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Oi is the old form of the dative, so that oukou is for xv qurY. 1. Adverbs of place.

Λθηνησι is for Αθηναις, the dative of Aθήναι; this ending One kind of adverbs of place is derived from the preposi- applits particularly to the names of cities. tions. I shall arrange opposite to each other the eighteen

Okv appears to be an ancient form of the genitive; the poets prepositions and the adverbs to which they severally give say ozbev for ooù, of thee; thus olxo@ev is equivalent to birth.

εξ οικου.

Hi is the termination of the dative, oow being understood; Prepositions. Adverbs.

Meaning

thus ally is for ev ally oồw, by another way. ενδον 1. EV

within EVTOS

2. Adverbs of Time. 2. εις

within (with motion) 3. προς προσω

forwards, in advance The principal adverbs of time are the following:

EKTOS 4.

εξω
outwards, externally

onlepov, to-day (from vijepa, a day) Lat. hodie 5.

at
backwards

αυριον, , 6. δια

διχα
sepurately, apart χθες, , yesterday

heri 7.

abore

προθες, , the day before yesterday nudius (nunc dies) tertius 8.

below

πρωι, ,

in the morning
9.
παρα and εξ

without, out of
oue, in the evening

t'espere
παρεκτος
10.)

vūv, vuri, now
and ξυν μεταξυ
μετά
11.

between
παλαι, , of old, formerly

olim, antea
12.
υπερ
υπερθε above, aloft
ουπω, ,

nondum 13. υπο υπαιθα before the eyes non, by this time

jam 14. про πορρω

in advance, moreover 15.

έτι, αμφι

jam, amplius on both sides

αμφις 16. пері περιξ around арті, , lately, but now

modo 17.

behind, at the back

αυτικά, ,

immediately
18.
αντικρυ in face of

TOTE,
then

tunc
ποτε,

some time These adverbs are often found before a genitive, and so per- Baua,

aliquando, tandem

often form the part of prepositions ; e.g.

sape

αει, always, successively semper, usque πορρω της πολεως, ,

OUTOTE,

nunquam
far from the city.

πριν, ,
previously, before

prius
εισω του χαρακος, ,'

ειτα, ,
next, then

deinde
within the entrenchments.

3. Adverbs of Quality. The following also may have a genitive; and others, which will be learned by practice, as

Adverbs of quality end in ws, and correspond to our adverbs Tole, far off

πελας, near

σοφώς, on the other side of

,

wisely Lat. sapienter } (a river)

EYYUS, near περαν,

πεπαιδευμενως, learnedly docte xwpis, separately

ευδαιμονως, , fortunately

feliciter ayxl, near

To this class may be referred There is another kind of adverbs which, by means of certain terminations, express the different relations of place.

outws, before a consonant, outw, thus, in this way, from oŭros; Place where you are. Place whither you go,

EKELVWS, in that way, from EKELVOS, that person. πού, ποθι, where ?

moi, , whither? And in general all the adverbs ending in ws. εκεί, εκείθι, there

Ereigt, thither

Others have the form of the genitive or dative of the first οικοι, οικοθι, at home

οικονδε, home

declension, Αθηνησι, at Athens

alloge, somcwhere else
Αθηναζε, το Athens

esiis (from obsolete nominatives), forthwith.

εική Place whence you come. Place through which you pass.

by chance.

ήσυχή (from ήσυχος), peacefully. ποθεν, whence ?

711, by what way Eksidev, thence EKELVY, by that way

Usage has suppressed the iota subscript as found in nouxo

vou. Other adverbs of quality have the terminations Ely TV οικοθεν, from home

oti, and consequently resemble datives of the third declension: allokv, from some other place ally, by some other way Aunvnbev, from Athens

havònuel, en masse, the whole people.

apaxnti, without combat. From this view you see that the terminations or particles

EXAmnioti, in the Greek language or manner. ου, θι, οι, σι,

denote the place where you are Some bave the form of accusatives :dt, ge, Ge, and sometimes 01, θεν

whence you come

patyy (nominative obsolete), in vain. through which you

owplav (nominative obsolete), gratuitously. 9 2

{pass Those of this division in gov and önı, correspond with the

Latin adverbs in tim :Ov is the termination of the genitive; thus toő represents enti που τοπου, in what place!

ayel.moov, gregatim, by focks.

kpußön, furtim, secretly.

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many times ?

και

Finally, some terminate in is :

Acc. dimnv (kata), in the form or manner of.

χαριν (προς), in fαυour of. johıs or poyes, scarcely, with difficulty ;

προίκα (κατα), gratuitously. and in :oda, with the teeth.

Sometimes the preposition is expressed and united to the daß, with the heel.

noun, as : Tuš kal das, with all one's might.

παραχρήμα (παρα, αt; χρήμα, the thing), at the moment.

povpyov (rpo, for; spyov, the deed), usefully, beforehand. 4. Adverbs of Quantity.

EXTO Wv (ek, from ; nous, the foot), at a distance, far from. The adverbs of quantity are susceptible of the same termi

Adverbs formed from adjectives imply a substantive :nations as those of manner. Here are some of them :

Dat. ιδια(εν ιδια χωρα), in particular; πεζγ(εν πεζή οδω), on foot. ayav, too much.

Acc. μακραν (εις μακραν οδον), a long way, at a distance. diav, extremely.

The neuter of the adjective is often employed as an adverb;

as the dat. holdy, much, by much; rjov, agreeably; devov and adnv, abundantly.

delva, terribly; totepa, whether? Erithoes, on purpose.
alıç, sufficiently.
Those which particularly mark number, end in aris :

Conjunctions.
TOOakıS (from 700os, how many ?), how often? how

The following is a list of the chief conjunctions :-
Tollakis (from nolue, numerous), many times.

Greek.
Latin,

English,
Tetparis (from Tetrapes, four), four times,

et

and. FEVTAKIS (from AEVTE, five), five times.

TE

que vel

or. The rest of the adverbs formed from the cardinal numbers,

ουτε, μήτε

neque, nec follow this analogy; except :

nor. ουδε, μηδε

et non únaonce, semel i ous, twice, 61 ; rpis, three times, ter. αλλα

sed

but.
ok

vero
tamen

however,
5 ddverbs of Interrogation.

μεντοι
καιτοι
atqui

yet. | asks a question simply,

do you say this?

apa
ergo

then,
η λεγείς τουτο;

OUV
igitur

therefore, åpa asks a question mostly with an do you, then, say this ? TOLVUD

igitur expressive then,

άγα λεγεις τουτο;

γαρ
nam

for.

UL μών (μη ούν), expects a negation, ηum ; μων λεγεις τουτο; you

av

si do not say thie, do you?

if.

εαν It is also used in simple interrogations.

EITE
sive

or, whether.

nisi, si non unless, if not. 6. Affirmation.

ει και

et si, etiam si and if.
καν
et si

and if. is, unv, yes, certainly, in truth.

ότι
quod

that. ápa, in the poets

ώς, ώστε ut

80 as, so that.
then, certainly, assuredly.

iva
ut

in order that.
ne, ut non

in order that not, lest. on,

επει
quia

because, since. pev denotes a contrast, and strengthens, = indeed, quidem. διοτι

quia

because, that. ye asserts something in addition, and gives emphasis to its γούν

itaque

therefore, word, = at least.

επειδη
cum or quum

since. vai (Lat, næ, English, nay), yes, truly.

επειδαν postquam

after that. OTE

} quum when,
7. Negation.

όταν
έως
dum

until,
ov (our before a vowel)
no, with direct negations and όπως

quomodo

how QUX4, Attic indicative mood.

ως, ώςπερ ovõapws, by no means

sicut μη, ου μη, μη ουχι I that not, with indirect negations

Of these conjunctions some are simple, as kau, te, ús; others unoapws, by no means

and imperative mood.

are compound, as ουτε (ου and τε), μεντοι (μεν and τοι), καιτοι (και and τοι), τοινυν (τοι and νυν), ώςτε (ωand τε), διοτι (δια

οτι, neuter of όςτις), γούν (γε and oύν), επειδη (επει and δη), 8. Doubt.

επειδαν (επει, δε, and αν), όταν (ότε and αν); and others are ισως, τάχα

two separate words, as ει μη, ίνα μη. mov, without accent } perhaps, probably.

There are other conjunctions, whether a single word, as δηκου

ηνικα, υλen, or several words united, as τοιγαρτοι (τοι, γαρ, δήθεν } apparently.

του), ηοιο then ; τοιγαρούν (τοι, γαρ, ούν), herefore, on that

account; or, again, several words in å separate state, ov prv There are some words which, without being adverbs, are alla, howerer; plyv et un, if only. employed adverbiaily. We have seen adverbs which have the One or two others deserve notice, as åte, seeing that, as being, form of the genitives, datives, and accusatives. We are now e.g; ite ayados, as being good (Latin, utpote bonus); nep, 10. see those cases themselves perform the office of adverbs. although, e.g. ayabos Tep, although good. Their cas-s are owing to certain prepositions which have been dropped in conversation :

There are certain words employed as adverbs, in the com

position of which there is a conjunction, e.g. ondovoti, eriGen. VURTOS (Oia), by night, at night,

dently; that is, onlov xotiv óti, it is evident that; evite, someDat. Bıç (ouv), by force, forcibly.

times, made up of ev, for eqtiv, and one (in Latin, est quando).

The Greek is rich in conjunctions. Some of its conjunctions KUKAY (Ev), in a circular, circularly.

express shades of meaning which can scarcely, if at all, be

Et pin

pa, τοι, ,

iva fin

as, as if.

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αδικον εκρινεν, ,

rendered into English, and which can be appreciated only in by plane geometry, when there is no occasion to apply any other principles

than those of that science.- ALPRED C. HILARY will find the work on the original, by the fine sense of a superior scholar,

Chemistry, published in Chambers's Educational Course, very good and

cheap. Interjections.

W. W. SNELLING will see one of his questions answered in the last para

graph. As to the other, we can only find room for a partial answer. The
Interjections, as expressing almost inarticulately the passions following is the order in which mathematics may be studied with advan-
and emotions of the mind, are also numerous in the language tage.
of the Greeks, who were a people of strong feelings. The

Arithmetic-Cassell's, Colenso, or De Morgan.

Algebra-Cassell's, J.und's Wood, or Coiengo. principal interjections are these :

Euclid-Cassell's,

Trigonometry-Hymers, Colengo, Hemming, or Snowball,
W, O! (sign of the vocative, ü, 0! expressing pain or Mechanics (including Statics and Dynamics)-Snowball, Pratt, Whewell,
lov, ah! alas!

surprise.) Moseley, Earnshaw, or Tate.
LEŪ, eheu! ho!

Conic Sectious_Hymers or Puckle.

Analytical Geometry-Hymers, O' Brien, or Young.
фей, ай!

Newton's Principia-Evans, or Whewell.
Baßai, ah! oh! (Latin, pape !)

Differential Calculus-De Morgan, Todhunter, Hemming, or Hall.
oval, woe!

Integral Calculus--Hymers, De Morgan, or Hall.
å, ah!

Optics-Griffin.
Airy's Tractx, etc. etc.

JAMES BURLEY: The scales appended to the maps in the POPULAR
alas! (Latin, hei!)

EDUCATOR explain themselves. The numbers affixed to different points of
the line, show how many niles are represented by the lengths of the line

between the zero point (or farthest point to the left) and the above points.
Ela, come! (Latin, eia!)

A WOULD-BE PHOTOGRAPHER: The instrument in question is an ordi-
Evya, well done ! (Latin, euge!).

nary camera obscura, and may be obtained of Horne, Thornthwaite and Co.,
Soma imperatives are used as interjections :-

Newgate-street, or any optical instrument maker.

PERSEVERANTIA: Professor De Lolme's Manual will be foand very useful, αγε

though not perhaps absolutely necessary. Dr. Beard's Latin Made Easy, φερε come ! (Latin, age !)

is scarcely required by one who has his lessons in the POPULAR EDUCATOR. 10

Andrews and Stoddard's Latin Grammar, is indispensable to a thorough
anaye, begone ! (Latin, apage!)

knowledge of Lalin. Dr. Beard's History of English Literature is not
published separately. The Historical Educator is now complete in two

volumes. You are mistaken in supposing that if a trader keeping his books
HISTORICAL ANECDOTES.

by double entry, sold £30 worth of sugar for ready money, no notice would

be taken of the transaction in the sugar account. Whether the money le Αγησιλαος περι ανδρειας και δικαιοσυνης ερωτηθεις, ποτερα pald at once or at a future time, makes no difference. An usher is an

assistant teacher, and the qualifications for the office are obviously, kuow-
βελτιων, Ουδεν ανδρειας, εφη, χρηζομεν, εαν παντες ώμεν | ledge, patience. good temper, and power of command, not to mention others.
δικαιοι. . Ou

μόνον
δε το μη αποδιδοναι χαριτας

The advantage of matriculation is, that it enables you to take a degree.

It is not necessary to know both French and German in order to αλλα και το μη πολυ μειζους τον μειζω δυναμενον. , Ala to matriculate at the University of London; either of the two is sufficlent. φιλοπονος ειναι, , πάν μεν το παρον ηδεως επινε, πάν δε το συν

Private students cannot take degrers there without matriculating and join

ing one of the colleges or institutions in c.nnection with the university.
τυχον ήξεως ησθιεν εις δε το ασμενως κοιμηθήναι πάς τοπος ην we cannot find rooin for lessons in civil law.
ikavos avia. Aidovros oe avto taj olla oūpa Ti@pavorov, Algebraical Problems. His solutions and occasional remarks do him great

D, HORNBY has solved Problems 56 to 19 of the Second Centenary of
ει απελθοι εκ της χωρας, απεκρίνατο ο Αγησιλαος, Ω Τιθραύστα, credit. - THOS. Bo κcock has solved sixteen of the Second Centenary and

F, II. BIRTWHISTLE all of them, except only No. 33. νομιζεται παρ' ημιν το αρχοντι καλλιον ειναι την στρατιαν η

ERGATEyámay obtain the books he mentions at any bookseller's, either εαυτον πλουτιζειν, και παρα των πολεμιων λαφυρα μάλλον new or second-hand. There are several religious newspapers which are πειράσθαι η δωρα λαμβανειν. : Αποθνησκων δε τους φιλους Record are the principal church weekly newspapers.

known to every body. The Enigli-h Churchian, the Guardian, and the εκελευσε, Μηδεμιαν εικονα ποιησασθαι· ει γαρ τι καλον εργον ED'ARD Wood inay get all the information he requires from any optie

cian. πεποιηκα, τουτο μοι μνημειον εστιν ει δε μηδεν, ουδ' οι παντες

GULIELMUS TALBATUS: We cannot promise what you wish at present. ανδριαντες. .

ARITHMETIC: 81,000,000,000,000,000,000,000,000,000. To find the true

discount of a given sum for a given time at a given rate, say-The amount
VOCABULARY AND REMARKS.

of £100 for the given time at the given rate : £100 :: the interest of the
given sum for the given time at the given rate : the discount required. In

business discount is the same as interekt.
Το μη πολυ μειζους, supply αποδιδοναι

W. M. WILLRY: We have been exceedingly gratified with your French
Ouvtuyov, whatever he met with ;

communication, which does you infinite credit, considering how short a
kouunivai (from xoquiao, I lie. I sleep), every place suffioed to time you have studied the language. It is satisfactory to know that our
afford him a pleasant couch (or bed).

A NEW SUBSCRIBEX's handwriting is good, but must be improved still
Διδoντoς, offering to give ; λαφυρον, ου, το, booty, spoil.

further before he can hope to get into a merchant's office.
Avčpravtes, all images would not (no image vould) be a (per- G. ARCHBOLD: Our Lessons in German will prepare you for translating
manent) memorial of me.

German letters, provided you make yourself familiar with the Germaa style
What are these parts (what is their mood, tense, person, man mercantile letters.

of writing. It would also be desirable to get a work containing solne Gero
etc.)? namely :-

L. G. LAMBE: We find no promise given in the place you mention. ερωτηθεις; χρυζομεν ; αποδιδοναι και εκρινεν και ησθιεν; κοιμη

ICONOCLASTES may get the works he wants from Paternoster Row. θήναι; απελθοι και απεκρινετο; πειράσθαι και πεποιηκα.

R. W. STY had better study the subjects he mentions in the order he

has given them. His hand-writing is hardly good enough for a clerk's
Decline the following:-ανδρειας και χαριτας και μειζους; τοπος ; εituation in these improved times.
δώρα και εικόνα και μνημειον; ανδριάντες.

JOHN TENNANT: We cannot engage to enter upon the subjects of which
you speak.

1. 11. Southell: The chief qualifications for a clerkship are superior
handwriting, and quickness and accuracy in accounts. Our lessons in
Bookkeeping ought to be amply sufficient, but they must be thoroughly

mastered, and our correspondent must get a racility in working ari:binetical ANSWERS TO CORRESPONDENTS.

questions correctly, besides improving his handwriting.

H, K. L.: Our lessons in Chemistry are closed.
We have received numerous expressions of gratitude for our past efforts
in the cause of Popular Education, and regret at the prospect of their dis-
continuance in the present publication. ur correspondents may be
assured that their communications will meet with all the consideration to
which they are entitled. We hope still to promote the education of the

LITERARY NOTICES.
people in other ways, and have repeatedly intimated our intention of giving
articles on drawing early in the coming year.

Cassell's LESSONS IN LATIN.--Price 24. 6d. paper covers, or 3s, beat
C. R. The lessons on Chemistry are concluded. Electricity and galvan-

cloth.
ism will be discussed in our lessons in Physics.-Tav: The principles in A KEY TO CASSELL'S LESSONS IN LATIN. Containing Translations of
plissics, corresponding to axioms in Geometry or any other subject, are

all the Exercises. Price Is, paper covers, or is. 6d. cloth.
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Acts of the Arostles in the Original
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Naturai and Artificial Magnets. The name of magnet is given to substances which possess the quality of attracting iron and some other metals, such as nickel, cobalt and chromium. We shall, however, give an account of experiments which prove that magnets act really upon all substances, sometimes by attraction, sometimes by repulsion, but with very slight effect.

There is a marked distinction between natural maynets and artificial magnets. The real magnet, or loadstone, is an oxide of iron, known in chemistry as the magnetic oxide. The magnetic oxide is very abundant. It is found in primitive formations, especially in Norway and Sweden, where it is worked as ironstone, and yields the best iron in the world.

Artificial magnets are bars or needles of tempered steel, without any natural magnetic qualities, but capable of acquiring them by friction with a magnet, or by means of electric processes to be hereafter described. Artificial magnets are also made of soft or malleable iron, that is, iron without any perceptible amount of foreign matter in its composition. Their magnetic power is not, however, so durable as that of steel rods. Artificial magnets have more power than real ones, and possess at the same time exactly similar qualities.

The attractive power of magnets exists irrespectively of dis- needle near the south pole a of the first, we shall at once see tance and the interposition of solid or other masses; but it north pole 6 of the moveable needle, there will be a power

a marked repulsion; while if we present the pole A to the decreases as the distance increases, and varies with the tem; ful attraction. The poles a and b then are not identical, as the perature. It has been shown that the magnetic force of a rod one is repelled and the other attracted by the same pole a of diminishes as its temperature is increased, but recovers its the magnet which we hold in our hand. We can in the same original intensity when it regains its primitive temperature, way verify the fact that the two poles of the latter magnet provided a certain limit is not passed ; for at red heat magnets also differ one from the other, by presenting them in turn to entirely lose their power.

The attractive power exercised by the magnet over iron is the pole a of the moveable needle. "In the one case the needle reciprocal, a fact

true as a general principle of all attractions. is repelled, in the other it is attracted. We may then at once This may be verified by holding a bar of iron towards a magnet, influence of two magnets :

lay down the simple axiom with regard to the reciprocal when the latter will be attracted. The attractive influence of the magnet is known as Magnetic poles of an opposite name attract."

“ The poles of the same name repel one another, and the Power or intensity, and the theory in natural philosophy is

That is, a repels A and attracts b; b repels B and attracts a. called magnetism, an expression which must not be confounded with Animal Magnetism, which is employed to signify demonstrated by the following experiment. "Place a piece of

The contrary action of the north and south pole may also be the power possessed by one person orer another by the force iron, a key for instance, close to a magnetic bar; then over of his will--a power far from being proved to exist.

this bar slide a second of the same power, fig. 363, taking care Poles and Neutral Lines.-Magnets do not possess the same magnetic force in every part. If you roll a magnetic bar in

Fig. 563. iron filings, these will be found to adhere to the ends of the bar, in the shape of tufts of hair standing on end, fig. 361,

Fig. 361.

B

The adherence of the filings rapidly decreases from the extre- to reverse the poles. The key will stick fast as long as the
mities till it disappears altogether in the middle of the bar. two poles are apart, but as soon as they are sufficiently near,
That part of the surface of the magnet where the attractive it falls, as if the bar that supported it had suddenly lost all
power is imperceptible, is called the neutral line or point, magnetic power ; but this will be seen not to be the case as
and the two points at the extremities where the power is soon as the second bar is removed.
greatest are called the poles. Every magnet, real or artificial, Theory of two Magnetic Fluids.-To explain the pheno.
has two poles and a neutral line. In the magnetising, how- mena to which we have already alluded, natural philosophers
ever, of rods and needles, opposite poles are sometimes pro- have been induced to adopt the theory of two magnetic fluids,
duced alternately situated between the extreme poles. These each Auid acting by repulsion on itself, and by attraction on
intermediate poles have been called consequent points. But the other Auid. One of these fluids is called the southern
usually there are only two poles, and we shall only speak of Auid, and the other the northern Huid, from the names of the

poles of the magnets upon which their influence is predomi.
The one pole is called the South or Antarctic pole; the other nant.
the North or Arctic pole; expressions which owe their origin to It is supposed that before the state of magnetism, these
the influence of the terrestrial poles on the magnet. In our Auids are combined around each particle and neutralise each
TOL. V.

133

two.

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other; but that they may be separated under the influence of put in contact with a magnet, a bar of steel becomes magnetic
a power greater than their mutual attraction, and may alter only by slow degrees. It is even necessary to rub it with one
their position around the particles without going out of the of the poles of the magnet, if we wish to give the whole force
sphere of action assigned to them in the neighbourhood of the of the loadstone. The separation of the two Auids presents a
particles. The fluids are then set with regard the cardinal resistance which is not found in malleable iron. It is the same
points; that is to say, in the magnetic sphere which surrounds with their recomposition; for a bar of steel, once magnetised, is
each particle, the northern fluid flows constantly in one direc- a very long time before it loses its magnetic power, By
tion, and the southern Auid in an opposite one; whence oxidation, pressure, or twisting, soft iron may acquire å
arise two resultant forces acting in contrary directions, the certain coercive force, but of shore duration.
points of application of which are the two poles of the magnet. Ex periments with Broken Magnets. The presence of the
As soon, however, as the setting of the fluid ceases, equili- two fluids in every magnet is demonstrated by the following
trium is again established around each particle, and the final experiment. Take a steel knitting-needle, which is magnetised
result is null, that is to say, there is neither attraction nor by rubbing it over with one of the poles of a magnet. Then
renulsion.

having thus proved the existence of the two poles and the neutral
The theory of two magnetic fluids readily explains many line by means of the iron filing experiment, break the needle
phenomena, and is therefore generally adopted as a means of in the middle, that is to say, at about the neutral line. Now,
demonstration. It will be seen, however, hereafter, that in if you bring the two halves successively in contact with the
all probability magnetic phenomena result, not from the oppo- poles of a moreable needle fig. 362, you will find that instead of
site actions of two particular fluids, but from particular cur- each containing only one fluid, each separate part has its two
rents of electric matter in magnetised bodies an hypothesis poles and its neutral line. If you again break these two magnets
which has the advantage of connecting the theories of mag- into two other parts, you will again find that each of these
netism and electricity together.

again is a complete magnet, with its two poles and neutral
Difference between Magnetic Substances and Magnets.-Mag- line, and so on as long as you can break the steel into lengths,
netic substances or bodies, are those which are drawn or We conclude, therefore, from analogy, that the very smallest
attracted by the magnet, such as iron, steel, nickel. These parts of a magnet contain both fluids.
bodies all contain the two fluids, but in a neutralised state. Action of Magnets on all Substances -- Diamagnetism.---
Ferruginous compounds are generally magnetic, and are the Coulomb, in 1802, observed that magnets act upon all sub-
mure so, the more iron they contain. Some, however--as per- stances in a greater or less degree; a phenomenon which he
sulphuret of iron for instance-are not attracted by the demonstrated by causing little bars of various substances to
magnet.

oscillate first between the opposite poles of two strongly
It is easy to distinguish a magnetic substance from a mag- magnetised bars, and then away from the influence of any
net; the former has no poles. On being presented successively magnet, and comparing the number of oscillations in the two
to the two extremities of a moveable needle a), fig. 362, it cases in equal times. At first the result of these experiments
attracts both, while a magnet would attract one and repel the was ascribed to the presence of ferruginous matters in the
other, if the same end of the same magnet were presented to substances upon which the experiments were made; but M.
them.

Lebaillif, and at a later period Messrs. Becquerel, demonstrated Magnetisation by Induction or Contact.-When a magnetic sub- that magnets have really an influence upon all substances. It stance is put in contact with a magnetic bar, the two fluids of has been proved that ihis influence is sometimes attractive, this substance are separated, and it becomes, as long as the con- sometimes repulsive. The substances which are attracted are tact lasts, a complete magnet, with its two poles and neutral called magnetic bodies, while those which are repelled bare line. For example, if you apply to one of the poles of the mag. | been denuminated diamagnetic substances.

Among these net, fig. 364, a small cylinder ab of soft iron, this cylinder may be mentioned bismuth, lead, sulphur, wax, water, etc.

Copper is sometimes magnetic, sometimes diamagnetic

, which Fig. 364.

probably depends on the degree of its purity:

Mr. Faraday, in 1847, noticed that powerful magnets had a strong repelling influence upon flames, which he attributed to a different degree of diamagnetism in gases. M. Edw. Becquerel subsequently made some important experiments on this subject, and found that, of all gases, oxygen has the greatest magnetic power.

Some natural philosophers have described the diamagnetism
as a property distinct from magnetism. M. Edw. Becquerel
has connected the phenomena of magnetism and diamagnetism
by an ingenious hypothesis. He considers that there are not

two distinct kinds of action between bodies and magnets; but
will in its turn bear a second, then a third, and so on to seven only one kind of magnetic induction, and that the repul.
or eight, according to the force of the bar. Each of these little sion exerted upon certain bodies is to be accounted for
cylinders is a magnet, but only while the influence of the mag. by the fact that these bodies are surrounded by a medium
netised bar lasts. If the contact between the magnet and the more magnetic than themselves.
first piece of iron be broken, immediately, or at all events after
a very brief interval, the other cylinders are detached and

TERRESTRIAL MAGNETISM-THE COMPASS.
retain no trace of magnetic force. The separation of the two The Directing Influence of the Earth on Magnets.-- When
fluids has therefore only been temporary. Nickel is also we hang a magnetic needle by a thread, as in fig. 362, or when
easily magnetised under the influence of a powerful magnet. we place it on a pivot upon which it can easily turn (fig. 365),

Magne isation by contact explains the formation of the tufts we observe that the needle, instead of settling down in any
of iron filings which cling to the poles of the magnet, fig. 361. chance position, always ends by becoming stationary in a posi-
The particles in contact with the magnet act upon the next tion which is more or less that of north and south. The same
ones, there again upon the following, and so on, which gives thing occurs if in a vase full of water we place a cork float, and
rise to the thread-like arrangement of the iron filings around on this lay a little magnetised rod. The cork oscillates at
each pole.

first, and when it stops, the straight line which joins the two
Coercive Power.—We call that coercive power, which in poles of the magnet is still about in the direction of the north
a magnetic substance more or less opposes the separation of and south. It must, however, be noted that in this experi-
the two fluids, and their subsequent recomposition when they ment neither the

cork nor the bar moves to the north or south.
have been separated. From the above experiment, it will be The action of the terrestrial poles on the magnet is not attrac-
seen that this power is imperceptible in soft iron, this metal tive, but merely a guiding influence.
being instantly magnetised by contact with a magnet. In

Similar experiments having been made in all parts of the
tempered steel, on the other hand, this power is great, and world, the earth has been assimilated to an immense magnet
greater in proportion to the

temper of the steel. In fact, when the poles of which are near the terrestrial poles, and the

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