« 前へ次へ »
Ciclope tohee-klô-pai Cyclops.
It may be here seasonably remarked, that many persons in Recinta rai-kloó-tah Recruiting.
England leam Italian for musical purposes only. The system Inglese in-glái-zai Englishman.
of pronunciation here given will be of peculiar advantage to Anglicano ah'n-glee-kahno Anglican.
them ; for in singing Italian airs, and in reading the scores of Egloga e-glo-gah
Eclogue. Ingiurie in-gloo-veeai Voracity.
Italian operas, nothing is so puzzling as the necessity of giving Tecla te klah Thecla (a woman's name).
to one note what to the eye seems two, and sometimes even Cili tcheé-lee
three syllables; and nothing is so hideous as to hear Mozart's Sidlo sée-klo
Shekel (a Hebrew coin and or Rossini's music distorted by a failure to vibrate double conEgla é-glah Egla, a name.
sonants, by the neglect of the two e's and the two o's, by hard Anili áhn-glee Englishmen.
enunciation of the gn and gl, by improper syllabic distribution Anglo áhn-glo Englishman.
of vowels and diphthongs, etc. gloó-tee-nai Glue, birdlime.
Two more tables will finish my lessons on pronunciation, and 10. Glia, Glie, Glio, Gli.
satisfactorily initiate the student into the difficulties of this Pronounced. English.
part of the language. In the concluding table I shall give
a general mirror of the pronunciation, to which the student who Torajlia to-váhl-lyah Table-cloth, towel. Okulia 0-nél-lyah
may have a doubt as to the proper pronunciation of a word Oneglia, a town in Sardinia. Famiglia fah-mil-lyah Family.
may always refer, and thus obviate the necessity of constantly Inrozlia in-vol-lyah Wrapper.
imitating the pronunciation of words by signs throughout the Aguglia ah-goól-lyah Needle.
grammar. Paglie páhl-lyai Straws.
I have already explained the importance of mastering the Teplie váil-lyai Vigils, evening parties.
difficulty to foreigners of giving the proper vibrated sound to Figlio fil-lyai Daughters.
double consonants. Hoglie mól-lyai
LESSONS IN GEOLOGY.–VII.
An old man.
EARTHQUAKES AND ALTERATIONS IN LEVEL.
The next phase of igneous action which we shall consider divides Luglio loól-lyo July.
itself into two divisions. Rozli ráhl-lyee Rays.
(1) Earthquakes proper, that is, when the land is shaken by vel-lyee Old men.
a series of upheavals and corresponding subsidences; and (2) Tigli til-lyee Linden-trees.
the gradual change of level which the land undergoes, whereby Sogli sol-lyee Thrones.
those rocks which are formed on the bed of the ocean by Fugli foil-lyee Was to him.
aqueous action are elevated so as to become dry land, and In the previous pronouncing table, the reader will have re- again, those parts already above the ocean level are depressed, marked that two vowels, when i is the first, may come together so that, in process of time, another layer of stratified rock is in one syllable without constituting a diphthong. The reason deposited on the submerged surface. cf this is, that in such cases the i is not heard, or scarcely per- These two classes of action are most closely allied. In all ceptibly touched in moro measured enunciation, and only serves probability, an earthquake is one of the results of the great the purposes of an auxiliary letter, to denote to the eye that igneous action which produces a change of level; that is to say, the preceding consonants c, 9, or gl, in such combinations as cia, when the fluctuations of the temperature of the earth's crust cho, ciu, etc., gia, gio, giu, etc., glia, glio, gliu, etc., are to have what canse the rocks to expand or contract, a corresponding alteramay be termed the squeczed sound. The letter i is not heard, tion of level takes place in the surface immediately above of scarcely heard, and why should it form a diphthong simply the locality, which experiences a change in its temperature. because in juxtaposition with another vowel? Tho samo obser. When this process is rapid--which seems to be the exception ration is applicable to such combinations as scia, scio, sciu, etc., and not the rulo—and if, by any means, water finds access pronounced shah, sho, shoo, etc. In all these cases a diphthong to the heated region below, a large generation of steam is the 13 seen, but not heard, or scarcely heard. And even three vowels result, and a sudden shock is imparted by the explosion to the in combination, when i is the first, may meet in one syllable rocks in the neighbourhood. This is propagated on all sides without constituting triphthongs; because in such cases as well, from the centre of disturbance in a wave, which reaches the i is preceded by the letters c, 9, and gl, not being pronounced surface, and as it rolls wider and wider from its centre, causes and only serving to denote the squeezed sound of these conso- all the phenomena exhibited in an earthquake, gradually denents. For example: libricciuolo (pronounced lee-brit-tchooô-le), creasing in its power until it becomes imperceptible
. a small book ; muricciuolo (moo-rit-tchooô-lo), a small wall ; Mr. Robert Mallet, C.E., of Dublin, very satisfactorily Rimicivolo (coô-mit-tchooô-lo), a little man; giuoco (jooô-ko), a accounted for the earthquake motion on this supposition, folzame; figliuolo (fil-lyood-lo), a child, son ; cavigliuolo (kah-vil- lowing out the theory on mechanical grounds. The earthquake 15006-10), a little peg or pin. In these examples, the three vowel in South Italy in 1857 afforded him an opportunity of testing combinations, or, more correctly speaking, associations, are the truth of his conclusions, and he found observation fully diphthongs
, and not triphthongs ; and it is only by confusion of supported his anticipations. A reference to the diagram (Fig. ins written for the eye, with literal representations of sound, 11) will enable the reader to comprehend the process of earththat grammarians have been led to class them as triphthongs. quake disturbances. In taking this view, I venture to differ from many authorities; FF is the surface of the earth. c is the point, it may be but I think I have shown reason for so doing.
many miles beneath, where the explosion which caused the disI have now explained the elements of Italian pronunciation. turbance occurred. The shock would be transmitted upon all Erceptions, philosophical reasons, delicacies, and refinements, I sides of c in a spherical wave. The lines do not represent a shall on future occasions explain' in “additional remarks " succession of waves which can only take place when there are a pronunciation ; and any necessary further remarks that may be succession of shocks, but the same wave in various positions. considered elementary, I shall likewise add from time to time. E c is the seismic-vertical. The effect of the earthquake in the
The remark that these explanations only contain the cle- immediate neighbourhood of E will be a vertical rising and mentary principles of Italian pronunciation, will serve to show falling, as if the ground had received a blow just beneath the the student really desirous of acquiring a knowledge, and not surface. By the records of many earthquakes this motion i smattering, of Italian, the importance and necessity of fol. appears to have been constantly experienced. The mode in lowing me closely and carefully throughout. The pace may be which the wave passes along the surface is shown at F (Fig. 12), tiresome, but, if taken now, will spare much labour for the where it appears as a ripple running along the ground. The future. The ingenious reader cannot fail to have noted that effect which this wavo has on the objects built on the surface the tables I have given are not expanded examples of words, will be evident by considering the behaviour of the pillar at bat systematic exercises , illustrating in natural order all
vocal r while the wave is passing beneath it. In the diagram the combinations, and thus giving an insight, from the very first, pillar is thrown out of its perpendicular by the advance of the into the structure of the language.
fore-slope of the wave.
If it cannot bear this disturbance, it
falls exactly along the path of the wave. If it be not thrown earthquake-waves Then, again, these latter waves have down as the wave passes underneath it, it assumes its perpen- different velocities in various rocks, and therefore the coseismal dicular position as it stands on its crest. Then it slopes the lines--that is, the lines which mark the emergence of the wave other way as it stands on its rear flank; and when the dis- are not always circalar, but may extend much further in one turbance has quite passed, and
direction than in another. Hence the surface has subsided to its
it happens that areas disturbed original level, the pillar, left
by an earthquake shock are freby the wave, suddenly totters
quently of very irregular shape. back to its perpendicular with
Varied and peculiar phenomena a kind of jerk. This motion
are recorded as preceding and has a more destructive effect
accompanying earthquakes, than that which first threw
such as irregularities in the the shaft from its position ;
seasons, deluges of rain, the un. and if the capital did not fall
usual haziness of the air, sudoff in the first instance, most
den calms, etc. ; but as these probably it will be thrown off by
are not general, they must be the return of the pillar to its
considered as accidental cir. upright posture. In any case
cumstances. It would be much the line drawn from the fallen
beyond the limits of our space object to the base of that which
to attempt to chronicle even the supported it must be in the
remarkable earthquakes which direction of the wave. By pass
have brought sudden destrucing through the visited district,
tion on thousands of human Mr. Mallet was enabled to map
beings. There is little or no very many of these lines, and
variation in the accounts, save on their production he found
as to the amount of damage that they all intersected within
produced by the shock. We half a mile. Thus he determined
allude to the Earthquake at the position of the point E
Lisbon, which happened on the (Fig. 13), directly under which
1st of November, 1755, as an was the centre of the disturb
example of all earthquakes.
The shock was preceded by no To find the exact depth at
premonitory symptoms, but which the explosion took place,
with a tremendous roar the city observations of fissured walls
reeled and fell. were taken. It will readily
It seems-from observations appear, on inspecting the diaCOLUMNS OF THE TEMPLE OF SERAPIS.
made on the principle above regram, that if the wave moved in
ferred to that the centre of the direction of the line c s, the wall of the house, being bent | disturbance was some eighty miles out at sea. The actual by the emerging wave, would be fractured at right angles to its scene of the gaseous explosion must have been deep-seated, for path. Therefore, a line perpendicular to the fracture would indi. | the effects of the shock were felt over an area four times as cate the angle
large as Exof emergence.
горе. The This being
water rose sud. found, the
denly twenty depth of the
feet in the West point c is at
Indies. The once given. In
greatCanadian the instance of
lakes felt the this Neapolitan
movement. In earthquake, the
Scotland, Loch centre of the
Lomond rose disturbance
on one beach was not more
more than two than seven or
feet, the water eight miles be
not participat neath the sur.
ing in the lurch face. The
which the land above statement is but a very crude out- Fig. 11.
Europe the line of the subject, as so many
turbance ex disturbing
In six mi. fere with the
nutes 60,000 direct results. For instance, 1
bon perished. the origin of the shock may
lected on the not be a point,
wide expanseof but the disturbance may be distributed over an area. This has received confirmation by the the way of the falling houses, when suddenly tho quay, with its loud rumbling subterranean noises, which sound as if a number living crowd, sank, with many ships in the harbour, and not a of violent explosions had succeeded each other in vast cavities body, nor the splinter of a wreck, ever rose ap from the watery far in the bowels
of the earth. These frequently precede the depth. We can only suppose that a fissure opened beneath the shocks, the sound-waves being able to travel faster than the harbour, and after engulphing the whole
, as suddenly closed.
gave. To the very north of
waves of disa
people in Lis.
Many had col.
marble quay, out of
In this earthquake a remarkable proof was offered of the fact that the land must have sunk, and the present floor have been above alluded to, that the wave is more readily propagated in raised above the level of the water. In the early part of the some strata than in others. The destructive effect was confined third century, the Emperor Alexander Severus beautified the to those houses which were built on the Tertiary strata. The temple, of which these are the pillars. lower part of the city, which rests on blue clay, was most At what time the temple was deserted we cannot conjecture; severely shattered; whereas that part of the city which was but in 1749 the following facts were brought to light by exca. built on the limestone or basalt escaped. The undulatory vating:- That when the soa broke in, the salt-water caused a hotmovement passed along the earth's surface at the rate of spring which existed to throw down a dark calcareous deposit, twenty miles an hour. The sea-wave rolled about four miles in two feet thick; above this a layer of volcanic tufa reposed, which that time. This wave is generally the cause of as much loss of must have been ejected from a neighbouring volcano; this deposit life as the actual violence of the shock. This may well be sup- is not regular, varying from five to nine feet in thickness. The posed from the fact that at Cadiz tho wave was sixty feet high. eruption seems to have formed a barrier which kept out the This wave is largest when the point of disturbance is under the waters of the sea, so that the hot-spring continued to deposit its 80s; then the sea-bound towns are subject to a double inunda. carbonate of lime, but without any marine admixture ; thus tion. The undulatory movement, when it reaches the shore, about two feet more were added to the matter which embedded cansos a great commotion, as, when a basin of water is moved, the bottom of the columns. More volcanic tufa was now placed the water does not at once participate in tho motion, and there- upon the lime deposits, either by a storm or another eruption, fore washes up the sides of the vessel. This disturbance no making a total deposit of eleven feet. All this time the land had Booner subsides than the sea-wave, which has fuin-wed the been sinking. The sea now surrounded the pillars, which finally "ground" wave at a slower pace, rushes in upon thu shore, its sank nine feet more; thus half their height was above the water, waters black with the sediment of the ocean-bed.
and of that which was beneath the surface eleven feet was South America has for centuries been the scene of repeated embedded and nine exposed to the water; in this space the earthquakes. A few years after Lima was first built, in 1582, the pillars were perforated by a bivalve, Lithodomus, which is indi. city was ruined, and since then the catastrophe has been re- cated in the figure by the dotted parts. Thus, if we include the peated some twenty times. In all the cities of that neighbourhood lower pavement, the land must have sunk twenty-five feet from the ecclesiastical year is full of anniversaries commemorating the commencement of the Christian era. When the upheaval terrible overthrows or marvellous escapos. But none of these began we cannot say, but we know it was in progress in 1530, calamities seem comparable to that which has just paralysed and in 1838 the pavement was again above the sea-level. The the country. Two shocks, on the 13th and 16th of August, downward movement has again commenced at the rate of about 1868, passed over Peru and Ecuador, ruining every town and one inch annually. city, and leaving between two and three hundred thousand dead Here, then, we have an evidence of a structure which has to putrify in the tropical sun. Arica, a seaport town, was com. undergono an upheaval and subsidence of at least twenty feet, pletely covered by the wave. The writer of these pages hears and still stands to attest the quietness and regularity, of the from one who survived that, upon the first shock, at 5.15 in the movement. afternoon, he, with some others, jumped upon a barge, when the From the cases cited, seeing the difficulty of proof on account great wave carried them on its crest completely over the town of the peculiar circumstances of position requisite for such proof, above the spire of the church, and left them unharmed nearly a we may consider that this motion of the earth's crust is far mile inland.
more general than we suppose, and may fairly be roquired to The chief geological effect of earthquakes is shown in tho account for the successive upheaval and depression necessary permanent alteration of the lovel of the land. In 1822 the coast for bringing the aqueous rocks to form the surface of continents. of Chili was raised some two feet, while further inland the elovation was more than double this quantity. In 1855 the coast of Nw Zealand for ninety miles evidenced a rise of nine feet.
READINGS IN FRENCH.-IX. (For many other facts illustrative of the alteration of level-a
F E DO RA. result of an earthquake-in all parts of the world, chap. xxviü. of Vol. II. of Lyell's “ Principles " may be consulted.)
SECTION 1. But that gradual alteration of lovel which is not accompanied C'était en mil huit cent douze ;' Napoléon, à la tête des ses by convulsive movements is more important than these local troupes victorieuses dans les plaines de la Moskowa, était entró Tariations. It is difficult to establish these facts, because we dans l'antique capitale de l'empire des czars, et de là menaçait have no standard which is not itself subject to alteration. Care. la nouvelle ville fondée par Pierre-le-Grand.? Poussé par un ful investigation of the coast of Sweden has shown that most of patriotisme fanatique, le gouverneur de Moscou, Rostopchin, the Scandinavian peninsula is rising at the rate of four feet a prit alors cette résolution qui a porté un coup si funeste au century. The coast is favourable for the observation. There succès de nos armes, celle d'incendior' la ville, dont l'empereur are no tides in the Baltic, and the cliffs descend perpendicularly Alexandre lui avait confié la garde. Nous ne raconterons pas into the sea ; the water-level has been repeatedly marked, and toutes les circonstances de cet épouvantable drame. Chassés de the rise judged by its change. In few other places are the leurs demeuresó en feu, croulant sous les efforts des flammes, same advantages. Mr. Darwin has suggested an ingenious c'était un spectacle affreux que de voir tous les habitants mêlés proof of the sinking of the ocean-bed in the Pacific. It is known à nos soldats, forcés de fuir en emportant ce qu'ils pouvaient that the coral insect cannot live below twenty fathoms, the dérober à la violence de l'incendie.6 pressure of the water beyond that depth being too great for its La petite fille d'un négociant, à peine âgée de six ans, so existence. How, then, can the fact be accounted for that many trouva perdue dans le tumulte.? Abandonnée, transio de froid, of the coral structures have their foundations resting on the elle errait çà et (a) las à travers les ruos que le feu épargnait ocean-bed at profound depths ? There is only one reasonable
Son père et sa mère avaient disparu,' et personne no solution of the difficulty, that they build upon å sinking founda- semblait vouloir la recueillir. La nuit se passa ainsi toute tion, and this very fact impels their labour and increases the entière; et quand le jour commença à poindre, Fædora, exténuéo demains they conquer from the sea.
de fatigue et de faim, s'affaissa devant la porte d'une églisel et We have reserved one well-known proof of this repeated se prit (b) à dormir. oscillation of the earth's crust, that of the Temple of Serapis, Sans doute elle ne se serait plus réveillée,"' la mort serait near Puzzuoli, in the Bay of Naples.
venue la surprendre, si une vivandière, qui par hasard vint (c) Tho ruins of this temple consist of three pillars of marble établir son petit marché de vivres!? près de cette église, ne l'eut hewn out of solid blocks. They are rather more than forty feet aperçue et ne se fut sentie touchéo de compassion pour la high.
malheureuse enfant. Elle aussi avait des enfants ! C'est The history of this remarkable tempie scems to be this :- pourquoi elle s'empressa de prodiguer ses soins à la petite From certain inscriptions discovered in the neighbourhood we orpheline 15 Fædora ne savait comment lui témoigner sa learn that
, in 105 B.C., a temple dedicated to Serapis existed reconnaissance.16 Elle devint bientôt pour sa seconde mère une on the sea-shore. In 1828 the handsome mosaic pavement aide fort intelligente. Peu à peu, elle apprit (d) à comprendre of this temple was discovered five feet beneath that from sa bienfaitriceli et put (c) lui exprimer tout ce quo son caur which the pillars rise. The cxistence of this parement indicates renfermait de reconnaissance et d'amour.
Cependant l'armée de Napoléon commença sa retraite, 18 et la focons et obscurcissait le ciel de manière à ce qu'on ne pût rien vivandière dut (f) quitter Moscou. Les parents de Fodora voir à trois pas devant soi. existaient-ils encore ? C'est ce que rien n'était venu révéler. 19 “C'est quelque voyageur égaré qui demande du secours ou qui Fædora partit donc avec l'armée française.20 Qu'on juge de ce est attaqué par les bêtes féroces,23 car il est impossible de se qu'un enfant de cet âge eut à endurer pendant une pareille livrer au plaisir de la chasse par un temps semblable,” s'écria retraite! Au passage de la Bérézina, Fædora eut encore le Polowski, et il donna l'ordre à ses gens d'aller à sa recherche. malheur de se trouver séparée de sa bienfaitrice, 21 soit (9) que Lui-même se mit (i) à la tête du cortège, 34 qui se dirigea vers la celle-ci eut péri dans les flots, soit qu'elle crût (h) la jeune enfant forêt. Quelque temps après, il reparut. Les domestiques por. égarée! Quoiqu'il en soit, l'orpheline ne la trouva plus, et elle taient sur un brancard le corps d'un Russe ensanglanté.25 se vit de nouveau délaissée.
Fodora se précipite au devant son compatriote ; elle-même
veut panser sa blessure. Bientôt celui-ci put témoigner 63 COLLOQUIAL EXERCISE.
reconnaissance aux hôtes du château et leur raconter son 1. En quelle année Napoléon 12. Que vint faire la vivandière histoire. entra-t-il dans Moscou ?
près de l'église ? 2. Quelle ville l'Empereur mena- 13. La vivandière ent-elle pitió de
COLLOQUIAL EXERCISE. çait-il de la ? la petite malheureuse ?
1. Où Fedora fut-elle conduite ? 14. Que raconta-t-elle à ses bien. 3. Par quoi Rostopchin fut-il 14. Pourquoi eut-elle pitié de
2. Qu'étaient devenus ses com- faiteurs ? poussé ? Fedora ?
15. Comment Polowski 4. Quelle résolution prit alors le 15. Que fit la vivandière ?
3. Où se trouva la petite Mos- femme traitèrent-ils notre hégouverneur ? 16. Fedora parut-elle reconnais
roïne ? 5. Où étaient les habitants ?
4. Que : * alle soudainement au 16. Apprit-on bientot des 6. Que s'efforçaient-ils d'em- 17. Qu'apprit-elle peu à peu ?
milieu de la forêt ?
velles de ses parents ? porter ? 18. Que fit l'armée quelque temps 5. Que fit Fædora à l'approche de 17. Prit-on soin de
son éduca7. Qu'arriva-t-il à la petite fille après ?
tion ? d'un négociant ? 19. Avait-on découvert les parents
6. Comment échappa-t-elle à un 18. Quel âge avait-elle ? 8. Que faisait la petite ? de Fædora ?
si grand danger?
19. Que faisait-on chaque année ? 9. Où étaient son père et sa 20. Que fit-elle alors ?
7. Que vit alors Fædora ?
20. Que faisait Fædora dans une mère ? 21. Qu'arriva-t-il au passage de
8. De quelle manière l'étranger de ces réunions ? 10. Dans quelle situation
regarda-t-il l'orpheline ?
21. Qu'entendit-on alors ? trouva-t-elle à la pointe du 22. L'orpheline retrouva-t-elle sa
9. Qui était l'étranger ?
22. Quel temps faisait-il dans ce jour ?
10. Que fit alors le gentilhomme moment? 11. Se serait-elle réveillée ?
23. Que dit Polowski cn enterdant
11. Que fit-il pour l'enfant ? NOTES.
le coup de feu ?
12. Par qui Fedora fut-elle ac- 24. Que fit-il alors ? (a) çà et là, here and there. (@) From pouvoir.
25. Que portaient les domes(b) Se prit à dormir, fell asleop; () Dut, was compelled to; from 13. Fut-elle longtemps à se ré- tiques? from prendre. devoir.
tablir ? (c) From venir. (9) Soit, be it ; from étre.
NOTES. (d) From apprendre. (h) From croire.
(a) Parvint, reached; from par-, (e) From pouvoir. SECTION II.
(f) Coup de feu, shot,
(b) De sorte que, so that. Cependant Fodora parvint (a) jusqu'en Pologne avec un dé. ) From recueillir.
(9) From accueillir.
(h) From apprendro. tachement de troupes ;' plusieurs de ses compagnons de voyage (d) Ce qui lui restait de forces, (i) From mettre.. avaient succombé, moissonnés par le froid ou par la faim, et les her remaining strength. autres se dispersèrent? tout à coup, de sorte (b) que la petite Moscovite se trouva seule, abandonnée au milieu d'une forêt.3
PNEUMATICS.-I. Mourante de froid, ayant de la neige jusqu'aux genoux, elle vit soudain un ours se diriger vers elle ; alors elle recueillit (c) ce
OBJECTS OF THE SCIENCE-PROPERTIES OF THE AIR-ITS qui lui restait de forces (d) et voulut s'enfuir. Mais, hélas !
WEIGHT-DIVING-BELL-AIR-PUMP-FIRE BALLOON. comment une enfant si faible, et dont tous les membres sont In our first lesson on Hydrostatics we saw that all bodies were presque engourdis, pourra(e)-t-elle échapper à ce danger ? Déjà divided into three great classes-solids, liquids, and gases l'ours est sur le point de l'atteindre, Fædora pousse un cri, according to the relations subsisting between their ultimate parappelant au secours. Par une faveur inespérée de la provi- ticles and the relative distances at which they are placed from dence, au moment où la bête féroce se précipite sur elle, un one another. Of the properties of the first and second of these coup de feu (f) part, et l'ours tombe. Bientôt un étranger classes we have treated in our lessons on Mechanics and Hydroarrive à la place où Fædora s'était arrêtée, à peine revenue de statics ; and the science which is now to engage our attention son effroi.?" Il regarde avec bonté et d'un wil de compassion is concerned with the motions, pressure, weight, etc., of the cette enfants dont le ciel venait de lui confier le salut.
third. The term “ Pneumatics" is derived from the Greek word C'était un gentilhomme polonais appelé Polowski ;' il tira do pneuma, which signifies " breath” or “air,” and it therefore sa gibecière de la viande froide, du pain, du vin, et en offrit à means the science which treats of air; not that it is occupied Fedora, ' ce qui la ranima bientôt. Puis il prit l'enfant par la exclusively with air, but as in Hydrostatics water is taken as a main et l'emmena dans son château," éloigné d'environ deux type of all liquids, so here air is taken as a type of all gases, lienes.
being the most familiar of them all. There are many different La, Fedora accueillie (g) avec bienveillance par la femme du gases, but in their physical properties they, for the most part, noble Polonais, 12 ne tarda pas à se rétablir dels toutes ses very closely resemble common air ; and the points of differenco souffrances. Elle put alors leur raconter tout ce qu'elle savait in their composition and chemical properties it is not our prode son histoire. 14 Émus jusqu'aux larmes par le récit de vince to treat of here. When, therefore, in these lessons we l'enfant, Polowski et sa femme la comblèrent des plus touch speak of air, it should be remembered that the results obtained antes caresses, is et Fædora n'eut bientôt plus que le souvenir de are, with necessary modifications, true of other gases.
In many of their properties gases are very closely allied to Plusieurs années s'écoulèrent's ainsi sans qu'on apprit (h) rien liquids, hence many of the principles we arrived at in Hydrodes parents de Fædora. Cependant, elle avait grandi en sagesse statics, as relating to liquids, apply equally to gases-their et en beauté ; rien n'avait été négligé17 pour former an bien son particles move over one another with scarcely any friction, and ceur et son esprit. Elle avait alors quinze ans.18 Chaque | they transmit pressure equally in all directions. année, le jour de sa délivrance était un jour de fête.19 Durant There is, however, this great difference, that the ultimate l'une de ces réunions, tandis que Fædora racontait de nouveau particles of any liquid have a certain amount of attraction for les accidents de son enfanc 20 si agitéo, et pas-ait en revue tous cach other, while those of a gas repel one another : and thus, if les bienfaits dont la comblaient tous les jours ses parents d'adop- the space in which it is enclosed be enlarged, it will at once es. tion, on entendit l'explosion d'un coup de feu” parti à quelque pand and completely fill it. If a liquid is contained in a vessel, distance du château,
tho pressure it exerts upon the sides results solely from its Le vent souflait avec violence, 22 la ncige tombait à gros weight; but when a gas is thus confined there is, in addition to
this, a pressure on all parts of the containing surface, arising from maintain a supply of puro air, pipes are brought down from the elastic pressure of the gas itself. A gas, too, is highly-in some powerful force-pumps, and by means of these the bell is fact, almost indefinitely-compressible, while, as we have seen, kept full, and supplied with fresh air. Thick glass windows are for all practical purposes, a liquid is absolutely incompressible. placed in the top to give light to those within. The condense
Now as air is by far the most important of all gases, we tion of the air by the pressure of the water produces a sense of shall inquire a little into its properties before considering gases oppression, and frequently a pain in the eyes or ears: this, howgenerally. The atmosphere, then, is a layer of air completely sur- ever, gradually passes away. The men are sometimes provided rounding the earth on all sides, and extending upwards to a height with a waterproof dress and helmet, clothed in which they can usually computed at about forty-five or fifty miles. It fills every get out of the bell, and walk about at the bottom, air being conspace on the earth's surface, and presses, as we shall see, on all veyed to them by pipes. Frequently, indeed, the bell is dispensed bodies with an immense force. We are completely surrounded with altogether, and these dresses only used; the air-pipe opening by it; we live, in fact, at the bottom of an immense ocean of it; into the helmet, and the excess and waste air escaping by a suitable and yet, except when it is put in motion, we scarcely notice its valve; heavy weights are then fastened to the feet to keep the presence. Though thus unnoticed, however, it is of the utmost man at the bottom. Sounds made under water are conducted importance to us. Without it all life, animal or vegetable, by it to a considerable distance, and hence by taps on the sides would droop and die ; our fires and lamps would refuse to burn ; of the bell messages are transmitted to the surface. One of and when the sun shone, instead of even gradations of light and these plans is frequently used for the recovery of property from shade, we should have either almost intolerable brightness or the sunken vessels, and for fixing tackle, so as to endeavour to raiso blackest darkness. No clouds would shade the sun, nor any rain them to the surface, and large amounts of treasure have frefall to water the earth; all would be a barren, lifeless blank. We quently been thus recovered. The action of the condensing. see, then, something of the benefits we derive from it, and these pump, for forcing down the air, will be explained in a future surely render it desirable for us to study some of its phenomena. lesson. Its chemical properties have already been explained in our lessons Since air is a material substance it has weight, and we must on Chemistry; we need, therefore, say little about them. It is now see how to prove this, and also to ascertain what its weight not a simple gas, but a mixture consisting almost entirely of really is. oxygen and nitrogen, in the proportion of nearly 21 parts by To weigh an ordinary substance, we have merely to place it volume to 79 of the latter. Small quantities of carbonic acid in one scale of a balance, and place our weights in the other. and watery vapours are also present. The former of these is a This plan, however, will not answer here, since the air presses poisonous gas given off in the breath, and by fires, and burning on both; we have, therefore, to proceed in a different way. A bodies, and would speedily accumulate, so as to destroy life, had large glass globe, having an opening which can be closed by a not the Creator mercifully caused that trees should feed upon it, stop-cock, is procured, and by means of an air-pump it is comremoving the carbon it contains, and building that into their pletely emptied of air, and very accurately weighed; the air is own structures, while they set free again the oxygen which was then admitted to it, and the difference thus produced in the united with it in the gas. Winds mix the different portions of weight accurately noted. By now filling the globe with water the air, and thus remove this gas from crowded cities and bring its cubic contents may easily be ascertained, and from this we in its place purer air.
can calculate the weight of a cubic foot or any other volume of The watery vapour in the air varies very greatly in amount, air. and, as will appear, performs a very important office, being the In this way it is found that 100 cubic inches of air weigh, cause of rain and dew.
at the ordinary temperature and pressure of the air, a little over Though we notice the presence of the air so little, it is a 31 grains, and hence a cubic foot weighs about 14 oz. Though material substance; that is, it occupies space to the exclusion this weight appears small, and actually is so, when compareil of other bodies.
with the weight of solids or liquids, yet if we calculate the A simple experiment will furnish conclusive proof of this. weight of air in any building we shall find it much more than Float a cork on a vessel of water, and invert over it a glass we expected. Suppose, for instance, we have a room 20 feet by jar. On pressing the jar down, the position of the cork will 15 and 10 feet high, it contains 3,000 cubic feet. The air in it show that the level of the water inside is below that ontside; therefore weighs about 3,750 oz., or rather more than 2 cwt. something, then, must be there to press it down, and that The weight of other gases may be ascertained in a similar way, something is the air contained in the jar. If we have a and by comparing the weights of equal bulks of them with that stop-cock inserted in the top of the jar, or use a bottle with the of air, at the same temperature and pressure, we can ascertain bottom cut off, on opening the mouth the air will rush out, and, their specific gravities. the pressure being removed, the water inside will rise to its In making this experiment an air-pump was required; and as former level. We see, then, that though the jar would have this piece of apparatus is necessary in nearly all pneumatic been stated to be empty, it was in reality full of air. In the experiments, it will be as well to explain its construction at same way a bladder or air-cushion may be filled with air, and once, before passing on to notice the effects produced by the will sustain pressure almost as if it were solid.
weight of the air. If we take a large sheet of thick cardboard, or an open The simplest instrument for removing the air from any vessel umbrella, and run, holding it so that the air meets its flat sur. is that known as the exhausting syringe, and is represented in face, the resistance we shall experience will afford an additional Fig. 1 on the next page. A is the globe from which the air proof that the air which thus opposes the motion is really a is to be removed; this is furnished with a stop-cock, B, and material substance.
screws on to the end of the syringe ; C D is the cylinder, which The experiment we mentioned above--namely, immersing a is accurately turned inside, and in which the piston E works airglass jar in water—though so simple, is an important one, as it tight. In order to prevent leakage past the sides of this, a illustrates to us the principle of the diving-bell. In laying the groove is turned in it, as shown, and cotton or some similar foundations of bridges, piers, or other structures rising out of packing is wound tightly round, and then saturated with oil. In water, it is very desirable, and, in fact, absolutely necessary at this way it is made to fit much more tightly, and the wear is times for some person to be down at the place where the work likewise greatly diminished. A pipe, closed by a stop-cock F, is going on. Now if a coffer-dam had to be constructed to opens into the cylinder near its lower end. keep out the water it would add greatly to the expense of the Let the piston be at the lower end of the cylinder; the valve work, and also to the time occupied, but this can be dispensed F must now be closed and B opened; the piston is then raised to with by the use of a diving-bell. This consists merely of a large the top, and the air contained in A will expand and fill the iron vessel, made strong enough to resist the pressure of the cylinder. B is now closed, and F opened, and as the piston water. It is open at the bottom, and has a ledge round it, on descends it will force the air contained in the cylinder through which people may sit. The bell is raised a little above the F. The taps are again reversed, and a similar process repeated level of the water, so that the workpeople may enter it, and till nearly all the air is removed. then it is gradually lowered into the water by means of chains; If the area of the cylinder be just equal to that of the globe, the air inside keeps out the water, so that those within remain one-half the air in the latter will be removed by the first stroke, dry. As the bell descends, however, the air becomes compressed, and the density of that within will be of what it was;
similarly, and the water rises a little way. To remedy this, and also to after the second stroke it will be d, after the third J, and so on.