« ΠροηγούμενηΣυνέχεια »
Irregular Verbs continued.
Schleifen i) to sharpen, ich schleife, 2c.
is Tislifi ich schlisse chleife or 'geschlissen.
liffen. i) Regular in all other signito whet,
fications, as, to demolish, or Schleißen, to slit, ich schleiße, 20 id; chliß ity fibližje ichleisc geschliffen.
to drag. Schliefen, to slip, ich schliefe, 2c.
ich chlor ich schloste ichließe geichlaffen. Schließen, to shut, ich schließe, 2c.
ich ich los ich folosic ichlieze geschlossen Schlingen, to sling, ich schlinge, 2c.
ic, ichlang ich idlinge inlinge geichlungen. Schmeißen, to fling. ich imeiße, 2c.
ich dimis ich idmisse Tomeise geschrnissen. Schmelzen K.), to melt ich schmelze, cu schmelzest inny ichmolz in Tamülze schmilz or gesamolzen. k) As an active verb it is re(ichinilzest), er sameizt
gular. (schmilzt) Schnauben, to snort, ich schniebe or schnaube izby lunos ich isnībe ichnaube geschnoben. Soneiden, to cut, ich foreide, 26.
ish Tuhnitt ich schnitte schneide geschnitten. Schrauben 1), to screw, ich schraube, 2c.
in ichraubte ich ichraubete idriube geldhraubt l) Commonly regular, schraubte, (ichrob) (chrobe)
(geschroben) geschraubt. Schreiben, to write ich fariebe, 2c
io farieb ich ihriebe chreise geschrieben. Schreien, to cry, id schreie, 26.
in drie ich Tchriee chreie geschriecn. Schreiten, to stride, ich schreite, 2c.
is christ in schritte dreite geschritten. Schroten, to bruise,to gnaw ich schrote, 2c.
ich strotzte ich schrotct? (chrote geschrcten. Regular now except in the
participle, and this is fre
quently geschrotet. Schwirenm), to suppurate, ich dware, 20.
id ist ich sdmore chwäre gesdinoren. m) Schwierst 2c. in the present Schweigen, to be silent, ich schweige, 2c.
ich ihnieg ich ichwiege schweige geschwiegen. is provincial. Schwellen n), to swell, ich Tchwelle, tu schwillst, er liv inwall ich idrille will or zeichwollen. n) Regular, when active. schwillt
sowelle Schwimmen, to swim, ich fdhuimme, 2.
it iwanım ich ichwamme ichwimme geschwom
n. Schwinden, to vanish, ich schwinde, 26.
iš mins id for winte cwinte geschwunten Schwingen o), to swing, ich (dminge, 2c
to iuwing or ich luwinge i schwinge geichwungen. 6) Schwung is less in usage jung
than schwang. Schwören, to swear, ich ichwöre, 26.
is ichwor or is uwöre or schnöre geschworen.
onur Tihnüre Sehen, to see, ich fehe, ju siebst, er fieht t ich als id jāņe
fiche gesehen. . Sein, to be, ich bin, 24. ich war, 2c. id därc fei
ich fandte and ich fentete Tende gesandt and
p) When active it is mostly Singen, to sing, ich finge, 24.
ich fang ich singe finge gesungen. regular. Sinfen, to sink, ich fingc, .
ich fant id fänke Tinte gesunken. Sinnen, to think, to muse, ich finne, 2c.
ich fann id fänne finne gesonnen.
(sonne) Sißen, to sit, ich fitze, 2c.
i jag ich fäße lige gesessen. Sollen, to be obliged, ich foll, du sollft, er foll
gejolli. Spalten g), to split, ich spalte, 26.
id paltete ich spaltete spalte gespalten. 9) Irregular only in the parSpeien, to spit, ich speie, ac.
ich spic id fpiee fpeie gespieen. ticiple, and this is someSpinnen, to spin, idt spinne, zc.
itt spann ich spänne spinnc gesponnen. times gespaltet when the verb (põnne)
is active. Spleißen, to split, ich fpleiße, uc.
ich spließ, spliß ich spilife (pleißc gespliffen. Sprechen, to speak, id spreche, bu sprichst, er spricht ich sprich id spräche sprid gesprochen.
BY CHARLES TAUSENAU, M.D.,
Of the University of Pavia, Professor of the Italian and German Languages
at the Kensington Proprietary Grammar School.
I now proceed to explain Italian pronunciation 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 syllable 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 vowels, representing seven sounds
I. a invariably sounded like the English interjection ah.
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 betwee
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
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 6 and 0. The first sound of eand 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 0 (the medium sound between 0 and co, 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: Englishmon must have some mark to ruling sounds of those vowels. The reason is this ; they are indicate when i 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 (pronounsign", as for example é, ô.
ced with a wider opening of the mouth and a deeper sound, and
something like e in Ict 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 circumflexcd 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 o!" to be carefully avoided. frequent than the latter; because unaccented syllables are more
The Italian consonants, seventede reber, are divided numerous than those accented. into mutes and semi-vowels. Mutes
't that require a
syllables having an yowel after them to render them pronoui.
Semi-vowels English equivalent in ai or ay, I shall have no difficulty in are those which require a vowel before i... anake 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 shor 1. 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
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 chce, and sounded like ch in without any sign above it, the vowel must invariably have
church before the vowels é andi. Before all other the first sound of o as above explained. I follow the authority vowels it is sounded like l in English.
not only of the educated classes of Florence and Rome, but
also that of Celso Cittadini and the best theoretical writers on III. d named in the alphabet dee.
Italian pronunciation. IV. g named in the alphabet jce, and sounded like g in ginger before the vowels e and i only. Before all
FIRST PRONOUNCING TABLE. other vowels it is sounded like gin gang, go, and guli, V. j named in the alphabet i(cc) lungo or jota, (i consonante,)
Showing the cornbination of vowels with mute consonants
in natural order. and sounded like y in yes only at the cominence
I take care
I drink consonant, but must be sounded like a lengthened
Beatrice, a woman's Boce (for roce) bó-thait
Voice, word [name VI. p named in the alphabet pec.
Hole VII, q named in the alphabet koo. It is an auxiliary letter, ' Ebano
Ebony only used before u with the sound of k
Obolo (Latin, obolus) ô-bo-los
A huge X, z named in the alphabet tsaita, sounded like tz in
* The reader must not forget my previous observat un ato same shar; sound occurs in words derived from before e and i is sounded like ch in tiic English word c'eurch.
† The acute accent over u marks not only the accent of tone, Latin, and ending in cia, wio, zione, &c.
but also the first sound of o as stated before. I shall mark each word in the following spelling tables, and I Once for all, I must reter iny readers to the opening explanaindeed 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 ebano. for that reason, I have not attempted to imitate it has nem Italian printing, I denominate the accent of tone, In every cumflex sign. In all cases of the e circumflexed, the reader must
English sound; and have therefore simply marked it by the ciralways one syllable on which, when we pronounce it, the voice studiously aroid the English sound of e, which could only create ought to pause with a marked elevation of tone. This prolon- stated, that an approximation to the circumflexed e is to be found
the greatest confusion. He may always bear in mind what I have 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 fiom 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 inore or $ The reader inust bear in mind, that this is the second or less jess in every language, but it is more or less sensibiy marked frequent sound of o, sunething like the English o in the words in one language than another, and it is strongly so in Italian; 1 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 comdepends the harmony 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 as
well as the peculiar sound of the o. acute sign is sometimes printed in Italian words, but in a very
ll I shall have occasion to speak of the two sounds of s when I few instances only, which I shall have occasion to point out hereafter. The grave accent (), from left to right, is used much more explain the sounds of the semi-vowels.
I give these as exercises for the special purpose of teaching frequently (the rules for its use will be given hereafter), and for
readers to pronounce double consonants, It is a fundamental this reason I prefer using, in order to avoid confusion, the acute rule of Italian pronunciation that double consonants must be accent as the arbitrary mark or sign of the accent of rone, uitered and wibrnic distinctly. This is essentially necessary, not Two-thirds of the Italian words have an accer:t of tone regu- only as it augments the beauty and marks the urlhography of lated by principles clear and invariable; which it would be words, but as it frequently distinguishes words he urltography of
ON PHYSICS OR NATURAL PHILOSOPHY-
GENERAL PROPERTIES OF MATERIAL BODIES.
(Continucd froin 23. 3.)
Porosity. This is the property of matter in consequence of
which inierstices exist between the particles of bodies; these
inierstices are itrmed pores.
stices, so small, that the attractire ind repulsive forces with I cut
which matter is endowed continue to exert their action; and incona
there are sensible pores, such as may be recognised by inspecPool, swamp
tion. The latter are merely holes, across which the molecular Bacchus
forces are incompetent to exert their action. It is to the existBeak
ence of physical pores that are due the phenomena of expanSpear
sion and contraction arising from variations of temperature. Dlouth
It is in sensible pores that the organic phenomena of exhalaJuice
tion and absorption take place - phenomena characteristic of Die for gaming
vitality, whether animal or regetable. I ought, I must Sensible pores are very apparent in sponges, in wood, and Finger
in a neat number of stones; whereas physical pores are never After, afierwards recognisable, and their existence can only be proved by arguGeneral
ment. They are inferred to exist chieny by considerations of Gluttonous
the diminution of volume which boules experience when Adeline, a woman's exposed to the infuence of cold, or to the furce of niechanical
pressure. I provoke to anger
In order to demonstrate experimentally the condition of. I adore
porosity, the loon experimentiray be performed. Take I unite, I assemble à long glass tube, térmiareti at its upper extremity by a others
coprer cup a tik 3). iind atiis lutinestremity by a foot piece of
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 other 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 sign, because a frequent change of sign only creates confusion, and the true pronunciation 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 e (ai).
to The reader must not forget my previous observation that before e and i is sounded as in the English word ginger.
It is obvious that not only before double consonants not in the save 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.
$9. The pronunciation of og depends on the vowel that follows the latter 9. 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 of d; and the second plate of an air-pump. The lower orifice of the copper cup a is g, which goes to the next syllable, like the English j in jay, only the voice must not pause too long on the d of the syllable where the closed by a thick 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. g, 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 the leather, and still being exerted above it, which will droduce the correct sound of the gg.
the mercury rushes through the pores of the leather and falls
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 fiat 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 number of minute bubbles of air, which evidently occupied this point it frequently occurs that a metal still subjected to he 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 thie weights compared, à 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 t 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 preyear 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 ooze 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,
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 occurs and the real volume. remark applies to masses of clay, and to the metal lead. In solidsThe apparent volume of a body is equivalent to that portion there is a limit to elasticity, beyond the boundaries of which
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 recurn 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, Ic 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 flat 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 comdriven. "When a sufficient number has been introduced in pressed molecules constituting the flattenea 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 auginentation of size, and the diminution of the act of changing place. The term rest signifies the opposite length, which cords undergo when they are moistened. Some of inotion, 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 till. This property is condition of absolute repose is nowhere discoverable. The' at once the consequency 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 parcompressible of all are the gases, many vi 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, max. volume 10, 20, or even 100 times smaller than that occupied 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 examstate 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 mosibility 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, parer, 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 moof compression. Metals are also compressible, a fact, suffici- tion of a boat in relation to the banks of a river, for the latter
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 subjected. In nature it appears, then, that we only recog-term equilibrium is used to designate this state of condition nise conditions of relative motion 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 selfragency. If the velocity 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 immediately 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, then, to it tends to describe at its point of application ; third, by assume that the billiard ball holds within itself a tendency to its intensity, or, in other words, its relation to some other rest rather than to continuance in motion, us certain philo- force 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.cer. motion proceeds without alteration, as we find exemplified in tain weight may be made or considered to produce the same the course of the planetş. 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 itself. 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 letters, such as P, Q, R, placed upon Hammers, pestles, pile-drivers, &c., are all, so many appli- 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 NOTIOXS CONCERNING FORCE AYD MOTION. artiales.
Forces.-- By the term Forces 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 tendency to accelerate motion at each instant are called accelerating 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 $ü. retarding force at another time: for example, when a stone is allowed to fall from a state of rest, at same elevation above. In 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 frag. indeed 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, atreaches 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 eleration than they its motion 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 the manner described in Boulders, like those on the flanks of hills in the Alps, are the latter of these cases, is called a continually retarding 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 and of all ages, primitive, volcanic, and fosexplosion of gunpowder; and second, those which continue to siliferous. Many of them are of enormous dimensions, varying act during the whole duration of the motion, as gravity, and from three feet to several yards in diameter. the traction of animals. The former are termed instantaneous, In some cases, such a boulder deposit consists of blocks that and the latter continued forces.
have been serered: and torn from the rock that lies imme. Equilibrium. When many forces are simultaneously operat- diately beneath then. In such circunstances the boulders are ing upon one and the same body, it may so happen that the l of the colourand lithological character of the underlying strata
OX THE TRANSPORTING POWER OF DRIFTING ICEBERGS.