sessor of such intellectual treasures. There is an animation in the manner and eloquence in the expression of the teacher who is inspired with his theme, which can not fail to attract the pupil to him, and to awaken all the dormant energies of his intellectual being. While, on the other hand, the sluggish, uninterested schoolmaster, who is not familiar with the branches he professes to teach, and who sees no excellency or worth in scientific truth, and no advantage in knowledge, will signally fail in awakening thought in others, and in developing mind. To such persons I can only say, the means I would suggest for exciting an interest in study are not for you to employ,-you can not appreciate them, and, therefore, have mistaken your profession.

Have you never observed what a new interest was imparted to certain subjects of inquiry by the enthusiasm of one whose whole soul was absorbed in the subject, and whose conversation abounded in interesting facts which his own researches had accumulated? Have you not often felt much of the same ardor kindling in your breast, when you thus incidentally came in contact with an earnest student of any particular branch of science? I shall never forget the influence upon my taste for geological science exerted by an ardent student of Geology, who spent a few days at the home of my youth. In his geological rambles, I accompanied him. A new field of science and of fact was spread out before me. Every rock in the vicinity was examined-its language explained, and its history told. Every ravine was explored; the outcropping strata were made to tell their order of superposition; and the pebbles and sand beneath my feet became eloquent, as they told of their watery birth and distant travel. And after his departure, I was busy with my hammer, making researches in this new world of thought and wonders; and, when in other localities, I neglected not to take a look at my new acquaintances, the rocks, and to hold such converse with them as my limited knowledge enabled me to do.

In the practical application of the truth I have endeavored to illustrate and enforce, I will suppose that the teacher has before him a class of primary scholars. It is evident, from what I have said, that his first, great duty is to awaken in their minds an interest in the studies taught in such schools. How is he to do this? By adapting himself to the mental capacity, taste, and

judgment of the child, and by gradually leading him, step by step, into the truths of science, until the mind, thus expanded and strengthened, shall be able to grasp its deeper mysteries and higher developments.

In the imparting of the first principles of any science in an intelligible and interesting manner, lies the secret of success in teaching its deeper mysteries. And this fact is of vital importance to one who would take the child from the wild, unrestrained walks of sportive infancy, into the region of thought and study. As he has always been surrounded by the interesting in nature, so the teacher must strew his new pathway with everything attractive and profitable. Primary books, many of them excellent, have been prepared for the use of pupils in this department, and may be used, if used with judgment, to great advantage. Without familiar illustration, however, and much oral instruction, no book will answer the purpose. And it must be so used that no pupil will look upon his lesson as a task. Let the book be regarded only as an aid, while the teacher, all alive with interest in the subject of the lesson, imparts such a glowing attractiveness to the principles and facts of the science, that the child's inquisitiveness will be thoroughly awakened and a mental restlessness produced, which can only be allayed by a clear understanding of the subject.

To this end the teacher must qualify himself by study, that he may be able to adapt himself to the understanding of his scholars. There can be no greater or more fatal mistake than to suppose that because the teacher knows more than the pupil, he does not need to prepare himself specially for giving instruction. It is no task to talk to children in an interesting and profitable maneasy ner. But few excel in this art, and too few are-for this very reason-good teachers in the primary department. The difficulty of giving instruction properly, arises from the fact that it consists not merely in communicating the facts of science; but also in teaching the pupil how to use the facts communicated as food for thought, and how to accumulate knowledge by his own effortsthat is, simply, how to learn. It is not the communication of facts that develops mind; but the exercise of the mental powers of the pupil. All our teaching should therefore be subordinate

to the great end of making the pupil think and act intellectually for himself.

As the study of Geography is introduced in every primary school embracing children from seven to ten years of age, it is of the highest importance that the method adopted in teaching it be truly philosophical. Since all knowledge of the external world is communicated to the mind through the senses, and the teacher should be careful to make correct impressions with reference to the physical facts he is about to communicate, he ought to give his first lessons in Geography without a book and with globe in hand. The first question usually found in primary geographies is, "What is geography?" Before the answer is learned from the book, let the teacher instruct his class in the meaning of the term, and, by referring to the globe, show that the world is round --that its surface is divided into land and water-that the object of geography is to describe this surface-that it tells us of all that is interesting about the different divisions of the land, and the rivers, the lakes, the seas, the oceans, and other divisions of water -that it speaks of the great nations of the world, the manners and customs of the people, the cities and their commerce, and what every country produces.

By familiar illustrations, which my limits will not permit me here to introduce, the teacher can make the definitions very plain and simple to the youngest pupil. He must, however, be very careful to present but one thing at a time to his class. Rapid progress will never be made by committing a page or two of definitions, embracing twenty or thirty different objects, and reciting them in the hot haste of a hurried recitation. This is the great error so prevalent in schools, in the study of Geography, and is the chief cause of its unpopularity among the pupils. Let the first lessons embrace but few topics, and let each one be so clearly illustrated by the use of globes, maps, and pictorial representations of mountains, lakes, seas, gulfs, and rivers, that these ideas may be accurately and indellibly impressed on the mind. All this should be done before the pupil is permitted to use a textbook; and each recitation should be conducted in such a lively, animated manner-the teacher interspersing his instructions with interesting illustrative remarks, drawn from history and daily

occurrences-that the pupil would not consider Geography a dry and useless study.

Here let the subject rest for the present. I have been more prolix on this branch of my theme than I intended; but its importance I have not exaggerated. The enthusiastic teacher alone can inspire his pupils with enthusiasm.

ON THE FIGURE OF THE EARTH.

BY T. C. MENDENHALL.

I have been much interested in the article by Mr. Henkle, in the March number of the Monthly, on the "Shape of the Earth," and propose to add a few thoughts upon the subject which I conceive to be an important one.

A few days ago I proposed this question to one of my classes: "If the ear, the eye and the hand were to testify in a doubtful case, which would be entitled to the most credit? " After some reflection they replied that first of all they would trust the hand, after that the eye, and then the ear. This principle applied in teaching requires that we, if possible, first make our pupils touch or feel a truth; failing in this, that we aim to have them see it; and that we rely but little upon their simply hearing it. The teacher may talk learnedly of centrifugal and tangental forces, of ellipsoids of revolution, and radii of curvature, but the vacant look of his pupils is too often evidence that he has only been heard.

To tell a boy that the earth is 8000 miles in diameter, and to have him establish the fact with his own slate and pencil, are two very different things. Of course, this is impossible with primary classes; but if your pupil can solve a simple equation of the first degree, you may tell him that if he put his eye at the water level at the end of a lake three miles in length, he will be able to see only the hat of a man six feet high standing at the other end;in two minutes he can tell you that the radius of the earth is 3926 miles. Other methods will suggest themselves to the teacher.

My principal design in the present article is to describe briefly

a series of experiments to illustrate the spheroidal form of the earth. I have thought that perhaps many of my fellow teachers were ignorant of them; and yet they are of so simple a nature as to be within the reach of every teacher in every district in the State. They were devised by M. Plateau, and originally published in the Memoirs of the Brussels Academy. An account of them has been translated and published in the Smithsonian Reports, to which I refer all who wish a description of the more perfect apparatus used in conducting the experiments, as I intend speaking only of the simplest and least expensive method. What I shall take, can be readily obtained by any one. The articles are: A clear glass bottle or jar, with a wide mouth, holding from a half pint to a pint; half a pint of alcohol; half an ounce of olive oil; a knitting-needle; a little disk of tin or iron as large as a three-cent piece; a piece of pine board; and some clear water. I have omitted from this list two important articles, because I suppose that a teacher is never without them-I mean a jack-knife and a piece of string.

Fill the bottle or jar half full of alcohol, and then add water until you obtain a mixture of the same specific gravity as the oil, so that a globule of oil will neither sink to the bottom nor rise to the surface, but remains suspended in the liquid, To accomplish this is not so difficult a task as one would at first suppose, and when done we have the interesting spectacle of a mass of oil entirely withdrawn from the influence of gravity, and, by conscquence, obeying those laws, and only those, which originate within itself. The shape assumed is that of a perfect sphere.

Make a hole in the iron disk, and pass a knitting-needle through it, putting it at such a height that the disk will reach the centre of the sphere of oil when the end of the needle rests on a piece of wood fastened at the bottom of the glass. Enough oil should be put in to make a sphere a little greater in diameter than the iron disk. Pass the disk in the oil, so that their centres shall coincide. The upper end of the needle can be held in position by a piece of wood pressed into the mouth of the jar, with a hole in it for the needle to pass through.

With this apparatus a variety of interesting experiments can, be tried, a few of which I shall mention. The effect of centrifu, gal force in producing an oblate spheroid becomes evident by

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