folded, and to cultivate those holy principles and dispositions which will qualify them for mingling in the society and engaging in the employments of the heavenly world. Such instructions, when amalgamated with Christian views and motives, could not fail of producing a beneficial impression on the susceptible hearts of the young, which might, in some measure, influence their conduct and train of thought through all the remaining periods of their lives.*

SECTION IX.-Experimental Philosophy and Chemistry.

The object of Natural and Experimental Philosophy is to .investigate the phenomena of the material world, in order to discover their causes, and the laws by which the Almighty directs the movements of the universe; and to apply the observations and discoveries we make to useful purposes in human life, and to expand our views of the perfections and operations of the Cre

*The most celebrated writers on Astronomy are Long, Ferguson, La Caille, Martin, O. Gregory, Vince, Herschel, Robison, La Lande, La Place, Biot, and various others. Popular works on this subject, which may be put into the hands of young persons, are such as the following:-Ferguson's "Gentleman and Lady's Astronomy"-Martin's "Gentleman and Lady's Philosophy," Vol. 1.-Bonnycastle's "Introduction to Astronomy"-Mrs. Brian's "Astronomy"-"The Wonders of the Heavens"- Gregory's "Astronomical Lessons," &c. But none of these works are adapted to the purpose of teaching. The best treatise of this kind I have seen, calculated to be a text-book for an intelligent teacher, is a work entitled "The Geography of the Heavens," by Elijah H. Burrit, A. M., lately published at Hartford, State of Connecticut. This volume comprises 342 closely printed pages, large 18mo., and several appropriate wood-cuts. It contains a very full and lucid description of all the particulars respecting the different constellations and principal stars, the general principles of astronomy, the facts connected with the solar system, problems, astronomical tables, and almost every thing that can be deemed interesting to the general student. Every page contains Questions, as exercises for the judgment of the pupil. It is accompanied by a large and beautiful Atlas, 16 inches by 14, containing 7 Planispheres, or Maps of the Heavens: 1. The visible heavens in October, November, and December. 2. Do. in January, February, and March. 3. Do. in April, May, and June. 4. Do. in July, August, and September. 5. The visible heavens in the North Polar Regions for each month of the year. 6. Do. in the South Polar Regions. 7. Planisphere of the whole heavens on Mercator's projection. "The first four maps are so constructed, that the pupil in using them must suppose himself to face the south, and to hold them directly over head, in such a manner that the top of the map should be towards the north, and the bottom towards the south." In the construction of these maps, and in the composition of the work, the latest discoveries have been carefully inserted. This work, since its first publication in 1833, has had an extensive sale in the United States, and been introduced into many respectable seminaries.

ator. This department of study has generally been divided into the following subordinate branches, Mechanics, Hydrostatics, Hydraulics, Pneumatics, Meteorology, Acoustics, Optics, Electricity, Galvanism, and Magnetism. This is a subject, the popular and experimental parts of which may be rendered highly entertaining and instructive to the minds of the young. But, however important the subject in all its branches may be to the regular scientific student, it would be inexpedient to attempt conveying more than a general view of the more popular parts of it to young persons from the age of ten to the age of fourteen, although many of the experiments connected with it may, with propriety, be exhibited even to children of an earlier age, in order to excite a taste for the study of natural science. Experimental illustrations of the subjects of Natural Philosophy sometimes require an extensive apparatus, which cannot be procured but at a considerable expense; but there are many interesting experi ments, illustrative of scientific principles and facts, which can be performed with very simple apparatus, and at little expense; and all that I propose, under this article, is to suggest a few of those experiments which almost every teacher may have it in his power to perform.

In the department of Mechanics,-illustrations might be given of the mechanical powers, which are generally arranged under the heads of the lever, the pulley, the wheel and axis, the inclined plane, the wedge, and the screw. A simple apparatus for illustrating these powers could easily be constructed by an ingenious mechanic, at a trifling expense, and might be rendered conducive both to the entertainment and instruction of the young. In particular, the nature and power of the lever, and the principle on which it acts, should be minutely explained, by experimental illustrations, and by showing its effects in the common operations of life. A long bar of iron or hard wood might be erected on a steady fulcrum, and placed in the area adjacent to the school, which might serve both for amusement and for illustrating the power of the lever. This bar might be divided into feet or half feet, or any convenient number of equal parts, and so constructed that any of those parts might be placed upon the fulcrum. By such a lever the different powers to be applied at different distances from the fulcrum, when a weight is to be raised, might be familiarly illustrated. A seat or swing might be fixed at one end of the beam, on which a boy might sit, while some of his companions, towards the other end, applied different powers or weights at different distances from the fulcrum, as a counterpoise; which would suggest various calculations respecting the powers requisite

to be applied in any given case, according to the distance from the point of support. It will tend to excite their interest in this subject, when they are informed that scissors, pincers, snuffers, oars, the balance, the see-saw, doors turning on hinges, the rudders of ships, cutting knives fixed at one end, and the bones of the arm, are all so many different kinds of levers; and that the operations of quarrying stones, raising great weights, poking the fire, rowing a boat, digging the ground, and such like, are all performed on the principle of this mechanical power. Similar contrivances might be adopted for illustrating the wheel and axle and other powers. A knowledge of the mechanical powers may be useful to every individual, whatever may be his trade or profession in future life, but particularly to those who may afterwards engage in the arts of carpentry, architecture, mining, engineering, and other operations where a knowledge of the mechanical powers is essentially requisite; and the impressions made upon their minds in early life by familiar illustrations of these powers, would tend to facilitate their study of such objects when they became the more particular objects of their attention.

The fundamental principles of Hydrostatics and Hydraulics might be familiarly illustrated by a variety of simple experiments, some of which might be rendered extremely amusing. That fluids press in all directions-that their pressure is in proportion to their perpendicular height-that a small quantity of a fluid may be made to counterpoise any quantity, however great—that a fluid specifically lighter than another will float upon its sur. face that the surface of all fluids which communicate with each other will be on the same level—that the velocity with which water spouts from holes in the side of a vessel, is in proportion to the square root of the distance of the holes below the surface of the water:-These, and similar positions, along with the principles on which syphons, jets, and artificial fountains act, can be illustrated with an apparatus which every intelligent teacher, if he has the least share of mechanical ingenuity, can easily construct for himself, with the assistance of glass vessels, which are to be found in almost every family. To show that water will find its level, and rise to the same height in tubes which have a communication, an instrument similar to the following, Fig. 1. may be constructed:-A B and E D are two tubes which have a communication with each other by means of the tube B D; if water is poured into the tube A B, it will run through the tube B D, and stand at the same elevation in the tube E D. To save expense, the tube B D may be made of wood, and plugged up at both ends; and the glass tubes A B, E D, fixed into it at each end with ce

Fig. 1.

E

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ment; and if BD be made flat on its under part, it will stand on a table without requiring any support. An instrument to show that a small portion of water will counterbalance a large quantity, may be made as follows:-A B, Fig. 2. is a vessel which may Fig. 2.

Fig. 3.

be either square or round, and which may be made either of wood or tin-plate; C D is a glass tube of a narrow bore, cemented into the short tube E, which communicates with the large vessel; if water be poured into either of these, it will stand at the same height in both, which proves, that the small quantity of water in the tube CD, balances the large quantity in the vessel A B, and illustrates what has been termed the hydrostatical paradox. Jels and fountains may be represented and illustrated by such an instrument as Fig. 3. where A B is the reservoir, and C D E a tube connected with it, bent at right angles at D; when these are fill

ed with water-the finger having previously been pressed upon the opening F-as soon as the finger is removed, the water rises in a jet, nearly to the height of the fountain, A B. A jet may likewise be produced by the instrument represented, Fig. 1. by plugging up the tube E D, and opening a hole at C, when a jet will arise after the tubes are filled with water. To show the different quantities and velocities of water spouting at different distances from the surface of a reservoir, such a vessel as that represented, Fig. 4. may be used. The water will issue from the Fig. 4.

orifice at C with greater velocity, and consequently in greater quantity than at B or A; if the orifice C be four times as deep below the surface as the orifice A, it will discharge twice as much water in a given time as A, because 2 is the square root of 4; if the orifice B be in the centre of the column of water, it will project the water to the greatest horizontal distance. The vessel here represented may be made either of wood or of tin-plate, and if a bent tube be inserted at D, and the holes A B C shut up, it may serve to exhibit a jet d'eau. The cup of Tantalus, the fountain at command, the hydraulic dancers and divers, and other entertaining devices might also be exhibited, and accompanied with explanations of the principles on which they act. By such means, several of the leading principles of hydrostatics might be easily impressed upon the youthful mind, and would doubtless be found of practical utility in future life, provided the teacher is careful to show, by familiar examples, how they explain many of the phenomena of nature and operations of art.

The science of Pneumatics affords scope for many curious discussions and experiments respecting the air and atmospherical phenomena, which may be rendered interesting to the young. In illustrating the pressure, elasticity, and other properties of the atmosphere, the assistance of the air-pump, with its usual appa