A natural philosophy : embracing the most recent discoveries in the various branches of physics, and exhibiting the application of scientific principles in everyday life ...

Front matter

WBti ill

BE VISED EDITION.

EMBRACING

Preface

The importance of the physical sciences is now so generally admitted that there are few institutions of learning in which they are not made regular branches of study. And very properly. — for what can be more interesting and instructive, what more worthy of the attention of intelligent creatures, what more calculated to inspire their minds with a thirst for further knowledge, and fill their hearts with reverent gratitude to the Divine Being, than an acquaintance with the laws of the material world, the mysterious influences constantly at work in nature, and the principles by which atoms and worlds are alike controlled ?

It is in the hope of investing this subject with a lively interest, and bringing it home to the student by exhibiting the application of scientific principles in every-day life, that the Natural Philosophy here presented to the public has been prepared. The author has sought to render a subject, abstruse in some of its connections, easy of comprehension, by treating it in a clear style, taking its principles one at a time in their natural order, and illustrating them fully with the facts of our daily experience. The range of topics is comprehensive. By avoiding unnecessary repetitions, room has been found for chapters on Astronomy and Meteorology; one of which subjects, at least, has heretofore been invariably omitted in similar treatises, though a summary of both is important, as time is seldom found for pursuing these branches in separate volumes.

The incorrectness of many of the text-books on Natural Philosophy has been a subject of general complaint. Grave errors, both of theory and fact, have been handed down from one to another, and the results obtained by modern research have been too often over-

4 .PREFACE.

looked. In preparing this volume, every effort has been made to ensure accuracy, the most recent authorities have been consulted, and it is believed that a faithful view is presented of the various sciences embraced, as far as they are at present developed. It is Lhe intention of the author to keep his book up to the times by constant revision, and to make such alterations and additions as the progress of discovery may require.

Two styles of type are used in the text ; a larger size for leading principles, a smaller size for descriptions of apparatus and experiments, explanatory illustrations, &c. By confining a class to the former when the saving of time is an object, a brief yet complete course may be taken. Questions at the bottom of each page will be found to facilitate the examiner's duty, and to afford the pupil a means of testing his preparation before reciting. At the end of such chapters as admit of it, easy practical examples have been introduced, to illustrate the rules and principles set forth.

An important feature of this work is its adaptation to use with or without apparatus. The majority of schools have few facilities for experimental illustration. The wants of these are here met by a free use of engravings, full descriptions of experiments, and explanations of their results.

New Yobk., July 1st, 1859.

Kecent discoveries in the different departments of Physics, and the general acceptance of new theories with respect to the kindred forces, Heat, Light, and Electricity, having rendered necessary certain alterations in the text, the opportunity has been improved to revise the whole work; and this New Edition is offered to the public in the belief that it will be found in all respects accurately to represent the present state of science.

New Yobk, January 2d, 1871.

Contents

CHAPTER PAGK

I. — Matter and its Forms .... ... 7

II. — Properties of Matter 12

Chapter I. Matter And Its Forms

1. Matter. — Whatever occupies space, whatever we can perceive by the senses, is known as Matter.

Different kinds of matter are called Substances. Earth, water, air, are Substances, being different kinds of matter.

A distinct portion of matter is called a Body. The earth, a rain-drop, a bubble, are Bodies.

2. Force. — Whatever acts on a body, to change its form, state, or relation to other bodies, is a Force. Heat, light, electricity, are Forces. It is by the action of Forces on matter that the various phenomena of the universe are produced.

3. Forms of Matter. — Matter exists in three forms ; Solid, Liquid, and A-er'-i-form.

A body is said to be Solid, when its particles, while they possess the power of vibration within certain limits, yet cohere so strongly as to oppose a decided resistance to impression or penetration by other bodies ; example, ice. Solid bodies are called Solids.

1. What is Matter? What are different kinds of matter called ? Give examples. What is a Body ? Give examples. 2. What is a Force ? What are produced by the action of forces on bodies? 3. In how many forms does matter exist? "Name

8 MATTER AND ITS FORMS.

A body is said to be Liquid, when its particles cohere so slightly that they can not only vibrate to and fro, but also roll freely around each other, and thus oppose but little resistance to penetration by other bodies ; example, water. Liquid bodies are called Liquids.

Aeriform means having the form of air, and matter is said to exist in this state when its particles repel each other, tending to separate and spread out indefinitely ; example, steam. Aeriform bodies are called Gases and Vapors.

Liquid and aeriform bodies are embraced under the general name of Fluids.

There are marked points of difference between solids and fluids. A solid has a permanent shape ; a fluid accommodates its shape to that which contains it. A solid may often be moved by moving a portion of its particles ; as a pitcher by its handle. Not so with a liquid ; when we move only a portion of its particles, the rest are detached by their own weight. Thus, by dipping a tumbler into a pail of water, we can not remove all the fluid, but only as much as the tumbler contains.

The same substance may, under different circumstances, appear in all three of these forms. Thus, water is a liquid ; when frozen, it becomes ice, which is a solid ; when exposed to a certain degree of heat, it is converted into steam, which is aeriform.

4. Classes of Bodies. — Bodies are distinguished as Simple and Compound.

A Simple Body consists of matter that can not be resolved into more than one element ; as, gold.

A Compound Body consists of matter that can be resolved into two or more elements ; as air, which is composed of two gases.

The simple bodies, or elements, of which every thing in the universe is composed, are sixty-four in number. Of these, fifty-one, distinguished by a peculiar lustre, are called Metals. The remaining thirteen are known as Non-metallic Elements.

them. When is a body said to be solid ? What are solid bodies called ? When is a body said to be liquid? What are liquid bodies called? What does aeriform mean? When is a body said to be aeriform? What are aeriform bodies called? What name is applied to both liquid and aeriform bodies? Mention some of the marked points of difference between solids and fluids. In how many forms may the same substance appear? Give an example. 4. Into how many classes are bodies divided? Name them. What is a Simple body ? What is a Compound body? How many simple bodies are there? How are they divided ? Name the principal met-

SIMPLE SUBSTANCES. 9

The principal metals are the seven known to the ancients,— gold, silver, iron, copper, mercury, lead, and tin ; antimony, which was next discovered, in 1490 ; bismuth, zinc, arsenic, cobalt, plat'-i-num, nickel, manganese, &c. The thirteen non-metallic elements are ox'-y-gen, hy'-dro-gen, ni'-tro-gen, chlorine [klo'-reen], iodine [i'-o-deeri], bromine [bro'-meen], fluorine [flu'-oreeri], se-le'-ni-um, sulphur, phosphorus, carbon, sil'-i-con, and bo'-ron.

These simple substances are rarely found ; nearly every body that we meet with is composed of two or more elements, and is therefore compound. Such is the case with air, which was anciently thought to be a simple substance, but was proved, towards the close of the eighteenth century, to be a mixture, by weight, of 23 parts of oxygen and 76 parts of nitrogen. Water, also, has been found to be a compound substance, made up of oxygen and hydrogen combined in the proportion, by weight, of 8 to 1. Of the sixty-four elements referred to above, twenty are so rare that their properties are not fully known ; thirty more are comparatively seldom met with ; the remainder constitute the great bulk of the globe and all that is thereon.

The consideration of the simple substances, with their properties and combinations, belongs to the science of Chemistry. The force that causes them to combine and produce compound substances, is called Chemical Affinity. Oxygen and hydrogen combine and form water, in consequence of their chemical affinity.

Chemical affinity subsists only between certain substances. If sulphuric acid be poured on a piece of zinc, the two substances will combine and form a compound entirely different from either. Pour the acid on a lump of gold, and no such change will ensue, because there is no chemical affinity between them.

5. Natural Philosophy. — Natural Philosophy is the science that treats of the properties and laws of matter. It is also called Physics.

Pythagoras was the first to use the term philosophy. From him and his followers it was borrowed by Socrates ; who, w r hen the other sages of his time called themselves sophists, or wise men, modestly declared himself a philosopher, or lover of wisdom. — Philosophy implies a search for truth ; and Natural Philosophy, as distinguished from Moral and Intellectual Philosophy, searches for the truths connected with the material world.

als. Name the thirteen non-metallic elements. What is said of the simple substances ? What kind of substances are air and water? Of what is air composed? Of what, water ? flow many elements constitute the great bulk of the globe ? What is said of the rest? To what science does the consideration of the simple substances belong? What causes the simple substances to combine? Give an instance of chemical affinity. Illustrate the fact that chemical affinity subsists only between certain substances. 5. What is Natural Philosophy ? With whom did the term philosophy 1-

10 MATTER AND ITS FORMS.

6. Modes of Investigation. — We arrive at the facts of Natural Philosophy in two ways ; by Observation and Experiment. Observation consists in watching such phenomena, or appearances, as occur in the course of nature. Experiment consists in causing such phenomena to occur when and where we wish, for the purpose of noting the attendant circumstances and results.

For example, we arrive at the fact that an unsupported body will descend to the earth's surface, when we see an apple fall from a bough ; this is by Observation. We learn the same fact, when, with the view of ascertaining what it will do, we let an apple drop from our hands ; this is by Experiment.

7. Modes of Measoni?ig. — Having obtained our facts in the two ways just described, and classified them, we next proceed from individual cases to deduce general laws. This is called Reasoning by Induction.

Thus, if we try the experiment "with many different apples, and find that each, when let go, will fall to the ground, we lay down the general law that all apples will fall in like manner. If we find that not only apples do this, but also other objects with which we make the trial, we go a step furthe:-, and announce another law, that all objects left unsupported will fall to the ground.

It is by this process that most of the laws and principles of Natural Philosophy have been established. Archimedes [ar-ke-me'-deez], the Sicilian philosopher, used it over two thousand years ago. Gal-i-le'-o revived it in modern times v and it may be said to lie at the foundation of all the great discoveries of Newton.

When we have two similar phenomena and know that one proceeds from a certain cause, we attribute the other to the same cause. This is called Reasoning by Analogy.

Such reasoning is employed in the case of all bodies that are beyond our reach. From what is near, we draw conclusions respecting what is remote. It is thus, for example, that the philosopher explains the motions of the heavenly bodies, extending to them, by analogous reasoning, the same principles that govern the motion of bodies on the earth.

8. Division of the Subject. — Natural Philosophy, hav-

•riginate? Who borrowed it from Pythagoras? What does philosophy imply? What is the particular province of Natural Philosophy ? 6. How do we arrive at the facts of Natural Philosophy? In what does Observation consist? In what, Experiment? Illustrate these definitions. 7. What is meant by reasoning by induction? Give an example. By what philosophers has this mode of reasoning been employed? What is meant by reasoning by analogy f Give an example. 8. What

DIVISION OF THE SUBJECT. 11

ing to treat of matter in all its forms, as well as the forces that act upon it, embraces the following branches : —

Mechanics, which treats of forces and their application in machines. To Mechanics belong

Hy-dro-stat'-ics, which treats of liquids at rest ;

Hy-drau'-lics, which treats of liquids in motion.

Pneumatics [nu-mat'-ics], which treats of gases and vapors.

Pyr-o-nom'-ics, which treats of heat.

Optics, which treats of light and vision.

Acoustics [a-cow 1 'sties'], which treats of sound.

Electricity, which treats of the force so called. To Electricity belong

Galvanism, which treats of electricity produced by chemical action ;

Thermo-electricity, which treats of electricity developed by heat ;

Magneto-electricity, which treats of electricity developed by magnetism.

Magnetism, which treats of magnets and the forces they develop. To Magnetism belongs

Electro-magnetism, which treats of magnetism developed by electricity.

Astronomy, which treats of the heavenly bodies.

Me-te-o-rol'-o-gy, which treats of the phenomena of the atmosphere.

branches does Natural Philosophy embrace ? Of what does Mechanics treat ? Hydrostatics? Hydraulics? Pneumatics? Pyronomics? Optics? Acoustics? Electricity ? Galvanism ? Thermo-electricity ? Magneto-electricity ? Magnetism ? Electro-magnetism? Astronomy? Meteorology?

Chapter II. Properties Of Matter

9. Every distinct portion of matter possesses certain properties. Some of these belong in common to all bodies, solid, liquid, and aeriform, and are called Universal Properties of matter. Others, again, are found only in certain substances, and these are known as Accessory Properties.

The Universal Properties of matter are Extension, Figure, Impenetrability, Indestructibility, Inertia [in-er f -sha], Divisibility, Porosity, Compressibility, Expansibility, Mobility, and Gravitation.

The principal Accessory Properties are Cohesion, Adhesion, Hardness, Tenacity, Elasticity, Brittleness, Malleability, and Ductility.

We proceed to consider these properties in turn.

10. Extension. — Extension is that property by which a body occupies a certain portion of space. The portion of space thus occupied is called its Place.

In other words, every body, however small, must have some size, or a certain length, breadth, and thickness, which are called its Dimensions. The greatest of these three dimensions is its Length ; the next greatest, its Breadth, or Width ; the least, its Thickness. But, instead of any of these terms, we use the word height to denote distance from bottom to top in the case of objects towering above us, and depth to denote distance from top to bottom in the case of objects extending below us.

11. Figure. — Figure is that property by which a body has a certain shape.

This property necessarily follows from Extension ; for since every body must have length, breadth, and thickness, it must also have some definite

9. What is meant by Universal Properties of matter ? What is meant by Accessory Properties ? Enumerate the universal properties. Mention the principal accessory properties. 10. What is Extension ? What is meant by the dimensions of a body ? What is Length ? Breadth ? Thickness ? When are the terms height and depth used ? 11. What is Figure ? From what does figure follow ? What is the

IMPENETRABILITY. 13

shape. While this is true of all bodies, it must be remembered that the form of solids is permanent, while that of fluids varies, to adapt itself to every new surface with which it comes in contact. A bullet keeps the same shape, w::erever it is placed ; whereas a quantity of water, poured from a tumbler into a pail, visibly changes its form.

12. Impenetrability. — Impenetrability is that property by which a body occupies a certain portion of space, to the Bxclusion for the time of all other bodies.

Impenetrability may be illustrated with a variety of simple experiments. Fill a tumbler to the brim with water, and drop in a bullet ; the water will at once overflow Fill a bottle with water, and try to put the cork in ; the cork will not enter till it has displaced some of the water : if it fit so closely that tho water can not escape, and a hard pressure be exerted, the bottle will burst.

The impenetrability of air is shown with the apparatus represented in Figure 1. A is a glass jar fitted with an air-tight cork, through which a funnel, B, enters the jar. C is a bent tube, one end of which also passes through the cork into the jar, while the other is received in a glass of water, D. Let water be poured into the funnel ; as it descends, drop by drop, into the jar, air passes out through the bent tube, and escapes through the water in D in the form of bubbles. Thus it is shown that water and air can not occupy the same space at the same time.

13. Impenetrability belongs to all substances, though in some cases it may appear to be wanting. A nail, for instance, is driven into a piece of wood without increasing its size ; but it effects an entrance by forcing together the fibres of the wood, not by occupying their space at the same time with them. In like manner, a certain amount of salt and sugar may be successively dropped into a tumbler brim-full of water without causing it to overflow. The particles of water, which are supposed to be globular, do not everywhere touch each other, and the particles of salt are accommodated in the interstices between them. These in turn leave minute Fig. % spaces, into which the still smaller particles of sugar find their ^p Z-— y^IN way. Fig. 2 exhibits such an arrangement. To illustrate it r^i^J^,^ familiarly, we may fill a vessel with as many orange^ s it f ( ; j will hold, and then pour on a quantity of peas, shaking the 9^7^ vessel slightly so that they may settle in the empty spaces.

difference between solids and fluids as regards figure ? 12. "What is Impenetrability? Give some familiar illustrations of this property. Describe the experiment with the apparatus represented in. Fig. 1. 13. "What is said of those cases in which impenetrability appears to be wanting ? Illustrate this with the nail. Explain how salt and sugar may be dropped into a tumbler full of water without causing it to Qve?-

When the vessel will receive no more peas, repeat the process with fine gravel, and it will be found that a considerable quantity will lodge between the oranges and peas.

14. Indestructibility. — Indestructibility is that property which renders a body incapable of being destroyed.

Matter may be made to assume a new form and new properties, but it can not cease to exist. The quantity of matter now in the world is precisely the same as when it was first called into being, and it will continue undiminished till the end of time. The Deity alone created, and it is only He that can destroy.

15. To this universal law we have some apparent exceptions; but, when closely examined, it will be found that they are exceptions in appearance only. Water, for instance, exposed to the air in a shallow dish, will at length disappear by evaporation ; but it is not destroyed. Assuming the form of vapor, it ascends, becomes incorporated with clouds, is condensed into rain, and falls, — to go through the same process again. — The oil in a burning lamp gradually gets lower and lower till at last it is all gone, and we say it is burned up ; but the process of combustion, or burning, only changes it into invisible gases, — not one particle of its substance is lost. In like manner, when fuel of any kind is consumed, there is only a change of form, not a destruction of the least portion of matter.

Such changes are constantly going on in the operations of nature. One body perishes, and of the materials that composed it another is formed. Our own frames may contain particles that were in the bodies of Adam, Noah, or Socrates ; or, if they do not now, may do so to-morrow, for they are constantly parting with portions of their substance, the place of which is as constantly supplied by new matter. It is supposed that the whole body, including even the innermost parts of its hardest bones, is completely renewed every seven years. Yet, amid all the countless transitions of nature, not a single particle of matter is destroyed or lost.

16. It was by a knowledge of the indestructibility of matter that Sir Walter Raleigh is said to have won a wager of Queen Elizabeth. Having weighed out a sufficient quantity of tobacco to fill his pipe, he came into the queen's presence, and as the wreaths of smoke curled up offered to bet her Majesty that he could tell their weight. Elizabeth accepted the bet, and Sir Walter quietly finished his pipe ; then, having shaken out the ashes, he weighed them, and, subtracting the amount from that of the tobacco originally put flow. 14. What is Indestructibility ? What can be dene to matter, and what not ? 35. What is said of the apparent exceptions to this law ? What becomes of water exposed to the air ? What becomes of the oil in a burLing lamp ? What is .said of the changes of nature ? What is said of the changes in the human body ? 16. How did Sir Walter Raleigh teach Queen Elizabeth that matter is indestructible * 17. What

INEKTEA. 15

In, told the queen the exact weight of the smoke. Elizabeth paid the wager, and thus learned to her cost that matter is indestructible.

1 7. Inertia. — Inertia is that property which renders a body incapable of putting itself in motion when at rest, or coming to rest when in motion.

When a stationary body begins to move, or a moving body comes to rest, it is not through any power of its own, but because it is acted on by some external agency, which we call a Force.

That no inanimate body can put itself in motion, is evident from our daily experience. The rocks that we saw on the earth's surface ten years ago are to-day in precisely the same place as the)" then were, and there they will remain forever unless some force removes them.

It is equally true, though not so obvious, that a body once in motion can not of itself cease to move. The earth revolves on its axis, the heavenly bodies move in their orbits, just as they did at the time of the Creation; they have no power to stop. It is true that on the surface of the earth a moving body gradually comes to rest, when the force which put it in motion ceases to act ; but this is owing to the resistance of the air and a force which draws it towards the centre of the earth — not to any agency of its own. Remove all external forces, and its inertia would keep it moving on in a straight line forever.

18. Familiar Examples. — It is in consequence of inertia that a horse has to strain hard at first to move a load, which, when it is once in motion, he can draw with ease. A car, through its inertia, continues moving after the locomotive is detached. Through inertia, a person standing erect in a stationary boat or wagon is thrown backward if it suddenly starts : his feet, touching the bottom, are carried forward with it, while his body by its inertia does not partake of the onward motion and falls backward. So, a person standing erect in a boat or wagon that is moving rap- „. „

idly, is thrown forward if it suddenly stops ; his feet cease to move at once, while his body continues in motion in consequence of its inertia, and falls forward.

19. An interesting experiment to illustrate inertia may be performed with the apparatus represented in Fig. 3. On the top of a short pillar is placed a card, and on the card a brass ball. Beside the pillar is fixed a steel spring, with an apparatus for drawing it back. If the

is Inertia? What is a Force ? What evidences of the inertia of matter have we in nature ? If inertia is one of the properties of matter, why does a moving body come to rest on the earth's surface ? 18. Give some familiar examples of inertia and its ;onsequences. 19. Describe the experiment with the inertia apparatus. "Describe

PROPERTIES OF MATTER.

spring is drawn back and then suddenly released, it will drive the card from the top of the pillar, while the ball in consequence of its inertia will retain its place.

Those who have not the above apparatus may balance a card with a penny placed upon it on the tip of one of the fingers of the left hand, and strike it

suddenly with the middle finger of the right hand, as represented in Fig. 4. If properly balanced and evenly struck, the card will /l^^^^^^^lj r 1 **' fly away, and the penny will be

] f ^^ " ( \v^- % left on the finger.

^R\ \sf) ^*v^ jfiltK. I n these cases, there is not

sufficient time for the card to overcome the inertia of the ball and the penny, and impart to them its own motion. When, however, motion has once been communicated by one body to another resting on it, the inertia of the latter keeps it in motion. A person riding in a carriage partakes of its motion, and if he jumps from it runs the risk of being thrown down, because his feet cease to move the instant they strike the ground, while the inertia of his body carries it forward. The circus-rider

Fig. 5.

v^tjnfp^ takes advantage of this fact.

While his horse is going at full speed, he jumps over a rope extended across the ring (see Fig. 5), and regains his footing on the saddle without difficulty.

To do this, he has only to leap straight up as he comes to the rope, for his inertia bears him along in the same direction as his horse.

A bullet thrown at a pane of glass breaks it into many pieces, but, fired at it from a rifle, merely makes a circular hole. In the latter case, all the particles of glass, on account of their inertia, can not immediately acquire the rapid motion of the bullet; and consequently only that portion which is struck is carried onward. On the same principle, a thin stick resting on twc wine-glasses (see Fig. 6) may be broken by a quick blow with a poker in its centre, without injury to its brittle supports.

the experiment with the card and penny. What is the effect of inertia, when motion has once been communicated to a body? Why is a person who jumps from a carriage in motion thrown down ? Explain the leap of the circus-rider. What is the effect of throwing a bullet against a pane of glass, and what of firing it ? What causes the difference ? What experiment may be performed to illustrate this point ? 20. To

DIVISIBILITY.

Fig. 7.

20. The heavier a body is, the greater is its inertia ; the more strongly does it resist forces that would set it in motion, change its motion, or stop its motion.

Instinct teaches this fact. A child, when nearly overtaken by a man, will suddenly turn, or " dodge" as he calls it, thus gaining ground, inasmuch as the greater weight and inertia of the man compel him to make a longer turn. So a hare, in making for a cover, often escapes a hound by making a num ber of quick turns. The greater inertia of the hound carries him too far, and thus obliges him to pass over a greater space, as seen in Fig. 7, in which the continuous line shows the hare's path and the dotted line the hound's.

2 1 . Divisibility. — Divisibility is that property which renders a body capable of being divided.

Atomic Theory. — Practically, there is no limit to the divisibility of matter. Most philosophers, however, hold what is called the Atomic Theory, — that if we had more acute senses and instruments sufficiently delicate, we would at last, in dividing and subdividing matter, arrive at exceedingly small particles, incapable of further division. Such particles they call Atoms, a term derived from a Greek word meaning indivisible.

According to this theory, <lifferent kinds of matter are made up of different kinds of atoms ; but in the same substance the atoms are always the same in shape and nature. It must be remembered, however, that no particle has yet been arrived at that can not be divided.