CHAPTER I.

TRANSCRIBER'S NOTE

Italic text is denoted by _underscores_.

Bold text is denoted by =equal signs=.

Obvious typographical errors and punctuation errors have been

corrected after careful comparison with other occurrences within

the text and consultation of external sources.

More detail can be found at the end of the book.

SCIENCE

FOR THE

SCHOOL AND FAMILY.

PART I.

NATURAL PHILOSOPHY.

BY

WORTHINGTON HOOKER, M.D.,

PROFESSOR OF THE THEORY AND PRACTICE OF MEDICINE IN YALE COLLEGE,

AUTHOR OF "HUMAN PHYSIOLOGY," "CHILD'S BOOK OF NATURE," "NATURAL

HISTORY," &C.

=Illustrated by nearly 300 Engravings.=

NEW YORK:

HARPER & BROTHERS, PUBLISHERS,

FRANKLIN SQUARE.

1873.

By Dr. Worthington Hooker.

=The Child's Book of Nature.= For the Use of Families and Schools;

intended to aid Mothers and Teachers in training Children in the

Observation of Nature. In three Parts. Illustrated by Engravings.

The Three Parts complete in one vol. Small 4to, Cloth, $2 00;

Separately, Cloth, 90 cents each.

PART I. PLANTS.

PART II. ANIMALS.

PART III. AIR, WATER, HEAT, LIGHT, &c.

=First Book in Chemistry.= For the Use of Schools and Families.

Illustrated by Engravings. Square 4to, Cloth, 90 cents.

=Natural History.= For the Use of Schools and Families. Illustrated

by nearly 300 Engravings. 12mo, Cloth, $1 50.

=Science for the School and Family.=

PART I. NATURAL PHILOSOPHY. Illustrated by nearly 300 Engravings.

12mo, Cloth, $1 50.

PART II. CHEMISTRY. Illustrated by numerous Engravings, 12mo,

Cloth, $1 50.

PART III. MINERALOGY AND GEOLOGY. Illustrated by numerous

Engravings. 12mo. Cloth, $1 50.

=Published by HARPER & BROTHERS, Franklin Square, N. Y.=

Any of the above Works sent to any part of the United States,

postage pre-paid, upon receipt of the Price.

Entered, according to Act of Congress, in the year one thousand

eight hundred and sixty-three, by HARPER & BROTHERS, in the Clerk's

Office of the District Court of the Southern District Court of New

York.

PREFACE.

Daniel Webster, in his Autobiography, speaks thus of his entering

upon the study of law: "I was put to study in the old way--that

is, the hardest books first, and lost much time. I read Coke on

Littleton through without understanding a quarter part of it.

Happening to take up Espinasse's Law of Nisi Prius, I found I

could understand it; and arguing that the object of reading was

to understand what was written, I laid down the venerable Coke

_et alios similes reverendos_, and kept company for a time with

Mr. Espinasse and others, the most plain, easy, and intelligible

writers. A boy of twenty, with no previous knowledge on such

subjects, can not understand Coke. It is folly to set him on

such an author. There are propositions in Coke so abstract, and

distinctions so nice, and doctrines embracing so many conditions

and qualifications, that it requires an effort, not only of a

mature mind, but of a mind both strong and mature, to understand

him. Why disgust and discourage a boy by telling him that he must

break into his profession through such a wall as this? I really

often despaired. I thought that I never could make myself a lawyer,

and was almost going back to the business of schoolkeeping. Mr.

Espinasse, however, helped me out of this in the way that I have

mentioned, and I have always felt greatly obliged to him."

Here is most graphically depicted a defect which is now, as it was

then, very prominent in all departments of education. It is even

more so in early education than in that of the college and the

professional school. Even in tender childhood pupils are put to

studying books of which, as was true of Webster with his Coke on

Littleton, they do not understand "a quarter part." If the rule is

not "the hardest books first," there are many things in the books

that it is not only hard but impossible for them to understand.

And the hardest things are often put first. For example, in a

very popular primary geography which lies before me the pupil is

introduced to the world and its grand divisions at the outset,

while he is taught about his own state and country only at the

conclusion of the book. And this unnatural mode is the one very

commonly pursued. Similar criticism can be passed upon most of the

books used in teaching young children. Some of them are wholly

useless. This is true of the grammars for primary schools. The

formal statements, called the rules of grammar, are beyond the

understanding of very young scholars, and therefore are useless

burdens upon their memories. They are as useless to them as the

three-fourths of Coke which Webster could not understand was to him.

If we follow education, upward from the primary school we find

the same defect throughout the whole course. In the books which

are used in teaching natural science it is especially prominent.

Even in the elementary books, or compendiums, so called, formal

propositions and technical terms render the study uninviting, and

to a great extent unintelligible. The pupil is apt to be disgusted

and discouraged, as Webster was with Coke on Littleton, and for the

same reason.

Another defect intimately connected with that of which I have

spoken is the very sparing and late introduction of the physical

sciences. They are generally postponed to the latter part of

the course of education, and then but little time is devoted to

them. Generally, when a pupil designs to go through college, the

study of these sciences is wholly neglected in his preparation,

because a knowledge of them is not required for admission. Then in

the college they are not attended to till the latter part of the

course, and in the short time allotted to them there is so much to

be learned that the teaching of them is a failure. Especially is

this true of Chemistry and Geology.

This defect is a _radical_ one. A thorough change should be

effected in this respect in the whole course of education. The

natural sciences should be made prominent from the beginning to the

end, not only because they are of practical value, but also because

they are as useful in their way for mental discipline as the study

of mathematics and of language. They can be taught to some little

extent to the youngest pupils. There are facts about air, water,

and the various objects that they see around them, which they can

understand if they be presented in the right manner. And the busy

inquiries which they make after the reasons of the facts, and their

appreciation of them if stated simply and without technical terms,

show the appropriateness of such teaching. Children are really very

good philosophers in their way. They have great activity not only

of their perceptive but of their reasoning faculties also, to which

due range should be given in their education.

Beginning thus, not a year should pass during the whole course

when the pupil shall not be engaged in studying some one of the

physical sciences to some extent. This continued attention to such

studies in a reasonable amount, so far from interfering with the

due prosecution of the other studies deemed so essential, _will so

promote the pupil's advance in them as to more than make up for

the time that is taken from them_. It will do this not only by the

genial influence which such studies exert upon the mind, but by

the contributions which they make to the knowledge of language and

mathematics; for language is largely built up from natural objects

and from the acquisitions of science, and there is an abundance

of interesting applications of portions of the mathematics in the

facts which the physical sciences develop to us.

I have said that the teaching of the natural sciences in our

colleges is generally a failure, and it always will be so as long

as the present plan is continued. In order to have it successful

there must be _the same gradation in teaching them that we have

in teaching language and the mathematics_. The college student

needs to be prepared for the lectures which he hears on natural

philosophy, chemistry, etc., and for his study of those branches,

by previous familiarity with the simpler portions of them acquired

in the school-room.

There is another very important reason for the early introduction

of the physical sciences into education. By far the larger portion

of pupils in our schools stop short of the college, or even the

academy and high school. That they should go forth into the world

with no knowledge of the principles that lie at the basis of the

arts in which so many of them are to engage is a shame and a wrong,

if the communication of such knowledge be indeed practicable, as

it undoubtedly is. Even those who are not to engage in these arts

will be greatly benefited by this knowledge, because in addition

to its constant practical applications in the management of life,

it will contribute to their mental power, and, what is no small

consideration, to their enjoyment; and it is in fact requisite to

constitute them well-informed persons.

If the views which I have presented be correct, there should be a

series of books on the natural sciences carefully adapted to the

different periods of the course of study. Those intended for the

young beginner should be exceedingly simple, and should not attempt

to present any thing like a full view of the subjects treated.

They should deal largely with familiar facts or phenomena. The

terminology of science and formal statements of principles, such

as we often see in so-called compendiums, should have no place in

them, but should be gradually introduced as the series advances,

and should be made complete only in the concluding books.

It has been the object of the author to supply a part of such a

series. The first book in the series is the "Child's Book of Common

Things," intended to teach the observation of familiar facts, or,

in other words, the beginnings of philosophy, to children as soon

as they have got well started in reading. Next comes the "Child's

Book of Nature," which in its three parts (Part I., Plants; Part

II., Animals; Part III., Air, Water, Light, Heat, etc.) extends

considerably the knowledge of the philosophy of things which the

child has obtained from the first book in the series. Then follows

the "First Book in Chemistry." On a level with this is my "First

Book in Physiology." The next step in the gradation brings us

to three books under one title, "Science for the School and the

Family;" Part I., Natural Philosophy; Part II., Chemistry; Part

III., Mineralogy and Geology. On a level with these is another

book, "Natural History," and another still is to be written, an

"Introduction to Botany."

The three books, of which the present is one, are intended for the

older scholars in what are commonly called grammar-schools. At the

same time they are suited to scholars who are advanced to a higher

grade who have not gone through the previous books of the series.

The preparation of books especially adapted to high schools and

colleges I have left to others, except in one branch of science,

Physiology, on which I some years ago published a work entitled

"Human Physiology."

All of these books are from the press of Harper and Brothers except

the two works on Physiology, published by Sheldon and Co., New

York, and the "Child's Book of Common Things," published by Peck,

White, and Peck, New Haven.

The general plan and style of these books are very different from

what we see in most of the books for schools on the same subjects.

The order of the subjects and the mode of developing them differ

from the stereotype plan which has so generally been adopted. One

prominent feature is the free use of illustrations from _familiar_

phenomena. This leads the pupil to reason or philosophize about

common things, thus giving an eminently practical character to his

knowledge. At the same time it makes the books suitable for use in

the family as well as the school, between which there should be

more common ground than the present mode of education allows.

The style which I have chosen for all the books I have written

for use in teaching is what may be called the _lecture style_.

There are three other kinds of style which are more commonly

used in school-books. The most common is what I term the _formal

statement style_. In this principles and rules are stated, and

then illustrations are given. This makes a formal and uninviting

book. The bare skeleton of the science is generally for the most

part presented, and the young pupil is apt to learn the statements

by rote without understanding them. It is a style fitted only

for books intended for advanced scholars. Another style is the

_catechetical_. This is an unnatural mode of communicating

knowledge; and besides, it encourages learning by rote as the

formal statement style does. In the third style, the _dramatic_,

conversations are held between the teacher and some learners. The

chief objection to this is that it undertakes to put in permanent

shape what should be extemporized in the recitation. What is needed

in the book is simply clear and concise statement in an interesting

style, and the living teacher and his scholars can best furnish

the conversational element as the recitation goes on.

In the lecture style there may be and should be as much precision

of statement as in the formal statement style, while it is more

interesting, because it is the natural mode of communicating

knowledge. In this style the facts are ordinarily so stated as to

develop principles; while in the other the order is reversed, the

principles being first stated and the facts given afterward. One

of the most successful books ever used in our colleges--"Paley's

Natural Theology"--is in the lecture style, and it is a matter of

surprise that this fact has had so little influence with those who

have prepared books for instruction.

Whatever may be true of advanced scholars, in teaching the young

student in science bare, dry statement should be avoided, and the

subjects should be presented in all their attractive features. I

would not be understood as advocating the dressing up of science

in adventitious charms. This is not necessary. Science possesses

in itself an abundance of charms, which need only to be properly

developed to attract the young mind; and the lecture style

furnishes the best vehicle for such a development.

One grand essential for giving interest to any study is the

presentation of the various points in the _natural order_ in which

they should enter the mind. _They should be so presented that

each portion of a book shall make the following portions more

interesting and more easily understood._ This principle, which is

so commonly transgressed, I have endeavored to observe strictly in

the preparation of these volumes.

Questions are put at the end of this book for those teachers who

desire to use them. There is also an Index.

W. HOOKER.

_January_, 1863.

CONTENTS.

CHAPTER PAGE

I. MATTER 13

II. PROPERTIES OF MATTER 19

III. THE ESSENTIAL PROPERTIES OF MATTER 33

IV. ATTRACTION 38

V. GRAVITATION 51

VI. CENTRE OF GRAVITY 67

VII. HYDROSTATICS 80

VIII. SPECIFIC GRAVITY 100

IX. PNEUMATICS 110

X. MOTION 133

XI. THE MECHANICAL POWERS 174

XII. SOUND 193

XIII. HEAT 207

XIV. LIGHT 258

XV. ELECTRICITY 287

XVI. MAGNETISM 308

NATURAL PHILOSOPHY.

CHAPTER I.

MATTER.

1. =Matter and Spirit.=--The distinction between matter and spirit

is almost universally recognized even by those who have given

little thought to such subjects. It is a distinction of which we

are conscious in our own persons. We know instinctively that there

is a something within us that causes the movements of our material

bodies, and that something we call spirit.

2. =Bishop Berkeley's Ideas.=--Some philosophers, in their

speculations, have denied that there is any such thing in

existence as matter. Bishop Berkeley, for example, taught that

the impressions which we suppose that we receive from material

objects do not come from real substances, but are the "effects of

the immediate agency of an ever-present Deity." It is no wonder

that the wisdom and learning of a man who could seriously adopt

such a belief could not save him from being the dupe of quackery.

He believed that tar-water was a sovereign cure for all diseases;

and Dr. Holmes playfully remarks of him, that "he held two very

odd opinions: that tar-water was every thing, and that the whole

material universe was nothing."

3. =Hume's Ideas.=--The infidel Hume went beyond Bishop Berkeley,

denying even the existence of the soul as an individual and

responsible agent. He made every thing to consist of ideas and

impressions, and said that these have no necessary connection,

but are "a bundle of perceptions that succeed each other with

inconceivable rapidity, and that therefore I myself of to-day

am no more the I myself of yesterday or to-morrow than I am

Nebuchadnezzar or Cleopatra." A wag proposed the following epitaph

for his tomb-stone as a suitable illustration of his theory:

"Under this circular idea, vulgarly called tomb,

Impressions and ideas rest which constituted Hume."

4. =Origin of the word Spirit.=--The name spirit came originally

from an attenuated form of matter, the air or breath, because the

air, like spiritual existence, is invisible. The formation of

language is to a large extent thus based on analogies.

5. =Spirit not an Object of Sense.=--None of the senses can

perceive spirit itself, though they perceive the effects which

spirit produces on material substances. If, for example, you move

your arm, it is the spirit within you, acting upon the muscles

through the nerves, that causes it to move; and you see here the

effects produced by spirit upon matter, but you do not see the

spirit itself.

6. =Effects of Matter on the Senses.=--Some forms of matter can

be perceived by all the senses; others can be perceived by only a

part of them; some by only one. Air you can not see, nor smell,

nor taste; but you can feel it, and hear the sound of its motion.

Sometimes matter affects only the sense of smell, or that with

the sense of taste. Sea-air smells salt; but the salt in the air

is so finely divided that we can not see it. And yet it is the

salt, entering the nostrils and coming in contact with the extreme

fibres of the nerve of smell, that produces the effect. So when we

smell a flower, matter comes from it in particles so fine that no

microscope can detect them, but they produce sensation when they

strike upon the nerve.

7. =Forms of Matter.=--Matter appears in three forms: solid,

liquid, and gaseous or aeriform--that is, like air. Sometimes

matter is spoken of as having only two forms--solid and fluid.

In this case fluids are divided into two classes, the elastic

and non-elastic. The air and the various gases and vapors are

the elastic fluids; while those which are called liquids are the

non-elastic fluids. A foot-ball bounds because the air in it is

an elastic fluid. If it were filled with a non-elastic fluid; as

water, it would not bound. When water takes the form of steam it is

an elastic fluid. Though it is very common to use the expression

elastic fluids, the division of matter into three forms is the one

usually recognized.

8. =Solids.=--In solid matter the particles can not be moved about

among each other; but each particle generally retains the same

position in relation to those particles which are around it--in

other words, it does not change its neighborhood. This is more

true of some solids than of others. It is absolutely true of such

hard solids as granite and the diamond. In these the particles are

always in the same relative position. But it is not so with gold

or lead. By hammering these you can change greatly the relative

position of their particles. India-rubber is a solid, but the

relative position of its particles can be much altered in various

ways.

9. =Liquids.=--It is the grand characteristic of a liquid that its

particles change their relative position from the slightest causes.

It is in strong contrast with solids in this respect. When you move

any portion of a solid body you move all the other portions of it,

and generally in the same direction. But a body of liquid can not

be moved all together as one body except by confining it; as, for

example, in the case of a water-pipe or a syringe. And then, the

moment that the water can escape, the particles use their liberty

of altering their relative position. As wind and other agents act

continually upon water, no particle stays for any length of time

in the neighborhood of the same particles. "Unstable as water" is,

then, an exceedingly significant expression. Water is never at

rest. A particle of it may at one time be floating on the surface

of the ocean, and at another be in depths beyond the sounding of

man. It flies on the wings of the wind, falls in the rain, runs in

the stream, is exhaled from a leaf, trembles in the dew-drop, flows

in the blood of an animal or in the sap of a plant, and is always

ready to be jostled along in its ever-changing course.

10. =Gases.=--The particles of gaseous or aeriform substances move

among each other even more freely than those of a liquid. Air,

therefore, is more unstable and restless than water. Even when the

air seems to be perfectly still its particles are moving about

among each other. You can see this to be true if you darken a room,

leaving a single shutter a little open. Where the light enters

you will see motes flying about in every direction, which would

not be the case if the air were really at rest. The particles of

air have a greater range of travel than those of water; for the

sea of atmosphere which envelops the earth rises to the height of

about fifty miles. How far water rises in its evaporation we know

not; but it is not at all probable that it rises to the uppermost

regions of the atmosphere.

11. =Filling of Spaces by Liquids and Gases.=--It is the freeness

with which the particles of liquids and gases move among each

other that enables them to insinuate themselves into spaces every

where. They are ever ready to enter into any substances which

have interstices or pores of such size as will admit them. There

are mingled with the grains of the soil not only water, but air

and gases. These are present also in all living substances, both

vegetable and animal. Water is the chief part of sap and of blood,

and air and gases always go with water. Part of the air that we

breathe in enters the blood in the lungs, and courses with it

through the system. The fishes could not live in water if there

were not air mingled with it. This can be proved by experiment. If

you put a fish into a close vessel it will soon die, because it

uses up all the air that is in the water. In an open vessel the

fish is kept alive by the constant accessions of fresh air to the

water.

12. =Solution.=--In solutions of solid substances in water it is

the freedom with which the particles of water move about among each

other that enables them to take in among them the minute particles

of the solid. And when water ascends into air by evaporation it

may be said to be a real solution of water in the air; for the

particles of water mingle with those of the air, just as the

particles of a solid mingle with those of water in a solution.

13. =Relation of Heat to the Forms of Matter.=--Some kinds of

matter are seen in all the three forms. Whether these shall assume

one form or another depends on the amount of heat present. Thus

when water is solid, ice, it is because a part of its heat is gone.

Apply heat, and it becomes a liquid, water. Increase the heat to

the boiling point, and it becomes steam, or an aeriform substance.

Alcohol has only two forms--liquid and aeriform. It has never been

known to be frozen. Iron is usually solid; but in the foundry,

by the application of great heat, it is made liquid. Mercury is

liquid in all ordinary temperatures; but it often becomes solid

in the extreme cold of arctic winters. A mercurial thermometer

is of course useless under such circumstances, and the alcoholic

thermometer is relied upon to denote the degree of cold. The

difference between mercury, water, and iron in regard to the liquid

state is this: It takes but little heat, comparatively, to make

mercury liquid, while more is required for this condition in water,

and much more for it in the case of iron.

14. =The Nature of Matter Unknown.=--What now, let us inquire, do

we know of the nature of matter? Can we say that we know any thing

of it? We may observe its phenomena, and learn its properties; but

with our most searching analyses of it we can no more determine

what matter is than we can what spirit is. Newton supposed

"that God in the beginning formed matter in solid, massy, hard,

impenetrable particles." This he believed to be true of liquids,

and even of gases, as well as solids. In the gas these hard

particles are much farther apart than in the solid. The supposition

is a very probable one; but if it be true it does not let us know

what matter is, for it leaves us in the dark as to the nature of

the particles. Newton farther supposed that these particles have

always remained unaltered amidst all the changes that are taking

place; these changes being occasioned by "the various separations

and new associations and motions of these permanent particles."

When, for example, any thing is burned up, as it is expressed, not

one of these particles is either destroyed or altered, but they

merely take on new arrangements. Though most of the substance has

flown off in the form of gas, the ultimate particles composing

the gas are the same now that they were when making a part of the

solid substance; and they may soon again become a part of some new

solids. Such changes in the forms of matter are every where going

on; and when you become acquainted with Chemistry, in the Second

Part, you will be familiar with them.

15. =Atomic Theory.=--These ultimate particles of matter are so

minute that they have never been seen by man. The smallest particle

that can be seen with the most powerful microscope is probably made

up of very many of them united together. These ultimate particles

we term atoms; and the theory in regard to the composition by them

of different substances is called the atomic theory. The atoms of

different substances are not supposed to be alike, but to differ in

both size and weight. This theory will be more particularly noticed

in the Second Part.

16. =Imponderable Agents.=--There are certain agents--light, heat,

electricity, etc.--which are supposed by some to be forms of

matter. If they are, they are exceedingly attenuated; for their

presence, as has been proved by many experiments, never adds in

the least to the weight of any substance. They have therefore been

styled imponderable agents. Their agency is of great importance

and very active, producing every where constant changes. Two of

them--heat and light--are obviously and immediately essential to

life. What their real nature is remains as yet an entire mystery.