in the smaller branches.
Their habits were described as follows :

" When the female of the typographic species is ready to de-
posit her eggs, which occurs about the middle or latter part of
spring, sooner or later, according to the temperature, she pene-
trates the bark, and bores, almost invariably from below up-
wards, a gallery that is cut along the outer layer of the sap-
wood, depositing her eggs, as she advances, on the right side
and the left. These are so quickly developed that the first
larvae will have themselves made considerable galleries before
the parent has finished. Each of these larvae digs a separate
path of its own, more or less inclined to that made by the
mother, and at the end of two or two and a half months they
are transformed to a perfect insect, which in turn proceeds to
lay a new lot of eggs, and, if favored by the heat of August,
these are sometimes found more destructive than the first.
This second growth is matured towards the end of September
or beginning of October, and will be ready to resume opera-
tions in the following spring. In the mean time they pass the
winter under the mosses and in the crevices of the bark, where
they endure the severest frosts of winter, for the perfect insect
is as hardy as its larvae are tender.

" The number of eggs deposited by one insect varies from
twenty to one hundred and twenty or one hundred and thirty,
and from this bark we may make some very instructive estimates.
Suppose that each laying of sixty eggs produces specimens in
which the sexes are equal, one female will have produced
thirty others, which would each before the end of the year be
represented by eighteen hundred of their kind. Half of these,

7*

78 OUTLINES OF FORESTRY.

before the end of the second year, have produced eight hun-
dred and ten thousand females, and by the end of the third
year seven hundred and twenty-nine millions of the producing
sex, and the forest will have fed one billion five hundred and
six million six hundred thousand of the progeny of this one
parent."

Concerning the destructive effects of the animal
kingdom, Geikie, in his " Text-Book of Geology,"*
page 456, writes :

"Many animals exercise a ruinously destructive influence
on vegetation. Of the various insect plagues of this kind it
will be enough to enumerate the locust, phylloxera, and Colo-
rado beetle. The pasture in some parts of the south of Scot-
land has, in recent years, been damaged by mice, which have
increased in numbers owing to the indiscriminate shooting
and trapping of owls, hawks, and other predaceous creatures.
Grasshoppers cause the destruction of vegetation in some parts
of Wyoming and other Western Territories of the United
States. The way in which animals destroy each other, often
on a great scale, may likewise be included among the geologi-
cal operations now under description."

Speaking of the influence of certain insects in
destroying forests from over extended districts,

* Reprinted, by permission, from a " Text-Book of Geology,"
by Archibald Geikie, LL.D. London : Macmillan & Co., 1882.
Pp. 971.

THE ANIMATE ENEMIES OF THE FOREST. 79

Pouchet, in his work entitled the " The Universe,
or the Infinitely Great and the Infinitely Little," *
page 218, says :

" If, when the warm breath of spring drives away the rigor
of winter and renews life in the fields, we enter one of the
great coniferous woods of Germany, we are astonished at the
tumult and activity which prevail in lieu of the silence we
went there to seek. Everything is in movement.

" Groups of woodmen, foresters, and overseers move about by
hundreds, and stretch away like columns of skirmishers ; it is
a complete army in the field, which opens out wherever there
is a large space, and of which the wings are sometimes lost in
the windings of the roads, or hidden by the projection of some
hillock. This mass of men always moves in order, distributed
in troops commanded by experienced leaders. They are all
provided with long weapons, which, at a distance, might be
taken for lances.

" Or, if the excursion is made by night, another spectacle
awaits us. The whole forest seems on fire. In every part are
burning great trees, erect and isolated, like huge threatening
torches, the flame of which rises to the clouds and casts a
baleful glance on all around. A few foresters, standing in
silence, contemplate the progress of the conflagration, and
watch its ravages. Lastly, at other times, as a final resource,
the entire forest is given up a prey to the flames, and whirl-

* Reprinted, by permission, from " The Universe, or the
Infinitely Great and the Infinitely Little," by F. A. Pouchet,
M.D. New York : Charles Scribner & Co., 1870. Pp. 790.

80 OUTLINES OF FORESTRY.

winds of fire, menacing and dreadful, spread on every side ; a
woody region, formerly so fertile, is entirely devoured by fire,
and only an immense mountain of charcoal remains of all this
mass of wealth.

" We ask, against what formidable enemy such an army of
men has been launched ? Who are they going to attack with
their rods which they brandish on all sides ? What redoubta-
ble aggressors are the others attempting to stay the march of,
with the long trenches they are scooping out? Why these
frightful fires in the middle of the night ? Why this general
conflagration ?"

THE DESTRUCTION OF THE FOREST 81

VIII. THE DESTRUCTION OF THE
FOREST.

The removal of the forests from any consider-
able section of country, in the end, is invariably
followed by some or all of the following results :

1. An increase in the frequency with which the
rivers in that section of country overflow or inun-
date their banks.

2. An increase in the frequency and severity of
droughts, as witnessed by a marked decrease in the
amount of water in the river channels, and by an
increase in the frequency with which the springs,
in such section of country, either show a marked
decrease in their flow or dry up altogether.

3. A rapid loss of the soil from such areas, re-
sulting from the more rapid surface drainage of
their surfaces.

4. A marked disturbance in the lower courses
of the rivers, rising in or flowing through such
section of country, produced by the filling up of
their channels by sand-bars or mud-flats.

/

82 OUTLINES OF FORESTRY.

5. A decrease in the healthfulness of the district
that borders on the lower courses of such rivers, —
that is, in those portions which lie in the lowlands
near the rivers' mouths.

6. An increase in the number and severity of
hail-storms, both over the areas themselves or in
the countries bordering thereon.

When the forests are removed from any section
of country, that part of the rainfall which for-
merly entered the ground, either by gradually
sinking into the porous soil, or by running along
the branches and trunks of the trees, and so enter-
ing and penetrating the more deeply-seated strata,
now drains rapidly off the surface. Instead of
reaching the river channel quietly and slowly
through discharge from the reservoirs of springs,
it now rapidly drains directly off the surface into
the river channel.

Instead of draining into the river channel con-
tinuously for a period of, say, three weeks, the
rain-water now drains into the channel in often a
period of as many hours. The channel rapidly
fills, the river overflows its banks, and the floods so
caused carry loss to the lowlands along the river
banks, and, not infrequently, death to the inhabi-
tants.

THE DESTRUCTION OF THE FOREST. 83

^N'ot only are the riches of the rainfall thus
squandered, to the loss of the inhabitants of the
river valleys, from the excess of water immediately
after a rainfall, but a still greater and more far
reaching loss occurs from the failure of the rain-
fall to fill the reservoirs of the springs, the contin-
uous discharge of which are necessary to maintain
the proper flow of water in the river.

The springs, having their reservoirs but partly
filled, are apt to fail shortly after the rainfall
ceases, so that even limited droughts may cause
them to dry up completely.

The damage, however, does not stop here. The
soil in which the forest grew, being no longer held
together either by the roots of the trees or under-
brush of the forest, or protected by a vegetable
covering, is rapidly carried away by the water.
The soil thus lost, resulted from the gradual dis-
integration of hard rocks, and contains as essen-
tial elements substances derived from the continued
growth of former generations of plants, and prob-
ably required centuries for its production. Its
removal in a few years is, therefore, a serious
matter.

The soil, the wealth of the highlands, is now
thrown into the river channel, and though some

84 OUTLINES OF FORESTRY.

of it fertilizes the lowlands, over which it is spread
during inundations, jet much collects in sand-bars
and mud-flats on the lower courses of the river.
These flats work injury because :

1. They hinder navigation, and thus interfere
with the commerce between diflferent parts of the
country.

2. They become sources of contamination to the
air of the lowlands, by breeding miasmatic and
other diseases.

Besides the disturbances thus caused to the
drainage of the region from which the forest has
been removed, considerable changes are brought
about in the rate at which the now bare soil re-
ceives the heat from the sun, and the rapidity with
which it throws it off into the air.

Areas covered with forests both receive and part
with their heat slowly, and are, therefore, not very
apt to become very hot in summer, or very cold
in winter.

Bare areas, or areas stripped of their vegetable
covering, both receive and part with their heat
rapidly, and are, therefore, apt to become very hot
in summer and very cold in winter.

The presence of the forest, therefore, tends to
prevent marked changes in the temperature of the

THE DESTRUCTION OF THE FOREST 85

air, while the removal of the forest tends to permit
sudden changes in such temperature.

These effects will be considered under the gen-
eral head of climate.

The axe of the pioneer, so often regarded as the
emblem of ci^dlization, is more correctly to be
regarded as an emblem of an entirely different
character.

The problem of the preservation and protection
of the forest is one of extreme difficulty, for the
following reasons :

The dense populations which now exist in most
of the temperate regions of the earth could not
continue to exist in the forest regions which once
grew on large parts of their areas.

The regions best fitted for the growth of men
are also best fitted for the growth of trees. Since
civilized man cannot continue as a dweller in the
forest, as the density of population increases, the
forest must be cut down.

In removing the forest to make way for man,
certain areas should be set aside in all sections
for the purpose of perpetually maintaining trees
thereon. The nature of such areas will, of course,
depend on a variety of circumstances. In general,
however, it can be shown that, on the slopes of

8

86 OUTLINES OF FORESTRY.

mountain ranges, which form the natural places
where rivers rise, forests should be especially
maintained.

Laws should, therefore, be enacted providing for
the replanting of trees on mountain slopes, either
when they have been removed by the axe of the
woodman, or by fire, or by any of the other
enemies of the forest.

The influence of the destruction of the forest
on the rapidity of drainage, and the consequent
liability to the destructive floods, is thus referred
to by the author in his " Elements of Physical
Geography," * page 64, as follows :

" Influence of the Destruction of the Forests on Inundations. —
When the forests are removed from a large portion of a river-
basin, the rains are no longer absorbed quietly by the ground,
but drain rapidly off its surface into the river channels, and
thus in a short time the entire precipitation is poured into the
main channel, causing an overflow. It is from this cause that
the disastrous effects of otherwise harmless storms are pro-
duced. The inundations are most intensified by this cause in
the early spring, when the ice and snow begin to melt. The
destructive effects of the floods are increased by the masses of

* Reprinted, by permission, from " The Elements of Physi-
cal Geography," by Edwin J. Houston, A.M. Philadelphia :
Eldredge & Brother, No. 17 North Seventh Street, 1891. Pp.
172.

THE DESTRUCTION OF THE FOREST. 87

floating ice, which, becoming gorged in shallow places in the
stream, back up the waters above. The increased frequency
of inundations in the United States is, to a great extent, to be
attributed to the rapid destruction of the forests."

Sir Charles Lyell, in his "Principles of Ge-
ology," * speaking of the effects produced by the
removal of the forest, says, on page 457 :

" When St. Helena was discovered, about the year 1506, it
was entirely covered with forests, the trees drooping over the
tremendous precipices that overhang the sea. Now, says Dr.
Hooker, all is changed ; fully five-sixths of the island is en-
tirely barren, and by far the greater part of the vegetation
that exists, whether herbs, shrubs, or trees, consists of intro-
duced European, American, African, and Australian plants,
which propagated themselves with such rapidity that the na-
tive plants could not compete with them. These exotic species,
together with the goats, which, being carried to the island, de-
stroyed the forests by devouring all the young plants, are sup-
posed to have utterly annihilated about one hundred peculiar
and indigenous species, all record of which is lost to science,
except those of which specimens were collected by the late
Dr. Burchell, and are now in the herbarium of Kew."

The protective action or plants generally as pre-
venting erosion by water or wind is clearly pointed

* " Principles of Geology," by Sir Charles Lyell, M.A.
London : John Murray, 1872. Pp. 652.

88 OUTLINES OF FORESTRY.

out by Geikie, in his " Text-Book of Geology/'*
on page 456.

" The protective influence of vegetation is well known.

" 1. The formation of a stratum of turf protects soil and rocks
from being rapidly removed by rain or wind. Hence, the
surface of a district so protected is denuded with extreme
slowness except along the lines of its water- courses.

" 2. Many plants, even without forming a layer of turf, serve
by their roots or branches to protect the loose sand or soil on
which they grow from being removed by wind. The common
sand-carex and other arenaceous plants bind littoral sand-
dunes and give them a permanence which would at once be
destroyed were the sand laid bare again to storms. In North
America the sandy tracts of the Western Territories are in
many places protected by the sage-brush and grease-wood.
The growth of shrubs and brushwood along the course of a
stream not only keeps the alluvial banks from being so easily
undermined and removed as would otherwise be the case, but
serves to arrest the sediment in floods, filtering the water and
thereby adding to the height of the flood-plain. On some parts
of the west coast of France extensive ranges of sand-hills have
been gradually planted with pine woods, which, while prevent-
ing the destructive inland march of the sand, also yield a large
revenue in timber, and have so influenced the climate as to
make these districts a resort for pulmonary invalids. In tropi-

* Reprinted, by permission, from a " Text-Book of Geology,"
by Archibald Geikie, LL.D. London : Macmillan & Co., 1882.
Pp. 971.

THE DESTRUCTION OF THE FOREST. 89

cal countries the mangrove grows along the sea-margin, and
not only protects the land, but adds to its breadth, by forming
and increasing a maritime alluvial belt."

The following, from tlie " Journal of the Society
of Arts," * shows the enormous demands made on
the forest by railroads for sleepers :

" The Belgian ' Bulletin du Mus6e Commercial' gives the
following information respecting the number of sleepers used
on various railways. In France alone the six larger railway
companies require a daily supply of more than ten thousand
sleepers, making an annual consumption of over three million
six hundred and fifty thousand. As a tree of ordinary di-
mensions cannot furnish more than ten logs, it follows that
more than a thousand fine trees are cut down every day solely
for the purpose of supplying the necessary sleepers for the
French railways. In the United States the amount required
is still greater. Over fifteen million sleepers are annually
used in this country, thus necessitating the annual destruction
of eighty thousand hectares, or one hundred and ninety-seven
thousand six hundred acres of forests. 'The Bulletin du
Mus6e Commercial' estimates at more than forty millions the
number of logs required for the railways of the world, and is
of opinion that the estimate is rather below than above the
mark."

* " Journal of the Society of Arts," vol. xxvii. London :
George Bell & Sons, 6 York Street, Covent Garden, 1889.
Pp. 924.

8*

90 OUTLINES OF FORESTRY.

IX. THE EARTH'S OCEAN OF VAPOR.

From every water surface on the earth there is
almost constantly rising and passing into the air
an invisible form of water called vapor.

Yapor is formed wherever water is sufficiently
heated under such circumstances that its particles
have freedom to expand, and thus occupy a greater
space.

The waters of the earth are caused to pass into
the atmosphere as vapor mainly by the heat of the
sun.

The vapor that passes into the air from the
ocean and other water surfaces spreads or diffuses
through the air, and is carried by the winds to
different parts of the earth's surface. The air di-
rectly over a water surface is, however, generally
moister than that over a land surface.

When, by any cause, water vapor loses the heat
which caused it to become a vapor, it again be-
comes visible as dew, fog, cloud, or mist, or falls
as rain, hail, or snow.

The rapidity with which water surfaces throw

THE EARTHS OCEAN OF VAPOR. 91

off vapor into the air varies with the following
circumstances :

1. With the amount of surface exposed.
Evaporation takes place only at the surface;

consequently, the greater the surface, the greater
the rapidity of evaporation. When wet clothes
are hung out to dry, they are so opened or spread
out that the air can act on them from all sides.
A pound of water placed in an open shallow dish,
and exposed to the air, will evaporate much more
rapidly than the same quantity would if placed in
an open, narrow-necked bottle.

For the same reason, an equal quantity of water
will evaporate still more rapidly when sprinkled on
the surface of a sheet hung out in the air to dry.

2. On the temperature of the air.

The capacity of a given volume of air for
water in a state of vapor rapidly increases with
its temperature. A cubic foot of dry air at the
temperature of melting ice, or 32 degrees Fahren-
heit, when saturated, holds a little more than half
a grain of vapor. It then being saturated can
hold no more water in an invisible state. In-
crease its temperature, however, to 212 degrees
Fahrenheit, and it can hold twenty grains, or
about forty times as much as it formerly held.

92 OUTLINES OF FORESTRY.

Consequently, any increase in the temperature
of air permits it to hold a greater quantity of
vapor. Conversely, any decrease in the tempera-
ture of air causes its ability to hold moisture as
vapor to decrease.

If, therefore, the temperature of the air be suffi-
ciently decreased, a part of the vapor it contains
will appear in some visible form.

3. On the quantity of vapor already in the air.
"When a given bulk of air has as much vapor in

it as it can hold, all evaporation ceases. Conse-
quently, the drier the air over a water surface, the
greater is the rapidity of evaporation.

4. On the velocity of the wind.

The wind brings fresh and drier air to the
water surfaces, and at the same time removes the
air into which such surfaces were discharging
their vapor. An increase in the velocity of the
wind, therefore, increases the rapidity of evapora-
tion.

5. On the pressure of the air.

The greater pressure the air exerts on a water
surface, the slower the rapidity of evaporation. A
low barometer permits a water surface to throw off
its vapor with much greater rapidity than a high
barometer.

THE EARTH'S OCEAN OF VAPOR. 93

"Wlien clouds reach the higher regions of the
atmosphere they disappear, because the particles
of water of which they are composed pass rapidly
into an invisible vapor, on account of the great
relief of pressure in the higher regions.

The earth's ocean of vapor is of the greatest
importance to its present race of animals and
plants. If any considerable change in either the
quantity or distribution of vapor should be main-
tained for any considerable time, the present race
of animals and plants would disappear.

Some of the more important ways in which the
ocean of vapor affects the economy of the earth
are as follows :

1. By the action of the \vdnds, the water vapor
is carried from the warm regions of the earth to
the colder regions, where, falling as rain or snow,
it gives out its heat and raises the temperature of
the air over such regions.

An interchange is thus effected between the too
great heat of the equatorial regions and the too
feeble heat of the poles, and a more equable, uni-
form temperature is insured than would othermse
exist.

The earth's ocean of vapor therefore acts to
moderate the excessive temperatures that would

94 OUTLINES OF FORESTRY.

otherwise exist both in the equatorial and in the
polar regions.

2. By acting as a screen interposed between the
earth and the sun, and thus preventing the earth's
surface from becoming too rapidly heated when
exposed to the sun's rays, or too rapidly cooled
when deprived of such rays.

Water enters so largely into the composition of
both animals and plants, that its absence from any
section of country invariably causes such section
to become a desert.

"Within certain limits, the wealth of any section
of country can be accurately estimated by the
number of inches of rain that fall in a given time
on its surface. This liquid wealth may be regarded
as a species of bank account of such section of
country, by which its solvency or bankruptcy may
be determined.

The ocean of vapor which forms the source from
which the rains are derived is, therefore, of great
importance to the operations of nature.

Even a hurried glance at the map of the world
will show that the earth's greatest expanse of water
surface occurs near the equatorial regions. Here,
also, the sun's heat is greatest. The air over the
equatorial regions would become too enormously

THE EARTHS OCEAN OF VAPOR. 95

heated to sustain the present life of the earth, were
the water surfaces replaced by land.

]^ot only does a water surface heat more rapidly
than a land surface, but the vapor which arises
from it, locks up much of the heat in a form that
is sometimes popularly called latent heat.

To change a pound of ice, at thirty-two degrees
Fahrenheit, into a pound of water, at thirty-two
degrees Fahrenheit, requires one hundred and
forty-two heat units, or one hundred and forty-
two times as much heat as is required to raise
the temperature of a pound of water one degree
Fahrenheit. To convert one pound of water at
sixty degrees Fahrenheit into vapor requires nearly
one thousand heat units, an amount of heat that
would be able to raise more than six pounds of
ice-cold water to the temperature of its boiling-
point. When the vapor is condensed and falls as
rain or snow, this heat reappears and raises the
temperature of the air. When, therefore, the ex-
cessive heat of the sun in the equatorial regions
falls on the extended water surfaces, much of the
heat is absorbed by the vapor, and the air is pre-
vented from growing too hot. This vapor is car-
ried by the winds to the polar regions, where it
gives up its heat to the air, and falls as rain or snow.

96 OUTLINES OF FORESTRY.

The vapor of water exerts another and still
more powerful influence on the climate of the
earth. Water vapor possesses in a marked de-
gree the power of absorbing heat rays of the sun.
About twenty-eight per cent, of the heat of the
vertical rays is absorbed before such rays reach
the surface, provided there is a sufficient quantity
of vapor in the air. When the heated earth throws
off or radiates its heat into the atmosphere, the
same water vapor absorbs a greater part of such
rays, and rapid cooling by radiation is thus pre-
vented. The presence of the water vapor, there-
fore, prevents either the rapid heating of the
earth's surface by the direct action of the sun's
rays, or the rapid cooling of such surface by
radiation.

If the earth's surface were deprived of this
screen of vapor, the air would become so rapidly
heated on the rising of the sun, and so rapidly
cooled on its setting, that the earth would be
unable to sustain its present plant and animal
life.

Tyndall, speaking of the influence that the
earth's water vapor exerts on the climate of Eng-
land, says, " The removal for a single summer
night of the clouds of vapor which cover Eng-

THE EARTH'S OCEAN OF VAPOR. 97

land would be attended by the destruction of
every plant which a freezing temperature could
kill."

The amount of vapor in the air of any country,
though dependent on the direction from which the
winds come, is also markedly influenced by the
nature of its surface.

The presence of forests over any section of
country has the effect of decreasing the rapidity
with which the wet surface parts with or loses its
water by evaporation. This decrease in the rapid-
ity of evaporation is caused :

(a.) Because the air over the forest is generally
moister than that over the open fields, and evapo-
ration takes place less rapidly in moist air.

(h.) Because the ground in the forest is shielded
from the direct rays of the sun.

{c.) Because the wet ground is protected from
the direct action of the wind.

The presence of the forest, therefore, tends to
keep the air moist for a longer time, and to thus
prevent the occurrence of marked contrasts in the
humidity of the air.

Some experiments made in France show that
the rapidity of evaporation is sixty-three per cent,
less in the forest than in the open fields.

^9 9

98 OUTLINES OF FORESTRY.

The influence of the vapor screen that is placed
between any surface and the sun on the climate of
the surface is thus referred to by Tjndall in his
" Heat as a Mode of Motion," * on page 417 :

" A few years ago a work possessing great charms of style
and ingenuity of reasoning was written to prove that the more
distant planets of our system were uninhabitable. Applying
the law of inverse squares to their distances from the sun, the
diminution of temperature was found to be so great as to pre-
clude the possibility of human life in the more remote mem-
bers of the solar system. But in those calculations the influ-
ence of an atmospheric envelope was overlooked, and this
omission vitiated the entire argument. An atmosphere may
act the part of a barb to the solar rays, permitting them to
reach the earth, but preventing their escape. A layer of air
two inches in thickness, saturated with the vapor of sulphuric
ether, would offer very little resistance to the passage of the
solar rays, but I find that it would cut off fully thirty-five per
cent, of the planetary radiation. It would require no inor-
dinate thickening of the layer of vapor to double this ab-
sorption ; and it is perfectly evident that, with a protecting
envelope of this kind, permitting the heat to enter, but
preventing its escape, a comfortable temperature might be
obtained on the surface of the most distant planet."

* Reprinted, by permission, from " Heat as a Mode of Mo*
tion," by John Tyndall, LL.D., F.R.S. New York : Appleton
and Company, 1883. Pp. 591.

THE EARTWS OCEAN OF VAPOR. 99

Alexander von Humboldt, in his " Cosmos," *
thus refers to the vapor of the atmosphere, on
page 330, of vol. i. :

" As the quantity of moisture in the atmosphere increases
with the temperature, this element, so important to the whole
organic creation, varies with the hour of the day, the season
of the year, and the degree of latitude and of elevation. Our
knowledge of the hygrometric relations of the atmosphere has
been materially augmented of late years by the method now
so generally and extensively employed of determining the
relative quantity of vapor, or the conditions of moisture of
the atmosphere, by means of the diiSerence of the dew point
and of the temperature of the air, according to the ideas of
Daniell and of Dalton, and by the use of the wet-bulb ther-
mometer. Temperature, atmospheric pressure, and the di-
rection of the wind have all a most intimate relation to the
atmospheric moisture so essential to organic life. The influ-
ence, however, of humidity on organic life is less a con-
sequence of the quantity of vapor held in solution under

difierent zones than the nature and frequency of the aqueous
precipitations which refresh the ground in the form of dew,
mist, rain, or snow."

* " Cosmos," vol. i., by Alexander von Humboldt. Lon-
don : Longman, Brown, Green & Longmans, 1849. Pp. 487.

100 OUTLINES OF FORESTRY.

X. RAIN.

The vapor which rises from the surface of the
ocean, and, indeed, from all water surfaces, mixes
or diffuses through the air, and is carried bj the
winds to different parts of the earth. The air over
parts of the earth at considerable distances from
any large body of water may therefore contain
much vapor.

The quantity of water the air can hold, in an
invisible state as vapor, increases rapidly with an
increase in the temperature. Consequently, when
air containing vapor is considerably chilled, it can
no longer hold as much as it formerly did, and a
part appears as rain, or as some other form of pre-
cipitation, such as dew, snow, hail, fog, cloud, etc.

The amount of water that falls, or is precipitated
from the air, depends not only on the quantity of
air that is chilled, and on the extent of this chill-
ing, but also on the quantity of moisture the air
contained before it was chilled.

The lowering of temperature necessary to pro-
duce rain may be caused in the following ways :

RAIN. 101

1. The moist air may blow along the earth's
surface towards colder regions.

2. The moist air may rise directly from the
earth's surface into the higher and colder regions
of the air.

As a rule, the moist air which blows along the
earth's surface towards the poles becomes chilled
and deposits its moisture as rain or snow. On the
contrary, the moist air which blows along the
earth's surface towards the equator becomes, for
the greater part, warmer and, thus, becoming
drier takes rather than gives moisture, and pro-
duces drought.

Therefore, as a rule, only the surface winds
which blow towards the colder regions of the
earth can be expected to bring rain.

In the tropical regions, however, any wind,
whether from the equator or from the poles, which
has crossed the ocean or any other large body of
water, and has thereby become saturated with
moisture, will deposit some of its moisture as rain
when it strikes the cooler coasts of a continent or
island. Even in such cases, however, the equa-
torial winds are more apt to cause heavy rainfalls
than those from the poles.

A warm, moist air, when sufficiently chilled, will

9*

102 OUTLINES OF FORESTRY.

cause a heavier rainfall than a cold, moist air, be-
cause the warm air has a greater capacity for hold-
ing vapor.

In general, the air of the equatorial zones of the
earth is both warmer and moister than that of the
temperate zones, and the air of the temperate zones
is both warmer and moister than that of the polar
zones.

Consequently the rainfall is heaviest in the equa-
torial zones, and is greater in the temperate zones
than in the polar zones.

The air near the coast of a continent or island is
moister than that over the interior. Consequently
the rainfall is heavier on the coasts than in the
interior.

When the earth's surface is intensely heated, the
air over it becomes so hot that it rises far above the
surface. If sufficiently moist, the chilling so caused
produces a heavy rainfall. Much of the rain in
the tropical regions is caused in this manner.

Mountains form excellent means for cooling the
air and causing its invisible water or vapor to fall
as rain. They act no matter from what direction
the wind may be blowing.

When the wind blows against the sides or slopes
of a mountain, it is forced by the pressure of the

RAIN. 103

wind behind it to slowly creep up the slopes of the
mountain, and becomes chilled in the colder re-
gions which lie near the summit. If this lowering
of temperature be sufficiently great, the moisture
will be precipitated from the air, no matter from
what direction the wind may come.

Mountains may, therefore, cause rain to fall
from any wind that is forced to blow over them,
provided they are sufficiently high to cause the
necessary amount of cooling. When a mountain
reaches sufficiently far upward into the air to cause
the temperature to fall below the freezing-point
of water, the condensed moisture falls as snow.

The reason so many rivers rise in mountains is
to be found in the fact that the mountains act to
chill the winds, and so rob the air of its moisture,
no matter in from what direction the wind, which
is forced to ascend their slopes, may happen to
blow.

Kearly all the rivers of the world rise in moun-
tainous districts. As a rule, the largest rivers of
the world rise in the highest mountains. This is
because the hisrher the mountain the colder its
slopes, the cold mountain slopes acting, as ex-
plained, to deprive the air of its moisture. .

The rain that falls on a mountain's slopes, like

104 OUTLINES OF FORESTRY.

that which falls on any other part of the earth's
surface, either runs rapidly off the surface or
sinks slowly into the ground.

The part that runs directly off the ground will
be greater than the part which sinks into the
ground, when the surface is bare and devoid of
vegetation. On the contrary, the part which sinks
into the ground will be greater than the part which
runs directly off' the surface, when the surface is
covered by forests. But the proportion of the
rainfall which sinks into the ground, as compared
with that w^hich runs directly off the surface, is
greater where the sides of mountains are covered
with forests than in any other case.

Since the rivers which rise in the mountains are
more regularly fed by the springs when the greater
part of the rainfall sinks quietly into the ground,
and since this occurs on mountains that are
covered with trees, the importance of keeping the
sides of the mountains well wooded is evident.

"When the sides of mountains are covered with
forests, the rivers that rise on their slopes are not
only less apt to overflow their banks during heavy
rainfalls, but are also less apt to dry up and be-
come shallow during droughts, than if such forests
were removed.

RAIN. 105

The forests should, therefore, be preserved on the
mountain-sides, in order to protect the lowlands
either from inundations or floods, or from the
effects of too small a quantity of water in the
rivers which flow through them during droughts.

The action of mountains in cooling the air and
causing the condensation of the moisture of the
air, is thus referred to by Tyndall in his " Heat as
a Mode of Motion," * page 384 :

" Mountains act as condensers, partly by the coldness of
their own masses, which they owe to their elevation. Above
them spreads no vapor screens of sufficient density to intercept
their heat, which, consequently, passes unrequited into space.
When the sun is withdrawn, this loss is shown by the quick
descent of the thermometer. The difference between a ther-
mometer which, properly protected, gives the true tempera-
ture of the night-air, and one which is permitted to radiate
freely towards space, must be greater at high elevations than
at low ones. This conclusion is confirmed by observation.
On the Grand Plateau of Mont Blanc, for example, MM.
Martins and Bravais found the difference between two such
thermometers to be twenty-four degrees Fahrenheit, when
a difference of only ten degrees was observed at Chamouni."

* Eeprinted, by permission, from " Heat as a Mode of Mo-
tion," by John Tyndall, LL.D., F.R.S. New York : D. Apple-
ton & Co., 1883. Pp. 591.

106 OUTLINES OF FORESTRY.

Huxley, in his " Physiography," * speaks as
follows, concerning the formation of rain, on page
47:

" In examining tlie distribution of rain, it will be found to
be regulated partly by the physical features of the country,
and partly by the character of the prevailing winds. In the
neighborhood of mountains, the rainfall is increased, since, as
has already been pointed out, a mass of moist air, when forced
up the side of a mountain, is chilled in the ascent, and its
moisture consequently discharged. Among our western coun-
ties, in the neighborhood of hills, the rainfall rises to eighty,
or even to a hundred, inches, and upwards ; while away from
hills, though still in the west, it is only from thirty to forty-
five inches. A table-land, or high plain surrounded by moun-
tains, will generally receive but little rain, since the winds
which reach it have been more or less drained of moisture in
sweeping over the surrounding hills. For a like reason, but
little rain is likely to fall on the lee side of a high hill, and
many mountains, consequently, have a wet and a dry side ;
the wet side being, of course, that towards which the predomi-
nant winds blow. As regards the influence of winds on rain,
it is evident that, when air has blown over a large expanse of
warm water, it must have become laden with moisture, which
will be readily precipitated on exposure to refrigerating influ-
ences. Hence, as in Britain, so in the greater part of Europe,
the southerly and westerly winds bring rain ; and most rain

* Reprinted, by permission, from " Physiography," by T. H.
Huxley, F.R.S. London : MacmHlan & Co., 1883. Pp. 384.

RAIN. 107

falls in the exposed westerly parts, such as the coast of Portu-
gal, Spain, France, Britain, and Norway. There are certain
conditions, however, under which rain is brought to our islands
by easterly rather than westerly winds."

Maury, in his " Physical Geography of the
Sea," * on page 120, says :

" We shall now be enabled to determine, if the views which
I have been endeavoring to present be correct, what parts of
the earth are subject to the greatest fall of rain. They should
be on the slopes of those mountains which the trade-winds or
monsoons first strike after having blown across the greatest
tract of ocean. The more abrupt the elevation, and the shorter
the distance between the mountain-top and the ocean, the
greater the amount of precipitation. If, therefore, we com-
mence at the parallel of about thirty degrees north in the Pa-
cific, where the northeast trade-winds first strike that ocean, and
trace them through their circuits till they meet high land, we
ought to find such a place of heavy rains. Commencing at
this parallel of thirty degrees, therefore, in the North Pacific,
and tracing thence the course of the northeast trade-winds,
we shall find that they blow thence, and reach the region of
equatorial calms near the Caroline Islands. Here they rise
up ; but, instead of pursuing the same course in the upper

* Reprinted, by permission, from " The Physical Geography
of the Sea, and its Meteorology," by M. F. Maury, LL.D.,
U.S.N. New York : Harper & Brothers, Publishers, Franklin
Square.

108 OUTLINES OF FORESTRY,

stratum of winds through the southern hemisphere, they, in
consequence of the rotation of the earth, are made to take a
southeast course. They keep in this upper stratum until they
reach the calms of Capricorn, between the parallels of thirty
degrees and forty degrees, after which they become the pre-
vailing northwest winds of the southern hemisphere, which
correspond to the southwest of the northern. Continuing on to
the southeast, they are now the surface winds ; they are going
from warmer to cooler latitudes ; they become as the wet
sponge, and are abruptly intercepted by the Andes of Pata-
gonia, whose cold summit compresses them, and with its low
dew-point squeezes the water out of them. Captain King found
the astonishing fall of water here of nearly thirteen feet (one
hundred and fifty-one inches) in forty-one days ; and Mr. Dar-
win reports that the sea -water along this part of the South
American coast is sometimes quite fresh, from the vast quan-
tity of rain that falls. A similar rainfall occurs on the sides
of Cherraponjie, a mountain in India. Colonel Sykes reports
a fall here during the southwest monsoons of six hundred and
five and one-quarter inches. This is at the rate of eighty-six
feet during the year ; but King's Patagonia rainfall is at the
rate of one hundred and fourteen feet during the year. Cher-
raponjie is not so near the coast as the Patagonia range, and
the monsoons lose moisture before they reach it."

DRAINAGE. 109

XI. DRAINAGE.

The rain that falls on the earth either runs
directly off the surface or sinks into the ground.

The part that runs directly off the surface col-
lects in small streams that discharge through a
river, either into a lake or into the ocean.

The part which sinks into the ground collects in
pockets or places below the surface, called reser-
voirs. As a rule, the water escapes from these
underground reservoirs by coming out at the sur-
face at some lower level, as a spring. During most
of the time the flow of water in a river is kept
up by the springs pouring their waters into the
many streams that empty into the river channel.

The water, therefore, that falls from the sky as
rain, flows directly from the earth's surface into a
river, or first collects in a reservoir, from which it
afterwards flows into a river.

The running of the water from the level where
the rain fell to a lower level is called drainage.

There are two kinds of drainage :

10

110 OUTLINES OF FORESTRY.

1. Surface drainage, or where the rain-water
runs directly off the surface.

2. Underground drainage, or where the rain-
water first sinks into the ground and then dis-
charges as springs into some stream that empties
into a river.

Surface drainage, for the greater part, takes
place rapidly, and occurs mainly during the time
rain is falling. It practically stops a few hours
after the rain ceases.

Underground drainage takes place slowly, and
may continue for many weeks after the rain ceases.

All the water in a river comes from the rain that
falls on the earth's surface. The rivers continue
to flow because the springs are continually empty-
ing their waters into the rivers, and, before they
run dry, more rain falls and keeps up the supply
in their reservoirs.

Some rivers are larger than others. This is
because :

1. More rain falls on those parts of the earth
through which they flow.

2. The land which slopes towards such rivers
covers a greater part of the earth's surface.

The water runs off the earth from a higher to a
lower level, because water runs down hill. The

DRAINAGE. Ill

direction in which water will drain from the land
will depend on the direction of the slope of the
land. If a large area of land so slopes that all the
water draining from it collects in streams flowing
into the ocean through a common river mouth,
and the rainfall on such area is large, the river
itself will be large.

The smaller streams and rivers which collect in a
single and larger river, and discharge their waters
through a common mouth, are called, collectively,
a river system.

The area of land that drains into a river is called
a river basin.

The size of a river, therefore, depends upon the
amount of the rainfall on its basin, and on the size
of its basin.

When the quantity of water discharged into a
river is greater than its channel can hold, a flood
occurs, or the river is said to inundate its banks.

A heavy rain-fall does not necessarily produce
an inundation. If the character of the river basin
is such that a comparatively small part of the rain-
fall runs directly off the surface, and a large part
sinks into the ground and collects in the reservoirs
of springs, and slowly passes through such springs
into the rivers, suflacient time may be given for

112 OUTLINES OF FORESTRY.

the river to safely discharge the waters of even a
very heavy rainfall.

If, however, the character of the surface is such
that the larger part of the rainfall runs directly off
the slopes into the river channel, then an inunda-
tion must necessarily attend every heavy rainfall.

If the greater part of the rainfall runs directly
off the surface into the river channel, and a com-
paratively small part goes to feed the reservoirs of
the springs, and if a long time elapses hefore the
next rainfall, the springs will dry up, and the
water in the river will get very low.

Any disturbance in the natural drainage of a
country may cause a damage of two different
kinds :

1. The damage due to the overflowing of the
rivers, or that directly due to too much water.

2. The damage due to the drying up, or the
getting too low, of the rivers in the intervals be-
tween the storms, or that due to too little water.

The proportion of the rainfall that sinks quietly
into the earth, as compared with that which flows
directly off its surface, depends on the character
of the surface. As a rule, a surface devoid of
vegetable covering — that is, a surface on which
no vegetation is growing — will permit a larger

DRAINAGE. 113

proportion of the rainfall to drain directly into the
river channels than will a surface covered by
vegetation. This is especially the case during the
colder parts of the year, when the ground is fi'ozen.

When rain falls on a surface covered by vegeta-
tion, the water, by slowly trickling down the stalks
or stems of the leaves and the branches and trunks
of the trees, finds a ready entrance into the ground
by following their surfaces and discharging into
the porous ground lying around their roots.

A forest permits this action of the water in sink-
ing into the ground to take place quite readily.

A forest, therefore, tends to decrease the amount
of rainfall that drains directly from the earth's
surface.

A forest also tends to prevent the occurrence of
too little water in a river, because it insures the
filling of the reservoirs of springs, which discharge
their waters into the rivers during the intervals
between the rainfalls.

Unless, therefore, forests are preserved, the
proper drainage of the earth will be disturbed,
and the rivers will have too much water in their
channels during the time of rains, and too little
water in the intervals between rains.

The rapid drainage of the surface when no
h 10*

114 OUTLINES OF FORESTRY.

longer protected by the forests is thus described
by Sir Charles Lyell, in his " Principles of Ge-
ology, or the Modern Changes of the Earth and
its Inhabitants," * on page 338, vol. i. :

" When travelling in Georgia and Alabama in 1846, I saw
in both these States the commencement of hundreds of val-
leys in places where the native forests had recently been re*
moved. One of these newly-formed gulleys or ravines is
represented in the annexed wood-cut, from a drawing which
I made on the spot. It occurs three miles and a half due west
of Milledgeville, the capital of Georgia, and is situated on the
farm of Pomona, on the direct road to Macon.

" In 1826, before the land was cleared, it had no existence ;
when the trees of the forest were cut down, cracks three feet
deep were caused by the sun's heat in the clay ; and during
the rains, a sudden rush of water through the principal crack
deepened it at its lower extremity, from whence the excavating
power worked backward, till, in the course of twenty years, a
chasm measuring no less than fifty-five feet in depth, three
hundred yards in length, and varying in width from twenty to
one hundred and eighty feet, was the result. The high road
had been several times turned to avoid this cavity, the enlarge-
ment of which is still proceeding, and the old line of road may
be seen to have held its course directly over what is now the
widest part of the ravine. In the perpendicular walls of this

* "Principles of Geology," by Sir Charles Lyell, F.R.S.,
M.A. London: John Murray, Albemarle Street, 1872. Pp.
650.

DRAINAGE. 115

great chasm appear beds of clay and sand, red, white, yellow,
and green, produced by the decomposition in situ of hornblen-
dic gneiss with layers and veins of quartz, which remains en-
tire to prove that the whole mass was once crystalline."

Marsh, in his book on " The Earth as Modified
by Human Action," * in referring to the effects
produced on the drainage of the land by the de-
struction of the forest, on page 254, gives the fol-
lowing quotation from a paper read by Blanqui,
read before the Academy of Moral and Political
Science in 1843, concerning the Alps of Provence :

" The Alps of Provence present a terrible aspect. In the
more equable climate of Northern France, one can form no
conception of those parched mountain gorges where not even
a bush can be found to shelter a bird, where, at most, the wan-
derer sees in summer here and there a withered lavender,
where all the springs are dried up, and where a dead silence,
hardly broken by even the hum of an insect, prevails. But if
a storm bursts forth, masses of water suddenly shoot from the
mountain heights into the shattered gulfs, waste without irri-
gating, deluge without refreshing the soil they overflow in
their swift descent, and leave it even more seared than it was
from want of moisture. Man at last retires from the fearful

* Reprinted, by permission, from "The Earth as Modified
by Human Action," by George P. Marsh. New York : Scrib-
ner, Armstrong & Co., No. 654 Broadway, 1874. Pp. 656.

116 OUTLINES OF FORESTRY.

desert, and I have, the present season, found not a living soul
in districts where I remember to have enjoyed hospitality
thirty years ago."

The influence of a vegetable covering on the
drainage of the surface is thus referred to by iX\-
see Reclus, in Ms work on " The Earth : A De-
scriptive History of the Phenomena of the Life of
the Globe," * on page 223 :

" The action of vegetation is not confined merely to imbibing
the water falling from the clouds ; it often, also, assists the
superabundant moisture in penetrating the interior of the
ground. Trees, after they have received the water upon their
foliage, let it trickle down drop by drop on the gradually
softened earth, and thus facilitate the gentle permeation of
the moisture into the substratum ; another part of the rain-
water, running down the trunk and along the roots, at once
finds its way to the lower strata. On mountain slopes, the mosses
and the freshly-growing carpet of Alpine plants swell like
sponges when they are watered with rain or melted snow, and
retain the moisture in the interstices of their leaves and stalks
until the vegetable mass is thoroughly saturated and the liquid
surplus flows away. Peat-mosses especially absorb a very con-
siderable quantity of water, and form great feeding-reservoirs
for the springs which gush out at a lower level. The immense

* Reprinted, by permission, from " The Earth," by Elis^e
Reclus. New York: Harper & Brothers, Franklin Square.
Pp. 573.

DRAINAGE. 117

fields of peat which cover hundreds and thousands of acres on
the mountain slopes of Ireland and Scotland may, notwith-
standing their elevation and inclined position, be considered
as actual lacustrine basins containing millions of tons of water
dispersed among their innumerable leaflets. The supera-
bundant water of these tracks of peat- mosses issues forth in
springs on the plains below."

The protective action of a vegetable covering is
thus alluded to by Prestwich in his " Geology,
Chemical, Physical, and Stratigraphical," * page
136:

" This surface soil, with its usual covering of herbage, serves
to protect the land from further degradation, and checks the
denuding action which would otherwise scour the surface after
every shower of rain. Instances have been adduced to show
how persistent are the features of such a surface. The posi-
tions of the many dolmens and other so-called ' DruidicaP
stones, so common on the downs of this country and in many
parts of France, shows that the level of the vegetable soil has
undergone little or no change since they were first erected.
The camp of Attila, situated in the great chalk plains of
Champagne, furnishes a well-known date, namely, a.d. 451.
Notwithstanding its more than fourteen hundred years, the

* Reprinted, by permission, from " Geology, Chemical, Physi-
cal, and Stratigraphical," by Joseph Prestwich, M.A., F.R.S.
Vol. i. Oxford, Clarendon Press, 1886. Pp. 477.

118 OUTLINES OF FORESTRY.

surface of this great earthwork, which is merely covered with
a thin growth of grass, remains almost as perfect and as sharp
as when first made and grassed over. Nothing of importance
has been removed from the surface by mechanical means, what-
ever may have been the solvent action of the rain on the rocks
beneath."

CLIMATE. 119

XII. CLIMATE.

By the climate of a country is meant the condi-
tion of its atmosphere as regards heat or cold,
moisture or dryness, healthfulness or unhealthful-
ness.

The atmosphere, or ocean of air that surrounds
the earth, gets practically all its heat from the
sun, either directly by absorption as the rays pass
through the air, or indirectly from the heated
earth.

Or, less concisely, the atmosphere receives its
heat from the sun :

1. Directly, by absorption.

2. Indirectly, from the heated earth,
(a.) By contact with the heated earth.

(6.) By radiation from the heated earth, — that is,
the sun's rays heat the earth, and the heated earth
throws out or radiates its heat in all directions.

(c.) By reflection from the heated earth, — that is,
the sun's rays strike the earth and fly off' from it
like light does when it strikes a mirror.

The equatorial regions of the earth are warmer

120 OUTLINES OF FORESTRY.

than either the temperate or the polar regions,
because they receive the sun's rays more directly
than any other part of the earth.

Regions of the earth that are situated the same
distance from the equator, however, often possess
different temperatures, not only because they are
exposed to warmer or colder currents of air or
water, but also on account of certain peculiarities
of their surfaces

The distribution of the land and water areas of
the earth exerts a marked influence in causing a
difference in climate in regions situated in the
same latitude.

A given quantity of the sun's heat falling on a
given area of water will produce therein a smaller
increase of temperature than if permitted to fall
on an equal area of land. Consequently, the air
over such body of water will be less warmed than
would the air over the land.

Water possesses a greater capacity for heat than
any other common substance; in other words, a
greater quantity of heat is required to cause a cer-
tain increase of temperature in a pound of water
than in a pound of any other common substance.

For example : the quantity of heat required to
raise a pound of ice-cold water to its boiling-point,

CLIMATE. 121

or to 212 degrees Fahrenheit, would be sufficient
to raise the temperature of a pound of ice-cold
iron to about 1600 degrees Fahrenheit, or to make
the ice-cold iron red-hot.

Although land and water areas may be situated
in the same latitude, and therefore receive equal
quantities of the sun's heat per unit of area, yet
the temperature of the land, and consequently of
the air over it, would become much hotter than
the temperature of the water, and of the air over
the water.

The higher the temperature of an area, the more
rapidly it loses its heat. A land surface, when
heating, becomes hotter than a water surface when
similarly exposed for the same time to the sun's
heat. The land also, when cooling, loses its heat
more rapidly than the water ; the air over the land
becomes chilled sooner than over the water.

Differences in the elevation of the land produce
differences in the climate. In general, an elevation
of three hundred and fifty feet will cause as great
a lowering of temperature as a difference of one
degree of latitude, or of about seventy geograph-
ical miles. Therefore, the same differences are
observed in passing from the base to the summit
of a high tropical mountain as are observed in

Y 11

122 OUTLINES OF FORESTRY,

passing along the surface of the earth from the
equator to the poles. Or, in other words, three
hundred and fifty feet skyward equals seventy
miles poleward.

In summer, when the sun is more nearly over-
head, and when in our hemisphere the earth is
gaining rather than losing heat, the land areas,
and consequently the air over them, rapidly become
heated; while the water areas, and consequently
the air over them, remain comparatively cool.

In winter, however, when the loss of heat is
greater than the gain, the land areas, and conse-
quently the air over them, rapidly become cooled;
while the water areas continue for a long time to
part with the great stores of heat that they have
taken in during the summer, and thus remain
comparatively warm.

Similar differences are observed between the
temperature of the air over the land and water
areas during the daylight while they are exposed
to the sun's heat, and during the night when they
are throwing it off.

There is another reason why the water areas are
heated less rapidly than the land areas : the heat
penetrates the water to a comparatively great
depth, is diffused through a great body of water,

CLIMATE. 123

and, consequently, heats it less. Moreover, the
water when heated is set in motion by reason of
the differences of density produced by the differ-
ences of temperature, and moves towards colder
districts, and its place is taken by water that moves
from colder districts. Such motions are seen in
the constant ocean currents.

The land, on the contrary, is heated to a com-
paratively small depth, remains in its place, and
may, therefore, rapidly become intensely hot.

The climate produced by an extended land area
is called a continental climate. That produced by
an extended water area is called an oceanic climate.
The continental climate is characterized by great
extremes of heat and cold, — that is, a continental
climate is apt to be very hot in summer and very
cold in winter. The oceanic climate, on the con-
trary, is characterized by a comparatively uniform
temperature, being neither very hot in summer nor
very cold in winter.

So far as the climate of the land is concerned,
the differences of climate above referred to are
greatly influenced by the nature of the surface.
If the surface is covered by vegetation of any kind,
especially by forests, it both heats slowly and cools
slowly.

124 OUTLINES OF FORESTRY.

If entirely bare, or deprived of vegetable cover-
ing, it both, heats quickly and cools quickly.

The climate of a forest, or, indeed, even of a re-
gion protected by a less dense covering of vegeta-
tion, closely resembles the equable climate of a
water area; that of a bare, arid district, diflers
greatly from that of a water area. Deserts, for
example, are characterized by great extremes of
climate, being very warm in summer, or in the
daytime, and very cold in winter, or at night.

The climate of a country, therefore, will be
greatly influenced by the presence of the forest
districts, and must necessarily be changed, to a
greater or less extent, by the removal of such
forests from extended areas.

Humboldt, in " Cosmos," * on page 318, thus
describes the influence of land and water areas on
oceanic or continental climates ; or, as he styles
them, on the insular or littoral climates :

"I have already alluded to the slowness with which the
great mass of water in the ocean follows the variations of
temperature in the atmosphere, and the consequent influence
of the sea in equalizing temperatures ; it moderates both the

* " Cosmos," vol. i., by Alexander von Humboldt. London :
Longman, Brown, Green & Longmans, 1849. Pp. 480.

CLIMATE/ 125

asperity of winter and the heat of summer : hence arises a
second important contrast, — that between insular or littoral
climates (enjoyed also in some degree by continents whose
outline is broken by peninsulas and bays), and the climate of
the interior of great masses of solid land. Leopold von Buch
was the first writer who entered fully into the subject of this
remarkable contrast, and the varied phenomena resulting from
it ; its influence on agriculture and vegetation, on the transpar-
ency of the atmosphere and the serenity of the sky, on the
radiation from the surface, and on the height and limit of per-
petual snow. In the interior of the Asiatic continent, Tobolsk,
Barnaul on the Obi, and Irkutsk have summers which, in
mean temperature, resemble those of Berlin and Munster, and
that of Cherbourg in Normandy, and during this season the
thermometer sometimes remains for weeks together at 30° and
31° C. (86° or 87.8° F.) ; but these summers are followed by
winters in which the coldest month has the severe mean tem-
perature of 18° to 20° C. (-4° to 4-4° F.)."

riammarion, in his work entitled '' The Atmos-
phere," * referring to the contrasts between con-
tinental and oceanic climates, says, on page 250 :

" The climate of Ireland, Jersey and Guernsey, of the Pen-
insula of Brittany, of the coasts of Normandy, and the South
of England, countries in which the winters are mild and the

* Reprinted, by permission, from " The Atmosphere," by
Camille Flammarion. New York : Harper & Brothers, Frank-
lin Square, 1873. Pp. 454.

11*

126 OUTLINES OF FORESTRY.

summers cool, contrast very strikingly -with the continental
climate of the interior or Eastern Europe. In the northeast
of Ireland (54° 56^), in the same latitude as Konigsberg, the
myrtle grows in the open ground just as it does in Portugal.
The temperature of the month of August in Hungary is 69.8° ;
in Dublin (upon the same isothermal line of 49°) it is 61° at
most. The mean temperature of winter descends to 36.3° at
Buda. In Dublin, where the annual temperature is only 49°,
that of the winter is, nevertheless, 7.7° above the freezing-
point, or nearly four degrees higher than at Milan, Pavia,
Padua, and all Lombardy, where the mean heat of the year
reaches 55°. In the Orkney Islands, at Stromness, a little to
the south of Stockholm (there is not one degree difference in
their latitudes), the mean winter temperature is 7°, or higher
than that of London or Paris. Stranger still, the inland
waters of the Faroe Islands never freeze, situated in 62° of
north latitude, beneath the mild influences of the west wind
and the sea. Upon the coast of Devonshire, one part of
which has been termed the Montpellier of the North, because
of the mildness of its climate, the Agave Mexicana has been
known to flower when planted in the open air, and orange-
trees trained upon the wall to bear fruit, though only scantily
protected by a thin matting.

" There, as at Penzance, Gosport, Cherbourg, and the coast
of Normandy, the mean temperature of the winter is 42°,
being but 18.5° below that of Montpellier and Florence."

CLIMATE AS INFLUENCED BY THE FOREST. 127

XIII. CLIMATE AS INFLUENCED BY
THE PRESENCE OF THE FOREST.

TVhen sunshine falls on an area covered by trees,
the heat is more thoroughly absorbed or taken in
than when it falls on an arid or uncovered surface.

The more thorough absorption of heat by a
wooded area is caused mainly as follows :

1. The greater extent of surface presented by a
wooded than by an unwooded area, not only by
the trees themselves, but often also by the under-
brush which exists in most forest regions.

2. The porous and better absorbing character
of the carpet of leaves that generally covers the
ground in forest regions.

3. The presence of a greater amount of moisture
in the air of a forest region than in a region that
is void of vegetation.

The marked increase in the area of a surface
covered by a forest over that of an equally large
unwooded surface would itself, apart from any
other circumstances, necessitate a smaller rise or in-
crease of temperature in the forest than would the

128 OUTLINES OF FORESTRY.

same quantity of the sun's heat falling on an equal
area of bare ground. Therefore, the sun's heat
when permitted to fall on a forest region is more
thoroughly absorbed, is spread over a greater sur-
face, and penetrates the ground more thoroughly
than it would if thrown on bare ground. For,
when the rays fall on a bare, dry, parched surface,
they penetrate the ground to but a small depth,
and heating a smaller amount, must necessarily
produce a greater increase of temperature.

The same is true as regards the loss of heat:
forest districts, which take in heat slowly, part
with it slowly; while bare, uncovered surfaces,
which take in heat quickly, part with it quickly.

It, therefore, follows that since the forests do not
rapidly heat, they do not become excessively hot
in summer; and, since they part with their heat
slowly, they do not become very cold in winter.

The fact that an area covered with forests does
not tend to become as cold in winter as bare,
uncovered ground, exerts a great influence on the
depth to which the frost extends downwards.

The non-conducting power for heat of even a
very thin layer of snow is well known. If snow
falls before the frost penetrates the ground to any
great depth, it will act as a covering to prevent the

CLIMATE AS INFLUENCED BY THE FOREST. 129

earth from losing heat. The frost will, therefore,
be prevented from entering the ground to any great
depth. In the temperate regions of the Northern
Hemisphere, in districts covered by forests, the
early snows of winter are, for the greater part, apt
to fa]] before the ground is frozen to any con-
siderable depth. In the early spring, when the
thaws come, the water derived from the melting
of the ice and snow can then drain quietly into the
ground and fill the reservoirs of the springs.

If, however, the forests are removed, the ease
with which the ground loses its heat generally per-
mits it to freeze before the first snow falls, and the
non-conducting power of the layer of snow causes
the ground to remain frozen until long after the
spring thaws have melted the snow. Under such
circumstances, the water derived from the melting
snow rapidly drains almost entirely oflT the sur-
face, and is apt to produce disastrous floods.

Tyndal] has shown that the ability of air to be-
come heated, by absorbing heat directly from the
sun's rays as they pass through it, depends almost
entirely on the presence of water vapor. The air
over a forest district is necessarily more moist, and
consequently better able to absorb heat and become
heated than the air over a dry, barren tract.

130 OUTLINES OF FORESTRY.

Moist air, moreover, is not only better able to
absorb the heat accompanying the direct rays of
the sun, but is especially able to absorb that kind
of heat which is thrown oft* from the heated earth.
Consequently, the air over a forest district absorbs
a much larger percentage of the heat flung off
from the heated earth than does the drier air over
a barren district. In this way, in winter, while the
ground is throwing off its heat, the moist air of
the forest tends to remain warmer than the air
over a dry, arid tract.

Forests exert a marked influence on the climate
of a country, especially at that time of the year
when the crops are liable to suffer injury from
early frosts.

The ease with which bare or poorly covered
ground throws off its heat permits such an area to
more readily reach the temperature of the danger-
point than would be the case if it were well
wooded. It must be remembered that the differ-
ence of a few degrees, or even of the fraction of a
degree, between the air over an uncovered district,
and the air over a covered district in the forest,
may make all the difference between the occurrence
of frost and its non-occurrence. It is, indeed, often
but the difference of a fraction of a degree, that

CLIMATE AS INFLUENCED BY THE FOREST. 131

may cause by an early frost the loss of millions of
dollars to an agricultural district.

Again, it is in the late autumn, at the time of the
early frosts which are so feared in the agricultural
districts, that a vegetable covering may be able to
flino: back to the earth sufficient heat thrown out
by the cooling ground to prevent the temperature
of the air immediately around growing plants
from reaching the freezing-point.

Forests exert a sheltering action at the time of
frosts in keeping the land to the leeward warmer
than that to the windward. !N'ot only do they
act as an actual barrier or screen, sheltering and
protecting the land immediately to the leeward
side, but this protecting action extends to a much
greater distance beyond the immediate neighbor-
hood of the forest than might be supposed.

The leaves of almost any forest tree, when ex-
amined under the microscope, show greatly ex-
tended surfaces in the shape of irregularities, or
spine-like projections. These extended surfaces
aid the tree greatly in throwing off from the very
slightly heated earth the stores of heat which it
possesses, even in the depth of winter, and which,
thus passing into the air, tend to prevent a too
marked fall of temperature during winter.

132 OUTLINES OF FORESTRY.

Generally, the air of the forest is cooler and
damper in summer than the air over the open
fields in the same district.

1st. Because the air of the forest is shielded
from the direct rays of the sun.

2d. Because the air is chilled by evaporation from
the moister ground.

A large tract of forest in any section of country
tends to prevent marked changes in its climate, as
compared with those that occur in the same region
over the open fields.
1 1. By permitting the wooded area to more thor-
oughly absorb the sun's heat on account of the
greater surface it presents.
[ 2. By keeping the air moister and, therefore,

better able to absorb the sun's heat.
1 3. By acting as a screen to the land to the lee-
ward of a cold wind.
,\ 4. By preventing the frost from penetrating the

ground to too great a depth before protected by a
covering of snow.

Geikie, in his " Text-Book of Geology," * in

* Keprinted, by permission, from " Text-Book of Geology,"
by Archibald Geikie, LL.D., F.R.S. London : Macmillan &
Co., 1882. Pp. 971.

CLIMATE AS INFLUENCED BY THE FOREST. 133

referring to the manner in which man may influ-
ence the climate of any particular part of the
earth, says on page 471 :

" Human interference affects meteorological conditions : 1,
by removing forests and laying bare to the sun and winds
areas which were previously kept cool and damp under trees,
or which, lying on the lee side, were protected from tempests ;
as already stated, it is supposed that the wholesale destruction
of the woodlands formerly existing in countries bordering the
Mediterranean has been in part the cause of the present desic-
cation of these districts ; 2, by drainage, the effect of this
operation being to remove rapidly the discharged rainfall, to
raise the temperature of the soil, to lessen the evaporation, and
thereby to diminish the rainfall and somewhat increase the
general temperature of a country ; 3, by the other processes
of agriculture, such as the transformation of moor and bog
into cultivated land, and the clothing of bare hill-sides with
green crops or plantations of coniferous and hard-wood trees."

!N"ot only does the forest prevent the excessive
heating of the land on which it grows, and there-
fore similar excessive heating of the air over the
land, by the greatly extended surface the trees and
undergrowth present to the sun's rays, but it also
acts by the direct absorption of the sun's rays
to cause the separation of the carbon from the
oxygen in carbonic acid, and the hydrogen from

the oxygen in the water in the vegetable king-

12

134 OUTLINES OF FORESTRY.

dom. Tyndall, in his '' Heat as a Mode of Mo-
tion," * page 529, says :

" In the building of plants, carbonic acid is tbe material
from which the carbon of the plant is derived, while water is
the substance from which it obtains its hydrogen. The solar
rays wind up the weight. They sever the united atoms, set-
ting the oxygen free, and allowing the carbon and the hydro-
gen to aggregate in woody fibre. If the sun's rays fall upon
a surface of sand, the sand is heated, and finally radiates
away as much heat as it receives. Let the same rays fall upon
a forest ; then the quantity of heat given back is less than
that received, for a portion of the sunlight is invested in the
building of the trees. We have already seen how heat is con-
sumed in forcing asunder the atoms of bodies, and how it
reappears when the attraction of the separated atoms comes
again into play. The precise considerations which we then
applied to heat, we have now to apply to light, for it is at the
expense of the solar light that the chemical decomposition
takes place. Without the sun, the reduction of the carbonic
acid and water cannot be effected ; and, in this act, an amount
of solar energy is consumed, exactly equivalent to the molecu-
lar work done."

Concerning the influence of the forests on cli-
mate, Hough, in his report to the United States

* Reprinted, by permission, from " Heat as a Mode of
Motion," by John Tyndall, F.R.S., LL.D. New York ;
D. Appleton & Company, 5 Bond Street, 1883. Pp. 591.

CLIMATE AS INFLUENCED BY THE FOREST. 135

Commissioners of Forestry for 1877, quoting from
a paper by M. A. C. Becquerel, on the " Climatic
Effects of Forests," * page 310, says :

" The forests exercise in many ways an influence upon the
climate, but to understand this we must define what we under-
stand by climate.

" The climate of a country, according to M. Humboldt, is
the combination of calorific, aqueous, luminous, aerial, electri-
cal, and other phenomena, which fix upon a country a definite
meteorological character that may be difierent from that of
another country under the same latitude and with the same
geological conditions. According as one or another of these
phenomena predominate we call the climate warm, cold, or
temperate, dry or humid, calm or windy.

" We always regard heat as exercising the greatest influence,
and after this the amount of water falling in difierent seasons
of the year, the humidity or dryness of the air, prevailing
winds, number and distribution of storms throughout the year,
clearness or cloudiness of the sky, the nature of the soil and
vegetation which covers it, and, according as it is natural or
the result of cultivation, the following questions arise for
consideration :

" 1. What is the part that forests play as a shelter against
the winds or as a means of retarding the evaporation of rain-
water?

* Reprinted, by permission, from a " Report upon Forestry,"

1877, by Franklin B. Hough. Washington Printing-OflSce,

1878. Pp. 650.

136 OUTLINES OF FORESTRY.

" 2. What influence do the forests exert, through the absorp-
tion of their roots or the evaporation of their leaves, in modi-
fying the hygrometrical conditions of the surrounding atmos-
phere ?

" 3. How do they modify the temperature of a country ?

" 4. Do the forests exercise an influence on the amount of
water falling, and upon the distribution of rain throughout
the year, as well as upon the regulation of running waters and
springs ?

" 5. In what manner do they intervene in the preservation of
mountains and slopes ?

" 6. Do the forests serve to draw from the storm-clouds their
electricity, and by thus doing diminish their efiects upon the
neighboring regions not wooded ?

" 7. What is the nature of the influence that they may be
able to exercise upon the public health ?

" From these questions we may see what questions we must
solve before being able to decide as to the influence that the
clearing off of woodlands may exercise upon the climate of a
country."

Much valuable data concerning the results of
the destruction of the forests on climate, rainfall,
and other meteorological conditions, were collected
by several scientific expeditions sent to Brazil
under the direction of Louis Agassiz.

In an account of the Thayer expedition in 1865
and 1866, Professor Hartt, in a description of the
" Geology and Physical Geography of Brazil," *
page 319, thus refers to the marked effects that have

CLIMATE AS INFLUENCED BY THE FOREST. 137

been produced by tlie wholesale destruction of the
forests by the burning over of their former areas, —

" The limits of the forests, of the belt of decomposition,
and of the area over which copious rains fall, coincide very
remarkably, and show a dependence upon each other, but the
forest belt has a smaller area than that of decomposition or of
the rains. The wooded belt seems to have narrowed greatly
within comparatively recent times, losing its foothold in the
west, where immense regions, now campos, over which the
climate and soil would normally be proper for the growth of
forests, have dried up, the climate has become hot, less rain
now falls, and the forest cannot regain its lost place. Doubt-
less there are many natural physical causes to be taken into
consideration in studying the distribution of the forest, catinga,
and campos florae ; but there is one agency that has been at
work in Brazil whose efiects we can hardly over-estimate, and
that is the burning over of the wood and campos lands by
man. The very physical features of the highlands of Brazil
determine a difference in the luxuriance in the florae of differ-
ent regions, and there are, as I have already shown, regions
where for ages the climate has been such that forests could
scarcely have had any noteworthy extension, so that there must
have always been in Brazil, naturally, virgin forests, catingas,
campos, and barrens. On the coast, where the forest is dense
and moist, and the climate is wet, forest fires are next to

* Reprinted, by permission, from " Scientific Results of a
Journey in Brazil," by Ch. Fred. Hartt. Boston : Field, Os-
good & Co., 1870. Pp. 620.

12*

138 OUTLINES OF FORESTRY.

impossible, and one never sees a scorched and dead wood, such
as covers so large an area in the province of New Brunswick,
for instance. But in the interior, where the catinga forests
drop their leaves, and are dead for several months in the dry
season, fires are easily kindled and the wood killed; and
fires set in open fields or campos, for the purpose of pro-
ducing a new crop of grass, may spread to the neighboring
catingas. It is the opinion of many writers that a large part
of the catinga and campos regions of the Brazilian highlands
was once covered by forests, and that their present bare ap-
pearance and the character of their florae is in a very great
measure due to frequent and extensive burning over of the
country. Every year the Brazilian campos lands are sys-
tematically and almost entirely burned over, for the purpose
of producing a new crop of grass. This burning, of course,
has destroyed all those trees and shrubs and plants of all
kinds that cannot bear the scorching, and has wrought a great
alteration in the character of the whole flora of the region ;
the climate also has sufiered a change, for with the destruction
of the woods and forests it becomes hotter, the unprotected
earth is like a furnace, streams run dry a few days after a
shower, and the springs disappear."

The following geographical instances of the
effects of forests on climate are referred to by
Becquerel in a previous quotation.

*

* Reprinted, by permission, fi:om " Report upon Forestry,"
1877, by Franklin B. Hough. Washington : Government
Printing-office, 1878.

CLIMATE AS INFLUENCED BY THE FOREST. 139

St. Helena.

Fully forested when discovered in 1502. The introduction
of goats and other causes led to the removal of its forests.
Heavy floods and severe droughts were the result ; replanting
of forest trees towards the close of 1700 resulted in a more
uniform rainfall and its better distribution. Subsequent de-
structions of the forest have again brought back the original
condition of aflfairs.

Island of Ascexsion".

When discovered in 1815 it was barren, and so destitute
of water that supplies were brought to it from the mainland.
The effects of planting trees resulted in an increased rainfall,
from 10.18 in 1858 to 25.11 in 1863. It now grows forty kinds
of trees, where but one grew in 1843 for want of water.

140 OUTLINES OF FORESTRY.

XIV. PURIFICATION OF THE ATMOS-
PHERE.

The atmosphere covers the earth's surface as a
vast ocean of air that extends upwards for a dis-
tance of several hundred miles.

It is composed mainly of a mixture of two gas-
eous substances, — namely, of nearly seventy-seven
per cent, by weight of nitrogen and about twenty-
three per cent, of oxygen. Besides these there is
a nearly constant quantity of carbonic acid gas,
and a variable quantity of the vapor of water.

The carbonic acid is nearly in the proportion of
four parts to ten thousand of air ; or very nearly
one cubic inch of carbonic acid gas to each cubic
foot of ordinary air.

The different ingredients of the atmosphere
serve various purposes in the economy of the
earth.

The oxygen is necessary for the existence of
animal life.

The carbonic acid is necessary for the existence
of plant life.

PURIFICATION OF THE ATMOSPHERE. 141

The moisture of the air is necessary for the
existence of both animal and plant life, although,
perhaps, it is more necessary for the existence of
plant life.

Every action of an animal results in the decay
and subsequent death of some part of its body.
Although this death does not take place immedi-
ately, yet the u^e of any part or member of the
body results in its waste and subsequent death.
In order to replace these dead parts some form
of nourishment is necessary. This nourishment
comes from the food of the animal, which, by the
process of digestion, goes to make up the blood.
The blood carries to the parts of the body which
require nourishment the materials needed for sub-
sequent growth, and, at the same time, takes away
or carries off the dead or decaying parts.

The blood is forced through the different parts
of the body by the action of the heart, which acts
like a force-pump. The blood goes to these parts
of the body as bright red arterial blood. It leaves
them so clogged with dead and decaying parts,
that it becomes changed into a dark, bluish-black,
venous blood.

The oxygen of the air is, in general, necessary
to the existence of animal life in order to burn

142 OUTLINES OF FORESTRY.

out or remove from tlie blood these dead and
decaying parts, and so change the dark, venous
blood to bright red arterial blood.

The oxygen brings about this change mainly by
combining with and slowly burning the waste
products so as to form water vapor and carbonic
acid gas.

If there was nothing to oppose this action of
animal life all the oxygen would, in the end, be
removed from the air and changed into carbonic
acid gas, and no further animal life would be pos-
sible on the earth. Plants, however, during their
growth, in the presence of sunshine, take in or
absorb carbonic acid gas. In the delicate structure
of the leaf this gas is broken up into carbon,
which is retained by the plant to form its woody
fibre, and into oxygen, which is given off and
passes into the atmosphere.

Plants, therefore, during active growth take in
carbonic acid gas and give out oxygen.

A wonderful balance is thus maintained in na-
ture, and the composition of the atmosphere is
kept practically constant.

"What animals reject, plants need for their ex-
istence. What plants reject, animals need for their
existence. It is like the case of the renowned

PURIFICATION OF THE ATMOSPHERE. 143

Jack Sprat aud his wife, of nursery lore, who
between them kept both plate and platter clean.
Each liked and thrived on what the other re-
jected.

If this balance between the plant and animal
kingdom is disturbed, the composition of the
atmosphere will be altered, and a marked change
will be produced in the earth's plant and ani-
mal life. Such changes have been observed in
the geological past long before the creation of
man.

The earth's atmosphere was originally vaster
than at present. The quantity of oxygen and
carbonic acid gas was enormously greater.

A careful estimate places the amount of oxygen
that exists, combined with the different substances
that form the fifteen or twenty miles of the earth's
crust that have been carefully studied, at least at
one-half of the total weight.

At an early age in the earth's life this oxygen
existed in a free state in the atmosphere, and be-
came fixed by combining with or oxidizing the
different materials of the crust. This oxidizing
action has now practically ceased, and the quantity
of oxygen present in the air is constant.

Prior to the Carboniferous age carbonic acid

144 OUTLINES OF FORESTRY.

must have existed in tlie air in enormous quanti-
ties ; for, the vast deposits of carbon, which form
the coal-beds now found in the different parts of
the crust, then existed in a gaseous condition in
the atmosphere combined with oxygen.

Animal life of the present type was impossible
in the unpurified atmosphere that existed before
the Carboniferous age. The conditions were, how-
ever, such as to favor dense and luxuriant plant
life, and at no time in the world's history, either
before or since, has such luxuriant vegetable
growth existed.

A twofold action of purification was effected by
the plants of the Carboniferous period ; namely,
the separation of the carbon and the liberation of
the oxygen.

The exact balance between the plant and ani-
mal life of the earth, so carefully established
by nature, cannot be disturbed without marked
changes in the entire races of animals and plants
that now exist.

The thoughtless and unnecessary removal of the
forests from over extended areas will not only dis-
turb the balance during the time such surfaces are
bare, but since, in many cases, such removal per-
mits this section of country to be denuded of its

PURIFICATION OF THE ATMOSPHERE. 145

soil, there will also follow a permanent disturbance
from the inability of such section of country to
sustain any plant life.

As to the purification of the atmosphere by
plants, Dana, in his " Manual of Geology," * says,
on page 353, —

" In the present era, tlie atmosphere consists essentially of
oxygen and nitrogen, in the proportion of twenty-three to
seventy-seven parts by volume. Along with these constitu-
ents, there are about four parts by volume of carbonic acid in
ten thousand parts of air. Much more carbonic acid would
be injurious to animal life. To vegetable life, on the contrary,
it would be, within certain limits, promotive to growth ; for
plants live mainly by means of the carbonic acid they receive
through their leaves. The carbon they contain comes princi-
pally from the air.

" This being so, it follows, as has been well argued, that the
carbon which is now coal, and was once in plants of different
kinds, has come from the atmosphere, and, therefore, that the
atmosphere now contains less carbonic acid than it did at the
beginning of the Carboniferous period, by the amount stowed
away in the coal of the globe.

" Such an atmosphere, containing an excess of carbonic acid
as well as of moisture, would have had greater density than

* Reprinted, by permission, from a " Manual of Geology,"
third edition, by James D. Dana. New York : Ivison, Blake-
man, Taylor & Co. London : Triibner & Co. Pp. 911.
Q k 13

146 OUTLINES OF FORESTRY.

the present ; consequently, as urged by E. B. Hunt, it would
have occasioned increased heat at the earth's surface, and this
would have been one cause of a higher temperature over the
globe than the present.

" During the progress of the Carboniferous period there was,
then, (1) a using up and storing away of the carbon of the
superfluous carbonic acid, and, thereby, (2) a more or less per-
fect purification of the atmosphere, and a diminution of its
density. In early time there was no aerial life on the earth ;
and, so late as the Carboniferous period, there were only rep-
tiles, myriapods, spiders, insects, and pulmonate mollusks.
The cold-blooded reptiles of low order of vital activity, cor-
respond with these conditions of the atmosphere. The after-
ages show an increasing elevation of grade and variety of
type in the living species of the land."

BAIL. 147

XV. HAIL.

Hail occurs at times when great differences of
temperature exist between neighboring masses of
very moist air.

By permitting great differences of temperature
to occur, the destruction of the forest is, in many
cases, followed by an increase in the number and
severity of hail-storms.

In order to understand the manner in which the
destruction of the forest may influence the occur-
rence of hail-storms, it will be necessary to study
some of the peculiarities of such storms and to re-
view what are now generally believed to be their
causes.

Although hail may fall at any time of the year,
yet it occurs most frequently in summer towards
the close of a very warm day.

The exact causes which produce hail are not
known. The conditions necessary for its occur-
rence appear to be the rapid mixture of very warm
and very cold moist air.

A hail-storm is generally preceded by the appear-

148 OUTLINES OF FORESTRY.

ance of several layers of dark, grayish clouds. In
most all cases, before the beginning of a hail-storm,
a violent movement is seen to take place between
these layers, apparently of a whirling character.
Generally, too, hail-storms are attended by violent
disturbances in the electrical equilibrium of the
atmosphere, as is evidenced by the frequent dis-
charge of the lightning-bolt and the almost con-
tinual roar of thunder. Then follows a fall of
hailstones, the size of which is much larger at the
beginning and towards the middle of the storm
than towards the close. Towards the close of the
storm, however, the quantity of hail which falls is
greatest.

If a hailstone be examined by cutting it in two,
it will be seen to consist of alternate layers of ice
and snow laid over one another in successive coats
like the layers of an onion. A cross-section of a
hailstone can be made by holding it against the
surface of a hot plate until half of the stone has
been melted away.

Hailstones vary in weight from a few grains to
several pounds. Records exist of hailstones weigh-
ing many pounds, sometimes of even several hun-
dred pounds. In such cases, however, it is more
than probable that the stones were produced by

HAIL. 149

the regelation, or freezing together, of numerous
smaller stones, as follows :

The excessive fall of small hailstones, that oc-
curs towards the close of the storm, often produces
heaps of hailstones several feet in thickness. The
separate hailstones readily freeze together, and are
afterwards cut into smaller masses by the action
of the water rapidly draining off the earth. The
fragments thus formed, in all probability, give rise
to stories of mammoth hailstones.

The severity of the lightning-flashes, which at-
tend nearly all great hail-storms, has led some
meteorologists to believe that hail-storms are caused
by the presence of an unusual quantity of free elec-
tricity in the atmosphere. The electrical theory
of hail is, however, at the present, almost entirely
discarded, it being now generally recognized that
the lightning is the effect of the hail-storm, and
not its cause.

Volta proposed the following electrical theory
for the production of hail. He imagined two
approximately parallel clouds near together, the
upper cloud formed of snow, and the under cloud
of rain. Assuming these clouds to be respectively
charged with positive and negative electricity, the
particles of snow in the snow-cloud might, he

13*

150 OUTLINES OF FORESTRY.

assumed, be alternately attracted and repelled into
and from the rain-cloud, and thus receive alternate
coatings of ice and snow until they finally fell to
the ground as hailstones.

In France, where the reckless destruction of the
forest has been attended by a marked increase in
the number and severity of hail-storms, miniature
lightning-rods have been erected in the fields to
prevent the occurrence of hail-storms. These
lightning-rods either took the shape of captive
balloons secured to the earth by tinsel threads, or
of bundles of straw set upright in the field, or of
metal rods permanently connected with the ground.
Their object was to gradually discharge the air of
its free electricity, and thus prevent the occurrence
of hail-storms. The name of such rods, paragreles,
is significant of their supposed action. Unfortu-
nately, they have proved futile in action, since again
and again the portions provided with this supposed
protection have been as severely visited by hail-
storms as unprotected portions.

An endeavor has been made to explain the
peculiar shape of hailstones by the existence of
a number of approximately parallel clouds com-
posed alternately of snow and rain. Drops of
rain falling from the upper cloud would thus

HAIL. 151

receive successive coatings of snow and ice as they
passed successively through the snow- and rain-
clouds, and would finally fall as characteristically-
shaped hailstones.

The theory now generally received in regard to
the formation of hailstones is, that in such storms
the wind rotates around a vertical rather than
around a horizontal axis. If such a whirling mo-
tion exists between a neighboring rain- and snow-
cloud, the particles of snow would be successively
dipped into the rain- and snow-clouds, and would
thus receive alternate layers of ice and snow.

A somewhat similar theory regards a hail-storm
as belonging to the type of the ordinary tornado.
The whirling motion of the air is supposed to
produce the alternate coatings of ice and snow by
the alternate exposure of the moisture to the dif-
ferent temperatures found in the denser and rarer
portions of the space around which the wind is
whirling.

Hail-storms often cause great damage. A single
hail-storm in France has been known to cause loss
to the agricultural districts amounting to the sum
of at least one million pounds sterling.

Although the exact cause of hail-storms is at
present unknown, yet the storms never occur

152 OUTLINES OF FORESTRY.

unless marked differences of temperature exist
between neighboring portions of the air. The
removal of the forest from any considerable section
of country permits such differences of tempera-
ture to occur. In point of fact, it has been no-
ticed in parts of the world from which the forests
have been removed, that the number and severity
of hail-storms have undoubtedly increased.

Destructive hail-storms may therefore be re-
garded as one of the evil results which naturally
follow the destruction of the forest.

As regards the supposed protective influence
of lightning- or hail-rods against destructive hail-
storms, Loomis, in his " Treatise on Meteorology," *
writes on page 135 :

" It has been proposed to preserve the vineyards and valua-
ble farms from the ravages of hail by erecting an immense
number of poles, armed with iron points, communicating with
the earth, for the purpose of drawing off the electricity of the
clouds. Multitudes of these hail-rods were erected in Switzer-
land, but without the expected success.

" It is believed that electricity performs altogether a subordi-
nate, if not an unimportant part in the formation of hail ;

* Reprinted, by permission, from " A Treatise on Meteo-
rology," by Elias Loomis, LL.D. New York: Harper &
Brothers, Franklin Square, 1868. Pp. 305.

HAIL. 153

and if we could draw off all the electricity from tlie hail-cloud
as fast as it was generated, it is not improbable that the hail
would be formed about as large and as abundantly as at present.
" But, even supposing electricity to be the sole agent in the
production of hail, hail-rods could not be expected to furnish
security against hail unless an entire continent could be studded
thick with them, for in the middle latitudes the hail- cloud ad-
vances eastward with a velocity sometimes of forty or more miles
per hour, and the hailstones which fall in one locality are those
which were forming when the cloud was many miles westward
of that point ; so that, to protect a small spot, the whole coun-
try for many miles westward should be armed with rods ; and
it is conceivable that a hail-cloud arriving over a region studded
with these rods might immediately pour down a large quantity
of hailstones which would have fallen farther eastward if the
rods had not discharged the electricity of the cloud."

The following description of a hail-storm that
occurred near Bordeaux, France, in 1865, is thus
given by Flammarion, in his work entitled " The
Atmosphere," * page 393.

" On May 9, 1865, for instance, a storm began at 8.30 a.m.
over Bordeaux and proceeded in a N.N.E. direction, passing
over Perigueux at 10 a.m., Limoges at noon, Bourges at 2
P.M., Orleans at 5.30 p.m., Paris at 7.45 p.m., Laon at 11 p.m.,
and collapsing a little after midnight in Belgium and the North

* Reprinted, by permission, from " The Atmosphere," by
Chamille Flammarion. New York: Harper & Brothers,
Franklin Square, 1873. Pp. 454.

154 OUTLINES OF FORESTRY.

Sea. Its mean breadth was from fifteen to twenty leagues.
The hail only fell in certain places : to the left of Perigueux,
over the arrondissement of Limoges, to the right of Chateau-
roux, to the southeast of Paris, from Corbeil to Lagny, and in
the arrondissements of Soissons and Saint-Quentin. At this
latter point it was of a formidable character. The crystal mass
which fell from the sky upon the Catelet meadows formed a
bed a mile and a quarter long and two thousand feet broad,
estimated to amount altogether to twenty-one millions of cubic
feet. The hailstones did not disappear for more than four
days afterwards. These hailstones sometimes destroy all the
crops, as, for instance, that which occurred in the neighbor-
hood of Angouleme on August 3, 1813. The day had been
fine, and the wind was due north until 3 p.m., when it sud-
denly veered right round ; the sky gradually became covered
vnth clouds, which, collecting one on the top of the other,
offered a terrible spectacle. The wind, which from noon until
5 P.M. had been rather violent, suddenly dropped. Thunder
was heard in the distance, and gradually became louder ; the
sky, at last, became totally obscured, and at 6 p.m. there was
a tremendous fall of hail, the stones being as large as eggs.
Several persons were severely wounded, and a child was killed
near Barbezieux. The next day the ground looked as it might
do in midwinter : the hailstones had accumulated in the hol-
lows and the roads to a height of thirty to forty inches ; trees
were entirely stripped of their leaves ; vines were cut into
pieces, the crops crushed, the cattle, sheep, and pigs especially
were severely injured. The whole neighborhood was deprived
of game, and some few young wolves were found dead. The
efiects of the storm were still visible in 1818."

REFORESTATION AND TREE-PLANTING. 155

XVI. REFORESTATION AND TREE-
PLANTING.

By reforestation is meant the replanting of trees
in any locality from which they have been removed
either accidentally or purposely.

Where the removal of the forests has been
made in a hap-hazard way, and no care has been
taken to protect the soil from the effects of rapid
drainage, the loss of the soil in some cases is so
great as to render the area not only unable to sus-
tain trees of the same character as those which
have been removed, but even to render it unable
to sustain any trees whatever. If, however, in the
removal of the trees, care has been taken that the
loss of soil is but trifling, it may be possible to
again reclothe the surface with trees similar to
those which have been removed.

The French term for this process of replacing
forests is rehoisement. Our English word reforesta-
tion may be safely taken as its equivalent.

The object of reforestation is to avoid the evils
which result from the removal of the forests by

156 OUTLINES OF FORESTRY.

perpetually maintaining forest tracts in portions
of the earth set aside for such purposes.

Where the loss of the soil following the destruc-
tion of the forests has been too marked to permit
the successful replanting of trees, some of the evil
effects following rapid drainage, such, for exam-
ple, as disastrous floods, with their consequent
droughts, have been in a measure lessened by re-
planting the bare surface with different species of
hardy grasses, which, by absorbing and holding
the rain, permit the water to drain slowly off the
surface.

The time required for the full growth of forest
trees is so great that, unless considerable encour-
agement is given to the planting of trees, reforesta-
tion will scarcely be attempted to any considerable
extent. In most cases where reforestation has been
attempted, laws have been enacted offering certain
premiums, either in land or in money, for success-
ful tree-planting.

"Where reforestation is carried out on a large
scale, under the encouragement of a government, it
is desirable that either seeds or seedlings be sup-
plied by the government, or that extensive nur-
series be established. Great care must be taken
to insure the planting of the varieties of trees best

REFORESTATION AND TREE-PL ANTING. 157

suited to exist in the particular section of country
that is to be reforested.

Since those sections of country where reforesta-
tion is to be attempted have already, by the removal
of the forests, been exposed to the loss of soil,
great care must be taken in the replanting of trees
not to needlessly disturb the soil. Two methods
may be employed in reforestation, — viz. :

1. Sowing.

2. Tree-planting.

Considerable difference of opinion exists as to
which of these two methods is preferable. Un-
questionably, however, each is best suited for par-
ticular cases, and, in point of fact, each has been
adopted with considerable success in different parts
of the world.

Seeding can, perhaps, be most profitably fol-
lowed in the temperate latitudes, in situations
where the growth of the tree is comparatively
certain. In higher latitudes the planting of trees
is, perhaps, preferable, since the germination and
continued growth of the seeds are by no means so
certain.

In the case of the destruction of the forest by
avalanches, replanting or reforestation is rendered
much more difiicult by the fact that the soil, in

14

158 OUTLINES OF FORESTRY.

such cases, is often so almost entirely removed by
the force of the rushing snow that little but the
bare rocks remain.

In Italy, laws passed in 1877, set aside the fol-
lowing classes of lands as suitable for being in-
cluded under the provisions of the forest regula-
tions,— namely :

Forest lands on mountain-sides, or in such
places as might, from their location, by the loss of
their trees, cause injury to the lowlands by ava-
lanches, or that might, by their drainage, influence
or modify the water-courses.

It is generally recognized in some of the west-
ern portions of the United States, that when trees
are planted in plots around the farm lands, or on
the sides of such lands, the protection thus af-
forded the rest of the land against the winds is
greater in actual money value than the rent of the
ground occupied by such forests.

"Whenever reforestation is attempted over ex-
tended areas, care should be taken as to the por-
tions which are best suited for such purposes.

It would seem that the following locations are
especially adapted as being suited for the perpetual
maintenance of forests on them, — namely:

1. Wetlands.

REFORESTATION AND TREE-PLANTING. 159

2. Lands covered with thin soil.

3. Lands covered with a rather poor soil.

4. Along the margins of all rivers, wherever
the land is not actually required for purposes of
roads or other public uses.

5. On the sides of all mountain-slopes, where
the soil is of the proper character.

6. On the slopes of all mountains subject to
avalanches.

The following translation of the French laws of
1860 for reforestation is taken from the report
of the United States Commissioners for 1877,*
page 338 :

Frexch Code of Eeboisement of Motjntains, July

28, 1860.

" Article 1. Subventions may be allowed to communes
and public bodies, or to individuals, for replanting lands on
the tops or slopes of mountains.

" Article 2. These aids may consist either in the delivery
of seeds, or plants, or in premiums in money. In those given
by reason of the work done for the general good, and in cases
of communes and public bodies, regard is to be had to their
resources, and the sacrifices they must make, and to their need,
as also to the sums given by general councils for reboisement.

* Reprinted, by permission, from a " Report upon Forestry,"
1876, by Franklin B. Hough. Washington: Government
Printing-office, 1878. Pp. 649.

160 OUTLINES OF FORESTRY.

" Article 3. Premiums in money given to individuals can-
not be paid until after the work is done.

Article 4. In cases where the public interests demand that
the works of reboisement should be made obligatory, either
on account of the condition of the soil, or the dangers that
may happen to the lands below, proceedings are to be had
as follows :

" Article 5. An imperial decree, issued in council of state,
declares the public utility of the works, fixes the boundaries
of land in which it is necessary to execute the reforesting,
and the time within which it must be done. This decree is
preceded (1) by an open inquiry in each of the communes
interested ; (2) by a deliberation in the municipal councils of
these communes, in conjunction with those most important ;
(3) the advice of a special commission, composed of the pre-
fect of the department or his delegate, a member of the gen-
eral council, a member of the council of arrondissement, an
engineer of bridges and roads or of mines, a forest-agent, and
two landholders of the commune interested ; (4) the advice of
the council of arrondissement, and that of the general council,

" The/)roc^s-ver6a/ specifying the lands, the plan of the places,
and the project of the works prepared by the forest adminis-
tration, with the concurrence of an engineer of bridges, roads,
or of mines, are to be deposited in the office of the mayor
during the inquiry, the duration of which is one month, be-
ginning with the publication of the prefectoral order, which
prescribes the opening of the inquest and the meeting of the
municipal council.

"Article 6. The imperial decree is to be published and
posted up in the communes interested. The prefect is also to

REFORESTATION AND TREE-PLANTING. 161

notify the communes and public bodies, as well as individuals,
by an extract of the imperial decree, concerning the indications
relating to the lands belonging to them. The act of notification
shall show the limit of time allowed for the work of reboise-
ment, and if there is occasion, the offer of aid from the admin-
istration on the advances it is disposed to make.

" Article 7. If the lands included within the limits fixed
by the imperial decree belong to individuals, the latter are to
declare whether they will undertake to do the replanting
themselves ; and, if so, they are to be held to execute the
work within the time fixed by the decree. In case they
refuse or fail to perform agreement, proceedings may be had
for their expropriation, on the ground of public utility, ob-
serving the formalities prescribed under Title II. and fol-
lowing, of the law of May 3, 1841. The proprietor expro-
priated in the execution of this article has the right to re-
gain possession of his property after reboisement, subject to
payment of charges for expropriation, the cost of labors in
principal and interest. He may relieve himself of the price
of the labors by relinquishing half of the property. If the
proprietor wishes to obtain repossession, he should make a
declaration to the sub-prefect within five years after notice that
the work of reboisement has been finished, under penalty of
forfeiture of this right.

" Article 8. If the communes or public bodies refuse to
execute these labors upon their lands, or if they are unable to
do it, the state may acquire, either amicably obtaining a part
of the lands which they will not or cannot replant, or by
assuming sole charge of the work. In the latter case, it will
retain the care and use of the lands until it is reimbursed its
I 14*

162 OUTLINES OF FORESTRY.

advances, in principal and interest. Nevertheless, the com-
mune shall enjoy the right to pasturage on the lands replanted
as soon as it is found beyond risk of injury.

" Article 9. Communes and public bodies may in all cases
exonerate themselves from repayment to the state, by relin-
quishing one-half of the replanted lands. This abandonment
should be made under loss of right of doing so, within tea
years from notice of the completion of the works.

" Article 10. The sowing or planting cannot be made on
more than a twentieth in one year of the surface to be planted,
unless a resolution of the municipal councils authorizes it to
be done to a greater extent.

" Article 11. Forest-guards of the state may be appointed
for the care of the sowing or planting done within the bounda-
ries fixed by imperial decrees. Injuries proved by these guards,
within the extent of these limits, shall be prosecuted in the
same manner as if done in woods subject to forest regulation.
The execution of the sentence is to be in accordance with arti-
cles 209, 211, and 212, and paragraphs 1 and 2 of article 210
of the Forest Code.

"Article 12. Paragraph 1 of article 224 of the Forest
Code is not applicable to reboisement done with aid or pre-
miums from the state, in execution of the present law. The
owners of lands replanted with aid or premiums of the state
may not pasture their cattle without special license from the
forest administration, until the time when such woods shall be
recognized by said administration as sufficiently protected.

" Article 13. A regulation of the public administration
shall determine (1) the measures to be taken for fixing the
boundaries indicated in article 5 of the present law ; (2) the

REFORESTATION AND TREE-PLANTING. 163

rules to be observed in preservation of works of reboisement ;
(3) the mode of determining the advances made by the state,
and the measures proper for assuring repayment of principal
and interest, and the rules to be followed in the relinquish-
ment of lands which article 9 allows communes to make to
the state.

" Article 14. The sum of ten million francs is appropri-
ated for paying the expenses authorized by the present law,
to the extent of one million a year. The minister of finances
is authorized to sell, with right of clearing, if necessary, woods
belonging to the state, to the value of five million francs.

" These woods may only be taken from such as are entered
in Table B, appended to this law. The sales shall be done in
succession, within ten years from January 1, 1861. The min-
ister of finances is likewise authorized to sell to communes,
upon approved valuation, and on conditions fixed by a rule of
the public administration, the woods hereinabove mentioned.
The five million francs needed to complete the expenses au-
thorized by the present law shall be provided by means of
extraordinary cuttings, and, if necessary, from the ordinary
resources of the budget."

164 OUTLINES OF FORESTRY.

XVII. THE BALANCE OF NATURE.

For sucTi a complex organization as the earth to
be properly maintained in operation, an exact bal-
ance must be preserved between its five great
geographical forms or parts, — namely, the land,
the water, the air, plants, and animals. So inti-
mately are these different parts associated with one
another, and so exact is the balance that is main-
tained between them, that no one can be changed,
either in amount or distribution, without markedly
affecting all the others.

The ^YQ, geographical forms receive practically,
entirely from the sun, all the energy by which
they are actuated, and which activity constitutes
the order of created things.

A part of the heat of the sun stirs the air or
water into vast movements called currents that
flow between the equator and the poles. By their
means an interchange is effected between the ex-
cessive heat of the equatorial regions and the
excessive cold of the poles. Another part heats

THE BALANCE OF NATURE. 165

the earth's surface, and causes vapor to pass off
from the water surfaces into the atmosphere.

Another part of the solar energy or heat is
directly expended in maintaining one or another
of the myriad forms of plant and animal life.

K any of the five great geographical forms ap-
propriates more than its share of the solar energy,
a disturbance of the balance of nature is effected,
which may produce far-reaching changes in the
operation of the entire mechanism.

Let us inquire as to some of the more evident
ways in which this balance of nature is preserved,
how it may be disturbed, and some of the effects
produced by such disturbances.

We will discuss this influence from the stand-
point of the five great geographical forms, —
namely, the land, the water, the air, plants, and
animals.

The Land and Water. — An exact balance, both
in the amount and distribution, of the land and
water areas of the earth is absolutely necessary for
the existence of the earth's present plant and ani-
mal life.

The total water areas of the earth are in excess
of the land areas in about the proportion of 2^
to 1.

166 OUTLINES OF FORESTRY.

The most extended water areas are situated iu
the equatorial regions, the greater part of the land
areas being situated either in the temperate or in
the polar zones.

At the equator, therefore, where the sun's heat
is greatest, there exists the greatest expanse of
water. Here are three readily-movable elements,
the air, the water, and vapor, each of which can
take in considerable heat without growing very
hot. The differences between the temperature of
the equatorial and polar regions produce vast cur-
rents, both in the atmosphere and in the ocean,
which effect an interchange between the excessive
heat at the equator and excessive cold at the poles.

Even a comparatively small change in the dis-
tribution of the land and water areas of the earth
would produce marked changes in its life.

If, for example, most of the earth's surface in
the equatorial regions was composed of land, an
excessive temperature would be thereby produced
that would render the equatorial regions abso-
lutely uninhabitable by any of the present races of
man. Consider, for example, tropical Africa. The
equator by no means crosses this continent at its
greatest breadth, and yet, notwithstanding the fact
that nearly all the continent is considerably more

THE BALANCE OF NATURE. 167

than one thousand feet above the sea level, large
parts of its interior are as yet absolutely unknown
to the white man.

What, then, would be the effect on the earth's
present life if, instead of the present excess of
water surface at the equator, there existed an ex-
cess of land surface ? Beyond doubt the present
life of the earth would be swept out of existence.

In the same manner any marked increase in
either the elevation or the extent of the land in
the polar regions would be followed by such an in-
crease in the severity of the cold as to sweep out
of existence much of the present life of the earth.
It was, in the opinion of most geologists, a change
in the elevation of the polar lands that caused the
severe cold of the glacial epoch, when most of the
northern continents were covered with enormous
ice-fields.

The Air. — Any change in the composition of the
earth's atmosphere, such, for example, as in the
amount of its oxygen or its carbonic acid gas,
would be followed by a change in its animal and
plant life.

The existence of animal life tends to decrease
the amount of oxygen in the atmosphere, and to
increase the amount of carbonic acid. The ex-

168 OUTLINES OF FORESTRY.

istence of plant life tends to increase the amount
of oxygen and to decrease the amount of carbonic
acid gas.

A wonderful balance is maintained in nature as
to the composition of the atmosphere, from the
fact that what plants reject, animals require for
their existence, and what the animals reject, plants
require.

Minerals, Plants, and Animals. — The mutual in-
terdependence of the mineral, the plant, and the
animal affords another illustration of the balance
of nature. Animals obtain their food either from
other animals or from plants. Plants, as a rule,
live on minerals. They are so constituted as to be
able to take the various substances directly from
the soil, and to change them into forms that can
be readily assimilated by animals. The continued
existence of animals depends on the continued
existence of plants.

IS'ature has very carefully insured the presence of
those germs or seeds that are absolutely necessary
for the birth of either animals or plants. To in-
sure the presence of the germs in all cases, the
number of such germs produced is always vastly
in excess of the number that can possibly live. In
the case of nearly all plants and animals the num-

THE BALANCE OF NATURE. 169

ber of germs produced by a single individual is so
great, that if they all lived and reproduced their
kind at the same rate, in a very little while the
earth itself would be too small to hold them.

Leuwenhoek has calculated that a single speci-
men of the domestic fly can produce seven hun-
dred and forty-six thousand four hundred and
ninety-six young in three months.

According to Professor Owen, a single aphis, or
plant louse, in the tenth generation produces one
quintillion young.

It has been calculated that if all the offspring
of a single edible oyster survived for but a com-
paratively few generations, the waters of such
shallow inlets of the ocean as the Chesapeake Bay
would be too small to hold them.

In order to avoid this excessive multiplication of
the animal and plant life of the earth, — and the
above are but a few of the numerous similar cases
that might be quoted, — and thus preserve the bal-
ance of nature, which would be disturbed by such
inordinate multiplication of any one species, all
forms of animate creation have their natural enemies
provided by nature to hold them in check. Those
only continue to exist that are best fitted to exist
under the conditions by which they are surrounded.
H 16

170 OUTLINES OF FORESTRY,

The principle of the survival of the fittest plays an
important part in preserving the balance of nature.

^Nearly every animal forms the food best fitted
to sustain the life of some other animal. In the
event of a too rapid multiplication of any particu-
lar form of life, some scourge or disease appears
which sweeps off the surplus and thus restores
nature's balance.

As far as careful measurements have been made,
it can be safely assumed that the total value of the
solar radiation is practically the same now as it
was many thousands of years ago. Consequently,
the total amount of energy which the earth thus
receives from the sun, and which goes to maintain
the present mechanism of nature, is constant.

The distribution of this solar energy is, however,
by no means constant. The general interchange
that is effected between the excessive heat of the
equator and the excessive cold of the polar regions
may take place rapidly or slowly, and thus produce
differences in the earth's general climate that not
infrequently give rise to a belief in a change in
the total heating power of the sun, when no such
change exists. For example :

A bare, uncovered surface heats with extreme
rapidity, and consequently the air over it becomes

TEE BALANCE OF NATURE. 171

intensely heated. This may give rise to an im-
pression that the sun's heating power has in-
creased.

Certain causes may tend to temporarily prevent
the free interchange of heat energy that usually
exists between hot and cold parts of the earth.
There will thus result an increase of temperature
in one locality and a marked deficit in another,
which would thus give rise to the impression that
variations in the solar radiation existed, when, in
reality, such variations existed.

In the case of the evaporation of water effected
by the sun, if the total value of the sun's heat be
constant it might at first sight be supposed that
the total quantity of evaporation must remain con-
stant, and that, therefore, the total quantity of
heat remaining the same, no change in its distri-
bution could effect a change in the amount of the
evaporation, and, consequently, in the value of the
rainfall. It must be remembered, however, in this
connection, that if circumstances existed in the
air of any locality by which during the time of
greatest heat the moisture was retained in the air
of such locality, and not be removed therefrom,
evaporation would necessarily be much smaller
than if such moisture were removed by any cause.

172 OUTLINES OF FORESTRY.

The total quantity of the evaporation, therefore,
would by no means be constant.

It is possible, therefore, that while the existence
of the forest over extended sections of country
tends on the whole rather to vary the distribution
of the rainfall through a change in the rapidity of
the drainage, that, nevertheless, it may also, to
some extent, tend to produce a change in the total
quantity of the rainfall.

The exact balance of nature that is required to
be maintained, in order that the present life of the
earth shall exist, can be disturbed by many means.
In perhaps no other way does man tend more to
disturb this balance than by the destruction of the
forests. The removal of the forests from over ex-
tended areas effects a disturbance of the balance
of nature that is manifested in the followins:
ways :

1. By a marked change in the heat in summer
and the cold of winter in the regions formerly
covered by forests.

2. By a marked change in the average amount
of moisture present in the atmosphere over such
regions.

3. By a marked change in the character of the
soil in such region.

THE BALANCE OF NATURE. 173

4. By a marked change in the drainage of such
region.

5. By a marked change in the number and se-
verity of floods and droughts in such regions.

6. By a marked change in the salubrity of the
regions through which the rivers flow which rise
in such districts.

7. By a marked change in the number and
severity of hail-storms in such regions.

8. By an increase in the damage to the agricul-
tural districts arising from the appearance of early
frosts in or near such regions.

The preservation of the forests, in at least certain
localities, is, therefore, imperatively demanded in
order to maintain the general balance of nature,
and to insure on the earth a place for the com-
fortable habitation of man.

George P. Marsh, in his work entitled " The
Earth as Modified by Human Action," * says on
page 8 :

" The revolutions of the seasons, with their alternations of
temperature and of length of day and night, the climates of
different zones, and the general conditions and movements of

* Keprinted, by permission, from " The Earth as Modified

by Human Action," by George P. Marsh. New York : Scrib-

ner, Armstrong & Co., No. 654 Broadway, 1874. Pp. 656.

15*

174 OUTLINES OF FORESTRY.

the atmosphere and the seas, depend upon causes for the most
part cosmical, and, of course, wholly beyond our control.
The elevation, configuration, and composition of the great
masses of terrestrial surface, and the relative extent and
distribution of land and water, are determined by geological
influences equally remote from our jurisdiction. It would
hence seem that the physical adaptation of different portions
of the earth to the use and enjoyment of man is a matter so
strictly belonging to mightier than human powers, that we
can only accept geographical nature as we find her, and be
content with such soils and such skies as she spontaneously
offers.

" But it is certain that man has reacted upon organized and
inorganic nature, and thereby modified, if not determined, the
material structure of his earthly home. The measure of that
reaction manifestly constitutes a very important element in
the appreciation of the relations between mind and matter, as
well as in the discussion of many purely physical problems.
But, though the subject has been incidentally touched upon
by many geographers, and treated with much fiilness of detail
in regard to certain limited fields of human effort and to
certain specific effects of human action, it has not, as a whole,
80 far as I know, been made a matter of special observation,
or of historical research, by any scientific inquirer. Indeed,
until the influence of geographical conditions upon human
life was recognized as a distinct branch* of philosophical
investigation, there was no motive for the pursuit of such
speculations ; and it was desirable to inquire how far we have,
or can, become the architects of our own abiding-place, only
when it was known by the mode of our physical, moral, and

THE BALANCE OF NATURE. 175

intellectual being is affected by the character of the home
which Providence has appointed, and we have fashioned, for
our material habitation.

********

" We cannot always distinguish between the results of man's
action and the effects of purely geological or cosmical causes.
The destruction of the forests, the drainage of lakes and
marshes, and the operations of rural husbandry and industrial
art have unquestionably tended to produce great changes in
the hygrometric, thermometric, electric, and chemical condi-
tion of the atmosphere, though we are not yet able to measure
the force of the different elements of disturbance, or to say
how far they have been neutralized by each other, or by still
obscurer influences ; and it is equally certain that the myriad
forms of animal and vegetable life which covered the earth
when man first entered upon the theatre of a nature whose
harmonies he was destined to derange have been, through his
interference, greatly changed in numerical proportion, some-
times much modified in form and product, and sometimes
entirely extirpated.

" The physical revolutions thus wrought by man have not,
indeed, all been destructive to human interests, and the
heaviest blows he has inflicted upon nature have not been
wholly without their compensations. Soils to which no nutri-
tious vegetable was indigenous ; countries which once brought
forth but the fewest products suited for the sustenance and
comfort of man — while the severity of their climates created
and stimulated the greatest numbers and the most imperious
urgency of physical wants — surfaces the most rugged and
intractable, and least blessed with natural facilities of com-

176 OUTLINES OF FORESTRY.

munication, have been brought in modern times to yield and
distribute all that supplies the material necessities, all that
contributes to the sensuous enjoyments and conveniences, of
civilized life. The Scythia, the Thule, the Britain, the
Germany, and the Gaul which the Roman writers describe in
such forbidding terms have been brought almost to rival the
native luxuriance and easily- won plenty of Southern Italy;
and, while the fountains of oil and wine that refreshed old
Greece and Syria and Northern Africa have almost ceased to
flow, and the soils of those fair lands are turned to thirsty and
inhospitable deserts, the hyperborean regions of Europe have
learned to conquer, or rather compensate, the rigors of climate,
and have attained to a material wealth and variety of product
that, with all their natural advantages, the granaries of the
ancient world can hardly be said to have enjoyed."

PRIMER OF PRIMERS. 177

XVIII. PRIMER OF PRIMERS.

Forestry treats of the care and preservation of
parts of the earth covered by trees, together with
the best means of replanting such areas when
deprived of their trees.

When the germs are present, trees will grow
naturally wherever suitable conditions of soil, heat,
and moisture exist.

The climatic conditions best suited for the
growth of trees are also best suited for the growth
of men. As density of population increases, the
trees must be removed from large areas :

1. For agricultural purposes.

2. For the location of roads.

3. For the wood or other products.

The principal product of the forest is wood,
which is required for fuel or charcoal, for building
purposes generally, for fences, for telegraph-poles,
for mining purposes, for railroad ties, or for bark
for tanning.

The object of forestry is to regulate the removal
of the forest where necessary, and to point out the

m

178 OUTLINES OF FORESTRY,

best manner in whicli tlie products of the forest
may be harvested.

Forestry does not endeavor to preserve intact
the virgin forests of the earth. On the contrary,
it teaches man how best to harvest the crops of
wood, or, where necessary, to safely effect the
entire removal of the forests.

Among the different kinds of areas in agricul-
tural districts suitable for tree-planting are, —

1. Areas covered with poor or thin soils, where
other crops will not thrive.

2. "Wet places, where other crops will not thrive.

3. On the borders of rivers or streams generally.

4. On mountain-slopes, hill-tops, or other eleva-
tions.

Forests should be maintained on mountain-
slopes, because, —

1. The rainfall is greatest on such slopes.

2. Because the rivers are born in the mountains,
and, when the forests are removed, the waters drain
so rapidly from the surfaces of the slopes that
dangerous floods occur, and much of the soil is
rapidly carried away.

3. Because the presence of the forest prevents
the occurrence of disastrous droughts.

4. Because the presence of the forest prevents

PRIMER OF PRIMERS. 179

sudden changes in the temperature of the air, and
thus tends to increase the number and severity of
hail-storms.

5. Because the presence of the forest tends to
prevent the occurrence of early frosts in the
neighboring agricultural districts.

6. Because the presence of the forest insures a
greater uniformity in the relative quantity of
moisture in the air at different seasons of the year.

All life, whether animal or plant, has its begin-
nings in a minute germ-cell containing a nucleus
surrounded by a transparent substance called pro-
toplasm.

Although cases exist where plants appear with-
out the apparent sowing of seed, yet, in all such
cases, seeds or germs must have been present.

The conditions necessary for plant-growth, named
in the order of their importance, are :

1. The germ or seed.

2. The sunshine and the heatshine.

3. The nourishment, or the food the plant re-
quires for its growth.

4. The cradle, or the soil in which the plant is
born.

When a particular species of plant life is to be
maintained, the character of the soil is of the

180 OUTLINES OF FORESTRY.

greatest importance. But if the other conditions
of heat, light, and nourishment exist, almost any
soil will be found that will be the best fitted for
some few of the great variety of plants.

The germ or seed is in all cases derived from a
plant similar to that which is produced when such
seed grows and bears fruit.

The soil forms the plant's cradle ; in it the plant
spreads its roots, and obtains the water and min-
eral ingredients required for growth.

The moisture and carbonic acid taken from the
air by a plant during its active growth form the
principal part of the plant's structure; the various
mineral matters taken from the soil form but a
comparatively small part of such structure.

During active growth in the presence of sun-
shine, plants take in or absorb carbonic acid from
the air. Under the influence of sunlight, this car-
bonic acid, together with its associated water, is
eventually decomposed, the carbon and hydrogen
being retained, and the oxygen thrown off into the
air.

The mineral matters in the soil must exist in
such conditions as will permit of ready assimi-
lation.

Every section of country possesses a nationality

PRIMER OF PRIMERS. 181

in its plant growth, or produces a particular vari-
ety of plants called its flora.

The differences in the distribution of light, heat,
and moisture in different parts of the earth cause
corresponding differences in the flora of such parts.

The flora of the equatorial regions consists of
such plants as are best fitted to exist under the
conditions of abundant heat, light, and moisture
of these regions.

In passing from the equator to the poles the
differences in the distribution of heat and moist-
ure cause corresponding differences in the variety
and luxuriance of plant life.

In passing from the base to the summit of a
high tropical mountain similar differences in the
variety and luxuriance of plant life are noticed, as
in going from the equator to the poles.

Seed-time and harvest seldom fail in nature,
because the germs of vegetable life are generously
scattered in all regions of the earth.

The agencies provided by nature for widely
scattering the seeds of plants are various. Some
seeds are provided with delicate hair-like wings,
which permit the wind readily to carry them great
distances from the plants which produced them.
Others are provided with hooks or bristles, which

16

182 OUTLINES OF FORESTRY.

catch in the fur of animals or in the plumage of
birds, and in this manner are often carried to
distant regions.

Some seeds, which are swallowed whole by
birds or other animals, often pass out uninjured
by the process of digestion at localities far distant
from where they were produced.

Civilized man either purposely or accidentally
carries seeds from one locality to another.

It sometimes happens that plants introduced
into a particular section of country from a dis-
tant land find the new soil and climate so favor-
able to growth as to completely drive out and
exterminate domestic species.

The germs or seeds of plants often exhibit a
remarkable tenacity of life under certain circum-
stances. Grains of corn or wheat taken from
Egyptian mummies have grown and borne fruit,
notwithstanding their centuries of rest.

In a densely-wooded section of country the
ground is often so thickly covered by trees as to
exclude all other forms of vegetable life. When,
however, the removal of a few trees lets in the
sunlight and heat, the seeds, which were possibly
slumbering in the ground for centuries, at once
spring into active life.

PRIMER OF PRIMERS. 183

"Wlien an artesian well is successfully dug in the
Sahara Desert, the appearance of the water is
almost invariably followed by the appearance of a
flora that often contains species peculiar to such
districts.

Wherever the virgin soil of the prairies is up-
turned, and thus exposed to the air, as by the
wheels of the settlers' wagons or other causes, new
species of plants appear.

In the Xorth Temperate Zone the burning of
pine forests is almost invariably followed by the
appearance of scrub-oak.

This wide distribution of plant germs, together
with their wonderful vitality, insure the natural
growth of a vegetable covering in all regions of
the earth where suitable conditions of soil, light,
heat, and moisture exist.

The character of the vegetation in any district
depends more on peculiarities in the distribution
of light, heat, and moisture in such districts than
on the character of the soil.

The peculiarities in the distribution of the rain-
fall in any country determine to a great extent the
character of the flora of such country.

When the rainfall in any region is entirely ab-
sent, no matter what the character of the soil may

184 OUTLINES OF FORESTRY.

be, or what the amount of light and heat such soil
receives, vegetation vrill be entirely absent, and
the region will become a desert.

Where rain falls during one part of the year,
and the rest of the year is dry, steppe regions
occur. Such regions are covered by vegetation
during the wet season, but resemble deserts during
the dry season.

Meadows and prairies occur where the rainfall
is well distributed throughout the year, and the
quantity is not very great.

Forests occur where there is an abundant rain-
fall well distributed throughout the year.

Forests cannot exist in any part of the E"orth
Temperate Zone where the rainfall is absent for
a considerable length of time, because the trees
would die during the dry season, and there would
be no germs for a new crop of trees to start grow-
ing from on the appearance of the rainy season.

In certain parts of the tropics forests may exist
despite long periods of drought, because in such
regions the growth of the trees is either considera-
bly retarded, or the trees obtain their liquid nour-
ishment from copious dews or directly from the
vapor of the air.

A certain depth and character of soil are neces-

PRIMER OF PRIMERS. 185

sary for the growth of trees. Such a soil was
formed by the gradual disintegration of hard
rocks, and by the growth and subsequent decay
of thousands of generations of plants.

Forests are generally found on the slopes of
mountains, where the rainfall is considerable and
well distributed throughout the year. The moun-
tains are, therefore, the natural home of the forest.

Forests are found especially on that coast of an
island or continent which is exposed to the preva-
lent wind, because there the rainfall is considera-
ble and no extended time occurs when the rain is
absent.

Soil was originally formed by the gradual disin-
tegration of the crystalline rocks that were pro-
duced by the cooling of the earth's crust.

Disintegration of rocks is effected by various
causes, mainly, however, by the action, in some
way or another, of water.

Sometimes the soil is found resting on the sur-
face of the rock from which it was derived by
disintegration. In such cases its general charac-
ter can be directly traced to the composition of the
underlying rocks by the gradual change which can
be observed from the loose, porous soil on top, to
the hard, untouched, virgin rock below.

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186 OUTLINES OF FORESTRY.

Soils maybe divided into gravelly, sandy, clayey,
calcareous, and peaty.

The agencies by which the hard crystalline
rocks may be broken up or disintegrated to form
soil are, —

1. The expansion produced during the sprout-
ing or growing of vegetation.

2. The alternate contractions and expansions
that attend the freezing or thawing of the water
that sinks into the rocks.

3. The cutting or eroding power of running-
water charged with suspended mineral matters.

4. The eroding or cutting power of glaciers.

5. The solvent power of water containing such
gases as oxygen or carbonic acid.

A plant, during its vigorous growth, by the ex-
pansion of its roots, may break or rend a rock,
and thus aid in its disintegration.

The alternate expansions and contractions that
attend the thawing or freezing of the water which
sinks into a rock gradually break the rock into
fragments, and thus aids in the formation of soil.

During the gradual movements of glaciers down
the mountain valleys, the fragments of hard rocks
lodged in the ice cut or grind the rocks which
form the sides of the valleys through which the

PRIMER OF PRIMERS. 187

glaciers move, and thus aid in the formation of
soil.

When water contains dissolved in it oxygen or
carbonic acid gas, it may gradually dissolve some
of the less insoluble ingredients of the hardest
rocks, and thus cause them to become permeable.

Clayey soils are derived from the disintegration
of feldspathic rocks.

Calcareous soils are derived from the disintegra-
tion of limestones.

Some soils possess the valuable property of ab-
sorbing moisture directly from the vapor in the
air. Soils containing a large quantity of vegetable
humus possess this property in a more marked
degree than any others. Clayey soils also possess
it to a marked extent.

The ability of soils to absorb the sun's heat will
vary with their color. Dark-colored soils absorb
the heat much better than light-colored soils.

The plants that are found growing naturally in
any locality are those which are best fitted to grow
in such locality. They will continue to grow
naturally only so long as these favorable con-
ditions are maintained.

Forests require for their continued existence a
certain character of soil, so that, although even all

188 OUTLINES OF FORESTRY.

the climatic conditions requisite for their growth
exist, they cannot appear until such soil is provided.

Like other forms of creation, the forest is forced
to maintain a continual struggle for existence.

Its enemies may be divided into two classes, —
namely, animate and inanimate.

The principal animate enemies of the forest are
plants, animals, and man.

The principal inanimate enemies of the forest
are fire, winds, floods, and avalanches.

The destruction of the forest by fire is generally
complete. Though in some cases a small fire may,
by destroying the less hardy forms of plant life,
increase the growth of certain trees, such, for
example, as the pitch-pine, yet, in general, exten-
sive forest fires generally so completely remove the
forests, that it is often impossible to re-establish
them.

Severe forest fires generally occur during the
dry season of the year. The rain which subse-
quently falls finds the ground unprotected by any
vegetable covering, and, rapidly draining off the
surface, carries away much soil.

The principal causes of forest fires are the camp-
fire, the burning of brush, the locomotive spark,
the lightning-bolt, and at times, perhaps, the heat-

PRIMER OF PRIMERS. 189

ing power of the sun's rajs concentrated by len-
ticular, resinous, or gummy nodules.

When its velocity is great, the wind sometimes
sweeps away the trees from extended areas. This
action of the wind is limited mainly to the edges
of the forest or to openings made in them by any
cause.

By overflowing their banks, rivers sometimes
undermine and carry away thousands of acres of
forest trees. The trees accumulate in the bed
of rivers and form masses called rafts.

An avalanche sweeping down the slope of a
mountain often completely removes the forest. A
plot of forest land, properly placed, will often
check the movements of avalanches.

The animate enemies of the forest often produce
their greatest destruction by the aid of the inani-
mate enemies. Thus, man destroys forests by fire ;
the beaver, by floods.

Various parasitic plants may grow on, and
thus cause the death of, even the most vigorous
trees.

Some forms of fungus-growth cause considera^
ble damage to the trees on which they grow.

The animal enemies of the forest vary in size
from minute insects to animals of large size.

190 OUTLINES OF FORESTRY.

The ravages of the animal kingdom are most
marked on the borders of the forest. In the
deeper recesses, the vegetable kingdom holds
almost undisputed sway, excluding the animal
forms by the density of its growth.

Domestic animals, when allowed to range freely
through the forest, may cause considerable damage,
by destroying the foliage, or by gnawing the bark
of trees.

Among wild animals, rodents are the most de-
structive by gnawing the bark, and often by com-
pletely girdling the trees.

Eabbits, mice, and beavers are among the ro-
dents that cause the greatest damage to the
forests.

Beavers destroy forests not only by actually
cutting down trees, but also by building dams
which cause the overflowing of the adjacent coun-
try, which thus destroys the timber growing
thereon.

Goats and other animals that live largely on the
bark of trees often work great destruction to the
forests.

Insects cause damage to the forests, either by
feeding on the parts of the tree necessary for re-
production or growth, or by making galleries or

PRIMER OF PRIMERS. 191

tunnellings through the wood. Many insects,
while in the larva state, cause great damage to
trees by boring or eating the wood.

Various caterpillars often cause so great a de-
struction to the pine-trees as to completely destroy
extensive pine forests.

The greatest enemy of the forest is man. As
lord of the forest he is entitled to its products, and
if he exercises judgment he can safely harvest his
forest crops.

The removal of the forests from any considera-
ble section of country is almost invariably attended
by some or all of the following results, — namely :

1. An increase in the frequency and severity of
the inundations of the rivers flowing in or through
such districts.

2. An increase in the number and severity of
droughts in such districts.

3. A rapid loss of the soil of the area from
which the trees have been removed.

4. A marked disturbance in the lower courses
of the rivers which rise in, or flow through, such
districts.

5. An increase in the number and severity of
hail-storms.

When the forests are removed from any area.

192 OUTLINES OF FORESTRY.

the rain which falls on such area, instead of
slowly draining into the river channel during a
comparatively long time, drains rapidly into it
and causes disastrous floods. The reservoirs of
the springs in such districts thus failing to receive
their proper supply of water, are apt to dry up
shortly after the beginning of the drought.

The rapid drainage of the areas from which the
forests were removed causes a loss of its surface-
soil.

The soil thus lost to the highlands is deposited
in the lower courses of the rivers, in the shape of
mud-flats, or sand-bars, which injuriously affect
navigation.

When soil, rich in vegetable humus, deposited
on the lowlands near the mouths of rivers, is ex-
posed to the sun's heat, is apt to cause miasmatic
or other diseases.

The ground left bare by the destruction of the
forest permits it to both take in and part with its
heat rapidly, and thus to permit the air over it
to rapidly grow hot in summer and cold in winter.

Forests should be maintained in some parts of
all regions where trees can grow. The best places
for such purposes are to be found on the slopes of
mountains.

PRIMER OF PRIMERS. 193

From every water surface of the earth vapor is
almost constantly passing into the atmosphere.
This vapor diffuses through the air over such
water surfaces, and is carried by the winds to
different regions of the earth.

The heat which turns water into vapor disap-
pears, or becomes what is commonly called latent
heat. When such vapor is sufficiently chilled and
falls as rain, snow, or other form of precipitation,
the latent heat becomes sensible and warms the
surrounding air.

The rapidity with which water evaporates or
passes into the air as vapor varies with the follow-
ing circumstances :

1. The extent of the surface exposed.

2. The temperature of the air.

3. The quantity of vapor already in the air.

4. The pressure.

The vapor which passes into the air exerts a
considerable influence in moderating the extreme
temperatures that would otherwise exist in the
equatorial and polar regions of the earth, in the
following ways, viz. :

1. By effecting an interchange between the
excessive heat of the equatorial regions and the
excessive cold of the polar regions.

in 17

194 OUTLINES OF FORESTRY.

2. By acting as a screen which both prevents the
earth's surface from being too rapidly heated on
exposure to the sun's rays, or too rapidly cooled
when deprived of such rays.

Since air can hold more vapor when hot than
when cold, if the temperature of a mass of warm
moist air is sufficiently cooled, the moisture it can
no longer hold as vapor appears as rain or as some
other form of precipitation.

The lowering of temperature required to pro-
duce rain is obtained :

1. By warm moist air blowing along the earth's
surface towards colder regions.

2. By warm moist air rising directly from the
earth's surface into the higher and colder regions
of the atmosphere.

Rain is generally caused by warm moist air
blowing towards the polar regions of the earth.
Cold dry air blowing towards the equatorial re-
gions has its capacity for moisture increased, and
tends rather to cause droughts than rain.

In tropical regions, a wind that has crossed an
ocean, and has thereby become saturated with
moisture, may bring rain on reaching the coast of
a continent or island, in no matter from what
direction it comes.

PRIMER OF PRIMERS. 195

More rain falls in the equatorial regions than
elsewhere ; more falls in the temperate than in the
polar regions. More rain falls on the coasts of
continents than in the interior.

Where the temperature is sufficiently high, as in
the equatorial regions, rain may be caused by the
chilling produced by ascending currents.

Mountains cause a heavy rainfall on account of
the air being chilled when forced to ascend their
cold slopes.

!N'early all the great rivers of the world rise in
mountainous districts.

The rain that falls on the earth either runs di-
rectly off the surface or sinks slowly into the
ground. The part that runs directly off the sur-
face collects in streams that discharge directly into
the rivers. The part that sinks into the ground
collects in underground basins, from which it
slowly emerges as springs.

When the mountains are covered by forests, the
rain which falls on their slopes, for the greater
part, drains slowly into the ground. When the
mountains are denuded of their forests most of
the rain drains rapidly off the surface. The de-
struction of the forests on mountain-slopes is,
therefore, apt to cause floods.

196 OUTLINES OF FORESTRY.

The running of the water from a higher to a
lower level is called drainage.

There are two kinds of drainage :

1. Surface drainage, where the water runs di-
rectly off the surface into the rivers.

2. Underground drainage, where it first sinks
into the ground and afterwards discharges as
springs into the rivers.

Underground drainage takes place slowly. Sur-
face drainage takes place rapidly.

The direction in which rivers flow depends on
the direction in which the land slopes.

The main stream, with all its tributaries and
branches, is called the river system. The land
which drains into a river system is called the river
basin. The size of the river depends on the ratio
between the quantity of the rainfall and the size
of the river's basin.

When a river basin is covered with a loose, por-
ous soil, such as it will have when covered with
almost any form of vegetation, the rain sinks
slowly into the earth and the river seldom over-
flows its banks.

When the area is such that most of the water
runs directly off the surface, as will generally be
the case when deprived of its vegetable covering,

PRIMER OF PRIMERS. 197

the rivers receiving such drainage are apt to over-
flow their banks during the wet season.

Any disturbance in the natural drainage of a
country may cause damage from the too rapid
drainage of its surface :

1. By insuring too much water in its rivers
during inundations.

2. By insuring too little water in its rivers
during drought.

The preservation of forests on mountain-slopes,
where the drainage is more rapid than elsewhere,
insures a proper drainage of its surface, and con-
sequently the proper flow of its rivers.

The condition of the air of a country as regards
its heat or cold moisture or dryness, healthfulness
or unheal thfulness, is called its climate.

The atmosphere receives its heat from the sun :

1. Directly, by absorption.

2. Indirectly, from the heated earth.

The atmosphere receives its heat indirectly from
the heated earth :

(a) By contact with the heated earth.

(b) By radiation from the heated earth.

(c) By reflection from the heated earth.

All parts of the earth in the same latitude do
not possess the same temperature, because the

17*

198 OUTLINES OF FORESTRY.

surface is higher in some places than it is in
others, in some places is covered with vegetation
and in others is bare, or is exposed to cold or
currents of wind or water in 3ome places and to
warm currents in others.

Differences in the elevation of the land cause
differences in the temperature of the air. An
elevation of three hundred and fifty feet will cause
the same lowering of temperature as a difference
of one degree of latitude, — viz., of 1° Fah.

The same changes of temperature are observed
in passing from the base to the summit of a high
tropical mountain as in passing along the earth's
surface from the equator to the poles.

Portions of the earth's surface covered by water
heat or cool slowly; consequently, the air over
such portions does not change its temperature
rapidly, or, in other words, such portions of the
earth possess an equable climate. Portions of
the earth covered by land heat and cool rapidly ;
consequently, the air over such portions changes
its temperature rapidly, or, in other words, such
portions possess a variable climate.

A surface covered with vegetation — such, for
example, as a forest — does not change its tempera-
ture as rapidly as it would if it were bare. Forests,

PRIMER OF PRIMERS. 199

therefore, tend to prevent sudden changes in the
climate.

A bare, uncovered area, such as a desert, is sub-
ject to sudden changes in its climate.

The climate produced by an extended land area
is called a continental climate; that produced by
an extended water area, an oceanic climate. A
continental climate is characterized by great and
sudden changes of temperature; an oceanic
climate, by a comparatively uniform temperature.
The forests tend to produce a climate characterized
by a comparatively uniform temperature. In this
respect, therefore, the forest climate is like the
oceanic climate.

The sun does not heat an area covered by forests
either as intensely or as rapidly as a bare area,
because :

1. The heat is spread over the greatly-extended
surfaces formed by the trees of the forest and its
underbrush.

2. The vegetable covering acts as a screen to
protect the ground from the direct action of the
sun's rays.

3. The air over the forest is moister than that
over the fields, and this moist air acts either as a
screen to protect it from the heat of the sun,

200 OUTLINES OF FORESTRY.

or to prevent the loss of its own heat by radia-
tion.

Therefore, an area of ground covered with for-
ests is subjected to smaller changes of temperature
than a bare, uncovered area.

The climate of the forest is more equable than
that of the open fields, because the forest takes
in and parts with its heat more slowly than the
fields.

A layer of snow tends to preserve the tempera-
ture of the ground on which it falls. If snow
falls on unfrozen ground, the ground will probably
remain unfrozen throughout the year until the
snow melts ; and, when the melting occurs, the
water will drain slowly into the earth. If, how-
ever, the snow falls after the ground is frozen, the
ground will probably remain frozen until the snow
melts, when the water will drain rapidly off the
surface.

The presence of the forest tends to keep the
ground unfrozen until protected by a layer of
snow, and in this way, when the snow melts, the
water sinks quietly into the ground, and disastrous
floods are thus avoided.

The forest, by keeping the air over it moister than
that over the fields, increases the ability of the air

PRIMER OF PRIMERS. 201

to take in heat, either directly from the sun, or in-
directly from the heated earth.

Forests prevent sudden changes of temperature
throughout the year. In early autumn they de-
crease the frequency of destructive frosts by pre-
venting the temperature of the air from rapidly
falling.

The presence of forests over extended areas pre-
vents the occurrence of sudden changes of tem-
perature.

1. By permitting such areas to more thoroughly
absorb the sun's heat, on account of the greater
surfaces they possess.

2. By keeping the air over the forests moister
than over the open fields, thus enabling it more
readily to absorb the sun's heat.

3. By acting as a screen to the lands lying to the
leeward of cold winter winds.

4. By preventing the frosts from penetrating
great distances into the ground, and, therefore, in-
creasing the chance of winter snows falling on
unfrozen ground.

The atmosphere is composed of a mixture of
about seventy-seven per cent, by weight of nitro-
gen and twenty-three per cent, of oxygen. It also
contains a nearly constant quantity of carbonic

202 OUTLINES OF FORESTRY.

acid gas and a variable quantity of the vapor of
water.

The oxygen of the air is necessary for animal
life. The carbonic acid gas is necessary for plant
life. The moisture is necessary for both animal
and plant life.

Animals take in oxygen and give out carbonic
acid gas. During growth, when exposed to sun-
shine, plants take in carbonic acid gas and give out
oxygen.

The presence of both animal and plant life,
therefore, is necessary to keep the composition of
the atmosphere the same.

In the geological past the earth's atmosphere
was vaster than at present. It contained more
oxygen and more carbonic acid than it does now.
Much of the oxygen, which then existed in a free
state in the air, is now combined with various ma-
terials that form the earth's crust.

The excess of carbonic acid which existed in the
earth's atmosphere during the geological past was
removed from it mainly by the plants of the car-
boniferous period, and now exists in the earth as
beds of coal.

In order to avoid any disturbance in the balance
between plant and animal life of the earth, forests,

PRIMER OF PRIMERS. 203

which represent the largest forms of plant life,
should be preserved.

Hail occurs when considerable differences of
temperature exist between neighboring masses of
very moist air.

The destruction of the forest, by readily per-
mitting such differences of temperature to occur,
tends to increase the number and severity of hail-
storms.

A hail-storm is generally preceded by the ap-
pearance of several layers of dark grayish clouds,
and a violent movement is often seen to occur be-
tween them, that is probably of a whirling char-
acter.

Hail -storms are almost invariably attended by
marked disturbances in the electrical equilibrium
of the atmosphere.

A hailstone is formed of alternate layers of ice
and snow. Various explanations have been offered
to account for the peculiar structure. Volta as-
cribed it to the alternate attractions and repulsions
occurring between neighboring snow- and rain-
clouds, when charged with opposite kinds of elec-
tricity.

In France, where Yolta's theories were formerly
received, lightning-rods were fruitlessly erected on

204 OUTLINES OF FORESTRY.

the fields in order to protect them from the ravages
of the hail.

The peculiar structure of the hailstone has also
been ascribed to a whirling motion of the air be-
tween snow- and rain-clouds around a horizontal
axis, whereby particles of snow are carried alter-
nately into the rain- and snow-clouds, and thus
receive their alternate coatings.

Another theory accounts for the alternate coat-
ings of ice and snow by the exposure of moisture
to the different temperatures occurring in denser
and rarer portions of space around which the wind
is whirling.

By reforestation is meant the replanting of trees
in any locality from which they have been removed
either accidentally or purposely.

Provided the removal of the forest has not been
attended by too great a loss of soil, the same kind
of trees may be successfully replanted.

There are two methods by means of which
reforestation may be effected.

1. Sowing or Seeding.

2. Tree Planting.

Seeding can be profitably followed in the tem-
perate latitudes where the growth of the tree is
comparatively certain. In higher latitudes the

PRIMER OF PRIMERS. 205

planting of the tree is, perhaps, preferable, since
the germination and continued growth of seeds
are by no means certain.

Where the destruction of the forest has been
caused by an avalanche, the removal of the soil,
in some cases, is so complete that trees cannot be
successfally replanted.

In some of the western parts of the United
States it is now recognized, from actual experience,
that when trees are planted in plots around the
farm-lands, the protection thus afforded the rest
of the farm-land, against the winds, is of greater
money-value than the rent of the ground occupied
by such trees.

The following locations are especially adapted to
tree planting :

1. Wetlands.

2. Lands covered with a thin or poor soil.

3. Along the margins of rivers where the land
is not required for roads or other public pur-
poses.

4. On the side of mountain-slopes where the soil
is of the proper character, or subject to destructive
avalanches.

An exact balance must be preserved between
the five great geographical forms, — namely, the

18

206 OUTLINES OF FORESTRY.

land, the water, the air, the plants and animals, in
order that the complex organization of nature may
be properly maintained in operation.

The energy which is the cause of nearly all
natural phenomena of the earth is received directly
from the sun.

One part of the sun's heat stirs the air and
water in vast movements between the equator and
the poles, and thus effects an interchange between
the too great heat of the equatorial regions and
the too feeble heat of the polar regions. Another
part of the solar energy is directly expended in
producing one or another of the myriad forms of
plant or animal life.

If the land, the water, or the air receives more
than its share of solar energy, a disturbance in
the balance of nature is effected, which produces
marked effects in the life of the earth.

The total water area of the earth bears a pro-
portion to its total land area very nearly as 25 is to
9, or as 2-^ is to 1.

The earth receives its greatest heat from the
sun at those parts of its surface where it has its
greatest water areas, only a comparatively small
part of the land being found in the equatorial re-
gions. There are produced, however, vast currents

PRIMER OF PRIMERS. 207

in the atmosphere and in the ocean, which effect
an interchange between the heat of the equator
and the cold of the poles.

Any change in the distribution of the land and
water areas of the earth, either as regards their
relative amount, or as regards their distribution,
would seriously affect the life of the earth.

If the greatest proportion of land existed at the
equator, such changes would be produced in the
earth's climate as to sweep its present life out of
existence.

Any change in the elevation of the present land
areas would produce a marked change in the
earth's climate. It was probably an increase in
the elevation of the polar lands that caused the
severe cold of the glacial epoch, when so much
of the northern continents were covered with
ice.

In order to preserve the present relative propor-
tions of oxygen and carbonic acid in the atmos-
phere, the present animal and plant life of the
earth must be preserved.

Animals are absolutely dependent on plants for
their existence. The plants can take their food
directly from the air and the soil. Animals re-
quire their food to be prepared for them by the

208 OUTLINES OF FORESTRY.

plants on which they live. The death of the plant
life of the earth would, therefore, be followed by
the death of all its animals.

Many animals multiply so rapidly that, unless
they were removed from the earth by furnishing
food for other animals, a marked disturbance would
be effected in the balance of nature.

APPENDIX.

LISTS OF TKEES SUITABLE FOK REPLANTING IN
DIFFERENT PORTIONS OF THE UNITED STATES.

In order to extend the scope of the Outlin:es of For-
estry, and to render it of greater practical value, the follow-
ing circular letter was sent to different well-known authorities
in forestry, inquiring as to lists of trees suitable for replanting
in different sections of the United States.

Circular Letter.

Philadelphia, January 23, 1892.

1809 Spring Garden Street.

Prof

Dear Sir, — I am about publishing a little work on For-
estry, and am desirous of obtaining a list of trees suitable for

planting for reforestation in such parts of.

and the adjoining States as have been denuded of forests,
or are capable of sustaining forest trees.

In the event of your being able to spare the time necessary
o 18* 209

210 APPENDIX.

to send me a list of such trees, I would, of course, make full
acknowledgment in the book of your contribution.

If your time is too fully occupied to send me the infor-
mation requested, can you inform me where I can obtain the
same?

Asking your pardon for thus trespassing on your valuable

time, I am,

Very respectfully, yours,

Edwin J. Houston.

The letters received in reply to the foregoing, together with
the lists of trees suitable for purposes of reforestation, are
hereunto appended.

From Thomas Meehan, Editor of Meehan^s Monthly , German'

town, Philadelphia.

Meehan's Monthly,
Germantown, Phil ad a., January 30, 1892,

Peop. Edwin J. Houston,

1809 Spring Garden Street, Philadelphia.
Dear Sir, — I have marked in the catalogue sent to-day
the names of such trees as are most desirable for planting on
the Northeastern Seaboard of the United States. A few are
rare, but will soon become common ; others are not likely to
become common for some years. In some cases the trees
marked would have but limited usefulness, but all are of
value in some respect or another.

When getting into the States along the seaboard of the
Virginia line, many of those named would be ineligible.

Very truly yours,

Thomas Meehan.

APPENDIX. 211

DECIDUOUS TREES.

MAPLES.

Acer campestre, or European Cork Maple.
" palatanoides, or Norway Maple.
" pseudo-platanus, or European Sycamore Maple.

HORSE-CHESTNUT.

jEsculus glabra, or American Horse-Chestnut.

" hippocastanum, or European Horse-Chestnut.

AILANTUS.

Ailantus glandulosa.

BIRCH.

Betula alba, or European White Birch.

HICKORY.

Carya alba, or Shell-bark Hickory.

" amara, or Bitternut Hickory.

" microcarpa, or Small-Fruited Hickory,

" sulcata, or Large-Fruited Hickory.

" tomentosa, or White Hickory.

SWEET CHESTNUT.

Chstaiiea Americana, or American Chestnut.

HOLLY.

Bex opaca, or American Holly.

JUNIPER, CEDARS.

Juniperua Virginiana, or Eed Cedar.

FIR.

Picea balsamea, or Balsam Fir.

PINE.

Pinus Austriaca, or Australian Pine.

" Banksiana.

" densiflora, or Japan Pine.

" Laricio, or Corsican Pine.

212 APPENDIX.

Pinus Massoniana.
" pungens.

" resinosa, or Red Pine.
" rigida, or Pitch Pine.
" mitis, or Yellow Pine.
" strobus, or White Pine.

JAPAN CYPRESS.

Retinispora obtusa.

ARBOR-VIT^.

Thuja ocddentalis, or American Arbor Vitae.

LOCUST, ACACIA.

Bobinia pseudacacia, or Yellow Locust.

MAIDEN-HAIR TREE. GINGKO.

Salisburia adiantifolia.

WILLOW.

Salix alba, or White Willow.

" Babylonica, or Weeping Willow.

" japonica, or Japan Willow.

" pentandra, or Laurel-leaved Willow.

" Pusselliana.

" vitellina, or Golden-Bark Willow.

ELMS.

Ulmus Americana, American Elm.

" campestris, or English Elm.

" fulva, or Slippery Elm.

" racemosa, or American Cork Elm.

EVERGREENS.
SPRUCE.

Abies alba, or White Spruce.
" Canadensis, or Hemlock.

APPENDIX. 213

Abies Douglasii, or Douglas Spruce.

" excelsa, or Norway Spruce.

" pungens, or Colorado Blue Spruce.
LARCH.

Larix Europcea, or European Larch.

SWEET GUM.

Liquidambar styracifiua,

SOPHORA.

Sophora Japonica,

DECIDUOUS CYPRESS.

Taxodium distichum.

LINDEN.

Tilia Americana, or American Linden.

" EuropcBa, or European Linden.

POPLAR.

Populus alba, or Silver Poplar.

" balsamifera, or Balsam Poplar.

" fastigiata, or Lombardy Poplar.

" grandidentata.

" monilifera, or Carolina Poplar.
OAK.

Quercus alba, or White Oak.

" bicolor, or Swamp White Oak.

" cerris, or Turkey Oak.

" coccinea, or Scarlet Oak.

" dentata (Daimio), or Japan Oak.

" falcata, or Spanish Oak.

" imbricaria, or Laurel Oak.

" macrocarpa, or Mossy Cup.

" nigra, or Black Jack Oak.

" obtusiloba^ or Post Oak.

214 APPENDIX,

Quercus palustriis, or Pin Oak.
" phellos, or Willow Oak.
" prinus, or Rock Chestnut Oak.
" robur, or English Oak.
" rubra, or Red Oak.
" tinctoria, or Black Oak.

MULBERRY.

Alorus alba, or White Mulberry.

" rubra, or American Red Mulberry.
BOX ELDER.

Negundofraxinmfolium, or Ash-leaved Maple.
SOUR GUM.

Nyssa multijlora.

IRONWOOD.

Ostrya Virginica.

EMPRESS-TREE.

Paulownia imperialis.

BUCKEYE.

Paviaflava, or Yellow Buckeye.

CHINESE CORK-TREE.

Phellodendron amurense.

PLANERA.

Planera cuspidata.

BUTTONWOOD, PLANE.

Plantanus occidentalis, or American Plane.
" orientalis, or Oriental Plane.
HONEY LOCUST.

Gleditschia triacanthos, or Honey Locust.

KENTUCKY COFFEE.

Gymnocladus Canadensis.

APPENDIX. 215

HOVENIA.

Hovenia dulcis,

IDESIA.

Idesia polycarpa,

WALNUT.

Juglans cinerea, or Butternut.

" regia, or English Walnut, or Madeira Nut, — south
of Philadelphia.

TULIP-TREE.

Liriodendron tulipifera, or Common Tulip-Tree, or Tulip

Poplar.

OSAGE ORANGE.
Madura aurantiaca.

MAGNOLIA.

Magnolia acuminata, or Cucumber-Tree.
*' macrophylla.
" tHpetala, or Umbrella-Tree.

CATALPA.

Catalpa bignonioides, or Catalpa.
" speciosa, or Western Catalpa.

NETTLE-TREE.

Ckltis occidentalism or Nettle-Tree.

CHERRY.

Cerasua avium alba plena, Double-flowering Cherry.
" Pennsylvanica, or Wild Red- Cherry.
" ranunculcBjlora.

DOGWOOD.

Cornus Florida, or WTiite or Large-flowering Dogwood.

PERSIMMON.

Diospyros Virginiana, or American Persimmon.

216 APPENDIX.

BEECH.

Fagus Americana, or American Beech.
" sylvatica, or European Beech.

ASH.

Fraxinus Americana, or White Ash.
" excelsior, or European Ash.
" quadrangulata, or Blue Ash.
" sambucifolia, or Black Ash.
" viridis, or Green Ash.

KATSURA.

Cerddiphyllum japonicum.

From B. S. Hoxie, Secretary of the Wisconsin State Horticultural

Society.

Wisconsin State Horticultural Society,

EvANsviLLE, Wisconsin, January 26, 1892.

Edwin J. Houston, Philadelphia, Pa.

Dear Sir, — Yours of the 28th at hand. I mailed to your
address our last volume, No. 2, I think. The list of trees
found on page 9, which we recommend for general planting,
will be found applicable to nearly all parts of our State.

The pine regions of Wisconsin are the parts that are now
being deforested, and no special effort is being made to re-
forest these areas. Oak, ash, maple, birch, elm, pine, and
spruce will grow on most of this land.

We have several townships bordering on Lake Superior in
Bayfield County, which some ten years ago were set apart
as a State Park. Last winter a bill was introduced to bring
this reservation into the market, — i.e., to sell the timber, but it

APPENDIX. 217

failed to pass, and if my pen and the press can prevent such
a bill, it will never pass. If I can be of any further assistance
to you, please write me.
I shall be glad to see your book when published.

Eespectfully,

B. S. HoxiE.

TREES AND SHRUBS RECOMMENDED.

Trees and shrubs recommended in the " Annual Report of
the Wisconsin State Horticultural Society." *

EVERGREENS.
For general planting in the order named :

White Pine.
Norway Spruce.
White Spruce.
Arbor Vitae.
Balsam Fir.
Austrian Pine.
Scotch Pine.
For ornamental planting in the order named :
Hemlock.
Red Cedar.
Siberian Arbor Vitae.
Dwarf Pine.
Red or Norway Pine.

* Annual Report of the Wisconsin State Horticultural Society, em-
bracing papers read and discussions thereon at the semi-annual meeting
held in Black River Falls, June 26, 27, 1890; also at Madison, June
2-6, 1891. Vol. xxi. p. 9.

X 19

218 APPENDIX.

DECIDUOUS TREES.
For Timber.
White Ash.
Black Walnut.
Hickory.
Black Cherry.
Butternut.
White Oak.
European Larch.
American Larch.

Street Shade- Trees.
White Elm.
Hard Maple.
Basswood or Linden.
Ashleaf Maple {Acer negundo.)
Norway Maple.
Hackberry.

For Lawn Planting.

Weeping Cut-leaved Birch,
American Mountain Ash.
Green Ash.
Horse-Chestnut.
European Mountain Ash.
Wisconsin Weeping Willow.
Oak-leaved Mountain Ash.
White Birch.

Weeping Golden-barked Ash.
Weeping Mountain Ash.
Weeping Poplar.

APPENDIX. 219

From Charles Mohr, Agent for the Forestry Division of the
United States Department of Agriculture, Mobile, Alabama.

U. S. Department of Agriculture,

Mobile, Alabama, January 31, 1892.

Pkof. Edwin J. Houston, Philadelphia, Pa.

Dear Sir, — Your letter of the 23d has been received.
According to your request, I send you enclosed a list of timber
trees, which might be regarded as adapted for the reforestation
of denuded areas in the Gulf States east of the Mississippi
Eiver.

In the selection of the trees, I had to be guided solely by
my observations made in the different sections of the regions
named, and had to confine myself entirely to native species,
no information being on hand in regard to trees from other
sections of the United States, or exotics.

To shorten matters, I refer you for information about the
habits of the species named in the list, to the preliminary of
important forest trees in the United States, in Mr. Fernow's
" Report to the Commissioners of Agriculture" (Forestry Di-
vision) for the year 1886, where, also, notes on the economic
uses of each will be found. The numbers in my list refer to
the same species mentioned in the above report.

I remain truly yours,

Charles Mohr.

White Cedar, ChamxBcyparis sphceroidea.
Red Cedar, Juniperus Virginiana.
Bald Cypress, Taxodium distichum.
Long-leaved Pine, Pinus palustris.
Loblolly Pine, PiniLS tceda.

220 APPENDIX.

Cuban Pine, Pinus Cubensis.

Short-leaved Pine, Pinus mitis.

White Oak, Quercus alba.

Cow Oak, " Michauxii. Rich, alluvial soil.

Chestnut Oak, " prinus.

Live Oak, " virens. Lower districts.

Red Oak, " rubra.

Black Oak, " tinctoria. Gravelly uplands.

Spanish Oak, " falcata. Throughout on lighter soils.

Water Oak, " aquatica. Of value for fuel only.

Willow Oak, " Phellos. Rapid growth on wet or dry

light soil. Timber more valuable.

Beech, Fagus ferruginea.

Chestnut, CorStanea vulgaris, var. American. In dry, some-
what silicious soils throughout.

Shell-bark Hickory, Carya alba. Upper and central districts.

Mocker Nut, Carya tomentosa.

Pecan, Hickoria Pecan {Carya olivceformis). Valuable for its
fruit.

Wild Cherry, Prunv^ serotina.

Sweet Gum, Liquidambar Styraciflua.

Black Locust.

Honey Locust.

Red Mulberry, Morus rubra. Shade-loving.

Magnolia, Magnolia grandifiora.

Cucumber Tree, Magnolia acuminata. In well-drained, deep,
and lighter loamy soil, through the State. Shade-loving.

Tulip- Tree, Liriodendron tulipifera.

Osage Orange, Maclura aurantiaca.

White Ash, IVaxinus Americana. Upper district.

APPENDIX. 221

Green Ash, Fraxinus viridis.

Red Maple, Acer rubrum.

Silver Maple, " dasycarpum.

"White Elm, Ulmus Americana. Upper district.

Slippery Elm, " fulva.

Water Elm, " alata. Alluvial, wet soil.

American Linden, Tilia Americana. Central to upper district.

Sycamore, Plantanus ocddentalis.

Cottonwood, Populus monilifera.

From Bobert W. Furnas, Secretary of the Nebraska State Board
of Agriculture.

Nebraska State Board of Agriculture,

.Brownville, Nebraska, January 27, 1892.

Edwin J. Houston, Esq.,

1809 Spring Garden Street, Philadelphia, Pa.

Dear Sir, — Reply to yours, First, twenty-third. Of the more
valuable hard-wood varieties of timber used for forestry pur-
poses on our prairies, or naturally timberless region, we find
the best, — black walnut, white ash, black and honey locust,
black cherry, Kentucky coffee-tree, hard maple, burr and
white oaks.

Of the soft woods, — soft maple, box elder, cottonwood, and
the catalpas, — speciosa, and Tea's hybrid.

Evergreens : red cedar, Scotch, Australian, and white pines.
Both American and European larch do well.
If I can serve the forestry cause in any way, command me.

Truly,

Robert W. Furnas.
19*

222 APPENDIX.

From Professor M. G. Kern, Editor of ColemarCs Rural World,

St. Louis, January 26, 1892.
Edwin J. Houston-, Esq., Philadelphia, Pa.

Dear Sir, — Your favor of the twenty-third inst. received.

Kindly excuse a few remarks on Western forestry, rather
outside of the list of available trees requested. But a part of
Missouri is heavily timbered, and in these sections the great
object of the population is to get rid of the timber for money
or for agricultural purposes. Many portions of the State are
cleared to the same extent as the older States, with abundance
of forest supplies for present use. Part of the State is prairie,
in which the need of timber culture is as great as in all open
plains. South of us is Arkansas, a mountainous native forest ;
west, Kansas, Nebraska, and North Iowa, with her endless
prairies. A wide field, indeed, for forest management, reforest-
ing, and timber culture. The soil brings forth, mostly with
rapid growth, all the indigenous species of our forests ; a list
of such could be valuable only in ratio to the value of the
timber grown.

Fast-growing soft woods are considered in wooded sections
as of little value, scarcely worth planting on a large scale.
They are generally planted for shelter, ornament, or quick
shade. No line of difierence as to hardiness can in reality be
drawn, though variety of conditions make certain kinds more
suitable to certain localities: we differ in this respect from
more northern latitudes.

The question of reforesting denuded sections has thus far
attracted but little public attention. Intelligent husbandry
steadily advancing, is gradually awaking to the necessity of
reforestation and the protection of native forests. The pros-

APPENDIX. 223

pective value of economic timber is realized by many, and
the growth of young native timber is encouraged by the usual
means of protection from cattle and disastrous fires.

Systematic forest culture, for which there is so boundless a
field, has thus far been practised to but small extent, though
every intelligent citizen knows that the most valuable kinds
of timber are being exhausted very fast. How long this spell
of popular indiflference will last cannot be foretold by the
wisest. Millions of acres in the lowlands and on hill-sides
capable of producing the most valuable timbers, lie idle as
though belonging to some Indian tribe.

Much popular education is surely needed to break the bar-
riers of indifierence and popular selfishness underlying all the
evil. We need a tow-line attached to the dormant intelligence
of the people (as far as American forestry is concerned), to
draw it into action. When once aroused from the dream of
inexhaustible forest wealth, the West will do its honest share
in forest culture, as her resources are almost without limit.

My most sincere wishes for the success of your forthcoming
work on Forestry. Command my services at any time when
special features of information from this section are desired.

Very respectfully,

M. G. Kern.

TREES PRINCIPAI.LY GROWN IN FOREST CULT-
URE IN MISSOURI AND ADJOINING SECTIONS.

Initial Step in Forest Culture.
Cotton-wood.

Black Walnut.

Soft Maple.

224 APPENDIX.

Box Elder.

White American Ash.

Sugar Maple (to sorae extent).

Second Step.

The introduction of Catalpa species. At present the
above with Black Walnut and White Ash are the leading trees.

Worthy of extensive culture, though sparsely planted thus
far, are :

Tulip-Tree (Yellow Poplar).

The leading White Oak species.

White Oak.

Over-cup Oak.

Burr Oak.

Post Oak.

White Hickory (under certain conditions).

Of Conifers.

Bald Cypress (for alluvial lowlands).

Ked Cedar, for limestone uplands and stony slopes.

White Pine, especially suited for sandstone formations
found in sections of Southwestern Missouri and Arkansas.
Ornamental trees of this species, met everywhere, show re-
markable vigor of growth and adaptation to the formation.

Black Cherry (to be recommended for general culture).

European Alder, for moist and loamy soils, of rapid
growth, and valuable wood. One of the best of temporary
nursery trees for larger plantations.

Soft Woods.
Soft Maple.
Box Elder.
Birch (both nigre and lenta).

APPENDIX. 225

"Willows.
Poplars.

Plantanus, Elms, Sycamore, for various purposes of shade,
shelter, and wind-breaks.

Evergreens.

American White Spruce deserves far more attention than
thus far enjoyed. It is the most lasting of all spruces.

Norway Spruce.

Scotch and Austrian Pine are valuable for close planta-
tions for shelter. They are, however, deficient as to longevity,
losing their vigor much sooner than the native American
species.

European Larch is suited to the northern parts of
Missouri, Iowa, and farther north.

Unptersity of Pennsylvania,
Philadelphia, Pa., February 27, 1892. ;

Prof. Edwin J. Houston,

1809 Spring Garden Street, Philadelphia, Pa.
My dear Professor, — I am in receipt of your favor of

the 20th inst., and I take pleasure in sending you a list of

trees suitable for planting in the Southwestern States and

California.

Betula occidentalis, Hook. Black Birch. For ornamental pur-
poses, grows ten to twenty feet high.

Quercus undulata, Torr. Oak. Four varieties, valuable for
timber and for masting, furnishing, as they do, an abun-
dance of sweet, edible acorns.

Salix cordata, Muhl., var. vestita, Anders, Diamond Willow,
abundant in Yellowstone regions, valuable for furnishing
unique canes.
P

226 APPENDIX.

Salix purpurea, L. Purple Willow, six to fifteen feet. Best of
hedge and osier willows. Correspond with United States
Department of Agriculture concerning.

Salix lucida, Muhl. Shining Willow, five to ten feet. One of
the most beautiful willows for ornamental planting.

Salix fragilis, L. Brittle Willow, Crack Willow, Bedford Wil-
low, sixty to eighty feet, affords best willow timber, and
contains large per cent, of tannin, and more salicin than
others.

Salix alba, L., vars. Salix cseruea and Salix Vitellina, Blue
Willow, and Golden Willow. Particularly useful as os-
sier or basket-making willows.

Populus nigra, Black Poplar, thirty to forty feet, of rapid
growth, wood valuable for flooring, cooperage, and for
gunpowder charcoal.

Populus tremuloides, Mx. American Aspen, " Quaking Asp,"
twenty to fifty feet.

Populus nigra, var. dilatata, Lombardy Poplar, tall, spire-
shaped tree, of rapid growth, to be set in rows for wind-
breaks.

Populus monilifera, Ait. Necklace Poplar, large tree, one
hundred and fifty feet high, light, soft wood, useful for
box manufacture, and especially for paper pulp.

Juniperus Virginiana, L. North American Bed Cedar, or Pencil
Cedar. The largest of American junipers, sixty to ninety
feet, fiirnishes a light, fragrant, and imperishable wood.

Abies concolor. Small Balsam Fir, or White Fir, eighty to one
hundred feet.

Abies nobilis,

Abies magnific

\ Red Fir.
\fica, J

APPENDIX. 227

Abies religiosa, the Sacred Fir of Mexico.
" bracteata, one hundred feet.
*• Canadensis, Mx. Common Hemlock, fifty to eighty feet.

Pseudotsuga Douglasii, Can. Douglas Spruce, one hundred
and fifty to three hundred feet.

Picea Engelmanni, Eng. Spruce, sixty to one hundred feet.
" pungens, Eng. Balsam Spruce, sixty to one hundred feet.

Pintis Jlexilis, James. Pine, sixty feet.

Piniis ponderosa, Dougl. var. Scrophulorum, Eng. Yellow
Pine, eighty to one hundred feet.

Salisburia adianiifolia (or Ginkgo biloba), forty to eighty feet.

Pinus edulis, Eng. The Pinon or Nut Pine, ten to fifteen feet.

Sequoya semperviceus, Sequoya gigantea, Eed Wood, two hun-
dred to three hundred feet, wood almost imperishable.
Both these trees should be planted, as they are likely to
become extinct unless rescued by cultivation.

Eucalyptus globulus, Blue Gum, peculiarly valuable in swampy
or malarial districts. One hundred and fifty varieties of
Eucalyptus, " the tree of the fiiture." Cf. article in Pop.
Sci. Mo., vol. xii. : " The Eucalyptus of the Future," by
Samuel Lockwood. See also, below, list by W. S. Lyon.

Eugenia jambos, Rose Apple, or Jamrosade, twenty to thirty
feet, should be cultivated in the Southern States for its
delicious fruit.

Catalpa bignonioides, Walt. Catalpa, thirty to fifty feet, a beau-
tiful tree, possessing great advantages for timber, being
the cheapest and easiest grown of all our forest trees,
native or introduced, and also the most rapid in its growth.

Paulownia imperialis, Siebold. A grand flowering-tree, forty
feet high, with immense leaves, of rapid growth, and par-

228 APPENDIX.

ticularly suited for parks, road-sides, and shade (from
Japan), has large, purple, fragrant pannicles of flowers in
the spring.

Schinus molle, the Pepper-Tree, or Peruvian Mastich-Tree.
The leaves exude an oily fluid, filling the air with fra-
grance, particularly after a rain.

Eriobotrya japonica, the Loquat, or Mespilus, should be intro-
duced into the Southern States, being one of the most
grateful acid summer fruits. The tree is a very hand-
some, broad-leaved evergreen.

Cinnamomum camphora, the common Camphor-Tree of China.
Growing trees can be had at the Agricultural Department,
Washington, D. C.

Dryobalanopos aromatica, the Sumatra Camphor-Tree. Both
of these should be introduced and cultivated in Cali-
fornia.

Aleurites triloba, Candle-Nut-Tree, thirty feet, native of the
Pacific islands, exceedingly useful for its oily nuts.

Ceratonia Siliqua, the Carob, or St. John's-Bread-Tree. Could
easily be cultivated in immense numbers from seed, as is
our ordinary locust-tree, and would be a valuable addition
to the country, as it would furnish a large amount of
food for cattle, the bread- bean pods being used for
feeding cattle and swine in all countries where the trees
grow, and is being imported largely into Europe and
England.

Blighia sapida, the Akee. A native of West Africa, but be-
coming widely dispersed, would grow in the more South-
ern States, and furnishes a valuable fruit, very whole-
some when cooked.

APPENDIX. 229

Per sea gratissima, or Alvocada Pear, or Alligator Pear, a small
tree, bearing large, purplish, pear-shaped fruits, much es-
teemed for dessert. Would be a valuable addition to the
fruits of Southern California.

Prunus amygdalus, the Almond, fifteen feet. Already culti-
vated in California.

Carya olivceformis, N. Pecan Nut. Is proving one of the
most valuable trees of Texas; recently introduced into
Georgia ; the yield of nuts is large, bringing good prices.

Castanea vesca, Spanish Chestnut. The tree furnishes a large
percentage of the food of the poorer classes of Southern
Europe, and its cultivation in this country should be en-
couraged. A Japanese " Giant" variety has been lately
introduced. Said to be of better flavor than the Spanish
chestnut.

Juglans regia, English Walnut, or Madeira Nut, sixty feet,
valuable both for its wood and its nuts ; the yield is large,
as many as twenty-five thousand nuts to a tree.

Morus alba, White Mulberry, the most valuable for feeding
silk-worms. Its cultivation should be encouraged. Sev-
eral varieties are ofiered by the nursery-men for the large
edible fruit.

Achras sapota, the Sapodilla, or Naseberry, a very sweet, high-
flavored fruit. Tree spreading, with fine, glossy leaves.

jEgle marmelos, the Bael-fruit, Elephant Apple, Maredoo, or
Bengal Quince, a small tree, of the orange family, pro-
ducing an odd fruit and trifoliate leaves.

Anacardium occidentale, the Cashew-nut. A tree of the Tere-
binth family, attaining considerable size, and in growth
resembling the walnut. The curious fruit is kidney-shaped,

20

230 APPENDIX.

about an inch long, and after roasting is a good substitute
for almonds, etc., at table.

Anona cherimolia, the Cherimoya, or Jamaica Apple, a loose,
spreading tree of the Custon Apple family, attaining a
height of twenty to twenty-five feet. The light-green
fruit is beautiful, delicious, and considered one of the
finest fruits of the world,

Anona muricata, Sour-Sop, fifteen to twenty feet high, fine
glossy foliage, fruit large, heart-shaped (six to nine inches
in circumference), green and prickly, contains a fresh,
agreeable, sub-acid juice.

Chrysophyllum cainito, the Star Apple. A tree of thirty to forty
feet, spreading branches, beautifully veined leaves, silvery
white on the under-side, fruit about the size of an apple,
wholesome, with an agreeable sweet flavor.

Mcus carica, Fig. Very easy of cultivation, and oflEered by
the nursery-men in several varieties; should be largely
cultivated in California and all our Southern States.

Malpighia glabra, Barbadoes Cherry. One of the favorite
trees of the Barbadoes and West Indies, usually planted
near dwellings, and as hedges. The trees are beautiful
evergreens, bearing cherry-like fruit of a pleasant taste.

Mammea Americana, the Mammea Apple, or St. Domingo
Apricot, sixty to seventy feet high, with broad, ovate,
shining leaves ; fruit angular, size of cocoanut, with juicy
yellow pulp of delicious flavor.

Mangifera Jndica, the Mango. This delightful fruit is now
being introduced largely into Florida. It is of very
rapid growth and fine form ; five or six varieties are
offered by nursery-men.

APPENDIX. 231

See " Popular Science," 1879, for an account of the ameliora-
tion of climate in dry barren districts by this tree.

Psidium Cattleyanum, the Cattley or Strawberry Guava, now
being much cultivated in Florida, is of fine appearance,
and the plum-like, claret-colored-fruit being of most
agreeable flavor.

Punica granatum, the Pomegranate. Easily grown and very
handsome ; small trees, flowers showy. One of the most
desirable fruits. Bark of the tree used in medicine.

Psidium Guaiava, the ordinary Guava. One of the most valua-
ble fruits for jellies and preserving. Several varieties
offered by nursery-men.

Tamarindu^ Indica, the Tamarind. A beautiful tree with deli-
cate blossoms, and soft, pinnately divided leaves, grows to
eighty feet in height. The pods pressed in syrup or sugar
form the preserved tamarind of commerce.

Zizyphus jujuba, the Jujuba. A small tree of the Buckthorn
family, bearing small yellow, farinaceous, delicious berries.
The lotus spoken of by Pliny as furnishing the food of
the ancient Lybian people called Lotophagi.

Melia azedarach, L. The Bead-Tree, or Pride of India. Beau-
tiful for streets and parks of our Southern cities ; thirty to
forty feet high, flowers fine, loose, terminal, lilac-like spikes.

Dichopsis gutta. The Gutta-percha. This is a tree of the
Star-apple family, attaining a height of from sixty to
seventy feet. Leaves smooth, ovate, rusty -brown on un-
der-side. This valuable tree is rapidly becoming extinct
in its native habitations, and efforts should be made to
introduce it into all tropical and subtropical climates.
The French government has recently decided to cultivate

232 APPENDIX.

it in Algeria. Why Bhould it not be introduced into
Southern California?
Mimusops globosa. The Ballata. Furnishes a milky juice
equal to the best gutta-percha of the East. This should
be tried. It is a native of British Guiana.
Butyrospermum Parkii, the Karite or Butter-Tree. An African
tree, furnishing from its seeds the Shea-butter of com-
merce, used in soap-making, and a gum or coagulated
juice which has recently been found to be equal to the
best gutta-percha. It is possible that this tree might be
made to grow in the warmer parts of California.
Cinchona calisaya, Cinchona succirubra, Cinchona condaminea.
These three species of cinchona have been successfully
cultivated in Mexico ; in the Canton of Cordova several
thousand cinchona-trees exist and are doing well. The
beautiful trees with large velvety leaves, turning red when
old, may be seen by those who travel by rail from Vera
Cruz to Mexico. It is worthy of serious effort to cultivate
this valuable tree in Texas and California.
Quillaja saponacia, Quillaia-bark Tree, Soap-bark Tree. This
large tree (fifty to sixty feet) yields in its bark a product
very valuable in cleaning delicate colored fabrics, and
could undoubtedly be grown with profit in California.
The sub-tropical trees mentioned in the above list can all
be obtained from the nursery-men {e.g., Siebrecht & Wadley,
Rose-Hill Nurseries, New Rochelle, New York), or of the
Agricultural Bureau, Washington, D. C, and they can be
successfully grown in any of the Southern States where
the winter temperature does not fall below 45° F. I have
not mentioned many well-known varieties, but have preferred

APPENDIX, 233

to call attention to such little-known trees as might perhaps be

cultivated (and, in fact, are already to some extent in Florida

and California) successfully, with profit in various ways to our

Southern States.

Very respectfully yours,

C. S. DOLLEY.

State Board of Forestry,
Los Angeles, California, June 6, 1892.

Prof. Edwin J. Hocston,

1809 Spring Garden St., Philadelphia, Pa.
Dear Sir, — I send you a few "notes." The second part
will deal with the much larger subject of lands outside of the
natural forest districts, suitable only for forest planting, and
the species we find most useful thereon. Our experiments
with these are practicable and tangible, and I trust will prove
of more value than the " glittering generalities" of the accom-
panying Part I.

I will endeavor within a week to give you the balance.

Very truly yours,

Wm. S. Lyon.

NOTES.

PART I.

ON TREES SUITABLE FOR REFORESTATION UPON THE

PACIFIC COAST.

There are portions of the Sierra Nevada Mountains which,
by the various processes of surface-mining, have been denuded
of their original forest cover, as well as of every vestige of
forest floor, — i. e., fertile soil.

20*

234 APPENDIX,

In many localities the areas laid bare amount to hundreds
of acres in single tracts.

In portions of Amador and Calaveras Counties, multitudes
of "prospects" join each other, extending for miles upon a
so-called " river-bar."

These " prospects" are frequently only holes that have been
excavated from four to ten feet in depth, and the auriferous
gravel thrown out and scattered far enough to nearly com-
pletely cover the original surface soil for from one to ten inches.

In Placer and Nevada Counties the process of hydraulic
mining has generally washed out vast flats or valleys in the
mountains, and leaving the resulting basin covered chiefly
with gravel, boulders, or blue clay.

These operations have been discontinued in some localities
for now more than thirty years ; in others, only recently.

Yet in all of them, and apparently with an utter dearth of
soil, the native timber is making an eflbrt to assert itself.

At Dutch Flat, where gigantic mining operations have only
ceased during three years, a very sparse setting of small
Psuedotsuga Douglasii, Pinus tuberculata, Libdocedrus decurrens,
and Pinus Sahinana have established themselves. The same
features exist upon the Mokelumne River, in Calaveras County,
where no mechanical disturbance has occurred since the
original covering up of the soil thirty years before.

Both localities are between three thousand and three thou-
sand six hundred feet in elevation, and the timber is such as
belongs to that elevation in the Sierras.

The uninjured timber in the more southern county and
adjoining denuded lands, can only be described as scrubby;
and 1 cannot say that that which has established itself upon

APPENDIX. 235

the worked-over sites has been notably depauperized by its
mulch of clay and gravel. At the point of southern observa-
tion Abies concolor occurs, and seems to thrive.

I noted with interest that young plants of the Douglas
spruce, growing about denuded fields in Nevada County, at
three thousand five hundred feet, showed great vigor, although
naturally fine specimens (mature) seldom occur in the prim-
itive forest below five thousand feet.

It occurs to me that this is an index that this plant may
prove valuable for future systematic reforestation. The other
species named, except for purposes of forest cover, are not
held in much esteem by lumbermen. At higher altitudes, and
in the regions covering our valuable pines and spruces, extend-
ing over nearly seven hundred miles from San Bernardino to
Plumas County, no mining operations (surface) have been
conducted, and, except in isolated cases of torrential erosions,
the forest floor is intact.

The original cover has been, however, heavily cut and
burned over. Their native reproductive powers seem in-
destructible.

Where deforestation has been caused by the axe, a full
proportion of young growths of Pinus lambertiana, P. CouUeri^
P. Jeffreyi. P. ponderosa, and Psuedotsuga Douglasii seem to
follow.

AVhere the denudation has occurred from fire, the more
relatively worthless White Fir, Flat-leaved Cedar, and Hem-
lock seem to preponderate.

In the mountains, — i. e., the natural timber district of the
State, — not a single instance occurs where reforestation, upon
any scale, large or small, has been undertaken.

236 APPENDIX.

No attempt or experiment with exotic species has ever been
tried within the timber belt, and the values of the endemic
species, and their readiness to conform to such unpromising
situations as those described, justify us in thinking that they
will best fulfil future systematic mountain reforestation.

PART II.

SPECIES USEFUL FOR REFORESTATION OF FOOT-HILL-LANDS,
WASHES, OR LANDS UNSUITABLE FOR GENERAL AGRI-
CULTURE IN California.

(A) Endemic Species.

First among them I rate the Pinus insignis, or Monterey
Pine. Naturally restricted to a narrow strip of land upon the
Mid-California seaboard, not extending inland more than ten
miles, it has taken kindly to transplantation to the interior
hotter, drier valleys for more than one hundred miles from
the sea. It rarely exceeds a height of thirty metres ; the tim-
ber is generally twisted, coarse in grain, deficient in strength,
not durable, and rates low for either lumber or fuel uses. Its
pre-eminent value is as a forest cover and wide adaptability to
soil and climate.

Extensive plantations upon arid, gravelly hill-sides, without
care or cultivation, have attained an average height of twelve
feet in five years from the seed, and isolated specimens have
made a growth of sixteen feet during that time. It resists
fire well, young plantations where badly burned over— i.e., with
three-quarters of the foliage destroyed — generally recuperating.

Cupressvs macrocarpa, a smaller tree, fifty to seventy feet,
nearly as local as the Pinua insignis , of still more rapid devel-

APPENDIX. 237

opment, of more widely-tried distribution, and adapted to soils
lacking in fertility ; thrives wherever our rainfall reaches an
average of sixteen inches, and resists extreme summer heat
well ; holds its lower branches and foliage with tenacity to a
great age, making it serviceable for wind-breaks or ornamental
hedging; the wood is light, but extremely durable under-
ground, making it valuable for posts. Its small size makes it
unavailable for general lumbering uses, other than as a cabinet
wood, for which it is well adapted.

These two are the only native conifers that have been suc-
cessfully planted upon lands deficient in moisture and fertility,
upon a scale, and over a period of time prolonged enough, to
assert that they will prove valuable for our so-called arid
hill-sides.

In a more experimental way, upon more restricted areas,
away from their native habitats, the subjoined coniferous spe-
cies have been planted, and success has only followed where
the soil was of reasonable depth, fair fertility, and where water
was not remote from the surface. Such plantations have
proven successful in the northern part of the State where water
surface was distant, but only where the average annual rain-
fall exceeds twenty inches, and where the plantations have
been made in nooks and valleys sheltered from drying winds.

In the. southern half of the State, these conditions are not
sufficient, and a deeply-cut, well-sheltered, canon cariying
water upon or near the surface is a sine qua non.

The species are :

Sequoia semper vir ens.

Sequoia gigantea.

ChamcBcyparis Lawsoniana,

238 APPENDIX.

All these are species reaching heroic dimensions, and the
first and last rank in the very first class as unsurpassed timber
trees.

The limits of their utility for forest planting is, owing to the
conditions stated above, restricted to very narrow limits.

Pintis Sabiniana and Juniperus California both extend into
the lower foot-hills, and naturally occur upon barren, stony
lands of poorest quality ; and though nothing more than occa-
sional experimental tests have been made, no question or
doubt as to their utility upon utterly waste lands exists.

Their relatively slower growth, and inferior fuel and timber
value, to the Monterey pine and Monterey cypress, explain
their neglect, rather than any doubt as to their successfiil
development.

For points where the conditions of soil and climate discour-
age the planting of the latter, these two species can be success-
fully introduced.

Of our native oaks, occasional tests have been made with a
few species. The most valuable, the Quercus densifiora, makes
but poor growth outside of humid and elevated ravines. Quer-
cus lobata demands soil of both depth and fertility. Under
these conditions it makes phenomenal growth. I have cut a
tree displaying but forty-five annular rings, that measured four
feet ten inches in diameter above any buttress.

Quercus agrifolia has proven most tractable of all upon dry,
stony sites. Transplants easily, and after establishment makes
fairly rapid growth. Its rather small size is an objection. The
timber is inferior, stands but little transverse strain, but yields
a superior fuel.

With our other trees no transplantations other than orna-

APPENDIX. 239

mental have been made of those extending below the conif-
erous timber belt.

Chief among them, the Oregon ash, Oregon maple, syca-
more, cotton-wood, and laurel occur mostly in canons, and
with the exceptions noted are unsuitable for general planting.

The cotton-wood, Populus Fremontli, has shown (on a large
scale) conformability to the lands strongly alkaline. Such are
waste lands for this purpose, as the process of reclamation is
tedious and costly. They comprise many thousands of acres
of our "West Coast bottoms, and no tree outside of this cotton-
wood and Tamarix gallica (exotic) that has been tested upon
them has heretofore proven satisfactory. Growth quick ; timber
warps badly ; rates low for fuel.

The Laurel, Umbellularia Californica, has been attempted
away from water-courses, with some measure of success. The
timber is invaluable for veneers, exceedingly hard and heavy,
and excels the cherry and redwood burl in beauty, but is of
such exceedingly slow growth that few attempts have been
made looking to its extended planting.

PART III.

(B) Exotic Species.

Considerable plantations have been made throughout the
State with Eucalyptus species.

These in size range from one to four hundred acres. Plan-
tations have been made with some fifty species, but ninety per
cent, embrace, —

No. 1, Eucalyptus globulus.

Nine per cent, are of

No. 2, Eucalyptus rostrata, and

240 APPENDIX.

No. 3, Eucalyptus virinalis, and less than one per cent, of
the other species.

No. 1, by reason of its more rapid growth, has been most
freely planted. It is confined to the thermal belt, sufiering
when young from low temperatures (2° to 4° F. of frost).
Nos. 2 and 3 are much hardier, and are equally resistant of
drought.

All will grow upon arid hills, but only make remunerative
growth where the subsoil is of an open, porous nature ; the
root must have an opportunity to get down. Upon rock or
impervious subsoils these three gums may be seen, fairly
vigorous, but not averaging over twelve to fifteen feet, now
with stem diameter of over two and a half inches, representing
five and six years' growth. Eesults about equal to one year
upon open, porous soils of fair quality.

In value for fuel or timber, they take precedence as
follows :

E. rostrata, 1.

" globulus, 2.

" virinalis, 3.

The former is reputed to be " teredo"-proof ; but there is
no timber as yet within the State large enough for wharf
purposes.

In a smaller way, tests have been made with other species ;
the following prove of greatest merit :

Euc. corynocalyx (Sugar Gum). Hard and durable timber.
Tree umbrageous, endures drought and sterile soils. Suscepti-
ble to light frosts.

Euc. diversicolor, characteristics not dissimilar from last.

Euc. populi folia, smaller tree than last, but hardier.

APPENDIX. 241

Euc. leucoxylon, rose-flowered variety, and

Euc. amygdalina, var. angustifolia, are the only two species
that extend beyond our extra- tropical limits, having success-
fully withstood the cold of 16° F.

Have not seen the E. amygdalina tested upon poor soils.
The former, however, is very tenacious of life upon dry and
poor lands.

Both make trees of the greatest magnitude.

In cultivable lands, Euc. Gunni will make more rapid growth
than E. globulus, and hence is profitable for a fuel crop that
can be cut every four years.

A few other promising sorts are, —

E. citriodora, for its essential oil. Dry exposures.

E. paniculata. Dry exposures.

E. punctata. Dry exposures.

Most species of Eucalypti make good fuel ; a few are very
durable under ground or in water, and though largely used
in the antipodes for railway building, ties, etc., are in dis-
repute here from the tendency of some species to check and
warp, disabilities that can be overcome by cutting in proper
season and reasonable attempts at curing.

Acacias.

Upon any soil non-alkaline, and wherever the rainfall ap-
proximates sixteen inches, these are indicated for general
forest uses.

They require but little assistance to be established, attain
marketable size in five to eight years, furnish an excellent fuel
(wood too small for most economic purposes), and some excel
all other trees in the quantity and quality of superior tan-
bark yielded to the acre. They have been fairly tested upon
L 7 21

242 APPENDIX.

hill, valley, and brush lands, where cultivation was impracti-
cable; the results have been promising, although, like the
eucalypti, a measurable and perhaps profitable increment in
growth has followed the cost of cultivation.

The most valuable species — i.e., the one richest in tannin — is
the Acacia pycnantha. It is, however, more sensitive to cold
than some others, and hence properly restricted to the thermal
section of the coast.

The next in value. A. decurrens, and its immediate congener,
A. moligsima, are suitable for a very wide range, thriving in
the littoral regions, as well as for one hundred miles inland,
and for a length of seven hundred miles north and south.

A. melanoxylon is less valuable for its tan-bark, but makes a
larger tree (twenty metres), and furnishes a valuable cooper's
wood and the best fuel. It requires, perhaps, more moisture
and a better soil than the other species to obtain its maximum
growth. Incidentally it is compact and symmetrical in habit,
hence serving well for wind-breaks or street-planting.

Casuarinas of different sorts have been fairly tried. Among
them C. stricta, C. teniusimus, C. suberosa, and C. equisitacetolia.
All are rapid growers and hardy, also adapted to arid sites.

The last-named has given larger evidence of versatile adapt-
ability to our requirements of soil and climate.

Allied to the acacias we have a tree of phenomenally rapid
growth, and conformable to waste lands. It is Albizzia lo-
phantha. It is of no possible economic value except for the
marvellous rapidity with which it furnishes forest cover, and
is thus rendered available for furnishing a quick and short-
lived protection to coniferous plantations.

Eastern United States Silva have been but sparingly at-

APPENDIX. 243

tempted. Reasonable success has followed the planting of
both Catalpa and Robbia psuedo Acacia in the northern half
of the State. In the south they exigently demand soil of
greater depth and fertility than we are willing to classify as
forest lands. The same holds true of most of the nut-bearers,
the Caryas and allies, although sporadic and unprofitable
attempts have been made with the English, the Black Walnut,
and the Pistachio.

Some plantations of Pinus pinaster give promise of doing
well, remote from the seaboard, and, to a limited extent, P.
Austriaca, P. strobus, P. cembra, and P. Laricio have been
planted.

Results, as far as obtained, indicate unsatisfactory growth,
although the limited period of observation makes it premature
to formulate any conclusions.

Isolated cases exist of above fifty additional exotic species
that have been planted for forest uses.

The data is sufficient to fiirnish material that is not largely
hypothetical.

If such be desired, a synoptical list can be supplied.

"William S. Lyon.

INDEX.

A.

Agricultural district?, necessity for
preservation of trees in, 14, 15.

Agriculture, demands of, for re-
moval of forests, 11.

Aims of forestry, 10.

Air, changes in composition of, ef-
fects of, on earth's life, 166, 167.

Alps of Provence, Marsh on, 115,
116.

Amazon, forest lands of, 28.

Animal and vegetable kingdoms,
wonderful balance in the compo-
sition of the atmosphere insured
by, 142.

Animals, minerals and plants, mu-
tual interdependence between,
168.

Animals, necessity for oxygen in
respiration of, 141.

Animate enemies of the forest, 64,
71 to 76.

Annual Report of New York For-
estry Commission, extract from,
18, 19.

Assimilation, definition of, 22.

Atmosphere, composition of, 140.
difiFerent composition of, in ge-
ological past, 143, 144.
heat received from the heated

earth, 119.
heat received from the sun by
absorption, 119.

Atmosphere, manner in which it
receives heat from the sun,
119.
possible danger from disturb-
ance of composition of, by
removal of forests, 144, 145.
purification of, 140 to 145.
Avalanche, influence of, in destruc-
tion of forests, 67.
Axe of pioneer, a badly-chosen
emblem of civilization, 85.

B.

Balance of nature, 164 to 173.
Bannwoelder, 67, 68.
Basin of river, definition of, 111.
Beavers, destruction of forests by,

73.
Beech plum, story of, 35, 36.
Beetles, destruction of forests by, 75.

C.

Calcareous soils, definition of, 51.
Carbonic acid, decomposition of, in
plants by sunshine, 22.

influence of, on growth of
plants, 22.

influence of, when dis-
solved in water, in dis-
integration of rocks, 55.

necessity of, for existence
of plants, 142.

of atmosphere, use of, 140.

21*

245

246

INDEX.

Carboniferous period, composition

of the atmosphere during, 144.
Caterpillars, destruction of forests

by, 73, 74.
Cause of deserts, 42.

of meadows and prairies, 43.
of steppe regions, 43.
Classes of land suitable for main-
tenance of forests, 158, 159.
Clayey soils, definition of, 50, 51.
Climate, definition of, 119.

influence of elevation of land

on, 121, 122.
influence of land and water

areas on, 120, 121.
influence of the presence of

the forest on, 127 to 133.
influences producing variations

in, 120, 121, 122.
of forest region, characteristics

of, 124.
peculiarities of continental, 123.
peculiarities of oceanic, 123.
Comparative unimportance of soil

for plant growth, 25.
Conditions influencing the rapidity
of spread of forest fires, 65,
66.
necessary for the growth of

plants, 20 to 24.
necessary for the growth of

trees, 42 to 47.
required for the production of
rain, 101.
Continental climate, peculiarities
of, 123.

D.

Dana, James D., extract from his
" Manual of Geology," 70, 145,
146.

Decaying leaves, influence of, on

disintegration of rocks, 57.
Decomposition of carbonic acid in

plants by sunshine, 22.
Definition of assimilation, 32.

of forestry, 9.
Deforestation and reforestation, 14.
Deserts, cause of, 42.
Destruction of forests, 81 to 86.
by fire, 64, 65, 66.
evil results following,
81, 82.
Disintegration of rocks, agencies

causing, 52, 53.
Distant planets, possibilities as to
the existence of life thereon, 98.
Distinctive flora of particular re-
gions, meaning of, 30.
Distribution of heat, influence of,
by destruction of forests, 84.
of solar energy, how affected,
170, 171.
Domestic and domesticated plant

species, 33.
Drainage, 109 to 113.
definition of, 109.
influence of mountains on, 16.
surface, definition of, 110.
underground, definition of, 110.
Droughts, caused by destruction of

forests, 81.

E.

Earth's ocean of vapor, 90 to 97.

Earthworm, influence of, in forma-
tion of soil, 56.

Egyptian mummies, reputed pres-
ervation of plant seeds in, 33.

Electrical theory of hail, 149, 150

Equatorial currents of air, why
rain-bearing, 101.

INDEX.

247

Equatorial land areas, eflFect of, on

earth's climate, 166.
Erosion, definition of, 54.

influence of, in the formation
of soil, 53.
Evaporation, circumstances influ-
encing rapidity of, 90, 91, 92.
of moisture, inconstancy of,
171, 172.
Excavations, growth of plants on
exposure of soil brought up by,
35.
Excessive multiplication of life,
how avoided, 169, 170.

Feldspathic rocks, clayey soils de-
rived from, 51.
Femow, B, E., definition of for-
estry, 17.
Fire, destruction of forests by, 64,

65, 66.
Fire-weed, curious conditions re-
quired for germination of, 37.
Flammarion, Camille, extract from

"The Atmosphere," 125, 126.
Flora, definition of, 26.

effect of elevation on, 48, 49.
effects of the distribution of
heat, light, and moisture on,
26.
influence of temperature on,

31.
on mountain slopes, why differ-
ent at different altitudes, 26,
27.
Forest, animate enemies of, 64, 71
to 76.
areas, intelligent protection of,
13.

Forest, climate, characteristics of,
128.
fires, conditions influencing the
rapidity of spread of,
65, 66.
how started, 65.
inanimate enemies of, 61 to 67.
influence of area on absorption

of heat, 127.
influence of forest area on loss

of heat, 128.
influence of presence of, on

climate, 127 to 133.
lands of the Amazon, 28
preserves, 14.
Forestry, aims of, 10.

associations, field for, 10, 13.
definition of, 9.
Fernow's definition of, 17.
laws, necessity for, 10, 13.
mistaken ideas concerning, 13.
Forests, dependence of, on climatic
conditions, 62.
destruction of, 81 to 86.
by beavers, 73.
by beetles, 74.
by caterpillars, 73, 74.
by goats, 73.
by grasshoppers, 73,

74.
by insects, 73, 74.
by man, 75, 76.
by mice, 78.
by typographer bee-
tle, 75.
distribution of heat, influence

of, by destruction of, 84.
disturbance of the balance of
nature affected by removal
of, 172, 173.

218

INDEX.

Forest, droughts produced by de-
struction of, 81.

encroachments on, necessity
for, 11.

influence of avalanches in de-
struction of, 67.

influence of inundations in
destruction of, 66.

influence of, on humidity of
air, 97.

influence of, on natural drain-
age, 113.

influence of, on preventing
disastrous frosts, 130, 131.

influence of, on rapidity of
evaporation, 97.

influence of parasitic plants on
destruction of, 71, 72.

influence of rodents on destruc-
tion of, 73.

influence of torrents on de-
struction of, 58.

influence of wind on destruc-
tion of, 66.

inundations produced by de-
struction of, 81.

loss of soil following destruc-
tion of, 81.

malarious diseases produced by
destruction of, 82.

natural drainage disturbed by
destruction of, 82.

necessity for preservation of
exact balance of conditions
to existence of, 63.

necessity for removal of, 11.

of mountain slopes, 46.

influence of, on
rapidity of
drainage, 104.

Forest of tropical regions, 46.

peculiar distribution of moist-
ure causing, 43.
products of, 11.
protection afi'orded by, against

frosts, 129.
why a regular distribution
of moisture is requisite for
growth of, 44, 45.
why the air of, is cooler and
damper in summer than air
over open fields in same
district, 132.
Formation of soil, 50 to 57.
Freezing and melting of ice, in-
fluence of, on disintegration of
rocks, 52, 53.

G.

Gases, absorption of, by soils, 56.
Geikie, Archibald, extract from
"Text-Book of Geol-
ogy," 60, 78, 88, 133.
Germ, necessity for existence of, for

plant life, 23.
Germ-cell, protoplasm of, 20.
Germs of plants, source of, 21.

wonderful vitality of,
21, 33, 34, 35, 36.
of seeds, wonderful vitality of,
33, 34, 35, 36.
Glaciers, definition of, 54

influence of, in formation of
soil, 54, 59.
Goats, destruction of the forests by,

73.
Grasshoppers, destruction of forests

by, 73, 74.
Gravelly soils, definition of, 60.

INDEX,

249

Guyot, Arnold, extract from
" Earth and Man," 28, 29, 48.

H.

Hail, 147 to 152.

influence of destruction of
forest on occurrence of,
147.
Volta's theory of, 149, 150.
Hail-rods, 150.

Hailstones, structural peculiarities
of, 148.
varying sizes of, 148, 149.
Hail-storms, damages caused by,
151.
electrical phenomena of, 148.
rate of the wind during,
151.
Hartt, Ch. Fred., extract from
" The Geology and Physical Ge-
ography of Brazil," 137, 138.
Heat and light, necessity of, for
plant growth, 24.
energy, disappearance of, on
evaporation of water, 95.
liberation of, on conden-
sation of vapor, 95.
units, 95.
Hough, Franklin B., extract from
" Report on For-
estry," 76, 77, 78.
extract from the " Re-
port of the United
States Commission-
ers for 1877," 159
to 16o.
extract from " Report
of United States
Commissioners of
Forestry," 135, 136.

Houston, Edwin J., extract from
** Elements of Physical Geogra-
phy," 29, 30, 86, 87.

Humboldt, Alexander von, extract
from '* Cosmos," 99, 104, 105.

Humidity of air, influence of, on
evaporation, 92.

Huxley, T. H., extract from
" Physiography," 106.

Hydrogen, in plant tissues, source
of, 23.

Hydroscopic properties of soils, 56.

I.

Inanimate enemies of the forest,

61 to 67.
Influence of mountains on drain-
age, 16.
Insects, destruction of forests by,
73, 74.
larvfe of, destruction of forests
by, 74.
Interests of lumbermen and for-
estry associations mutual, 18.
Inundations caused by destruction
of forests, 81, 82, 83.
causes of, 81, 82, 83, 111,

112.
influence of, on destruction of

forests, 66.
influence of the surface on the
number and severity of, 112.
Island of St. Helena, Lyell on the
destruction of its forests, 87.

Jack Sprat, of nursery lore, 143.
" Journal of the Society of Arts,"
extract from, 89.

250

INDEX.

L.

Land and water areas, exact bal-
ance between, 165.

Lands suitable for preserving forests
on, 15.

Le Conte, Joseph, extract from
" Elements of Geology," 69.

Lindley, John, extract from his
« Botany," 39 to 41.

Loomis, Elias, extract from " Trea-
tise on Meteorology," 152, 153.

Lyell, Charles, extract from " Prin-
ciples of Geology," 69, 87, 114,

115.

M.

Mackenzie River, raft in, 67.

Malarious diseases produced by de-
struction of the forests, 82.

Man, destruction of forests by, 75,
76.

Marsh, George P., extract from
*' The Earth as Modified by Hu-
man Action," 38, 89, 68, 115,
116, 173, 174, 175, 176.

Matter, organic and inorganic, dis-
tinction between, 29.

Maury, M. F., extract from " Phys-
ical Geography," 107, 108.

Meadows and prairies, peculiar dis-
tribution of moisture causing, 43.

Method, nature's, of distributing
plant germs, 32.

Mice, destruction of forests by, 78.

Mineral matters, necessity of, for
plant growth, 25.
source of, in plant tissues,
23.

Minerals, plants and animals, mu-
tual interdependence between,
168.

Mississippi River, raft in, 67.

rafts, Lyell on, 69.

Moist air of forest, influence of, on

absorption of heat, 130.

Moisture, effect of variations in

amount, on character and

distribution on flora, 42.

how absorbed by plants, 22.

of atmosphere, use of, 141.

principal food of plants, 22.

Mountain rains, how caused, 102.

slopes, forests of, 46.

necessity for preservation

of forests on, 47.

Mountains the birthplaces of rivers,

47, 103. 104.

the natural home of the forest,

reasons for, 15, 16, 17.

the natural home of the rivers,

16.
Mud-flats, damages produced by, 84.

Mutual interests of forestry associ-
ations and lumbermen, 18.

N.

Natural drainage, damages pro-
duced by the disturbance
of, 112.
disturbed by destruction
of forests, 82.
Nature, balance of, 164 to 173.
Necessity for preservation of for-
ests on mountain slopes, 47,
of germs for the existence of

plants, 23.
of oxygen for growth of plants,
23.
New York Forestry Commission,
extract from Annual Report of,
18, 19.

INDEX.

251

Oceanic climate, peculiarities of,

123.
Oxygen of atmosphere, use of, 140.
necessity for, in respiration of
animals, 141.

P.

Paragr^les, 150.

Parasitic plants, influence of, in

destruction of forests, 71, 72.
Peaty soils, definition of, 51.
Pine forests, appearance of scrub

oak on burning over of, 36, 37.
Plant germs, nature's method of
distributing, 32.
wide distribution of, 32 to

38.
wonderful vitality of, 33,
34, 35, 36.
nationality, 26.
seeds, wonderful vitality of,
33, 34, 35, 36.
Planting of trees, when advisable,

157.
Plants, animals, and minerals, mu-
tual interdependence be-
tween, 168.
conditions necessary for the

growth of, 20 to 24.
decaying, influence of, in for-
mation of soil, 50.
necessity of oxygen for growth

of, 23.
source of germs of, 21.
source of seeds of, 21.
Polar currents of air, why generally
drought-producing, 101.
land areas, eflect of, on earth's
climate, 167.

Prairies, new growth of plants
marking wagon-tracks on, 36.

Precipitation, forms of, 100.

Pressure of air, influence of, on
rapidity of evaporation, 92.

Prestwich, Joseph, extract from
*' Geology, Chemical, Physical,
and Stratigraphical," 117, 118.

Products of the forests, 11.

Protoids, definition of, 29.

Protoplasm of germ-cell, 20.

Pouchet, extract from " The Uni-
verse," 78, 79, 80.

Purification of the atmosphere,
140 to 145.

Railway sleepers, demands on for-
ests for, 89.
Rain, 100.

causes of, 100.

Huxley on the distribution of,

106.
Maury on the distribution of,
107, 108.
Rainfall, distribution of, 102.

true index of the wealth of a
country, 94.
Reclus, Elis^e, extract from
"Earth," 67, 68, 69,
116, 117.
extract from " Ocean," 30,
31, 48, 49.
Red River, raft in, 67.
Reforestation, 155 to 159.
and deforestation, 14.
definition of, 155.
necessity for government en-
couragement of, 156.
objects of, 155, 156.

252

INDEX.

Reforestation of mountains, French
code for, 159, 160,161, 162,
163.
various methods employed in,

156.
when possible, 155, 156.
Regions, steppe, peculiar distribu-
tion of moisture causing, 43.
Reservoirs, definition of, 109.
River basin, definition of, 111.
rafts, 67.

system, definition of. 111.
Rivers, cause of difference in size

of, 110.
Roads, demands of, for removal of

forests, 11.
Rocks, agencies causing disintegra-
tion of, 52, 53.
crystalline, original source of

soil of, 50.
disintegration of, 50.

influence of solvent
power of water on,
54, 55.
influence of sprouting
vegetation on, 53.
influence of layer of decaying
leaves on disintegration of,
57.
Rodents, influence of, on destruc-
tion of forests, 73.

S.

Sahara desert, appearance of plants
on irrigation of, 34.
wadys in, 34.
Sand-bars, damages produced by,

84.
Sandy soils, definition of, 60, 51.

Scrub oak, appearance of, on burn-
ing over of pine forests, 36,
37.
Seeding of trees, when advisable,

157.
Seeds, circumstances preventing
germination of, 40, 41.
vitality of, circumstances in-
fluencing, 39 to 41.
Snow, protection afforded ground

by, against frosts, 129.
Soil, alternate freezing and thaw-
ing, influence of, in forma-
tion of, 54, 55.
formation of, 50, 51.
influence of earthworm in for-
mation of, 56.
influence of erosion in forma-
tion of, 54.
influence of glaciers in forma-
tion of, 54, 59.
loss of, following destruction of

forests, 81, 83, 84.
necessary gradual formation of,

66, 57.
or cradle, necessity of, for plant

growth, 24.
vegetable, definition of, 60.
Soils, calcareous, definition of, 51.
classification of, 50.
clayey, definition of, 60, 51.
distribution of, 51, 52, 53.
gravelly, definition of, 50.
hygroscopic properties of, 56.
influence of color of, on power

of heat absorption, 56.
peaty, definition of, 51.
power possessed by, of absorb-
ing gases, 56.
sandy, definition of, 50.

INDEX,

253

Sources of hydrogen in plant tissue,
23.
of mineral matters in plant
tissues, 23.

Species, domestic and domesticated,
33.

Springs, source of water discharged
by, 109.

Sprouting vegetation, influence of,
on disintegration of rocks, 53.

St. Helena, Lyell on the destruc-
tion of its forests, 87.

Struggle for existence in the vege-
table world, 61.

Subsoil, definition of, 60.

Sunshine, influence of, in germina-
tion of seeds of plants, 21.

Surface drainage, definition of,
110.

Surface, influence of, on rapidity
of evaporation, 91.

T.

Temperature of air, influence of, on
rapidity of evaporation, 91.
of equatorial and polar regions,
how balance is preserved be-
tween, 164, 165.
Tree-planting, 155 to 159.

when advisable, 27.
Trees, conditions necessary for

growth of, 42 to 47.
Tree-sowing, 157.
Torrents, influence of, on destruc-
tion of forests, 58.
Tropical flora, why different from
temperate or arctic flora,
26.
rains, how caused, 102.
regions, forests of, 46.

Tropical regetation, Guyot's de-
scription of, 28, 29, 30.
Tyndall, John, extract from " Heat
as a Mode of Motion," 98, 105,
134.
Typographer beetle, destruction of
forests by, 75.
Hough on, 76, 77.

U.

Underground drainage, definition
of, 110.

V.

Vacuum, influence of, on germina-
tion of seeds, 40.
Vapor, earth's ocean of, 90 to 97.
of air, chilling necessary for
precipitation of,
100.
influence of, on econ-
omy of the earth,
93, 94.
Vegetable fibre, source of carbon
in, 22.
mould or humus, 50.
world, struggle for existence
in, 61.
Vegetation, agency of, in prevent-
ing loss of soil, 88.
Velocity of wind, influence of, on

rapidity of evaporation, 92.
Volta's electrical theory of hail,
149, 150.

W.

Wadys in the Sahara Desert, 34.
Water or moisture, necessity of, for
plant growth, 24.

22

254

INDEX.

Water, solvent power of, influence
of, in disintegration of rocks,
64, 65.
vapor, screening influence of,
on sun's heat, 94.

Wide distribution of plant germs,

30 to 38.
Wind, influence of, in destruction

of forests, 66.
Winged seeds, 32.

THE END.

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DATE

: DUE

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9 1972

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THE UNIVERSITY OF
E.miSH CCLUMBIA

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