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quantity of gold and silver was dug up in Spain. 12. The soldiers, the assistance of a well-filled purse, how frequently the effect of seized with fury, stabbed their general. 13. The horse suddenly fell, a room is destroyed by gaudily-framed engravings and oil. and threw the consu) off upon his head.
paintings that do not harmonise with the paper-hangings. There EXERCISE 156,-ENGLISH-LATIN.
are very few, if any, optical contrivances which could be used for 1. Convertesne facultatem tuam dicendi ad patriæ perniciem ? 2. wall-decorations, and therefore the convex mirror becomes a Facultatem meam dicendi convertam ad omnium bonum. 3. Facul special favourite, and is found hanging in many tastefully-decotatem suam dicendi ad patriæ salutem conservationemque convertit. rated apartments. A room with a bow-window looking into a 4. Proditor deprehensus in conspectu civium necabitur. 5. Cave ne flower-garden, used perhaps as a library, and having only a equus corruat, teque lapsum super caput effundat. 6. Militesne ducem plain paper on the walls, becomes enchanting when seen reflected confodient? 7. Hic liber vetustate exesus est. 8. Regina ingentem in miniature within the frame of a circular convex mirror, nummorum numerum procudet. 9. Nuntius animum meum laceravit. which should have a plain oak frame with a few gilt stars upon 10. Animus meus conspectu mortis mariti laceratus est. 11. Senes juvenesque vivendi cupiditate incendentur.
it. Convex mirrors are spoilt by being mounted in shining gilt
12. Non potes verum videre, quamdiu error tuæ menti offusus est. 13. In Italiam provectus frames; the reflection of the light from the glass is quite brilest. 14. Ad illas provehentur oras. 15. Dux urbem fortiter defendit. liant enough, and will make a room look light and cheerful that 16. Urbs a civibus bene defendetur. 17. Britanniæ coloniæ toto orbe might otherwise be condemned as a dull one. People often terrarum diffunduntur.
wonder why objects should be reduced when seen in a conver EXERCISE 157.-LATIN-ENGLISH.
mirror; something has been done to explain this by Fig. 7 (page 1. It is necessary that you should both learn and confirm that 249), and the next will demonstrate the manner in which the which you have learnt by action. 2. Things ill-acquired depart ill. face of a person looking into a convex mirror is diminished. 3. As the swallows are present in the summer time, but retire driven One ray may be taken from the forehead (Fig. 8), and another off by the cold, so false friends are present in the prosperous period of from the chin-of course the rays reflected from the forehead life; but as soon as they see the winter of fortune, they all quickly and chin cover the whole of the mirror-but only a few can be depart. 4. It is uncertain what is about to happen. 5. What has reflected to the eye; thus the ray that falls at centers the eye fallen to the lot of each, that let each retain. 6. Alexander grieved at o, which, transferring every image along that line in which that his old and guiltless friend Clitus had been killed by him. 7. To it is reflected, sees the forehead in the line oon; the have faithfully learnt the liberal arts softens the manners (of men), and does not allow them to be barbarous. 8. Benefit attained through a
same with the ray ar refleoted to o, the line of vision will be friend does not gratify so much as the love itself of a friend. 9.
ors, and as the angle of vision is diminished, the face is Hannibal was not deceived (in thinking) that the enemy would carry reduced in size. The student may copy this diagram, and, by on the affair more fiercely than advisedly. 10. From the time when drawing other lines, try if any other rays can enter the eye money began to be in honour, the true honour of actions declined. 11. The ancient wood fell which no one cut down with iron. 12. Epaminondas is said to have played excellently on the lyre. 13. Cato narrates that the ancient Romans, at their feasts, sang the praises and virtues of illustrious men to the sound of the late. 14. The signal is given to the companies, and the horns and trumpets have sounded.
EXERCISE 158.-ENGLISH-LATIN. 1. Gallina ovum peperit. 2. Gallinæ ova parient. 3. Quot ova gallinæ tuæ in dies pariunt? 4. Mater tua filium peperit. 5. Dux publicis ædificiis non parcet. 6. Miles, furore captus, ducem suum occidit. 7. Putasne hostes etate confectis parsuros esse ? 8. Ignoro hostesne mulieribus infantibusque parsuri sint. 9. Induciæ viginti dierum pactæ cum hoste sunt. 10. Voces concinuerunt. 11. Signo dato, frater tuus cecinit ad fides clarorum virorum laudes. 12. Viginti
Fig. 11. millia militum nostrorum cæsa sunt.
EXERCISE 159.-LATIN-ENGLISH. 1. Take for granted that every day has shone upon you as the last. 2. The judges were so inflamed by the reply of Socrates that they con- except those reflected from the part of the convex mirror demned to death a most innocent man. 3. Beason, when it is grown included within cr. up and perfected, is rightly named wisdom. 4. The question is, if a wise man has unknowingly received base for good coin, whether, when reverse of a convex one. The concave enlarges the appearance
The optical properties of a concave mirror are exactly the he has discovered it, he will pass it for good. 5. It is incredible to of objects. A small portion only of the surface of a convex mirror 6. When money is coveted, and reason is not immediately applied to reflects at any one time to the eye the image presented before correct that desire, that evil enters the veins and clings to the vitals. it, whilst a much larger surface of a concave mirror comes into 7. Endymion fell asleep, I know not when, on Latmus, a mountain in use. This is well shown by the accompanying illustration (Fig. Caria, and has not yet awaked. 8. An orator should abstain from 9), reproduced from Walker's diagrams, published upwards of words which, on account of their age, have become obsolete. 9. Have sixty years ago. you at length recovered from the disease under which you laboured so Rays issue from every part of the face upon all parts of the long? 10. My wound, which seemed to have already healed up, has mirror, but it is only a c that can paint the forehead ; that may now broken out afresh.
is reflected to the eye from c, and as everything is seen along EXERCISE 160.--ENGLISH-LATIN.
that line in which the ray comes last to the eye, the mind puts 1. Dies tibi illuxit supremus. 2. Dies fratri meo illuxitne supremus ? the lines a c and oc together, and they make the line ocd the 3. Stultis meis verbis pater exarsit. 4. Judices exardescere non real distance which has been travelled by the ray from the debent. 5. Iuter Romanos Carthaginesque terribile bellum exarsit. forehead, and where the forehead will be seen ; certainly rays 6. Nostris hostibus omnia exoleverunt. 7. Nos adulterinos nummos issue from the forehead
and all parts of the mirror, but then rays pro bonis accepisti ? 8. Imprudens accepi. 9. Nunc id rescivi, nec that fall on the mirror at x would be reflected to the chin eos pro bonis solvam. 10. Romani et aborigines brevi coaluerunt. uselessly, since, as the same author shrewdly observes, we cannot 11. Endymion in monte obdormiscet. 12. In pulvino obdormivi. 13. Multa verba obsoleverunt, obsolescent multa verba. 14. Ardor meus
see with the chin. In short, it is only that particular place, c, Don defervescet. 15. Vulnus recruduit. 16. Vulnera men non con- which (by the law of the angle of incidence and reflection) can sanuerunt. 17. Nescio an mei vulnera patris consanuerint.
be reflected to the eye.
, by the same law, be reflected to the eye, and along the line RECREATIVE SCIENCE.–V.
ong the chin is visible. The whole visage being seen under THE REFLECTION OF LIGHT, AND DECEPTIONS WITH
the angle dog, must be greatly magnified. PLANE AND CONCAVE MIRRORS.-II.
The opposite properties of convex and concave mirrors are
shown at once in Fig. 10, where the face of a man, a, looking into The decoration of the walls of dwelling-rooms is a matter of the convex surface of a b is reduced to that of a boy, and the face the greatest importance to those who have tasteful and elegant B, gazing into the concave surface, is enlarged to that of a giant ideas, and like to see themselves surrounded with objects of Parallel rays converge to a focus when projected on to s beauty; and it is well known that with the best intentions, and concave mirror. If the hand is held before a concave mirror,
and outside the focus, its inverted image is seen hanging in the make use of flat mirrors for burning. Hutton says the astonishing air.
philosophico-military exploit of Archimedes has been recorded In Fig. 11 diverging rays proceeding from the hand cd, are by Diodorus Siculus, Lucian, Dion, Zonaras, Galen, Anthemius, made converging when they fall upon the mirror ab, and the in. Tzetzes, and other ancient writers. The account of Tzetzes is so verted image is seen at m, the diverging rays cd being brought particular that it suggested to Father Kircher the specific to a point at o s, where they cross and enter the eye.
method by which Archimedes effected his purpose. " Arthi. It is in this manner that the concave mirror has been medes," says that author, " set fire to the fleet of Marcellus by used, probably from the most
a burning-glass, composed of ancient times, to produce
small square mirrors, moving illusory spectres, and by con.
every way on hinges; and cealing the mirror, and illu.
which, when placed in the sun's minating the object properly,
rays, reflected them on to the very amusing effects may be
Roman fleet, so as to reduce it shown. Nearly every old work
to ashes at the distance of a on optics gives & diagram
bow-shot.” This account gained and directions for using the
additional probability by tho concave mirror, of which Mr.
effect which Zonaras ascribes Walker's is probably one of
to the burning mirror of Prothe best.
clus, by which he affirms that In Fig. 12 let a be the
the fleet of Vitellius, when bemirror, d the actor concealed
sieging Byzantium, now Conby the cross partition, c, e a
stantinople, was utterly constrong light, also concealed by
sumed. But perhaps no histothe partition i. If d holds a
rical testimony could have book, or any other object, the
gained belief to such extraorFig. 8.
light reflected from it will pass
dinary facts, if similar ones between the screens, or parti
had not been seen in modern tions, e and i, to the mirror, and
times. In the memoirs of the be from thence reflected to %,
French Academy of Sciences where the image of the book
for 1726, p. 172, we read of a will appear so tangible, that
plane mirror of twelve inches the spectator, looking through
square reflecting the sun's rays the opening x, will suppose he
to a concave mirror sixteen could take hold of it. The con
inches in diameter, in the focus federate, d, may actuate vari.
of which bodies were burnt at ous moving figures, as flying
the distance of 600 paces. The birds, angels, demons, etc., the
great naturalist Buffon coneffects of which at z would be
structed a burning apparatus very surprising.
by combining 168 pieces of lookA concave mirror becomes a
ing-glass six inches by eight, burning mirror when held in the
so that he could, by mesun. The heat at the focus is
chanism connected with each, very powerful. It is not, how.
concentrate the rays of the ever, supposed that this was the form of reflector used by sun to one focus; and by using 224 mirrors he was able to melt Archimedes when he destroyed the fleet of Marcellus by con- plates of silver at a distance of forty feet; with 112 mirrors he centrating the rays of the sun upon his ships. The celebrated set fire to planks covered with wool at a distance of 138 feet; Kircher went to Syracuse, and observed that the Roman ships even with twelve mirrors combustibles could be inflamed at a could not have been at a less distance from the walls of the distance of twenty feet. city than thirty-three paces; and, as the focus of a concave It was with the concave mirror the ancients re-kindled the mirror is at the distance of half the radius, he calculated that the sacred fire, so carefully watched by the vestal virgins. Plutarch, concave mirror used by Archimedes must have been a portion of in his life of Numa Pompilius, says that the instruments used a sphere of at least forty-six paces radius, and therefore most for this purpose were dishes, which were placed opposite to the difficult, if not (in those days) impossible to construct. Vitellio san, and the combustible matter placed in the centre; by which states that Anthemius of Tralles, the engineer who lived in the it is probable he meant the focus, conceiving that to be at the time of the Emperor Justinian, was the first who proposed to centre of the mirror's concavity.
CORRESPONDENCE IN FRENCH.-VI.
Mete, le 15 Janvier 1865.
Messieurs Armand Roubot et Cie, à Londres. 22.-LETTER IN REPLY TO AN ORDER FOR AN ARTICLE WHICH HAS BEEN SOLD.
Messieurs,-Le porteur de cette lettre, Mons. F. Decretelle,
de cette ville, est un des nos anciens amis. Il se propose de Bremen, March 19th, 1866.
faire un voyage en Angleterre, et nous prenons la liberté de Messrs. Smith Brothers, London.
vous le recommander. Gentlemen,---I regret extremely to have to inform you that En cas où M. Decretelle aurait besoin de quelque argent the article in question has been sold to Mr. Barton, of your pour ses dépenses de voyage, ayez la bonté de lui compter ce city. Perchance you might come to an understanding with qu'il vous demandera, jusqu'à concurrence de £500 (nous disons him.
cinq cents livres sterling) contre sa traite sur nous à trois jours I have some pretty articles of a different kind (a list of which de vue. Ci-joint nous vous donnons sa signature. I subjoin) that might possibly suit you.
S'il vous est possible de l'aider à atteindre le but de son I am, Gentlemen,
voyage, nous vous en serions très-reconnaissants.
Toujours dévoués à vos ordres en pareille occasion,
Nous vous saluons cordialement,
HENRI DE LA TOUR & FILS. Messieurs Smith Frères, à Londres.
Messieurs,- Je regrette infiniment de vous dire que l'article 25.--LETTER ACKNOWLEDGING RECEIPT AND ADVISING demandé a été vendu à M. Barton, de votre ville. Peut-être
PAYMENT OF BILLS. pourriez-vous vous entendre avec lui à cet effet.
Injons, October 7th, 1866. J'ai de jolis objets d'un autre genre (dont je vous envoie une Messrs. Reilton, Sons & Co., Bradford. liste) qni, probablement, pourraient vous convenir.
Dear Sirs,—We duly received your favour of the 3rd inst. Agréez, Messieurs,
covering l'assurance de ma parfaite considération,
fr. 200 per 12th inst. J. LEMAITRE.
300 15th 1,200 17th
on St. Etienne. 23.—LETTER ACCOMPANYING INVOICE OF Goods.
on Vienna. Messrs. J. Ellison, Wine Merchants, London.
2,168 14th on Grenoble. Gentlemen, ---Agreeable to the order contained in your letter with which we shall do the needful, placing the amounts to your of the 15th of April, and in accordance with the prices and con- credit under advice. ditions laid down, I have bought for your account 20 tierces of Please take note that the following bills have been duly paid: brandy, 27 degrees, and forwarded them to your brother in Paris.
fr. 700 25th ultimo Subjoined you will find the invoice amounting to:
on Grenoble. 30,760 fr., with which I debit you. In conformity with your
» 2,000 31st wishes, I have drawn on your account, on Messrs. J. Lafitte of
„ 5,000 31st
on St. Etienne. Paris, at three months, payable to my order, for the above which amounts we have placed to your credit. amount.
Believe us, dear Sirs, I wrote to you on the subject of your account with me at
Yours truly, length in my last, and have nothing more to add.
M. BERTHOU & Co.
Lyon, le 7 Octobre 1866.
Chers Messieurs,—Nous avons bien reçu votre honorée du 3,
Cognac, le 10 Mai 1867. couvrant À Messieurs J. Ellison, Négociants en Vins, à Londres.
fr. 200 au 12 ct. Messieurs, -- En exécution de l'ordre contenu dans votre
300 honorée du 15 Avril, j'ai acheté aux prix et conditions y fixés,
sur St. Etienne, pour votre compte, 20 tierçons eau-de-vie, 27 degrés, et je les ai
4,000 19 expédiés à M. votre frère à Paris. Vous en trouverez ci-joint la
375 15 sur Vienne. facture s'élevant à :
2,168 14 sur Grenoble. 30,760 francs, portés à votre débit. Pour me conformer à dont nous soignerons le nécessaire à votre crédit sous avis. vos désirs, je viens de disposer pour votre compte, sur MM. J. Veuillez prendre note que les traites suivantes ont été dûment Lafitte de Paris, une traite payable à mon ordre à trois mois payées : pour la somme ci-dessus.
fr. 700 au 25 dernier Je me suis étendu dans ma dernière au sujet de votre compte
300 28 sur Grenoble. chez moi, et je n'ai rien à ajouter à mes observations.
2,000 31 J'ai l'honneur d' tre, Messieurs,
sur St. Étienne. Votre obéissant serviteur,
dont nous avons passé les montants à votre crédit. FRANÇOIS MARTIN.
Agréez, chers Messieurs,
nos salutations distinguées, 24.—LETTER OF INTROD CTION, AND OF CREDIT.
M. BERTHOU & CIK. Metz, January 15th, 1865. Messrs. Armand Roubot & Co., London.
26.--LETTER FROM AN AGENT ADVISING RECEIPT OF AN Gentlemen,-The bearer of this letter, Mons. F. Decretelle, ACCOUNT, AND HIS OPERATIONS THEREWITH. of this city, is one of our oldest friends. He purposes visiting
Paris, December 2nd, 1866. England, and we take the liberty of recommending him to your To the Directors of the Western Banking Corporation
(Limited), Manchester. Should M. Decretelle require some funds for travelling Gentlemen,- I have herewith the pleasure to inform you that expenses, please to let him have all he wants, to the extent of I have this day received from Mr. Bernard the sum of fr. 250,000, £500, taking his draft on us at three days' sight. Subjoined which, according to your instructions, I have handed over to we send you his signature.
Messrs. Moullyn Bros., requesting them to remit it to you in If you can in any way further the ends for which he has short bills on London at the most favourable rate of exchange, undertaken this journey, we should feel greatly obliged. or, if it should be more convenient to them, to transfer the above We are at your service on similar occasions,
amount to your credit with one of their London correspondents. And remain, Gentlemen,
I am, Gentlemen,
Your obedient servant,
Paris, le 2 Décembre 1866. herewith beg to inform you that we have to-day received from À Messieurs les Directeurs de la Western Banking Corporation Messrs. Hawkes & Co., of your city, for your account, £4,200, (Limited), à Manchester.
which we place to your credit under to-morrow's date. Messieurs,- J'ai l'avantage de vous informer par la pré
We are, dear Sirs, sente que j'ai reçu aujourd'hui de M. Bernard la somme de
Yours truly, fr. 250,000, que, conformément à vos instructions, j'ai versée
S. BARRETT & Co. chez Messieurs Moullyn Frères, en les priant de vous la
Manchester, 12 Décembre 1866. remettre en papier court sur Londres au meilleur change possible, ou, s'il entrait mieux dans la convenance de ces Messieurs W. Carter et Cie, à Dublin. derniers, de faire transférer ce montant à votre crédit chez un Chers Messieurs,-Sans aucune des vôtres à répondre, nous de leurs correspondants de Londres.
avons l'avantage de vous informer par la présente que nous Recevez, Messieurs, l'assurance
avons reçu aujourd'hui de Messieurs Hawkes et Cie, de votre de må parfaite estime,
ville, pour votre compte £4,200, que nous passons à votre crédit, FRÉDÉRIC TOURVILLE.
valeur à demain.
Recevez, chers Messieurs, 27.- LETTER REFUSING TO SUPPLY GOODS ON CREDIT.
Nos sincères salutations,
S. BARRETT & CIB. London, January 17th, 1866. Messrs. A. Perrin & Co., Paris.
30.—LETTER ABOUT NON-ACCEPTED BILLS. In answer to your note, I beg to state that it is impossible for me to open any new accounts.
Liverpool, Sept. 28th, 1860. The price of the goods ordered is 570 francs.
Messrs. Costenoble, Lewis & Co., San Francisco. If you will confirm the order, and, as is customary, accompany
Gentlemen,-In answer to your favour of June the 26th, I it by a bank-post bill on London, or a bill payable at sight on return you the enclosed Bill on Smith Bros. of Paris, I will at once send the articles you desire to your agent.
Dollars 1,950, with the protest for non-acceptance, for the Waiting your reply,
costs of which you will please to credit me with I have the honour to be,
Dollars 3.-I am in a similar position as yourselves, having Gentlemen,
also a bill in hand on the same Smith Bros. of Your obedient servant,
Dollars 1,428, drawn by Jones & Co. of your town, payable LEWIS PRATT.
the 20th October, which he has also refused to accept, and
which I enclose, with the protest, requesting you to exact a Londres, le 17 Janvier 1866.
sufficient security from the drawers, and to inform me of the Messieurs A. Perrin & Cie, à Paris.
result. Begging you beforehand to excuse the trouble I am En réponse à votre lettre, j'ai l'honneur de vous informer que je ne puis ouvrir de nouveaux comptes.
I have the honour to be, Gentlemen, Le prix des articles que vous me demandez est de 570 francs.
Your obedient servant, Si vous voulez bien m'en confirmer la demande, et l'accom.
LEWIS MARTIN. pagner comme d'usage de son solde en un mandat sur la banque de Londres ou un bon à vue sur Paris, je remettrai aussitôt chez
Liverpool, le 28 Septembre 1860. Fotre commissionnaire les articles que vous désirez.
MM. Costenoble, Lewis et Cie, à San Francisco. En attendant vos ordres,
Messieurs,—En réponse à votre lettre du 26 Juin, je vous J'ai l'honneur d'être,
renvoie ci-inclus la lettre de change sur Smith Frères de Messieurs,
Doll. 1,950, avec son protêt, faute d'acceptation, dont il Votre obéissant serviteur
vous plaira de me créditer le coût de LEWIS PRATT. Doll. 3.-Je suis dans le même cas que vous-mêmes, ayant
aussi une lettre de change sur ces MM. Smith Frères de 28.--LETTER ACKNOWLEDGING RECEIPT OF REMITTANCES, Doll. 1,428, tirée par Jones et Cie, de votre ville, pay
London, Jan. 22nd, 1864. able le 20 Octobre, dont il a aussi refusé l'acceptation, et Messrs. Daniel Bros., Liverpool.
que je vous envoie ci-incluse avec son protêt, en vous priant Gentlemen,-Your favour of the 7th inst. came duly to hand d'exiger une sûreté suffisante des tireurs et de m'informer du covering your remittances for
résultat. En vous demandant pardon d'avance de l'embarras 148 12 6 pro 18th February
que je vous cause, 225 6 0 25th
J'ai l'honneur d'être, Messieurs, 420 0 0 5th March
Votre tout déroué,
LEWIS MARTIN. £793 18 6 on London, which we place to your credit under usual reserve. We remain, Gentlemen,
LESSONS IN ASTRONOMY-V.
LATITUDES-MERIDIAN-POLE STAR-GREAT AND LITTLE
HAVING now given a brief sketch of the history of our science, Messieurs, -Votre honorée en date du 7 courant nous est bien and seen the way in which the most important discoveries in it parvenue couvrant vos remises de
have been effected, we must pass on to the more practical parts 148 12 6 au 18 Février
of the science. We shall, as may be expected, meet with a few 225 6 0 25
difficulties as we advance, and there will be a few definitions 420 0 0 5 Mars
and technical terms that it will be necessary for us to learn ;
but the tax thus imposed on the student will be no very heavy £793 18 6 sur Londres,
one, and the increasing interest which will be felt in the que nous passons à votre crédit sous les réserves d'usage. starry heavens will far more than make amends for any little Recevez, Messieurs, nos salutations distinguées, trouble.
A. BROWNLOW & CIE. It is usually the best and simplest plan to acquire a general
notion of the scope of any science before entering into its 29,-LETTER ACKNOWLEDGING RECEIPT OF MONEY FROM details—to know the problems which are proposed before we AGENT
attempt their solution, and so it is best for us to become geneManchester, Dec. 12th, 1866. rally acquainted with some of the phenomena of the stars and Meseta. W. Carter & Co., Dublin.
planets before fully inquiring into the causes of those pheDear Sirs,— Without any of your favours to reply to, we nomena. To accomplish this, let the student on the first clear
night seat himself at a window commanding an extensive view at all, but to remain constantly fixed in the same place, while of the heavens; or, better still, let him go out in some place all the others revolve around it. This star is called the pole where his view of the sky is as extensive as possible, and watch star, and is well known, for before the discovery of the mari. for a short time the movements of the stars. If the night be ner's compass it was used by sailors as their guide, being situated dark and clear, comparatively few will at first be seen, as the due north. Very frequently, however, cloudy or dull weather pupil of the eye is contracted by the bright light of the room would hide this star, sometimes for many days together, and which has just been left. In a few minutes, however, the eye hence they were unable to go far out of sight of land, and. becomes accustomed to the light, and then the whole arch of consequently navigation was but little practised in those days. heaven is seen to be thickly studded with stars. These differ If the student does not know this star, it is important for very greatly in brightness and size, so that he will soon be able bim to find it at once, as it will be of great assistance to him in to fix on a few of the more conspicuous, and turn his main learning the names and positions of others. The difficulty attention to them.
which at first sight strikes us of learning the names of the A compass should now be referred to, so as to ascertain the true constellations soon disappears if we become familiar with a few north and south points, and an imaginary curve passing vertically of the brighter ones, as by referring to them we shall soon be overhead should be traced across the sky between these points. able to identify the rest. Further on in the course of these This line is called the meridian ; and it will aid the student at first lessons we shall give illustrations of the position of the stars in if some prominent objects, as, for instance, trees or buildings, can the most important constellations. It will, however, be a great be fixed on to indicate permanently its position. Failing these, assistance to procure a complete set of maps of the stars, or, some poles may be placed in the ground. In observatories, one better still, a celestial globe; and a few hours' observation with telescope is usually mounted on its axis in such a way that it can the aid of either of these will soon enable us to find any star, only be directed to parts of the sky bordering upon this line, and or turn our attention to any part of the heavens which we may this is then known as the transit instrument. Its mode of con- desire. struction and uses will be fully explained by-and-by.
The constellation of the Great Bear (Ursa Major)-or, as it is If now the position of any bright star be noticed, as may be sometimes called, Charles' Wain, or the Plough-is well known done by watching it against some fixed object, like the corner to most, it being a very conspicuous one, and one of those of a house or the trunk of a tree, we shall soon find that it which never set in this latitude. There are a considerable appears to be in motion; and further observation will show number of stars in this constellation, but seven of them are that nearly all the stars appear to be similarly in motion, especially bright, and are arranged as shown in the lower part though the rates at which they travel seem to vary slightly. of the accompanying figure. Four of them seem to form an
Let us now face towards the south, and we shall soon see irregular square, while the other three, situated in the tail of that the stars on our left hand—that is, towards the east-are the Bear, are arranged in a curved line going from one of the rising higher and higher above the horizon; and if we could corners of the square. map out their courses, or imagine them to leave threads of light Careful examination on a clear night will show that the behind them, we should see that all these tracks would be arcs middle star of the tail is in reality double, consisting of two of circles, and would be parallel to one another.
stars so close together as apparently almost to touch one These stars rise higher and higher till they come to the another. They are called respectively Mizar and Alcor. A meridian, and here they are at their greatest elevation above telescope reveals a similar fact with regard to the first star in the horizon. They then commence to descend towards the west, the tail. We shall find as we further examine the sky many and it will be found that exactly the same time elapses between of these double stars, and a telescope often shows them to be the rising of any star and its coming to the meridian that there of different colours, so that they are very beautiful objects. is between this period and its setting in the west.
The two stars in the quadrangle which are farthest from the The point in the path of a star or planet on any given day tail are called "the Pointers,” because, if a straight line be which is most elevated above the horizon is called its culminat- drawn on a map so as to join them, and then be prolonged to ing point, and this point is always on the meridian. Hence any about five times the length, it will almost pass through the of the heavenly bodies is said to culminate when it comes to Pole Star, which is the star at the tip of the tail of the Little the meridian of any place. The term meridian signifies mid- Bear (Ur Minor). This constellation, which is shown in the day, and the line is so called because, when the sun attains its upper part of the figure, is almost exactly the same shape as greatest altitude and crosses the meridian of any place, it is the one we have described, but it is turned in the opposite mid-day there.
direction, and the stars in it are much fainter, the pole star If now we look quite to the south, we shall find that the being the brightest of them all. stars there only describe very small arcs, rising but a little way We spoke of the pole star as remaining at rest; this is not, above the horizon, and setting again in a very short time not however, perfectly correct, as it is not situated exactly at the far from the same point, the highest altitude attained at any pole, but about one and a half degrees from it, and hence it time not being more than a few degrees.
appears to describe a circle of about three degrees in diameter. Now let us turn half round, so as to face the north instead This, however, is so small that it is only by the use of good of the south, and, as before, observe the stars. We shall soon iustruments that we can ascertain the fact, and in ordinary use be struck with the difference in the phenomena exhibited. We we may look upon the star as indicating the place of the pole shall row see that some of the stars never set, but describe or imaginary axis round which the whole starry concave appears small circles, crossing the meridian twice in the course of the to revolve. twenty-four hours. We cannot, however, trace them completely As we shall have frequent occasion in our lessons to speak of round their paths, as during a part of the time they are hidden degrees, it is as well for us to clearly understand at once what from the naked eye by the brilliancy of the sun's light. Even we mean by a degree, and the mode in which we may measure by day, however, they may be seen with the aid of a good tele- it. It is clearly necessary for us to have some means of scope, if the means are possessed of directing it to them. It is measuring the apparent distances of the heavenly bodies from said, too, that at the
bottom of a well or mine any bright stars one another, and this can only be done by measuring the anglo which happen to be vertically over the month may be seen, and which imaginary lines drawn from them to our eyes subtend. some have even seen stars during the day by looking up a If we think a moment, we shall see that it is in the same way chimney. In either case, the rays of the sun are to a great that we forn our estimate of the dimensions of ordinary objects extent cut off by the walls or sides, and thus the faint light of around us, and hence, when we bring them nearer to the eye the star reaches the eye. It is, of course, only the brighter they appear larger, because the rays drawn from their extremes stars that can be seen in this way, and as the number of stars to the eye contain a larger angle. Now, we want some means of the first and second magnitudes visible at any one time does of measuring and expressing in words the angle
thus contained, not exceed fifty, it will easily be understood that it will only be and this we do by means of degrees and fractions of a degree. on rare occasions that these effects will be witnessed.
A degree, then, is the 360th part of a circle-i.e., if we draws If now we look to a point on the meridian situated about large circle on paper, and divide its circumference into 360 equal fifty-one degrees above the horizon, or rather more than half parts, and then draw straight lines from these divisions to the way from the horizon to the zenith, as the point directly over centre of the circle, the angle contained between any two adjahead is called, we shall find a star which appears not to move cent lines will be just one degree. On any circle
we can draw