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Popular Edurator

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VOLUME THE SIXTH.

READING furnishes the mind only with materials of knowledge; it is thinking makes what we read ours. We are of the

ruminating kind, and it is not enough to cram ourselves with a great load of collections ; unless we chew them over
and over again, they will not give us strength and nourishment. There are, indeed, in some writers, visible instances
of deep thought, close and acute reasoning, and ideas well pursued. The light these would give would be of great use,
if their readers would observe and imitate them: all the rest at best are but particulars fit to be turned into knowledge;
but that can only be done by our own meditation, and examining the reach, force, and coherence of what is said; and
then, as far as we apprehend and see the connection of ideas, so far is it ours; without that, it is but so much loose
matter floating in our brain.-Locke.

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LONDON:

JOHN CASSELL, LA BELLE SAUVAGE YARD, LUDGATE HILL.

UDCCCLV.

THE PRESENT Series of the Popular EDUCATOR is now completed. It was our intention to have closed it with a Supplement to Volume V., consisting of some 200 pages. But the difficulty of completing so many subjects in that limited space, together with urgent appeals from numerous Readers and Correspondents, induced us to postpone its termination till the completion of another Volume, uniforin with the five preceding. This will explain the continuity of the paging from the commencement of the Fifth Volume to the close of the work. The appearance of uniformity will be greatly preserved by having the entire Series bound in three double volumes.

In presenting these Six Volumes to the Public, we may confidently call them an EDUCATIONAL CICLOPEDIA ; comprising a vast amount of solid and useful information in a popular form, and at a price unprecedented cren in the present age of Cheap Literature. The higliest encomiuins have been bestowed upon our labours by a large portion o! the Public Press, by learned Profess rs, by Teachers of Youth, and by a host of Students who have profited by our publication. Every post has brought us numerous expressions of gratitude for tlic seasonable and valuable aid we have rendered, and of deep regret that we have brought our labours to a closc. We take our respectful leave of on friends, thanking them sincerely for the assurances they have given us that we have not incoured in rain.

PAGR

633

551

583

XXVIII. La vierge aux ruines. Sections I., II., III., IV.,

V., with exercises, etc.
XXIX. L'enfance du poète, with exercises, etc.

L'emploi du temps, with exercises, etc.
XXX. Les hirondelles, with exercises, etc. Le vieus

roi et la jeune fille ; Sections I., II., with ex.

ercises, etc.
XXXI. Sections III., IV., with exercises etc.

charité; Section I., with exercises etc. ....
XXXII. Section II., with exercises. Eudoxie ; Sections

I. II., with exercises, etc......

XXXIII. Section III., with exercises, etc.

XXXIV. Section IV., with exercises, etc. Le vaisseau

en péril, with exercises, etc. .......

615
632

647

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PAGB

LESSONS IN ALGEBRA.

XXI. Powers of Roots; Evolution ; General Rule for

Evolution; Reduction of Radical Quantities 416

XXII. Addition of Radical Quantities; Subtraction of

Radical Quantities; Multiplication of Radical

Quantities....

454

XXIII. Division of Radical Quantities; Involution of

Radical Quantities; Evolution of Radical

Quantities...

453

XXIV. Reduction of Equations by Involution ; Reduc-

tion of Equations by Evolution; Adfected

Quadratic Equations.

513

XXV. Method for Completing the Square; Second

Method for Completing the Square; Demon-

stration ; Other Methods of Completing the

Square, General Rule

527

XXVI. Problems in Adfected Quadratic Equations ;
Ratio and Proportion......

566
XXVII. Compound Ratio ; Proportion; Arithmetical
Proportion and Progression....

691
XXVIII. Geometrical Proportion and Progression ..... C24
XXIX. Problems in Geometrical Progression; Evolu-
tion of Compound Quantities

656
XXX. Applicatiou of Algebra to Geometry

719

LESSONS IN ARITHMETIC.

XXX. Decimal Fractions; Decimal Table; Exercises;

Adaition of Decimal Fractions

464

XXXI. Subtraction of Decimal Fractions : Muliiplica-

tion of Decimals ; Contractions in Multiplica-

tion of Decimals; Division of Decimal Frac-

tions; Contractions in Division of Decimals 486

XXXII. Periodical, or Circulating Decimal ; Reduction

of Circulating Decimals; Addition of Circu.

lating Decimals, etc. etc.

510

XXXIII. Percentage; Commission; Brokerage; and

Stocks

644

XXXIV. Inierest; Compound Interest..

574
XXXV. Discount; Bank Discount; Insurance ;

606
XXXVI. Life Insurance; Profit and Loss

640

XXXVII. Analysis

673

BIOGRAPAY.

XV. William Pitt

557

XVI. James Thomson

589

XVII. David Hume

623
XVIII. Samuel Johnson...

637
XIX. William Robertson

654
XX. Edward Gibbon

670
XXI. Oliver Goldsmith.

6S1
XXII. William Cowper

099
XXIII. Felicia Dorothea Hemans..

714
XXIV. Sarah Margaret Fuller

730
XXV. Laura Bridgman.....
XXVI. Catharine Maria Sedgwick

762

XXVII, Mrs. Trollope

778

XXVIII. Mary Russell Mitford

795

XXIX. Lydia Huntley Sigourney

811

LESSONS IN FRENCH PRONUNCIATION.

I. Alphabet ; Accents ; Cedilla; Dieresis; Hy-

phen; Apostrophe; Euphonic t; Parenthesis;

Asterisks

412

II., III. Name and Sound of the Vowels

432, 447

IV.' Consonants

462

V. Compound Vowels

497

VI. Diphthongs; Nasal Vowel Sounds; Nasat Diph-

thongal Sounds

524

VII. Liquids; General Rule for Pronouncing and

Reading French

559

FRENCH READINGS.

XXIV. La Marguerite et l'épi de hlé. Section II.,

with exercises, etc. Le chien du Louvre,

Section I., with exercises ...

451

XXVII. Section II., with exercises

539

LESSONS IN GEOLOGY.

LVII. Classification of Rocks; Permian Formation 555

LVIII.

Lithological Character of the

Coal Rocks

587

LIX.

on ibe Coal Measures ...... 617

LX.

651

LXI. Ola Red Sandstone, or the Devonian Furma-

tion; Lithological Character of the Devonian;

Organic Remains of the Devonian; Some

Geological Phenomena of the Deronian

Period

716

LESSONS IN GREEK.

XLVII. Formation of Words ; Verbs ; Compounds ;

Recapitulation....

421

XLVIII. Invariable Words

437

XLIX. Syntax; Preliminary Explanations; Subject;

Predicate; Agreement; Government

450

L The Parts of a Simple Sentence considered sepa-

rately; their Agreement.

465

LI. Voices of the Verb... ..................

479

LII. Tenses of the Verb................

499

LIII. Moods

515

LIV. Enlargement of Simple Sentences..

546

LV. Attributives ; the Demonstrative Pronouns ;

the Article

676

LVI. Attributive Words with Substantive Import;

Enlargement of the Predicate...

609

LVII.

the Single Accusative .. 641

LVIII. The Predicate with a Double Accusative 674

LIX. Import and Use of the Datire

701

LX. Import and Use of the Genitive ..............

736

LXI. Syntax of the Prepositions

764

LXII. Interrogative and Imperative Sentences 798

LESSONS IN ITALIAN.

XXXIV. Irregular Verbs ending in ere long (continued) 419

XXXV., XXXVI.

449, 467

XXXVII.' Irregular Verbs ending in "ere short ;"Verbs

ending in cere ....

481

XXXVII.

501

XXXIX. Verbs ending in dere

530

XL. Verbs ending in urre, contracted from cere; Verbs

ending in gere

561

XLI. Vebs ending in ggere ; Verbs ending in gliere;

Verbs ending in guere......

593

XLII. Verbs ending in lore; Verbs ending in mere;

Verbs ending in pere .

627

XLIII. Verbs ending in orre; Verbs ending in rere;

Verbs ending in tere; Verbs ending in arte;

Verbs ending in vere....

659

XLIV. Table of Terminations of the Verbs in isco 676

XLV., XLVI.

".... 688, 703

XLVII. Impersonal Verbs ; Participle ; Adverb ..... 722

XLVIII. Preposition ; Conjunction; Interjection 739

XLIX. Syntax: Of Articles

762

L.

of Nouns, Adjectives, Comparatives

and Superlatives, Numerals....

766

LI.

or Personal, Possessive, Demonstra.

tive, Relative, and Interrogative Pronouns.. 786

LII.

Of Indefinite Pronouus; of Verbs .. 801

LIII. or Participles, Adverbs, and Conjunctions.... 813

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LESSONS IN MORAL SCIENCE.

LESSONS IN READING AND ELOCUTION,

I. Conscience, or the Moral Faculty; The Moral

Faculty, Original and Universal; A Moral

XXIII. Religion the Guardian of the Soul; Study of

Faculty being supposed, whether its Dictates

Human Nature essential to a Teacher; The

are Uniform ? How far áll Ben are agreed in

Stage; Education ..

543

their Moral Judgments ....

414 XXIV. The Press; Greece in 1820; Trying to Please;

IL Whether Conscience is the same as the Under-

The Wild Boy; The Mocking Bird

531

standing, or a Faculty different from and

XXV. Characier of Julius Cæsar; Scrooge and

independent of it ; Moral Sense compared

Marley .....

613

with the Taste; Moral Obligation; Supre-

XXVI. Our Control over our Physical Well-being;

macy of Conscience

429

Classical Learning : Dame Nature's Charms 695

III. Whether we always do right by obeying the XXVII. The Lyre : Edmund Burke; Truth ..... 711
Dictates of Conscience? Whether there is XXVIII. God, the Creator; The Ursa Major

791
in the mind a Law or Rule, by which Man

XXIX. Excellence of the Holy Scriptures : Crescentius;
judges of the Morality of particular Actions ?

Rectitude of Character; Address to the
The Moral Feeling which accompanies every

Ocean; the Bible; the Downfall of Poland;
Moral Judgment; Belief in God, as con-

the Love of Truth

SOS
nected with the Operation of Conscience .. 444 XXX. The Scholar's Mission; the Treasure tiat

IV. Moral Agency, and what is necessary to it;

waseth not Old; the Young Mariner's Dream;

Man a Moral Agent; Man not under a Fatal

the Victor Angels ....

820

Necessity

460

V. Man's Direction and Government of his Actions,

LESSONS IN SPANISH.

and his consequent Responsibility; Objec-

tions to the Uniform Influence of Motives;

L Orthography and Pronunciation; Different

Summary View of Liberty

476

Methods of Spelling: Sound of Diphthongsand

VI. The kind of Indifference which has been con-

Triphthongs; Syllabication ; Accent; Punc.

sidered essential to Free Agency; Whether

tuation

469

Men are Accountable for their Motives, or

II. Of the Article and the Noun

484

whether Desires and Affections which pre-

III. Of the Adiective

503

cede Volition have a Moral Character? The

IV. Degrees of Comparison of the Pronoun... 517

Division of Motives into Rational and Animal;

V. Possessive Pronouns

532

Whether Morality belongs to Principles as

VI. Relative Pronouns; Interrogative Pronouns 519

well as Acts, or is confined to Acts alone ?.. 494 VII. Demonstrative Pronouns; Iudefinite Pronouns 563

VII. Moral Habits; Nature of Virtue

509 VIII. The Verb

579

VIII. Different Hypotheses....

541

IX., X., XI., XII. Conjugation 596, 611, 629, 614

IX. Whether Virtue and Vice belong only to

XIII. Reflective Verbs: Passive Verbs

661
Actions ?
572 XIV., XV. Irregular Verus

677, 691

X. Author of our Being, considered in Relation to

XVI. List of Irregular, Defective, and Impersonal

Moral Science

603

Verbs.....

703

XI. Phenomena of the Universe ...

635 XVII. List of Verbs with Irregular Past-Participles;

XII. Duties of Man to the Creator as thus manifested 668

Of the Adverb, the Conjuuction, the Preposi-

LESSONS IN PHYSICS, OR NATURAL PHILOSOPHY.

tion, the Interjection, the Article, the Noua,

the Adjective

725

LIII. The Eye considered as an Optical Instrument;

740

Sources of Light, and the Action of Light on

XVIII. List of Numerals, of Pronouns, of Verbs

XIX. Use of the Moods and Tenses of Verbs

754

Plants; Double Refraction; Polarisation 409

XX. Of the Passive Verb, the Regimen of Verbs,

LIV. Circular Polarisation.......

425

Verbs followed by certain Prepositions, ike

LV. Magnetism; Properties of the Magnet; Terres-

Use of the Verbs Ser and Estar

768

trial Magnetism; the Compass

441

XXI. Idiomatic Use of certain Verbs; of the Adverb

LVI. Magnetisation and Laws of Magnetic Action .. 457

XXII. Of the Conjunction

803

LVII. Electricity; Measure of Electric Forces

473
XXIII. Of the Preposition and Interjection

815

LVIII. Action of Electrised Bodies on Bodies in their

Natural State; Electrical Machines

489

LIX. Effects produced by the Accumulation of both

THEORY AND PRACTICE OF TEACHING.

Electricities

505

LX. Various Effects of Statical Electricity ; Dyna-

1. Spirit of the Teacher; Responsibility of the

mical Electricity; Voltaic Pile

521

Teacher....

695

LXI. Dynamic Electricity; Chemical Theory of the

II. Personal Habits of the Teacher

710

Pile : Constant Current Piles

537

III. Literary Qualifications of the Teacher

731

LXII. Constant Current Piles......

553

IV. Right Views of Education; Right Modes of

LXIII. Physiological, Physical, Magnetic and Chemical

Teaching; Pouring-in Process

760

Effects of the Galvanic Pile or Battery... 569

V. Drawing-out Process; the more Excellent Way;

LXIV. Magnetic Effects; Galvanometer

595

Waking-up Mind; Conducting Recitations.. 773

LXV. Chemical Effects of the Galvanic Pile or

VI. Exciting Interest in Study; Incentives to Study;

Battery

601

Emulation ; Prizes

780

LXVI. Electro-Dynamics; Electro-Magnetism

620

VII. Proper Incentives; School Government

80+

LXVII., LXVIII.

633, 613 VIII. Requisites in the Teacher for Good Government 812

LXIX Dynamical Electricity; Phenomena of Induc-

|

tion; Apparatus founded upon Currents of

LESSONS IN TRIGONOMETRY.

Induction

665

LXX. Phenomena of Induction; Practical Applica-

I. Plane Trigonometry; Solutions of night-Angled

tions of the Galvanic Battery

631

Triangles

734

LXXI. Dynamical Electricity; Practical Application

II. Solutions of Oblique-Angled Triangles

751

of the Galvanic Battery....

697

III. Trigonometrical Formule...

771

LXXII. Thermo-Electrical Currents.....

713

IV. Spherical Trigonometry; Right-Angled Sphe-

LXXIII. General Laws and Velocity of Electrical Cur-

rical Triangles.....

754

rents; Animal Electricity....

729 V. Oblique-Angled Spherical Triangles

796

LXXIV. Application of Electricity to Medical Purposes 745 VI. Trigonometrical Formu'v..

817

LXXV. Meteorology; Aerial Meteors, Aqueous Meteors 761

LXXVI. LXXVII. » Luminous Meteors

....... 777, 793;

MISCELLANEA.

LXXVIII.

809

POETRY:

Address to the Readers of the Popular Educator

520

The Rich Man's Son and the Poor Man's Son ......

436 Correspondence.

Elijah's Interview

744 Answers to Correspondents.

After the Battle...........................

744 | Literary Notices, etc. etc.

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Irradiation is a phenomenon in which white objects, or those ON PHYSICS, OR NATURAL PHILOSOPHY. of a bright colour, when seen on a dark ground, appear larger

than they really are. The reverse takes place with a black No. LIII.

object on a white ground. It is thought that irradiation arises

from the circumstance that the impression on the retina extends (Continued from page 396.)

more or less beyond the outline of the image. The effect of

irradiation upon the apparent magnitude of the stars is very THE EYE CONSIDERED AS AN OPTICAL perceptible, and they may thus appear several times larger INSTRUMENT.

ihan they really are.

According to the researches of M. Plateau, irradiation varies In sensible part of the Retina.—The retina is not equally sensi- considerably in different persons, and even in the same person tive in every part, as is proved by the following experiment of on different days. This philosopher has also shown that Mariotte. Let two black spots be made on white paper, at a irradiation increases with the Lrightness of the object and the distance of from half an inch to an inch from each other. Then, length of time it is observed. It is perceptible at all distances, when the paper is brought very near the eye, let the right eye is increased by divergent lenses and diminished by convergent be fixed upon the left spot without preventing it from seeing ones. the other. If the paper be now slowly withdrawn, the right

Accidental Halo. Contrast of Colours.—Colours which instead spot will disappear for a time, but reappear soon afterwards if of following the impression of an object like accidental colours, the paper is still further removed. The same thing will hap- appear round the object itself when attentively looked at for pen if the right spot is looked at with the left eye. Mariotte some time, are called accidental halos. The impression of the has remarked that at the moment when the spot ceases to be halo is the reverse of that of the object; that is to say, if the visible, its image is projected upon the insertion of the optic object is distinct, the halo is obscure, and vice versa. nerve in the interior and lower part of the eye. This insensible Contrast of colours is a reciprocal action which takes place part of the eye is called punctum cæcum, or the blind point. between two colours nearly allied, and by virtue of which

Continuance of the Impression on the Retina.-On whirling each of them assumes the complementary colour of the other. round a lighted coal with rapidity, we perceive a sort of band This contrast was observed by M. Chevreul, who profoundly of continuous fire. Similarly, the rain which falls in drops, investigated the subject, with a view to ascertain the laws of appears like liquid threads in the air. These appearances are the phenomenon. It is attributable to the reciprocal action of owing to the fact that the impression produced by objects the accidental halos above mentioned. M. Chevreul found on the retina remains after the object is removed or replaced that on red and orange being placed side by side, the red by another. The duration of this continuance varies accord- inclined to violet and the orange to yellow. If the experiment ing to the sensibility of the retina and the intensity of the be made upon red and blue, the red inclines to yellow and the light. M. Plateau of Brussels has discovered, by various blue to green. With yellow and blue, the yellow passes into methods, that it is on the average about half a second. orange and the blue to indigo, and similarly with many other

The impressions of colours as well as forms remain after the combinations. It is needless to remark how important is the removal of the objects that produce them, for if we divide a bearing of this subject upon the manufacture of cloth, carpets circle into sectors and paint them different colours, on turning and other coloured articles. Those who would wish to be it round, the colours mix and produce the sensation of the successful in combining colours must understand the principles colour which would be formed by their mixture. Thus blue of the effect of contrast. and green produce the sensation of green; yellow and red The Eye not Achromatic.-It was long the custom of philo. that of orange, blue and red that of violet; and the seven sophers to attribute to the human eye the property of perfect colours of the spectrum that of white, as is shown by Newton's achromatism, but this notion cannot be admitted without disc. There are several curious apparatus, the effects of which qualification after the various experiments of Wollaston, are explained by the continuance of the impressions upon the Young, Fraunhofer and Muller. Fraunhofer observed that in retina. Such are the thaumatrope, the phenakisticope, the a telescope with two glasses a very fine thread placed inside kaleidophone, and Farraday's wheel.

the instrument is distinctly seen through the eye-piece when Accidental Images.-If a coloured object be placed upon a the telescope is illuminated with red light only, but ceases to dark ground and looked at attentively for some time, the eye be visible, if, without altering the position of the eye-piece, soon becomes wearied and the intensity of the colour grows the telescope is illuminated with light of a violet colour. To feeble. On directing the cyes to a white piece of paper or on see the thread again, it is necessary to diminish the distance the ground, we perceive an image of the same form as the between the two glasses, much more than is required by the object, but of a complementary colour; that is to say, a colour refrangibility of violet light. Hence it is evident that part which would form white if it were combined with that of the of the effect is due to the aberration caused by the refrangiobject. In the case of a green object, the image is red, and bility of the eye. rice versa; if the object is yellow, the image is violet. These Muller found that, on looking with a single eye at a white disc coloured appearances were remarked by Buffon, who gave on a black ground, the image is clear when the eye is adapted them the name of accidental images or colours. Accidental to the distance of the disc, that is to say, when the image is colours continue for a length of time, proportioned to that formed on the retina. But he observed, that if the eye is not during which the object was observea, and to the intensity of adapted to this distance, that is to say, if the image is formed the light upon it. Generally speaking, they do not disappear at a distance either in front or at the back of the retina, the gradually and without interruption, but present alternate disc appears to be surrounded with a very narrow blue band. disappearances and reappearances. It is well known also that He concluded from this and other experiments that the eye is if, after having looked attentively at a coloured object, we achromatic as long as the image is received from the focal close the eyes rapidly, and as firmly as possible, so as to distance, or as long as the eye is adapted to the distance of exclude the light, and even screen them from the light by the object. It is not yet known what is the precise cause of means of a thick piece of cloth over them, the accidental images this apparent achromatism of the eye, but it is generally

attributed to the delicacy of the pencils of light which pass Various theories have been proposed to account for the through the aperture of the pupil, and to the fact that the rays phenomenon of accidental colours. That of Darwin is deser- being of various refrangibility, and meeting the media of the ving of mention. He thinks that the part of the retina wbich eye almost perpendicularly, are very little refracted, and hence is wearied by one colour, becomes insensible to the rays of the dispersion is not perceptible. As to spherical aberration, that colour, and is only capable of impressions of the com- we have already seen how that is corrected by the iris, plementary colour ; also, that this part of the retina spon- which is a real 'partition, arresting the marginal rays that taneously assumes an opposite mode of action, which produces have a tendency to go beyond the crystalline, and only sufferthe sensation of the complementary colour. The first part of ing those to pass which are nearest the axis. this theory does not explain the appearance of accidental Short Sighi and Long Sight. The usual cause of short-sightcolours even in darkness, and the second part is merely a edness is a too great convexity of the cornea or crystalline. statement of the phenomenon of accidental images.

The eye being then too convergent, the focus instead of being VOL. Y.

131

still appear.

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