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ap for the weal and pleasure of others. Thus will be avoided time, some iron-rust, which is the oxide of that metal, we shall many of those scenes of discord in after years which are the never be able to drive off the oxygen and leave the pure iron outgrowth of the gratification of every whim in childhood. behind ; but if we heat the oxides of gold, silver, platinum, or
Unselfishness is the very life of the marriage estate. Without mercury, the heat will be sufficient to overcome the affinity the existence of the spirit of self-sacrifice there will come con- which unites the gas and the metal—the former will escape and flicts of will, and many other elements of discord and division. the latter romain. We do not advise the student to attempt to If true happiness in every stage of life is dependent upon a collect oxygen by this means, for more heat is required than is consideration for others, it is pre-eminently so in that relation given by a spirit-lamp; but the experiment may be successfully in which through a long course of years there is a companionship in anxiety and duty, as well as in pleasure.
Nothing enfeebles the whole life so much as selfishness. The age of the decline of Rome was an era of the greatest personal gratification, and obliviousness of the wants and woes of others. Nothing braces the character so much as a spirit of self-surrender for the common good. This has been existent in the best days of all empiros, and its presence or absence mark a rising or doclining poople.
One of the beautiful moral aspects of the family constitution is to be seen in the blessings which result from the care and training of children. It is, perhaps, one of the best antidotes to selfishness to have those we must by the very instincts of our nature love, dependent upon us for many years. Amongst the best curos for covetousness are the constant demands which a family makos upon the estate, as it hinders the growth of a too great self-care to have around and about us those whose sicknossos and necessities demand alike our sympathy and help.
Easy as it is to detect the presence of selfishness in others, it is most difficult to detect it in ourselves. Selfishness uses so many masks, and approaches the heart in so many insidious ways, that we sometimes think we are practising virtue when we are in reality only pleasing self. It becomes, therefore, the
Fig. 15. duty, as it is in reality the wisdom, of all men to crush the shown, as in Fig. 14. With the red oxide of mercury (HưO) noxious weed of selfish inclination, and to cultivate with assi- in the test-tube put a piece of charcoal; the oxide will give duity and care the graces of a self-denying character.
off the oxygen, the charcoal will burn brightly, and globules of
mercury will be found at the bottom of the tube. Fig. 15 shows LESSONS IN CHEMISTRY.-V.
convenient forms of clips for holding test-tubes; A can be made
by the student; s is an india-rubber strap; w, a piece of wood OXYGEN.
which serves the purpose of a hinge. SYMBOL. ATOMIC WEIGHT .. 16
- DENSITY , . 16. 2. The more general way is by heating in a Florence flask potasThis, the most widely-spread, and the most important of all sium chlorate (KCIO2). By adding one-third its weight of the the elomonts, was discovered independently by Priestley and the black oxide of manganese (Mn0,), the gas will come off at a lower Swedish chemist Scheele, in 1774.
temperature; the manganese itself undergoes no change, but It constitutes of the atmosphere,, of the weight of water, acts by its presence : this phenomenon is called catalysis. The and at least s of the materials composing the solid crust of the red oxide of iron (Fe,0), the black oxide of copper (CuO), or even earth. It is a tasteless, colourless, inodorous gas.
sand, has the same effect, though not in so eminent a degree.
The apparatus is arranged as in Fig. 16. The stand is con
venient, but superfluous, as the flask may be held by a clipper, or It cannot be got from the air very readily; for we are not a piece of paper, as the test-tube in Fig. 14. Instead of making acquainted with any re-agent which will absorb the nitrogen with which it is associated; yet there are substances which will com
bine with oxygen at cer-
bends in the glass tubing, it is as well to have a short piece of Melted silver has also small india-rubber tubing to join the tube from the cork and the
the property of absorb- delivery-tube, thus forming a flexible bend. A bowl is filled with Fig. 14,
ing oxygen from the air, water, and the jar into which the gas is to be received is laid dowa
which it gives off as it in it; when in this position it must be covered completely by the returns to the solid state. It need not be said that these water, and there must be left in it no air-bubbles. "Now raiso it methods of obtaining oxygen from the atmosphere are neither up, mouth downwards, but not out of the water, so that the jar easy nor inexpensive.
will be full of water so long as its mouth is below the surface. 1. The most simple of all methods of obtaining this gas Should there not be a bowl at hand deep enough to allow the would appear to be by heating the oxides of the noble metals. jar to be completely covered when lying down, & shallow dish Such metals are " those which can be reduced from their oxides may be used. In this case the jar must be filled with water until by heat." If we heat to any temperature, or for any length of it rans over the brim; then place over the mouth a piece of glass
TO PREPARE OXYGEN.
cat circular-a flat piece of tin or sheet-brass will do as well ; where it is diluted with nitrogen. This the following experi-
of the gas, pass a small plate glass; lift it
hand the full one is re- red; with one
moved, with the other the hand slide the
second one should be placed glass off the to receive the gas. The chemical action is expressed and ex- mouth of the jar plained in this equation
sufficiently to KC10,= KCl + 0,;
admit of the en
Fig. 19. that is, potassium chlorate, when heated, becomes potassium trance of the chloride and oxygen.
charcoal, and the charcoal will burn brilliantly in forming with Do not place the flask on a cold substance while it is hot, but the oxygen carbonic acid gas (CO2). when cold fill it with water ; after a few shakes pour it into a
2. Place in the
" deflagrating spoon ” —which is a small metal tall jar, and add more water. The potassium chloride is very cup soldered to a piece of wire (Fig. 20)-some sulphur; light it soluble, and the unaltered MnO, goes to the bottom; let it —it burns with a pale blue flame; introduce it into a jar of stand all night, then pour off the supernatant liquid;" fill the oxygen—it burns brightly into so, (sulphurous acid), whichjar again with water, and again let the MnO, subside ; pour off causes the well-known suffocating smell. the clear water, which contains the last traces of the Kci, and
3. Repeat this experiment with phosphorus. The student is throw the Mno, upon a filter, and afterwards dry it; it is then advised to use the red amorphous phosphorus, which is not so fit again for use. This will give the student some practice in inflammable as the stick phosphorus. ' An intensely brilliant manipulation, but practi.
light is emitted during the formation of the cally it is not worth the
white fumes, which are phosphoric acid (P,0.). trouble, since the Mno, is
4. The following experiment is very illustraso cheap.
tive of the fact that burning is chemical combi.. 3. Oxygen may be got,
nation. Take a piece of fine iron wire-buch. when large quantities are
as that of which “ribbon-wire” is made; coil' required, with more economy
it into a spiral, round a pencil; stick the endi from the black oxide of
of it into as small a piece of cork as you can; manganese itself; but since
dip this into any inflammable liquid, such as great heat is required, an
naphtha ; pass the other end through a hole: iron bottle must be used, as
in a disc of tin ; light the cork, place it in a in Fig. 18. In this bottle
jar of oxygen, as in Fig. 21, and the wire will the delivery tube is passed
burn with beautiful scintillations into Fogo
Fig. 20. through a cork in the end
which is the same oxide of iron as the lodestone. of the pipe. The retort
It is better to fit a piece of cardboard in the bottom of the is filled with manganese
jar, and leave about an inch of water in it: for the fugod oxide broken into lumps about the is so hot that if it touch the glass the jar will crack. Fig. 18. size of a pea; then the pipe
From the above modes of preparing oxygen we may take
is screwed in, and, to ensure examples of one method of finding what weight of the subperfect tightness, the screw is luted with white lead.
stance is required to give a certain quantity of another. The action is
Take the equation
KCIO, KCl + 0, ; 3Mn0, = Mn,O, + 0,;
the atomic weights of these elements are that is, the peroxide has been by the heat reduced to a lower oxide.
39:1 + 35.5 + 48 = 39'1 + 355 + 48
122-6 = 746 + 48. 4. A process which answers well, and which is more economical That is, from every 122.6 parts by weight of potassium chlorate, than that in the second, is the following :- Take 3 parts by weight 48 parts by weight of oxygen come off; of pulverised potassium bichromate (K,0,2Cr0,–1 atom of potash and 2 of chromic acid), and 4 of sulphuric acid (H,SO); kilogramme of the salt gives off -392 of
or, from 100, 39.2 come off ; that is, 1 heat it in the Florence flask, and the chromic acid parts with the gas, or nearly 1 kilogramme.
3Mn0,= Mn, 0, +20. The compound under the line is chrome alam.
3 x 55+3 x 2x16=3*55+4x 16+2 x 16 Combustion is simply chemical combination, and when this
261 = 229 + 32; combination is violent, sufficient heat is developed to produce that is, from 261 parts of manganese fire,
by weight we get 32 of oxygen, or about The affinities of oxygen are remarkably strong, and it is of the weight of the MnO, But the capable of entering into combination with every body in nature commercial black oxide of manganese except Fluorine; therefore fire is generally oxygen entering into is seldom very pure, and usually yields
Fig. 21. combination with the body burning; though we shall find about half this weight of gas—a pound instances of this phenomenon in which oxygen takes no part. giving off about 1,400 cubic inches. The relation between
In the fires of our houses the oxygen of the air is combining volumes and weights will be given in due time. with the coal, which is carbon, to form an invisible gas, car. Oxone is the allotropic form of oxygen; that is, it seems to be bonic acid gas (CO2), which passes up the chimney. Hence we oxygen in “another form,” probably condensed, and therefore say that oxygen is the great supporter of combustion. Of course more active. It is produced by the slow oxidation of phosphorus. combustion will be more violent in the pure gas than in the air, If a piece of this substance be placed at the bottom of a jar in
half its oxygen.
which is a little water, the oxygen of the air in the jar partly I “ The idea of contempt” ascribed to it by Latham does not becomes ozone.
necessarily, for it did not originally, belong to the word. This body is also formed when electric sparks pass between
"I will be a swift witness against those that defraud the hireling in two points. The sulphurous smell in the neighbourhood of a his wages."— Malachi iii. 5 (compare Job vii, 1, 2; xiv. 6). strong eleotric machine, or of a flash of lightning, is the peculiar smell of ozone. Ozone is a very powerful oxidising agent. It
Stripling may be connected with the Latin stirpes, stirps, can even soparate the iodine from the compound potassium offshoot; so that stripling is a little branch, a youngster.
“He is but an yonglyng, iodido-forming potash and liberating the iodine. This fact has been used as a test for ozone. Iodine makes a blue com
A tall, worthy stryplyng."-Skelton. pound with starch, so that if a piece of paper be dipped in a
The last line shows that nothing contemptuous belonged to the mixture of starch paste and potassium iodide, if any ozone be word in the olden time. Consult the ensuing :present the paper becomes blue. This test alone, however, is
“Now a stripling cherub he appears, not decisivo, for nitric acid, which is sometimes found in the air,
Not of the prime, yet such as in his face will do the same thing. It has been said that the health of a
Youth smiled celestial.”- Milton, “Paradise Lost." district depends upon the quantity of ozone in the atmosphere- Ly, a termination of Saxon origin, having the force of our like, but this fact is not satisfactorily established. Since it is a great and so forming an adjective or an adverb; as childlike, childly, oxidiser it is a powerful bleacher, for by oxidising the colouring in German kindlich ; manlike, manly, manlich. When ly is added matter it destroys it. It is hoped to apply it to the bleaching to a noun, it forms an adjective, as love, lovely; when it is added of sugar, which has hitherto been effected by charred blood. to an adjective, it forms an adverb, as wise, wisely. Such a A powerful magneto-electric machine has lately been sont out to formation as “holily" (1 Thess. ü. 10) is to be avoided for tho the West Indies to produce ozone, wherewith to bleach sugar. sake of euphony. Ozone was discovered by Professor Schönbein, of Baslo, to whose Mont, from the Latin mentum (as in ornamentum, an ornament; genius we also owe gun-cotton.
adjumentum, an assistance), through the French ment (as in the French mandement, or Latin mandatum, a command), is a suffis
which denotes the result of the act indicated in the verb from LESSONS IN ENGLISH-XVIII.
which the noun is derived : thus, velo means I veil or cover; and SUFFIXES (continued).
velamen or velamentum is a veil or covering ; so aliment (from Words have been curiously formed by abbreviation; the word' the Latin alo, I nourish) is a means of nourishing, nourishment. omnibus affords an instance : derived from the Latin “omnibus," Hence, devotement properly indicates not the act, but the result; the dative case of the plural number of the Latin adjective omnis, not the doing, bat the state of feeling which ensues from the doing, all, and so signifying for all that is, every man's carriage-tho the devotion. In practice, however, the usage seems reversed. word has been shortened into bus, and so it is now generally “Her (Iphigenia) devotoment was the demand of Apollo."—Hurd. tormed in common parlance. Mob appears to have been formed
“Oh, how loud in the same way. What is now called the mob used to be called
It calls devotion genuine growth of night! the rabble. But as the rabble aro mobile vulgus, a fickle crew,
Devotion! danghter of Astronomy ! HQ were they called mobile vulgus, and by contraction, mob.
An undevout astronomer is mad." Ştill mob and rabble are not identical. Rabble is the general
Young, “ The Complaint." term, the class, and mob is a collection of persons belonging to that class. Palsy is a contracted form of the now more fashion
It is our intention now and then to enliven our lessons with a ablo paralysis. Botween alms and eleemosynary there would conversation on English grammar, supposed to be held between seem to be no connection; both, however, come from the same an educated man on the one hand, and one whose education is Greek term, and the former is only a shortened form of the imperfect on the other. We do this because there are many root from which the latter is derived. Well do we remember of our readers who may gain much useful information from a kickshaws, a term of our youthful days, used to signify some
lesson brought under their notice in a conversational form, that thing contemptible. Little did we then suspect that it was they may fail to gather from lessons written in the ordinary only the English way of pronouncing the French quelque chose ; way. We therefore recommend our readers to study the fol. i.e., something, contemptuously travestied to mimic and ridiculé lowing dialogue with care, and endeavour to re-write the substance French prisoners in England.
of it from memory when they have read it over three or four Kin, from the Anglo-Saxon cyn, kin, offspring, son, signifies times, and noted the principal points in it. the son of; as in Wilkin (Wilkins); seen in another form
CONVERSATIONS ON ENGLISH GRAMMAR.-I. namely, Wilson. Kin, from its signification, has also a diminutive force; as in lambkin (a lamb's child), or little lamb. What
William. Well, I have failed again; a packer I am, and a is little is dear, hence diminutives are terms of endearment. packer I must remain, fond as I am of reading, and desirous as But what is little may be despised. ., Sometimes, therefore, And yet, if I had fair play, I could, I am sure, do the counting
I am of getting an employment more suitable to my tastes. diminutives imply contempt; as in manikin.
house work as well as some that are there. “This is a dear manikin to you, Sir Toby." - Shakespeare.
Thomas. Not quite, William; true, you are intelligent and Le (see el), among the suffixes already given.
trustworthy; you also write a good hand, and are ready at Les, from the Anglo-Saxon læs (German, los, destitute of), has accounts; but you are a very poor grammarian. not a comparative but a negative force; as, an læs twentig, William. Not so poor as you think; though I am, I grant, one less twenty, or, as we should say, twenty minus one. Hence far behind you, Thomas; but then you have been to college, it appears that the idea of less is privation or negation. Con- and ought to know grammar. sequently less, the comparative of little, is altogether a different Thomas. Yes, and I am willing to teach you, for I am sure word. And thus we are also led to understand the true force you will never get forward as you wish, and as I should like to of less when employed as a suffix; as, motionless, or without
until you can write your mother tongue correctly. motion ; deathless, free from death. Two negatives thus make William. I know that, and I have studied English grammar; a positive: death, the privation of life, and less, the negation of but it is very difficult. death, combine to declare the idea of ever-enduring existence, Thomas. Yes, and you still write bad English: for instance, the most positive, the most real, the most permanent of all con- | your letter of application for the vacant situation contains not ceivable things, the very essence of Deity; life itself.
less than three grammatical mistakes, and is enough of itself to Let, according to Latham, “seems to be double, and to consist prevent your success. How can you expect to rise in the world of the Gothic diminutive l, and the French diminutive t.” It when you cannot speak and write English? In a counting is found in streamlet, tartlet, hamlet (Anglo-Saxon, ham, home; house they want their letters written grammatically. It would as in hamstede, homestead).
be a disgrace to a house to send out letters containing errors of Ling, of Saxon origin, denotes descent, and hence offspring ; grammar liko those which you commit.. also that which is little, and that which is beloved ; e.9., darling William. I dare say you are right; and so I must remain a (dear child), gosling (little goose), nestling. Hireling is properly packer. & child of hire, a person whose services are obtained by hire. Thomas. That does not follow ; learn the English grammar.
William. A very easy precept, but a very hard job.
LESSONS IN DRAWING.–XVIII. Thomas. Not so hard as you think. William. Excuse me, I have tried, and I have failed.
TREATMENT OF REFLECTIONS IN WATER. Thomas. Becanse you have tried by yourself.
It is not the rule that because we can see the objects we must William. By myself I must still try, or give it up.
consequently see the reflections; and, on the other hand, it is Thomas. No, I will assist you, if you will mako one more very common to see the reflection of an object, or of light, when effort. Let us talk over the matter; I think I can make tho the eye doos not see the object itself, something intervening study easy to you. Once a week we will converse together on between the eye and the object, but not between the eye and the English grammar, and if you will only reflect in the intervals reflection. The leading principle, upon which is founded all on what I say, and follow my guidance, I have no doubt you other data connected with our subject, is that the reflections of will in time understand the subject thoroughly.
all objects and their parts are always perpendicularly beneath the William. I agree, and am very much obliged to you for the objects and the parts themselves respectively. Fig. 112, a simple offer.
subject of posts, etc., will explain this. The top of the post a Thomas. Oh, never mind the obligation; men should always is perpendicularly over the roilection b, and so with the rest ; try to assist each other, and I am very desirous to see you in but it must be borne in mind that the proportion to be drawn such a position as your character and talents mark you out for. of the reflection of an object is regulated by or according to William. Let us begin this evening.
the position of the object, and also with regard to the point Thomas. Very well, and you must come to my house every from which we view it. If we view the posts (Fig. 112) as they Tuesday evening at eight o'clock, and we will see what can be are drawn, perpendicularly and parallel with the picture plane done. But to begin :-As a fundamental rule, you must observe that is, the upper parts neither advancing towards the eye that grammar is a science in which authority goes a very long nor receding from it, but exactly over the position of the lower way. At first, you will do well to consider that everything parts—then the reflections will be the same in length, with the depends on authority.
slight exception resulting from the perspective of distance. William. What authority ?
We will endeavour to make this clear by the help of a few Thomas. That of the best writers in the language. If you problems. In order fully to understand these problems, we study English grammar, then you take as your authorities or recommend the pupil to work them out, and as the principles guides such men as Shakespeare, Milton, Dryden, Johnson, of construction are the same throughout, we advise him to Pope, Macaulay. Their practice is your model. As they write, repeat them with a few of the conditions varied—for instance, so you must write.
Grammar then, you see, is, for our purpose, greater or less inclinations of the slopes, and greater or less imitation. Those who write English grammar derive the in- elevations of those objects which are most in advance. Our structions they offer from the usages of the best English authors, first subject will be to draw the reflection of a wall (Fig. 113). or, as they are termed, the English classics.
Let A be the end section of a wall situated on the margin of a William. “Classics !” why, I thought the term “classics" was river. It is required to show its reflection, B, below the water's confined to the Greek and Roman authors, such as Homer and edge, CD; st being the position of the eye on the horizontal line. Virgil.
Draw a line, sis?, perpendicularly as much below the base CD Thomas. Oh, no; every literature has its “classics.” The as it is above it, making s? E equal to s' E. From the upper part word is derived from “ class," and denotes those writers who, of the wall F draw a line to s', and where this line cuts the by common consent, are placed in the first class. The practice base c p in u will give the point through which a line is to be of such writers sets the fashion in the language in which they drawn from si to meet a perpendicular line from F, which will write, and they are followed by all who wish to speak and write give the depth of the reflection required. Now in order to that language correctly. Now you are to suppose that I have apply the above rule in showing the face of the wall and its studied our English classics, and have hence ascertained how I reflection, we must proceed as follows :-In Fig. 113 draw at ought to speak and write. In that study I have been preceded pleasure the line acdb, and repeat this line, with its respective by others. Their conclusions afford me aid. Under that aid divisions, in Fig. 114; through the several points a cdb draw I have formed a system of rules, and that system of rules is horizontal lines at right angles with ab; make A B equal to called “ English grammar." English grammar, then, you see, the length of the given wall, and draw the rectangle A G H B; is a science. Science, you know, means knowledge; it is know. A EFE will represent the wall, EFHg the reflection. The ledge, the materials of which are systematically arranged; pupil must be reminded that the line a cdb in Fig. 113 is the arranged, that is, into a system, arranged in a set order, picture plane or medium through which we see the wall, and and with a view to a certain purpose or result; and English upon which it is supposed to be traced (see Vol. I., page grammar consists of a continued set of rules derived from the 72, Def. 3, “Station Point”). We have previously observed practice of well-educated Englishmen, so arranged as to form that in consequence of the position of the eye being above the & complete whole, and communicate useful information to the reflection, and on a level with some portion of the object, it learner.
will repeatedly occur that the reflections of many parts of the William. Well, I understand that; but in our house every- solid cannot be seen, although the parts themselves are in sight,
" they does,” and you told me yesterday that was and form, perhaps, the most important portions of the object. wrong.
Let us illustrate this by Fig. 115, which is a mass of masonry, Thomas. It is wrong; remember, I said that we are guided having two slopes, A and B. Having drawn the profile or by the practice of educated Englishmen, and educated English-section G, proceed as in the lasć case, being careful to draw lines, men say, “ they do.”
or visual rays, from every angle to s', and also to s?. Where William. But what does the word grammar signify? I these rays cut each other respectively in w,t,9, lines from s' will thonght a grammar was a book; you say it is a science. determine the lengths of the reflection. We must apply this to
Thomas. It is both. Grammar is a word of Greek origin. a front view, as in the former case. Draw the perpendicular It comes from a Greek word, ypanua (gram'-ma), which denotes line E E? (the picture plane), and mark the points where the a letter, a letter of the alphabet. Hence grammar is the science visual rays cut the picture plane in a, b, c, etc. Repeat this line of letters-letters, that is, employed to express ideas. Listen: in Fig. 116, and copy from Fig. 115 the distances of the diviletters represent sounds, and form syllables and words; words sions upon it, and proceed with the horizontal lines from these represent sounds; and the sounds they represent stand for distances as in the last problem. Upon the line marked g, thoughts or ideas; while those thoughts or states of mind which represents the water's edge, make ro equal to the given represent things, objects in the inner world or in the outer length of the wall; d being the horizontal line, and the observer world. This statement will require thought. Do not trouble being supposed to stand opposite the centre of the wall, the point yourself too much about it now; you will understand it by-and- of sight will be at ps. Now the lines F Ps and G P s are horiby. But observe that grammar is the science by which you zontal lines in perspective–that is, the perspective of the base learn to express your ideas correctly, that is, according to the gu (Fig. 115): therefore, where the visual rays from the points neages of the best authors. And a book in which these usages in the base cut the picture plane in f (three lines close together) are set forth as rules is also called a grammar. Every language will give the points, k, l, m, whenco the perpendiculars of the has roles peculiar to itself. Hence we have“ French grammar," wall must be drawn, the lower slope in must be drawn “Greek grammar," as well as “English grammar.”
between the lines e, ġ (see Fig. 115), and the perpendicular
ko; the same with the upper slope. The reason why neither for himself. The same may be satisfactorily proved with of these slopes are seen in the reflection is because the point regard to clouds. It is common, also, in their cases to see pooincides with g (Fig. 115) on the picture plane: therefore the brilliant reflections of light clouds on the water, when to the same line, ra, represents both extremities of the slope. If the eye there is nothing to account for them. These reflections slope B had had a greater elevation—that is, had it been at a are invariably caused by light clouds which are hidden from greater angle
view behind then the
other clouds, upper extre
the reflections mity would
affording have admitted
the only evi a line to se,
dence of their and conse
existence. quently would
Why is this? have at the
And where is picture plane
the root of the Ek'at a higher
mistake that point than g;
is so frequentand that point
ly made, that, of intersection
tion, whatever been shown
we paintabove below g in the
the water must reflection. And
be necessarily also for rea
repeated by Jons given
its reflection! above, we see
It is simply parts reflected
this, that which are not
6. visible in the
the whole objects them
view, sky and selves. Figs.
all included, 117 and 118
as one single will satisfy the
plane, never mind upon Fig. 112.
thinking there this point.
are parts more The subject is a cottage on a bank with a large notice-board in remote than others, and consequently many are reflected which front of it. The profile view (Fig. 117) will explain the dis- are shut out from the eye by intervening objects. tance of the board from the cottage, and this will account for Water not only receives reflections, but, conditionally, is the great difference between the details of the projection A and capable of receiving shadows. If the water is perfectly clear, the reflection B in Fig. 118. If the pupil fail not to work no shadows occur, and the reflections are more or less vivid in ont this problem
proportion as the also (of which,
water is more or being constructed
less impregnated by the same rules
with colouring as the former, we
matter, say clay, give no detailed PP
or as rivers geneexplanation, but
rally appear after prefer leaving it
heavy rains. Then as it is, for an
the strength of exercise), he will
the reflections and more readily un.
shadows alternate derstand it, and Fig. 118.
in proportion to the method of
the clearness or construction also;
opacity of the remembering that
When it the visual rays
is very thick and drawn from every
muddy, the she important point of
dows of objects the whole passing
are cast as forcibly through P P (the
upon the surface picture plane) de
as they are on a termine the points
road; and as it to be transferred
becomes clearer, to the correspond
the reflections being plane on the
come more bril. left in Fig. 118.
liant and the We remark that
shadows weaker: the notice board
the earthy par: covers part of the
ticles mingled with roof in the pro
the water receive jection A, whilst
the shadow, not it is clear of the
the water itself. roof in the reflection B. Also compare the chimneys in both | In perfectly clear water the light passes through the water cases with respect to their apparent position with the board. itself, as through a piece of glass, lighting up the bed of the In the reflection B the sills of the windows are on a line with river, so that we are able to distinguish readily the stones, the base of the post, and the thresholds of the doors cannot weeds, fish, and whatever else may be at the bottom; then the be seen because they are hidden by the bank. There are shadow which falls upon the water sinks as it were, and is seen other differences, which the pupil will be able to discover at the bottom only.