particularly in those myriads of animalcula which | collects the rays into a focus before it, so as to act are invisible to the unassisted eye. Such animal- as a powerful burning glass, and in this way a hole culæ may be procured almost at any season, but may be burned in a thin board. 3. When hung at particularly during the summer months, by infusing an elevation of about 5 feet, and a person placed opin separate open vessels, small bits of grass or hay, posite to it, at 6 or 7 feet distant, he will see his imleaves of flowers, or other vegetable substances, age hanging in the air in an inverted position, bewhen, after a week or ten days, animalcula of dif- tween him and the mirror, and if he approach a litferent kinds, according to the nature of the substan- tle nearer the mirror, and hold out his hand towards ces infused, will be perceived in vast numbers, by it, the image will appear to do the same, as if about the aid of the microscope, in every drop of the infu- to shake hands, and if he stretch his hand still sion. A compound microscope is perhaps as good nearer the mirror, the hand of his image will ap an instrument as any other for giving a steady and pear to pass by his hand, and approach nearer his satisfactory view of such objects; and the only ob- body. 4. Such a mirror is of use in explaining the jection to its use for a school is, that only one indi-construction of a reflecting telescope. When it is vidual can see the object at a time. When a teacher held opposite to a window, the image of the sash is not furnished with an instrument of this kind fit- and of the objects without the window will be seen ted up in the usual way, he may, with little trouble, depicted in its focus on a piece of white paper held construct a compound microscope, by means of the between it and the window which represents the eye-piece of a common pocket achromatic telescope, manner in which the first image is formed by the which may be purchased for one guinea, or less.- great mirror of a reflecting telescope;-and the The eye-pieces of such telescopes contain four glas- manner in which the small speculum of a Gregoriscs arranged on a principle somewhat similar to that an reflector forms the second image, may be shown of the glasses of a compound microscope. If we by holding the mirror at a little more than its focal screw off one of these eye-pieces, and look through distance behind a candle, and throwing its magniit in the usual way, holding the object end about a fied image upon an opposite wall, in the same way quarter of an inch distant from any small object, as the lens, fig. 1, p. 87, by refraction, produced the such as the letters of a printed book, it will appear enlarged image CD. 5. If a bright fire be made in magnified about ten or twelve times in length and a large room, and a very smooth, well-polished mabreadth; remove from the tube the third glass from hogany table be placed at a considerable distance the eye, which is the second from the object, and near the wall, and the concave mirror so placed look through it in the same manner, holding it more that the light of the fire may be reflected from the than an inch distant from the object, and it will ap-mirror to its focus on the table-a person standing pear magnified more than twenty times in diameter, or above 400 times in surface. If, by means of small pasteboard tubes, or any other contrivance, we atiach the glass that was taken out to the outside of the object-glass of the eye-piece, so as to be nearly close to it, we shall have a magnifying power of nearly forty times; or, if we substitute for these two object-glasses a single glass of about a half-inch focal distance, we shall form a pretty good compound microscope, magnifying above forty times in diameter, and 1600 times in surface, which will afford very pleasing views of various objects in the animal and vegetable kingdoms. The magnifying powers now stated will differ somewhat in different eyepieces, according to their lengths and the focal distances of the glasses of which they are composed.The tube of the eye-piece thus arranged, may be occasionally fitted into a pasteboard tube supported by three pillars, in which it may be moved up or down for adjusting it to distinct vision, and the object placed underneath and properly illuminated.These hints are suggested, on the score of economy, for those who have no regular microscopic appara

tus.

at a distance toward the fire, but not directly in the line between the mirror and the fire, will see an image of the fire upon the table, large and erect, as if the table had been set on fire.

Various illusions and deceptions have been produced by means of concave mirrors. Pagan priests are supposed to have rekindled the Vestal fire by this instrument; and with the same instrument, on a large scale, Archimedes is reported to have burned the Roman fleet. When the mirror is concealed from the view of a spectator by certain contrivances, he may be easily deceived and tantalized with a shadow instead of a substance. He may be made to see a vessel half full of water inverted in the air without losing a drop of its contents. He may be desired to grasp what appears a beautiful flower, and, when he attempts to touch it, it vanishes into air, or a death's head appears to snap at his fingers. He may be made to behold a terrific spectre suddenly starting up before him, or a person with a drawn sword, as if about to run him through. An exhibition of this kind was some time ago brought before the public, which was effected by a concave mirror. A man being placed with his head downVarious amusing experiments besides the above wards, in the focus of the mirror, an erect image of might be exhibited to the young, such as the optical him was exhibited, while his real person was conparadox, an instrument through which objects may cealed, and the place of the mirror darkened; the be seen, although a board or other opaque body be spectators were then directed to take a plate of fruit interposed between the eye and the objects-the from his hand, which in an instant, was dexterously prism, which, in a dark room, separates the primary changed for a dagger or some other deadly weapon. colors of the solar rays-the multiplying glass, It may not be improper occasionally to exhibit such which makes one object appear as if there were deceptions to the young, and leave them for some ten, twenty, or thirty-the burning glass, which, by time to ruminate upon them till the proper explanameans of the sun's rays, sets on fire dark colored tions be given, in order to induce them to use their paper, wood, and other inflammable substances-rational powers in reflecting on the subject, and parand optical illusions produced by the various refractions and reflections of light in water, combinations of plane mirrors, and by concave speculums. A concave mirror, about 5 or 6 inches in diameter, and 10 or 12 inches focus, which may be procured for about half-a-guinea or 15 shillings, is of great utility for a variety of exhibitions. 1. When held at nearly its focal distance from one's face, it represents it as magnified to a monstrous size. 2. When held in the solar rays, directly opposite the sun, it

ticularly to teach them to investigate the causes of every appearance that may seem mysterious or inexplicable, and not to ascribe to occult or supernatural causes what may be explained by an investigation of the established laws of nature; and to guard them against drawing rash or unfounded conclusions from any subject or phenomenon which they have not thoroughly explored, or do not fully comprehend.

Having enlarged much farther than I originally

SECTION X.-Mathematics.

intended on the preceeding departments of Natural | nation of the rationale of each experiment. Griffin's Philosophy, I have no space left for suggesting any Recreations in Chemistry; Thomson's, Turner's, hints in relation to electricity, galvanism, and mag- Parkes', Graham's and Donovan's treaties, or any netism. If the teacher is possessed of an electrical other modern system of chemistry, may also be conmachine and a galvanic apparatus, and is acquaint- suited.* ed with his subject, he has it in his power to exhibit a great variety of very striking experiments which can never fail to arrest the attention of the juvenile mind, and prepare it for entering on expla- A knowledge of certain departments of the manations of some of the sublimest phenomena of na- thematical sciences is essentially requisite for unture. But without these instruments very few ex- derstanding many of the discussions and investigaperiments of any degree of interest can be performed tions connected with natural philosophy, astronomy, in relation to these subjects. The illustration of the geography, and navigation, and for various practiphenomena of magnetism requires no expensive ap- cal purposes in the mehanical arts; and, conse paratus. Two or three small, and as many large quently, ought to form a portion of every course of bar magnets-a large horse-shoe magnet, a mag- general education. During the first stages of elenetic compass, and a few needles, pieces of iron, mentary instruction, a knowledge of the names and and steel filings, may be sufficient for illustrating some of the properties of angles, triangles, squares, the prominent facts in relation to this department parallelograins, trapezoids, trapeziums, circles, of philosophy. But as I have already thrown out a ellipses, parallels, perpendiculars, and other geomefew hints on this subject in the lesson on the Saga-trical lines and figures, may be imparted, on differcious Swan, it would be needless to enlarge. My ent occasions, by way of amusement, as is generally only reason for suggesting the above hints and ex- done in infant schools, which would prepare the periments is, to show that any teacher, at a very way for entering on the regular study of mathemasmall expense, may have it in his power to illus- tical science. The usual method of teaching mathetrate, in a pleasing manner, many of the most inter- matics is to commence with the "Elements of Euesting and practical truths connected with natural clid," proceeding through the first six, and the elephilosophy. Most of the apparatus alluded to venth and twelfth books, and afterwards directing above could be procured for two or three pounds, the attention to the elements of plane and spherical provided the experimenter apply his hands and con- trigonometry, conic sections, fluxions and the highstruct a portion of it himself, which he can easily er algebraic equations, in which the attention of the do when the materials are provided. In regard to student is chiefly directed to the demonstration of philosophical apparatus of every description, were mathematical propositions, without being much exthere a general demand for it from all classes of ercised in practical calculations. This is the scien the community, it might be afforded for less than tific method of instruction generally pursued in colone half the price now charged for it, as certain leges and academies, and if youths of the age of portions of it might be constructed of cheaper mate- fourteen or fifteen were capable of the attention and rials than are now used; as elegance in such instru- abstraction of angelic beings, it would likewise be ments is not always necessary for use; as competi- the natural method. But a different method, I pretion would reduce their price to the lowest rate, and sume, ought to be pursued in schools chiefly devoted as there would be no necessity for great profits when to popular instruction. After the pupil has acquired the manufacturers were certain of a quick and ex- a competent knowledge of arithmetic, let him be tensive sale. conducted through the different branches of practical geometry, including the mensuration of surfaces and solids, artificers' work and land-surveying, exhibiting occasionally a demonstration of some of the rules, in so far as he is able to comprehend it.➡ After which, a selection should be made from Euclid, (chiefly from the first book,) of those proposi tions which have a practical bearing, and which from the foundation of practical geometry and the

Chemistry-Chemistry, in its present improved state, is a science so interesting and useful, so intimately connected with the knowledge of nature, the improvement of the useful arts, and with every branch of physical and practical science, that an outline, at least, of its leading principles and facts should be communicated to all classes of the young. The distinguishing properties of the simple substances, such as oxygen, nitrogen, carbon, hydrogen, chlorine, iodine, sulphur, and phosphorus-particularly oxygen, nitrogen, carbon, and carburetted hydrogen, should be minutely described, and illustrated by experiments, and their extensive influence in the system of nature particularly detailed. The laws of chemical affinity-the nature and properties of heat, its radiation and expansive power, and the effects it produces on all bodies-the composition and decomposition of water, the nature of crystallization, the properties of earths, and metals, acids, and alkalies, the nature of combustion, chemical action and combinations, the component principles of animal and vegetable substances, and various other particulars, may be impressed upon the minds of the young, and rendered familiar by a variety of simple experiments which can be easily performed. Many of the most important and luminous facts of this science may be exhibited by the aid of a few Properties of Bodies, Mechanics, Hydrostatics, Florence flasks, glass tubes, common phials, tum- Hydraulics, Pneumatics, Acoustics, Optics, Astroblers, wine and ale glasses-of which I intended nomy, Electricity, and Magnetism," with questions exhibiting some specimens, had my limits permit- in the margin of every page for exercising the judg ted. In the meantime I refer the reader to Accum's ment of the student. It is calculated for being an volume entitled "Chemical Amusements," which excellent text-book in colleges and academies; but contains a perspicuous description of nearly 200 in- would require to be somewhat reduced and simpliteresting experiments on this subject, with an expla-fied, to adapt it to the use of common schools.

*Notwithstanding the numerous excellent treatises on natural philosophy and chemistry which have been published of late years, we have scarcely any books on these subjects exactly adapted for the use of schools. Blair's "Grammar of Natural Philosophy," and "Conversations" on the same subject by Mrs. Marcet, contain a comprehensive view of the leading subjects of natural philosophy, which may be recommended to the perusal of young per sons; but they are scarcely adapted to the purpose of teaching. Dr. Comstock of America, formerly mentioned, (page 75,) lately published a "System of Natural philosophy," for the use of students and preceptors, which has already passed through nine editions. This volume contains about 300 closely printed pages, and above 200 wood-cuts, and comprises a popular and scientific illustration of the

them; while their fellow-students, who had no previous experience in practical calculations, lagged far behind them, and seldom entered into the spirit of such subjects. I could point to several individuals of this description, who ultimately attained the highest mathematical prizes bestowed at the colleges and academies at which they attended.

SECTION XI.-Physiology.

operations of plane trigonometry. These, which might be comprehended within the limits of thirty or forty propositions, should be arranged into a kind of system, which might be divided into propositions relating to quadrilateral figures, triangles, circles and conic sections. The demonstrations of these should be clear and explicit, and as simple as the nature of the subject will admit, and the steps of the demonstration of each proposition should be thoroughly understood before proceeding to another.At the same time, the bearing of the truths demonstrated upon the several practical operations of geometry, and their general utility, should be distinctly pointed out as the teacher proceeds in his demonstrations; and the pupil having previously been occupied in calculations relating to geometrical figures, will be enabled to appreciate such demonstrations, and will feel a greater interest in such exercises than he would otherwise do, were he to consi-moons of Jupiter, the rings of Saturn, and thousands der them as relating merely to abstract truths which have no useful tendency. He might next proceed to the statements and calculations connected with the different cases of plane trigonometry, applying them to the mensuration of all the cases of terrestrial heights and distances, and to the determining of the distances and magnitudes of the heavenly bodies and the altitude of the lunar mountains.

This is a department of knowledge which has never yet been introduced into any seminary, as a branch of general education. It is somewhat unaccountable, and not a little inconsistent, that, while we direct the young to look abroad over the surface of the earth and survey its mountains, rivers, seas, and continents, and guide their views to the regions of the firmament, where they may contemplate the of luminaries placed at immeasurable distances,— that, while we direct their attention to the structure and habits of quadrupeds, birds, fishes, and insects, and even to the microscopic animalculæ in a drop of water-we should never teach them to look into themselves, to consider their own corporeal structures, the numerous parts of which they are com posed, the admirable functions they perform, the This is the whole course of mathematical instruc- wisdom and goodness displayed in their mechanism, tion I would deem it necessary to communicate in and the lessons of practical instruction which may the first instance ;-and, with a knowledge of the be derived from such contemplations. An intellipractical operations of geometry and trigonometry, gent writer in the "American Annals of Educaand of the principles on which they are founded, tion," has justly remarked-"The person who the pupil would be enabled to understand all the should occupy a dwelling seventy, eighty, or a hunprominent parts of useful science to which mathe-dred years, and yet be unable to tell the number of matical principles are applicable, and to apply them its apartments, or the nature and properties of any to the practical purposes of life. If he feel a peculiar of its materials, perhaps even the number of stories relish for mathematical investigations, or if his si- of which it consisted-would be thought inexcusatuation or profession in future life require an exten-bly ignorant. Yet, with the exception of medical sive knowledge of the higher departments of this men, and here and there an individual belonging study, he can easily prosecute, at his leisure, such to the other professions, is there one person in a studies to any extent, on the foundation of what he thousand who knows any thing about the elementahad previously acquired. When a young person, ry materials-the structure or even the number of of the age of twelve or fourteen, commences the apartments in the present habitation of his mind?" study of "Euclid's Elements," or any similar work, It is not because this study is either uninteresting he is at a loss to conceive what useful purpose can or unaccompanied with mental gratification, that it be served by fixing his mind on squares, parallelo- is so generally neglected; for to "know ourselves," grams and triangles, and pestering himself in de- both physically and intellectually, is one of the first monstrating their relations and proportions. After duties of man, and such knowledge has an extenencountering some difficulties, he perhaps acquires sive practical tendency, and is calculated to gratify a pretty clear conception of the demonstrations of the principle of curiosity, and to produce emotions the first and most simple propositions; but as he of admiration and pleasure. "Does it afford no proceeds in his course, the propositions become pleasure," says the writer I have now quoted, "to more complex and difficult to be conceived, and the study the functions of the stomach and liver, and steps of the demonstration more tedious and com- other organs concerned in changing a mass of beatplicated; he forgets the conclusions formerly de- en food, perhaps some of the coarser vegetables, into duced, his mind becomes bewildered, and, in too blood?-of the heart, and arteries, and veins, which many instances, he follows his preceptor in the convey this fluid, to the amount of three gallons, dark, relying more on his authoritative assertions through all parts of the body once in four minutes? than on a clear perception of the force of his demon--of the lungs, which restore the half-spoiled blood strations; his ideas become confused, and he loses to its wonted purity, as fast as it is sent into them, all relish for the study, because he cannot perceive and enable it once more to pursue a healthful the practical purposes to which such abstract specu- course through its ten thousand channels?-of lations can be applied. This, it may be affirmed, is the brain, and especially the nerves, which by the case with more than one-half of those who at their innumerable branches spread themselves over tempt the study of pure mathematics at an early every soft part of the human system (and some of age, without having previously been exercised in the harder parts) which they can possibly penetrate, the practical operations of the science. It is for this in such numbers that we can nowhere insert the reason I would recommend a short course, or out-point of the finest needle without piercing them?line of practical geometry and trigonometry before proceeding to the demonstration of theorems, or the more abstract parts of mathematical science. So far as my experience goes, I have uniformly found, that those who had been well exercised in the different branches of mensuration, and the practical parts of trigonometry, previous to their entering on a course of pure mathematics, have acquired a relish for such studies, and become eminent proficients in

of the skin, every square inch of which contains the mouths or extremities of a million of minute vessels? Is all this, I say, uninteresting? Is there no wisdom displayed in the construction of so complicated, and yet so wonderful a machine, and endowing it with the power of retaining an average heat of 96 or 98 degrees, whether the surrounding atmosphere be heated to 100 degrees or cooled to 32, or even to a much lower point? Is there, more

over, no mental discipline involved in the study of physiology?"

nature of perspiration, and the functions of the skin, children are permitted to wallow in dirtiness and The evils arising from ignorance of the corporeal filth, to remain moist, cold, and benumbed, and to functions, and of the circumstances by which they pass days and even weeks without being washed or are impaired, are numerous and much to be de- receiving a change of linens; by which they are, plored. From ignorance of the structure and func- sooner or later, subjected to cutaneous and inflam tions of the digestive organs, parents, in many in-matory disorders. Ignorance of this subject has stances, allow their children to eat and drink every likewise led to those awkward attempts, particularthing they desire, and to gorge their stomachs, till ly on the part of the female sex, to remodel the hudiseased action of the organs connected with diges- man frame, as if they could improve the mechantion necessarily ensues, accompanied with the other ism and symmetry devised by Infinite Wisdom.disorders which generally follow in its train. To Hence the derangement of the physical system prothe same cause is owing the practice of administer- duced by laced stays, strait jackets, corsets, and ing to infants, cordials, elixirs, laudanum, and spi- other absurd articles of dress, by which the ribs are rituous liquors-a practice in which no person will compressed, the spine bent out of its place, and the indulge who is acquainted with the laws which re- free expansion of the lungs prevented; the consegulate the functious of the corporeal frame, and quences of which are,-diseases of the breast, shortwhich has a tendency not only to injure the indivi-ness of breath, external callosities, defective diges dual, but to perpetuate a degenerated race through tion, tubercles of the lungs, and a tendency to pulsuccessive generations. From ignorance of the i monary consumption. The following figures show