FRENCH READING S.-No. XXVI. LA MARGUERITE ET L'E'PI DE BLE. Lorsque les deux enfants repassèrent le soir, la marguerite était fanée sur la tête de Marie, qui n'y songeait déjà plus et s'en revenait en faisant l'école buissonnière. . Louise, chargée d'une récolte d'herbe, éleva sa figure blonde au dessus de la haie,2 et jeta un regard d'espoir à son épi floris sant. -Souviens-toi de ces petites filles,3 me dit mon père avec gravité. Je soupçonne qu'elles ressemblent l'une et l'autre, aux objets si différents de leurs vœux. Puis il me fit l'histoire de la marguerite et celle du froment. Dans les champs et dans les jardins, la marguerite est la même; jolie, coquette et inutile. Celle qu'on nomme la pâquerette, s'établit dans l'herbe courte, pour l'étoiler de son bouton d'or et de son blanc diadème. Celle qui prend le nom de reine des prés, se dresse et se balance sur sa tige au dessus de tout ce lui l'environne. Mais quand la faux du moissonneur vient l'abattre, elle n'offre au sol qu'une graine funeste et à la dent des bestiaux qu'un fourrage détesté. Enfin, celle qui brille dans les parterres, n'a que son éclat d'un jours et ne présente à l'homme ni parfum ni produit. NOTES AND REFERENCES.-a. L. part ii., § 49, R. (1).-6. faire l'école buissonnière; this familliar expression may be rendered in English by: to play the truant, to stay away from school. -c. L.S. 36, R. 2-d. the singular of bestiaux, is bétail.-e. from naître; L. part ii., p. 96-f. from suivre; L. part ii., p. 106.-g. from mourir; L. part ii., p. 96.--h. L. S. 36, R. 2.-i. from L'histoire du froment, au contraire, est l'histoire de la civi-reconnaître; L. part ii, p. 102.--j. travail is the subject of the lisation me. Il naît avec elle, il en développe et en verb.-k. distrait, taken.—l. from valoir; L. part ii., p. 108. suit les progrès, et il ne meurts que sous les latitudes où elle expire. Ceci est la plus admirable harmonie de la nature. -C'est Marie! m'écriai-je ?20 -Oui, c'est Marie, toujours vaine comme la première fleur que nous lui donnâmes. Elle a passé sa jeunesse oisive dans les fêtes; et elle attend un mari qui ne viendra jamais, car elle n'a d'autre dot que les marguerites desséchées de notre jardin. De là, nous allâmes dans un champ de blé mûr,22 et nous vimes une autre jeune fille,23 d'une beauté calme et grave, dont les vêtements annonçaient l'aisance, et qui, les mains posées sur un tronc d'arbre, contemplait doucement la moisson dorée. Je reconnus Louise, et mon père me dit : Cette moisson est à elle25 et vient, sillon par sillon, année par année, du premier épi qu'elle a reçu de nous et qu'a multiplié son travail. Elle n'a distrait de ses produits, à chaque saison, que la part des pauvres,26 multipliée aussi par sa charité; et elle obtiendra sa récompense après la récolte, en épousant le plus sage et le plus riche fermier du canton. Une telle leçon ne vaut-elle pas un petit coin de terre, et n'ai-je pas raison d'avoir un champ de blé dan mon jardin ? Heureux si mes épis trouvaient autant de Louises que mes marguerites rencontrent de Maries!........ JARDINEUR. En fuyant la main qui l'attire1s Avec tristesse il semble dire: Ce n'est pas lui! 17 COLLOQUIAL EXERCISE. 1. Que dit d'abord le poète au passant? 2. Pourquoi le passant doit-il se découvrir le front? 3. Que devra-t-il placer sur la tombe? 4. Que devra-t-il donner à l'ami du brave? 5. Qu'arriva-t-il le jour de la bataille? 6. Le maître et le chien furentils blessés ? 7. Que fit le chien voyant son maître mort. 8. Que laissa-t-il couler sur le corps de son frère d'armes ? etc.; and from the Technological and Scientific Dictionaries of both Languages. By Professor DE LOLME and HENRY BRIDGEMAN, Esq. The following are the distinctive features which render this Work superior to any of the same class now extant. It has been compiled with unusual care from the very best authorities. It contains correct renderings of all the most modern words and phrases-including those of science, art, manufacture, commerce, law, politics, etc., as well as familiar conversation-which are indispensable to a knowledge of language, but yet are rarely, if ever, to be found properly translated in any Dictionary. The idiomatic usages of the two languages-the constructions of verbs, the force of prepositions, and the changes of meaning caused by different combinations of words-are more copiously and carefully illustrated than elsewhere within the same limits. The meanings are also classified and arranged in such a manner as to prevent the possibility of mistake. To crown all, the Work is as moderate price as it is comprehensive in aim, accurate in detail, and superior in arrangement. The French-English Division, price 4s. paper covers, or 56. neat cloth; the English-French Division, price 4s. paper covers, or 58. strongly bound. 9. Le chien suivit-il le convoi de son maître ? 10. Paraissait-il triste? 11. Où se traîna-t-il avec peine? 12. Comment la gloire y jeta-t-in elle son maître ? 13. Pourquoi ne le connaissaiton pas ? 14. Que devint alors le fidèle animal? 15. Son chagrin paraissait-il se dissiper? 16. Etait-il sensible aux caresses qu'on lui faisait? 17. Que semblait-il dire avec tristesse ? NOTES AND REFERENCES.-a. que ton front se découvre, let thy brow be bared! uncover thy brow.-b. il, the master of the dog.-e. vint les atteindre, struck them.-d. from survivre; L. part i., p. 108.-e. parent, relation.-f. juillet, the revolution of July, 1830. ANSWERS TO CORRESPONDENTS. IN compliance with the urgent request of several correspondents, it is our intention to give a few Lessons in Spanish, commencing in our next number, and to complete our Lessons in Arithmetic. EDMUND LEE may procure the missing numbers of the POPULAR EDUCATOR by ordering them of any bookseller. W. R.: The bookbinder will understand how to bind the maps and engraving. CONVEX had better apply to the Secretary of the Society of Arts. ALEPH: The difficulty under which you labour is one which most students of Hebrew experience. Hurwitz's Grammar may perhaps relieve, if it do not remove it. R. J. KENT: In Italian c'è is pronounced tchai. The usage of which you speak is not to be imitated. THOMAS BOTTOMLEY has solved all the second portion of the Second Centenary of Algebraical Problems except five. We are surprised he cannot understand our solution of No. 39, which we made as simple as we could. If he will try again, we think he must succeed. A correspondent, whose name is not put to his solutions, has solved all the first thirty-two of the Second Centenary of Algebraical Problems. The first solution contains a reference to "Cassell's Algebra." There are four papers, numbered 1, 2, 3, and 4. We shall be happy to give the name if the writer will furnish us with it. CHARLES SUTTON has solved twenty-one of the Second Centenary of Algebraical Problems, from No. 33 to 56, omitting Nos. 35, 39, and 52. He will find a solution of No. 39 in Nɔ. 126 of the P. E. Some of his solutions are longer than they need have been, but they are very creditable on the whole. ONE THIRSTING FOR KNOWLEDGE will find what he wants in "Cassell's Arithmetic," p. 5. J. MATHER: Thanks. Most of your corrections are right, but that of page 25, ex. 7, is wrong. Surely 8x2 y2 9x = 8z ye 9 JOHN CHARLES JONES: We cannot give more information than has already appeared in these pages on the subject of the University of London. 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A frame r supports the needle a b, and a level n serves by means of the three screws to give a horizontal position to the diameter passing through the two zeros of the circle Mм. To observe the inclination, we begin by determining the magnetic meridian, which is done by turning the plate a upon the circle m till the needle becomes vertical, which takes place when the needle is in a plane perpendicular to the magnetic meridian. Then turning the plate A through 90 degrees on meridian. The angle dea which the magnetised needle then the circle m, we bring the vertical circle м to the magnetic makes with the horizontal diameter, is the angle of inclination. But there are two causes of error which must be taken into account. First, the magnetic axis of the needle may perhap not coincide with the axis of the needle itself, whence arises an error which is corrected by the method of turning already described. Secondly, the centre of gravity of the needle may possibly not coincide with the axis of suspension, and then the angle dea is too small or too large, according as the centre first case the action of gravitation is contrary to that of terres of gravity is above or below the centre of suspension, for in the trial magnetism in turning the needle, while in the second it is in the same direction. This error is corrected by reversing the poles of the needle, which is accomplished by rubbing it with the contrary poles of two bars in such a manner, that each pole of the magnet is rubbed by a pole of the same name as its own. The direction of the needle being then changed, if its centre of gravity was before above the point of suspension, it is now below, and the angle of inclination which was before too small is now too large. The true value is found by taking the mean between the two. Astatic Needle and System.--A needle withdrawn from the magnetic action of the earth is said to be astatic. This is the case with a needle moveable about an axis in the plane of the magnetic meridian in a direction parallel to the inclination. An astatic system is the combination of two needles of the same power placed parallel, with their contrary poles opposite each other, as seen in fig. 371. If the two needles are of exactly VOL. V. the same power, the contrary action of the earth upon the poles a' and b, as well as on a and ', is self-destructive, and the system is completely astatic. MAGNETISATION AND LAWS OF MAGNETIC ACTION. Sources of Magnetisation.-The various sources of magnetisation are the influence of powerful magnets, terrestrial magnetism, and electricity. There are three methods of magnetising by magnets, simple touch, separate touch, and double touch. Whichever of these methods be employed, there is a limit to the degree of acquired magnetic power, depending upon the temper and intensity of the magnets employed. When this limit is attained, the bar is said to be magnetised to saturation. When it has been passed, the bar soon returns to it, and even tends to sink below it, if the magnetic power is not retained by means of a process to be described presently. Method of Simple Touch.-This consists in sliding the pole of a powerful magnet from one end of the bar we wish to magnetise to the other, and repeating the operation several times, but always in the same direction. This process is incapable of producing any great effect, and consequently is only applicable to small bars. It has the further inconvenience of frequently developing consequent points. 134 Method of Separate Touch.-This was adopted by Knight in this country in 1745, and consists in placing the two contrary poles of two bars of equal intensity at the middle of the bar we wish to magnetise, and making them both slide simultaneously towards one of the ends of the bar, holding them vertically. Each magnet is then brought back to the middle of the bar, and the operation is repeated several times on both sides till the bar is magnetised. Duhamel improved this method by placing the two ends of the bar to be magnetised at the contrary poles of two fixed magnets, whose action combines with that of the moveable magnets, the relative position of the poles being the same as in fig. 372. This process gives the most steady magnetic power. Method of Double Touch.-In this method, introduced by Mitchell, the two magnets employed in friction are still placed at the middle of the bar we wish to magnetise, with their contrary poles towards each other; but instead of sliding towards its extremities in contrary directions, they are kept at a certain distance from each other by a small piece of wood placed between them, and slide together from the middle to one extremity, then from this to the other extremity, and so on in such a manner that each half of the bar undergoes the same number of these operations. It is to be observed that in the various processes of magnetisation the magnets lose none of their power, which proves that the magnetic fluids do not pass from one bar to another. straight line (fig. 374). The bundle represented in fiz. 373 is formed of five plates of steel placed side by side, that in fig. 374 consists of twelve plates arranged in three layers with four plates in each. The form of the horse-shoe is preferable Fig. 374. for supporting a weight by means of the magnet, because use is made of both poles at the same time. The magnetic power of a bundle is not equal to the sum of the separate forces of the bars, owing to the repulsive action of neighbouring poles upon one another. Armatures or Keepers of magnets, are the pieces of soft iron which are placed in contact with the poles, to preserve or increase the magnetic power. Fig. 375 represents a natural magnet with its armatures. On the surfaces corresponding to the poles are two plates of soft iron, each terminated by a massive block. Under the influence of the natural magnet these plates become magnetised, and the letters A and B representing the position of the poles of the natural magnet, it is easy to see that those of the armatures are respectively represented by ab. Now these armatures, when once they are Fig. 372. Magnetisation by the Action of the Earth.-The action of the earth upon magnetic substances being similar to that of A B magnets, terrestrial magnetism constantly tends to separate the two fluids which are in a neutral state in soft iron and steel. But in the latter substance, the coercive force being very great, the action of the earth is insufficient to produce magnetisation. It is not so with a bar of soft iron, especially if it is placed in the magnetic meridian parallel to the inclination. Yet even this is only an unsteady sort of magnetisation. Magnetic Bundles. Armatures of Magnets.-A magnetic bundle is a collection of magnetised bars united parallel to each other at their poles of the same name. Sometimes it is made in the shape of a horse-shoe (fig. 373), sometimes of a Fig. 373. go on increasing till they have reached a certain limit that is. never passed. The substance supported a'b', which is of soft iron, acts as a second armature, for being magnetised by induction, its poles a' and b' react upon the poles a and b of the former. To furnish artificial magnets with armatures, place them in pairs, as represented in fig. 376, with the contrary poles opposite each other; then put two small bars of soft iron A B in connexion with the poles, these becoming magnetised by induction, their poles react upon the magnetised bars and preserve their intensity. As for moveable needles (figs. 362 and 365) as they turn towards the magnetic poles of the globe, the influence of this latter acts as an armature. Torsion Balance.-This apparatus consists of a glass box (fig. 377), with a glass cover capable of being removed at pleasure, and having an opening near the edge to admit a magnet a b. In the centre of this cover is a second opening, into which a glass tube is fitted so as to turn with slight friction against the edges of the orifice. This tube has in the upper part of it a micrometer, or combination of two pieces, one of which D is fixed and divided round its edge into 360 degrees, and the other E which is moveable, has graduations marked on it, to show the number of degrees through which it is turned on the dial-plate D. On the left of the figure at e and d the two pieces which constitute the micrometer are represented on a large scale. To the disc e are affixed two uprights, through which passes a horizontal axis. Upon this axis a very fine silver thread is wound, supporting a magnetised Fig. 377. needle ▲ B. Lastly, at the bottom of the box is a dial-plate with divisions to measure the displacement of the needle A B and consequently the torsion of the silver thread, or the force with which it returns to a state of rest. The index a of the disc e being at zero on the dial d, the box is placed in such a manner that the centre and the zero of the lower dial-plate may be in the magnetic meridian. Then, taking the needle AB away, replace it by a similar needle made of copper or any other non-magnetic metal. Turn the glass tube, and with it the pieces E and D in such a way that this needle may stop at the zero point of the lower dialplate. The magnetised needle not being yet inserted, remove the non-magnetic needle, and put the magnetised needle A B in its place, which will then be exactly in the magnetic meridian, and the torsion of the silver thread is null. The apparatus being thus arranged, it is necessary before introducing the magnet ab to know the action of the earth upon the moveable needle A B when it is a certain number of degrees out of the magnetic meridian. For this purpose, turn the piece E till the needle A B is moved one degree in the same direction. The number of degrees minus one, through which the micrometer has been turned, represents the total torsion of the thread. In the experiments made by Coulomb, this number was 35, but it varies with the length of the thread, its diameter, and the intensity of the bar a B. Now the needle remaining at present in equilibrium, it is evident that the force of the torsion of the thread is precisely equal and opposite to the directing influence of the earth. This action, then, in the experiments of Coulomb was represented by 35 for a deviation of one degree; but the force of torsion being proportional to the angle of torsion (vol. iv. p. 101), and the directing action of the earth, when there has once been equi librium, being equal to it; it follows that this latter force, for the deviation of 2°, 3°, etc., is represented by twice, three times, etc. 35 degrees. The action of the earth being determined, put the magnet a b into the box, taking care to put poles of the same name opposite each other. The pole of A of the needle is then repelled, and if N represent the number of degrees which measure the angle of deviation when the needle A B is in equilibrium, this needle tends to return to the magnetic meridian with a force represented by N+ 35 N, the part N being due to the torsion of the thread, and the other part 35 N to the action of the earth. But since it does not return to the magnetic meridian, the repulsive force exercised between the poles a and A must be itself equal to N+ 35 N. Now turn the disc E in such a way that the angle of deviation N may become half what it was. According to the position of the needle A B in the accompanying figure, it would be necessary to turn it from right to left. Representing the displacement of the disc E by n, we see that the suspension thread is twisted n degrees to the left at its upper end, and degrees to the right at its 2 N N experiments are made with arcs, N and so small as to be 2' · nearly equal to their chords, that is to say, that when the arc is bisected, a A, the distance between the two poles is also apparently bisected. Method of Oscillations.-This consists in making a magnetised needle oscillate in equal times, first under the sole influence of the earth, and then under the combined influence of the earth and the attracting pole of a magnet placed at two unequal distances one after the other. From the three numbers of oscillations observed, the law of Coulomb may be deduced by calculation. Measure of Terrestrial Magnetism.-A great number of philosophers and navigators have employed themselves in measuring the magnetic intensity of the earth in different places and at different periods. Several methods have been adopted, which consist in making a needle of inclination or declination oscillate for a given time, and then deducing the relative intensities from the number of oscillations. Their observations have led to the establishment of the following laws. 1. The intensity of the earth's magnetism increases as we recede from the equator, and it appears to be half as great |