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mean, with be

most perfect eans. The

Irregular Verbs continued.

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were 193 he idea 1

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INFINITIVE
PRESENT INDICATIVE.

IMPERAT. PARTICIP.

REMARKS.
Schleifen i) to sharpen, ich schleife, ?c.

ich schliff ich schliffe fchleife or geschliffen. :) Regular in all other signito whet,

schleif

fications, as, to demolish, or Schleißen, to slit, ich schleiße, ?c

ich schlig ich schliffe fohleiße geschliffen. to drag.
Schliefent
, to slip, ich schliefe, ac.

ich schloff ich schlöffe schliefe geschloffen.
Schließen, to shut, ich schließe, uc.

ich schloß ich schlosse schließe geschlossen. Schlingen, to sling, ich schlinge, ae.

ich schlang ich schlänge schlinge geschlungen. Schmeißen, to fling ich schmeiße, c.

ich schmiš ich schmisse schmeiße geschmissen. Schmelzen k), to melt ich schmelze, du schmelzest ich schmerz ich schmölze fehmitz or geschmolzen. k) As an active verb it is re(schmilzest), er schmelzt

schmelz

gular,
(schmilzt)
Shnauben, to snort, ich schniebe or dynaube ich schnob ich schnöbe schnaube geschnoben.
Schneiden, to cut, ich schneide, x.

ich schnitt ich schnitte schneide geschnitten.
Shrauben 1), to screw, ich sdhraube, xc.

ich schraubte ich schraubete schraube geschraubt 1) Commonly regular, schraubte, (schrob) (trobe)

(geschroben) geschraubt.
Schreiben, to write ich schriebe, 26.

ich schrieb ich schriebe schreibe geschrieben.
Schreien, to cry,
ich schreie, 3.

ich scrie ich schriee (dreie geschrieen.
Schreiten, to stride, ich schreite, a.

ich schritt ich schritte schreite

geschritten. Schroten, to bruise, to gnaw ich schrote, uc.

ich schrotete ich sdrotete schrote geschroten. Regular now except in the

participle, and this is fre

quently geschrotet. Schwarenm), to suppurate, ich schwäre, ac.

ich schwor ich schwöre dwäre geschworen. m) Schwierft a. in the present Schweigen, to be silent, ich schweige, 2c.

ich schwieg ich schwiege ichweige geschwiegen, is provincial Schwellen n), to swell, ich schwelle, bu schwillst, er ich schwoll ich schwolle schwill or geschwollen. n). Regular, when active. schwillt

schwelle Schwimmen, to swim, ich schwimme, a.

ich schwamm ich schwämme schwimme geschwoms Schwinden, to vanish, ich schwinde, 26.

ich schwand ich sdwände ichwinde geschwunden. Schwingen o), to swing, ich schwinge, ac.

ich schwang or ich schwänge schwinge geschwungen.) Schwung is less in usage sch:yung

than sehwang. Schwören, to swear, ich schwöre, 2c.

ich schwor or ich schwöre or schwöre geschworen.

schwur schwüre
Cehen, to see,
ich sehe, du siehst, er sieht ich fah ich sähe

gesehen.
Sein, to be,
ich bin, 2.

ich war, ze. ich wäre sei gewesen.
Senden, to send, ich sende, xc.

ich sanfte and ich sendete sende gesandt and
sendete

gefendet.
Sieben p), to boil, ich siede, 26.

ich sott ich fötte fiebe gesotten. p) When active it is mostly
Singen, to sing,
ich finge, sc.

ich sang ich fänge finge gesungen. regular.
Sinfen, to sink,
ich finke, 2c.

ich sant id fänke finte gesunken.
Sinnen, to think, to muse, ich sinne, ac.

ich sann ich fanne siune gesonnen.

(sonne)
Sißen, to sit,
ich fine, 16.

ich fas

ich fäße fiße gesessen. Sollen, to be obliged, ich soll, du sollst, er fort ich sollte ich sollte

gesollt. Spalten Q), to split, ich spalte, c.

ich spaltete ich spaltete spalte gespalten. ) Irregular only in the parSpeien, to spit, ich speie, sc. ich spic ich spiee

ticiple, and this is some. Spinnen, to spin, ich spinne, c.

ich spann ich spänne spinne

gesponnen. times gespaltet when the verbs (spönne)

is active, Spleißen, to split, ich spleiße, 26.

ich spließ, spliß ich spilfse spleiße gespliffen. Sprechen, to speak, id) spreche, du sprichst, er sprichtlich sprach id) spräche sprich gesprochen.

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9

II.
I now proceed to explain Italian pronunciatiou in a method
of recent adoption by some ingenious teachers of Italy, by
which all the combinations of the vowels and consonants, and
consequently all the ingredients and component parts of the
language, will pass under the eye of the reader. Let him learn
from the very beginning of his labours to pronounce each sylla-
ble of the following words and tables, and he will soon acquire
a correct method of pronunciation. No word or combination
of words can offer any difficulty to him, because he will have
mastered the component parts of all words in these tables.

The Italian language has five yowels, representing seven
sounds :

1. a invariably sounded like the English interjection ah.
II. i invariably sounded like ee in see.
III. u invariably sounded like oo in too.
IV. 1. e invariably sounded like ay in say, but with a slight

opening of the mouth only, and with an elevated
and clear tone. It is called, on that account, the

close sound of the vowel. 2. e invariably sounded something like e in let, set, and

the first e in every, but with a wide opening of the mouth, and with a deep sound. It is called, on that

account, the open sound of the vowel. V. 1. o invariably sounded with a medium sound between

o and 00 , which has no equivalent in the English language, but which may be easily caught by the ear from hearing an educated Roman or Tuscan speak. Perhaps an approximation is the o in bone, hole, and note, but with a slight opening of the mouth only, and with an elevated and clear tone. It is called, on that account, the close sound of the vowel

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2. o invariably sounded something like o in Lord and inexpedient to lay down now, as they would not at this stage

orange, but with a wide opening of the mouth, and of our progress be thoroughly understood, but which I shall with a deep sound. It is called, on that account, take occasion to point out in convenient places as I proceed, the open sound of the vowel.

One remark more with respect to the vowels • and . The first sound of e and the first of o occur in the majority of I have called the first sound of e as ay in say, and the syllables, and may be called the ruling sounds of those two first sound of o (the medium sound between o and c, which vowels. No distinguishing sign is used in Italian to mark the cannot be adequately marked by an English equivalent) the two e's or two o's. Englishmen must have some mark to ruling sounds of those vowels. The reason is this; they are indicate when e and o are to be sounded with their second or heard in all syllables without distinction, whether they have open sounds. I shall, in these cases, place on e and o this the accent of tone or not, while the second sound of e (pronoun. sign 4, as for example è, i.

ced with a wider opening of the mouth and a deeper sound, and

something like e in let and ever) and the second sound of o The pronunciation of what, for the sake of distinction, I shall (also pronounced with a wider opening of the mouth and denominate the circumflexed sounds of e and o is not uniform deeper sound, and something like o in orange and lord) can only throughout Italy; but as the pronunciation of Rome and be heard in accented syllables, of which there can be in each Florence is the standard, all departures from it may be word only one. The former sounds, therefore, are much more reckoned provincialisms, which ought to be carefully avoided. frequent than the latter ; because unaccented syllables are more

The Italian consonants, seventeen in number, are divided numerous than those accented.
into mutes and semi-vowels. Mutes are those that require a With regard to the e in unaccented syllables having an
vowel after them to render them pronounceable. Semi-vowels English equivalent in ai or ay, I shall have no difficulty in
are those which require a vowel before them to make them marking the pronunciation; but with regard to o in unaccented
pronounceable.

syllables, as there is no equivalent, I should be obliged to use Let me first enumerate the mutes, and show by tables their perhaps be unable to determine which was the accent of tone

the acute accent, and thus confuse the reader, who would combinations with vowels in Italian words. There are ten

in a word and which the accent marking the peculiar sound of mutes :

o. I beg it therefore to be understood once for all, that where 1. b named in the alphabet bee.

I shall have occasion to use an o in unaccented syllables II. c named in the alphabet chee, and sounded like ch in without any sign above it, the vowel must invariably have

church before the vowels é and i. Before all other the first sound of o as above explained. I follow the authority vowels it is sounded like k in English.

not only of the educated classes of Florence and Rome, but III. d nained in the alphabet dlee.

also that of Celso Cittadini and the best theoretical writers on

Italian pronunciation.
IV, 9 named in the alphabet jee, and sounded like 9 in

ginger before the vowels é and i only. Before all
other vowels it is sounded like g in gang, go, and gull.

FIRST PRONOUNCING TABLE.
V. j named in the alphabet i(ee) lungo or jota, (i consonante,)

Showing the combination of vowels with mute consonants and sounded like y in yes only at the commence

in natural order.
Italian,
Pronounced.

English
ment of a word or syllable and before a vowel.
At the termination of a word it is no longer a

Bado
bah-do

I take care
Bevo
bai-vo

I drink
consonant, but must be sounded like a lengthened

Bice
bée-tchai

Beatrice, a woman's
VI. p named in the alphabet pee.

Boce (for roce)
bó-tchbait

Voice, word [name
Buco
bóo-ko

Hole
VII. q named in the alphabet koo. It is an auxiliary letter,

Ebano
e-bah-not

Ebony
only used before u with the sound of k.

Abete
ah-be-tai

Fir-tree
VIII. t named in the alphabet tee.

Ibile
Gh- bee-lai

Able
IX. v named in the alphabet vee (u consonante).

Obolo (Latin, obolus) ô-bo-log

Farthing
Abuso
ah-bóo.za |

Abuse
X. z named in the alphabet tsaita, sounded like tz in

Babbo (Tuscan) bahb-bos
Suitzerland, or like du in adze. These sounds vary

Papa
in different parts of Italy. After I, n, and r, it is
generally pronounced like tz in Sritzerland,

The

• The reader must not forget my previous observation that e same sharp sound occurs in words derived from before e and i is sounded like ch in the English word church, Latin, and ending in zia, zio, cione, &c.

† The acute accent over o marks not only the accent of tone,

but also the first sound of o as stated before. I shall mark cach word in the following spelling tables, and Once for all, I must refer my readers to the opening explana. indeed each word given as an example or illustration, with an tion, where I stated that there is no English equivalent to the accent, which, being merely arbitrary, used for the occasion to second, open or circumflexed sound of the e, as in the first syllable of facilitate the progress of the English learner and not used in mano. For that reason, I have not attempted to imitate it by an Italian printing,

denominate the accent of time. In every curetiek sign. 'In all cases of the e circumflexed, the reader mouse Italian word composed of more than one syllable, there is studiously avoid the English sound of e, which could only create always one syllable on which, when we pronotince it, the voice the greatest confusion. He may always bear in mind what I have oughi to pause with a markce elevation of tone. This prolon- stated, that an approximation to the circumtlexed e is to be found gation and elevation of the voice on the syllable is similar to in the' e of the English words let and ever; only uttered with a the transition of the voice from one tone to another in music, wider opening of the mouth and deeper sound! The circumflexed in order to descend to the level of the original tone from which eis invariably the accent of tone. the voice was raised. The accent of tone exists more or

The reader must bear in mind, that this is the second or less less in every language, but it is more or less sensibiy marked frequent sound of o, something like the English o in the words in one language than another, and it is strongly so in Italian; orange and lord, but with a wider opening of the mouth and deeper and on the marked use of this accent in a great measure sound. I give it the circumflex mark, because it is the less com depends the barmony of the language. I shall mark this accent nion sound. Wherever it occurs in my lessons, it will invariably by the acute sign from right to left. It is true that this denote, as in the case of the circumflexed e, the accent of tone ar acute sign is sometimes printed in Italian words, but in a very well as the peculiar sound of the o. few instances only, which I shall have occasion to point out here

If I shall have occasion to speak of the two sounds of s when I after. The grave decent(), from left to right; is used much more explain the sounds of the semi-vowels. frequently (the rules for its use will be given hercafter), and for my readers to pronounce double consonants. It is a fundamental

I give these as exercises for the special purpose of teaching, this reason I prefer using, in order to avoid contusion, the acute mecanlialian pronunciation that double consonants

must be accent as the arbitrary mark or sign of the accent of tone. uttered and vibrate distinctly. This is essentially necessary, not ed by principles clear and invariable ; which it would be l words, but as it frequently distinguishes words of totally different

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Italian. Pronounced.

English.

ON PHYSICS OR NATURAL PHILOSOPHY
Bebbe (for bevve) béb-bai**

He drank
Gibbi (for gobbi) jib'-beeft
Hunchbacks

No. II.
Gobbo
gób-bo
A hunchback

GENERAL PROPERTIES OF MATERIAL BODIES.
Dubbi
doob.bee

Doubts
Cado
kah-do
I fall

(Continued from p. 3.)
Cece
tchái-tchai

Chickpease
Cito
tchée-to
Quickly

Porosity. This is the property of matter in consequence of
Coda
kó-dah
Tail

which interstices exist between the particles of bodies; these
Cute
kbo-tai
Skin

interstices are termed pores.
Ducato
doo-káh-to

Dukedom, ducat Pores are of two kinds; there are physical pores, or inter-
Ricevo
ree-tchái-vo
I receive

stices, so small, that the attractive and repulsive forces with
Incido
in-ichée-do
I cut

which matter is endowed continue to exert their action; and Ancona an-kó-nalt Ancona

there are sensible pores, such as may be recognised by inspecLacuna lah-kóo-nah Pool, swamp

tion. The latter are merely holes, across which the molecular Bacco bák-ko Bacchus

forces are incompetent to exert their action. It is to the existBecco bek-ko Beak

ence of physical pores that are due the phenomena of expan. Picca pik-kah Spear

sion and contraction arising from variations of temperature,
Bocca
bók-kah
Mouth

It is in sensible pores that the organic phenomena of exhala.
Succo
sook-ko
Juice

tion and absorption take place-phenomena characteristic of
Dado
dah-do
Die for gaming

vitality, whether animal or vegetable.
Devo
dái-vo

I ought, I must Sensible pores are very apparent in sponges, in wood, and
Dito
dée-to
Finger

in a great number of stones; whereas physical pores are never
Dopo
dô-po

After, afterwards recognisable, and their existence can only be proved by argu.
Duce
doo-tchai
General

ment. They are inferred to esist chiefly by considerations of
Edace
ai-dahutchai
Gluttonous

the diminution of volume which bodies experience when Adele ah-de-lai

Adeline, a woman's exposed to the influence of cold, or to the force of mechanical
name

pressure.
Adiro
ah-dée-ro

I provoke to anger In order to demonstrate experimentally the condition of
Adoro
ah-do-ro
I adore

porosity, the following experiment may be performed. Take
Aduno
ah-dóo-no

I unite, I assemble à long glass tube, terminated at its upper extremity, by a others

copper cup a (tig 3), and at its lower extremity by a foot piece of
Adda
áhd-dah

The river Adda
Edda
ed-dah
The Edda of Scan-

Fig. 3.
dinavian literature
Iddio
Id-dée-o

God
Adduco
ahd-dóo-ko

I lead to
Gaza
Gáh-dzah

Gaza in Palestine
Geto
jê-to

Jess (in falconry)
Gita
jée-tah

A walk, trip
Godo
gó-do

I rejoice
Gufo
góo-fo

A horned owl
Legame
lai-gáh-mai

A tie, ligament
Angelo
ahn-jai-lo

Angel
Angina
ahn-jée-nah

Inflammation of the

throat
Vigore
vee-gó-rai

Vigour
Arguto
ahr-góo-to

Ingenious, witty
Paggi
páhd-jeess

Pages (attendants)

(To be continued.)
meaning, but differing only in spelling by the single consonant
instead of the double one; as, for example, caro, dear, and carro,
a car; as I shall have occasion later more fully to illustrate.
Where a, or any o! her vowel precedes a double consonant, a
particular stress must be laid on that vowel, and its sound
must be shortened. I have not attempted to indicate that
shortening of the sound of the vowel by any new sigo, because a
frequent change of sign only creates confusion, and the true pro-
nunciation is obvious from the necessity of giving a vibrating clearness
to the double consonants.

** The English e, whenever it is sounded as in the word get,
corresponds to the shortened sound of the first sound of < (ai).

# The reader must not forget my previous observation that g before e and i is sounded as in the English word ginger.

# It is obvious that not only before double consonants not in the same syllable, but even before one consonant in the same syllable, a or any other vowel must be shortened in the Italian, as perhaps in any other language.

It is therefore unnecessary to use any sign.

The pronunciation of so depends on the vowel that follows the latter g. If that vowel is e or i, the gg's are pronounced some the same metal, capable of being screwed upon the exhausting what as if the first g had merely the sound ofá; and the second %, which goes to the next syllable, like the English j in jay, only plate of an air-pump. The lower orifice of the copper cup a is the voice must not pause too long on the d of the syllable where the closed by a tick piece of buff leather. Let some quicksilver be first g occurs; the stress must be laid on it, and the voice must now poured into the copper cup until the buff leather is entirely glide as quickly as possible to the pronunciation of the second covered; then create a vacuum by means of the air-pump. 9, which must be very soft. In this way there will be effected a Immediately this is done, atmospheric pressure being removed more equal distribution of the sound j between the two syllables, from below ļhe leather, and still being, exerted above it, which will droduce the correct sound of the gye

.:c mercury rushes through the pores of the leather and falls

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down the tube in a shower of minute drops. In a similar way ently demonstrated by the process of coining, which consists water may be caused to pass through the pores of wood, if a in making an impression on a flat metallic disc by the sudden disc of the latter, cut perpendicularly to the direction of its pressure of a die. In connexion with the compressibility of fibres, be substituted for a piece of leather.

solids, it should here be remarked that a certain point exists If a little chalk be thrown into water, there presently escapes at which no further amount of compression is possible. At a number of minute bubbles of air, which evidently occupied this point it frequently occurs that a metal still subjected to the pores existing within the substance of the chalk, and from continuous pressure crumbles to powder. As regards liquids, which the air is driven by reason of the water which enters, their amount of compressibility is so exceedingly slight, that In short, if the piece of chalk be weighed before and after during a long period the property was altogether denied. immersion, and the weights compared, a considerable increase Experiment has, nevertheless, demonstrated the existence of will be found to have resulted as the consequence of putting such compressibility in liquids, and we shall hereafter treat of it into water. In this manner, we may determine the total of it fully under the head of hydrostatics. volume of the existing pores by estimating the space which Elasticity.- Elasticity is the property by the exercise of corresponds to a bulk of water equal in weight to that which bodies are enabled to resume their primitive volume, experienced by the chalk by immersion. As regards the or primitive form, when the force which altered this form or porosity of metals, this quality has been demonstrated by an volume ceases to act. Elasticity may be developed in bodies experiment performed by the Florentine academicians in the by pressure, by traction, by flexion, or by torsion. At pre. year 1661. The experiment was as follows :

sent we are merely concerned in regarding the elasticity of A hollow sphere of gold having been filled with water, pres. pressure ;, the other species of elasticity taking place only in sure was applied by forcing in a screw. Subjected to this solids, will be placed amongst the specific properties of material treatment, the contained water was found to oože through the bodies. Gases are eminently elastic; that is to say, if they are golden sides of the sphere, and to appear externally in small compressed, and the compressing force be removed, they at once dew-like drops. Subsequently to this experiment of the reassume their original bulk. A similar observation applies to Florentine academicians, a modification of it has been fre- some liquids which may have been subjected to compression; but quently repeated, various metals having been substituted for the property of elasticity in solid bodies is not complete. If gold. In every instance a similar porosity was demonstrated the compressing force has been extreme, or very long applied, to exist.

solids rarely assume their original condition on the removal of The Apparent and Real Volume of Bodies. A slight reflection on the compressing force. Nevertheless, the quality of elasticity is what has been laid down concerning porosity, will lead to the very apparent in caoutchouc, ivory, glass, and marble. In fatty inference that distinction requires to be made between the bodies the quality is scarcely recognisable; and a similar apparent volume which bodies occupy and the real volume. remark applies to masses of clay, and to the metal lead. In solids The apparent volume of a body is equivalent to that portion there is a limit to elasticity, beyond the boundaries of which of space which it fills ; its real volume is that portion of space either rupture takes place, or the exact original condition of which it would have occupied if all porosity in its substance the bodies does not reappear. In the case of sprains, for could have been annihilated ; in other words, the real volume example, the limits of the elasticity of the ligaments affected is the apparent volume diminished by the volume of the pores. have been exceeded. Gases and liquids are affected by no The real volume of a substance is invariable, but its apparent such limit, and therefore always reiurn to their primitive volume diminishes or augments with the volume of the volume. pores.

Elasticity is the result of a condensation of molecules, Applications of the Preceding Facts. The quality of porosity therefore of a change of form, which as regards solid bodies has been taken advantage of in the construction of filters may be demonstrated by the experiment which follows. Upon with paper, felt, stone, and charcoal, substances frequently a plane of marble, which has been smeared with a little oil

, drop employed in domestic economy. The pores of these bodies a ball of ivory, of glass, or of marble; the ball rebounds to an are sufficiently large to admit the passage of liquids, but elevation something less than that of the space through which at the same time sufficiently small to refuse passage to the it fell, after having left on the marble surface, at the point of extraneous substances which the liquids may have held in contact, a circular impression, the diameter of which increases suspension. Another frequent and useful application of the in proportion to the height from which the ball fell

. It porosity of a body, is that of splitting large masses of stone follows from a consideration of the preceding

experiment, that by the expansion of a wooden block. The process is as follows. the ball at the moment when it struck the table must have Channels or clefts are first made around the base of the mass become fat over a certain space of its surface, and that the to be separated, and into these clefts dry wooden wedges are rebound of the ball is due to the springing back of the com driven. When a sufficient number has been introduced in pressed molecules constituting the flattened surface into their this manner, they are moistened with water, which, penetrating original position, between their pores, the wood swells and exerts enormous Mobility-Motion- Repose.-Mobility is the property by which force, by means of which gigantic blocks are separated from material bodies pass from one point to another. The term the parent rock. A variation of the same force may be motion is applied to that state of a body which is involved in recognised in the augmentation of size, and the diminution of the act of changing place. The term rest signifies the opposite lengin, which cords undergo when they are moistened. Some of motion, and also a permanence in the same place. times the force thus called into operation is taken advantage Rest and motion may be understood each in the two senses of for the raising of heavy burdens.

of absolute and relative. Absolute rest would consist in the Compressibility. - It is in consequence of this property that complete privation of motion ; but we know of no such state. bodies are capable of being forced by pressure into smaller If we take the most extended view of the universe, still this spaces than those which they ordinarily fill

. This property is condition of absolute repose is nowhere discoverable. The at once the consequence of porosity, and the proof of its exist- absolute motion of a body would consist in its displacement ence. Indeed, the most porous bodies are those which are as regards another body in the state of absolute rest. also the most compressible. The extent to which different The condition of relative rest is that assumed by a body bodies may be compressed varies exceedingly. The most in relation to surrounding objects, although in reality it par: compressible of all are the gases, many « which are suscep takes with them of a common motion. For example, an object tible of. reduction, when sufficient pressure is applied, to a which remains in the same place in a boat whilst sailing, may volume to, 20, or even 100 times smaller than that oocupied be said to be in a condition of rest so far as concerns the under their original conditions. Nevertheless, in the generality boat, but it is really in a condition of motion as regards the of aëriform bodies, a limit exists beyond which the gaseous river-sides. Such an object, then, furnishes us with an exaunstate ceases, and a liquid body results.

ple of the state of relative rest. The compressibility of solids is much less than the compres The relative motion of a body is only its apparent mo. sibility of gases, and varies for different bodies of the solid tion, that is to say, the kind of motion which is discriminated class.' Woven fabrics, paper, cork, wood, and all porous by comparison with certain other bodies assumed to be fixed, tissues, are susceptible amongst solids of the greatest air.ount although they are really in motion. Of this kind is the mo. of compression. Metals are also compressible, a fact suffici- tion of a boat in relation to the banks of a river, for the laster

participates with the boat in the double motion of rotation forces mutually neutralise each other's effects, and that conand translation in space, to which our globe is continually sequently the original state of the body is not affected. The bubjected. In nature it appears, then, that we only recog- term equilibrium is used to designate this state of condition nise conditions of relative moiion or relative rest.

in a body. Care must be taken not to confound the two Inertia.-Inertia is a purely negative quality of matter, and states of equilibrium and rest. In the former state a body is constitutes the well-known inability of matter to pass of itself submitted to the action of several mutually destructive forces; from the state of rest to that of motion, or to modify the kind in the second a body is not acted on by any force. Nevertheof motion with which it may have been impressed.

less, it is a question whether there be any body actually at If occasionally objects fall when left to themselves, this rest in the material universe. To this question we would result is dependent upon the exercise of an attractive force, answer in the negative. which draws them towards the centre of the earth, and not Characters, Unit, and Representation of Forces.-Every force upon their own self-agency. If the relocity of a billiard ball is characterised-first, by its point of application, that is to on the table gradually diminishes, this result is attributable say, the point at which it iinmediately exerts its power ; partly to the resistance of the atmospheric air, and partly to second, by its direction, that is to say, the straight line which friction against the cover. It would be incorrect, ihen, to it tends to describe at its point of application ; third, by assume that the billiard ball holds within itself a tendency to i its intensity, or, in other words, its relation to some other rest rather than to continuance in motion, as certain philoforce considered as unity. sophers of antiquity were in the habit of propounding, when The force chosen as unity in any particular question is they compared the natural tendency of matter to a lazy indi, altogether arbitrary ; but whatever may be the amount of vidual. In all cases where there is no resistance, continued traction or pressure developed by a force, inasmuch as a cermotion proceeds without alteration, as we find exemplified in tain weight may be made or considered to produce the same the course of the planets in their orbits around the sun. effect, it is customary to refer forces to some unit of weight,

Application of the Preceding Deductions.-A great number of and in this country the pound weight, or some multiple of it, phenomena are explicable by the doctrine of the inertia of is generally the unit. Thus a force is said to be equal to 20 matter. For example, when one is desirous of leaping across a pounds, if the pressure of_20 pounds can be substituted ditch, he takes a preliminary run, in order that at the instant for the action of the force. From a study of the characters by when the spring is made the impetus generated by running which a force is determined, the force itself is completely may be superadded to that resulting from the spring itselt. known when its point of application, its direction, and its

A person who alights from a carriage in motion participates intensity are given. In order to represent the different in the motion of the carriage, and if the individual thus alight- elements of a force, we draw an indefinite straight line ing does not take care to give his body an impression contrary through its point of application, and in the direction along in direction to that imparted by the carriage, he falls on touch which it is exerted. Then upon this line some arbitrary unit ing the ground in the direction of the carriage. It is the of length is marked, commencing from the point of applicaquality of inertia which renders so terrible the accidents from tion, and extending in the direction of the force. This unit concussion on railways. In fact, if the locomotive itself of length is then repeated as often as the given force contains should be brought suddenly to a pause, all the train would the unit of force. As the consequence of this arrangement, continue its progress by reason of the force already acquired, we have a straight line which completely determines the and the carriages would be boken by striking against each force, In order to distinguish forces froni each other, they other.

may be represented by lotters, such as P, Q, R, placed upon Hammers, pestles, pile-drivers, &r., are all so many app!i- the line indicating their several directions. In order to faci. cations and'illustrations of the principles of inertia; so in litate the understanding of many physical phenomena, it will like manner are the fly-wheels of steam-engines, and the be necessary to refer to certain principles which are demonregulators of the motions of machinery.

strated in mathematical treatises on natural philosophy.

These principles will be cited in the next and subsequent PRELIMINARY Notions Concerning FORCS AND Motion. articles,

Forces.-- By the term Force, is understood any cause capable of producing motion, or modifying motion when once produced. Thus, the muscular action of animals, weight,

LESSONS IN GEOLOGY.-No. XLII. magnetic attraction and repulsion, and the tension of vapours, are all forces. In general the term powers is applied to

By THOMAS W. JENKYN, D.D., F.R.G.S., F.G.S., &c. designate those forces which tend to produce a certain effect;

CHAPTER III. and the term resistance, to those forces opposed to the production of such effects. The former in consequence of their ON THE INFLUENCE OF ATMOSPHERIC AGENTS ON THE tondency to accelerate motion at each instant are called accele. rating forces, whilst the general expression of retarding forces is applied to the latter ; yet the same force may be considered as

SECTION VIII.-ON ICEBERGS. a continually accelerating force at one time, and a continually şii, ON THE TRANSPORTING POWER OF DRIFTING ICEBERGS. retarding force at another time: for example, when a stone is allowed to fall from a state of rest, at some elevation avore Iy the lessons which were given you on the formation and the ground, the action of gravity with which the earth, and agency of glaciers, you have learnt that all the rocky fragindeed all matter, is endowed begins to affect the stone, and ments, which glaciers brought down from the lofty ridges of continuing to do so during the whole period of its fall, it the Alps, were deposited in a terminal moraine, and that, at reaches the ground with accelerated force ; but if a stone be some earlier epoch, they had left behind them on the sides and projected perpendicularly upwards from a place on the ground, ledges of the mountain, at a much higher elevation than they its inotion upwards will be continually retarded by the action reach in our day, enormous blocks of stone called boulders. of gravity during the whole period of its ascent, until it come For illustrations of this process, consult the diagrams in the to a momentary state of rest, and its progress upwards will be Lessons on Glaciers. stopped. Gravity, when it acts in ihe manner described in Boulders, like those on the flanks of hills in the Alps, are the latter of these cases, is called a continvally retaiting force. found in very extensive districts all over the north of Europe

Instantaneous and continued Forces.-Forces are capable of act. and America. Some of the blocks are waterworn, others are ing upon bodies in one of two ways. First, during a very rugged and angular. They consist of fragments derived from short period, as, for instance, that consequent on the shock or rocks of all kinds a:d of all ages, primitive, volcanic, and fosexplosion of gunpowder; and second, those which continue to siliferous. Many of them are of enormous dimensions, varying aci during the whole duration of the motion, as gravity, and from three feet io several yards in diameter. the traction of animals. The foriner are terined instantancous, In some cases, such a boulder deposit consists of blocks that and the latter continued forces.

have been severed and torn from the rock that lies imme. Equilibriun. --- When inany forces arc simultaneously operat. diately beneath them. In such circumstances the boulders are ng upon one and the same body, it may so happen that the of tho colour and lithological character of the underlying strata,

EARTH'S CRUST.

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