A system of natural philosophy: in which are explained the principles of mechanics, hydrostatics, hydraulics, pneumatics, acoustics, optics ..

Front matter

Copyright N°

IS&&

COPYRIGHT DEPOSIT.

Preface

TO THE FIFTH STEREOTYPE REVISION.

The author has the satisfaction of being again called upon by his well-known, and enterprising publishers to superintend the proofs of a new set of stereotype plates for this work, being the fifth which its circulation has required in this country.

In this improved edition, although large portions of the contents have been re-written, and much new matter added, the author has been careful not to make such changes as to render it unfit to be used in classes with the last edition.

In attempting to make this copy more complete and useful than the former ones, the author has availed himself of the addi¬ tions and corrections, made by Professor Lees of “ the Naval and Military Academy of Edinburgh,” and of those of Professor Hoblyn, Lecturer in “ The Institute of Medicine and Arts,” London, these two gentleman having done him the honor to associate their names with that of the author, in two several editions of this work.

In the Chapters on the Steam Engine, and Astronomy, it was found that many paragraphs might be omitted with advantage to the essential parts of the subjects. These erasures have been replaced by a description of the Railroad Locomotive, and by the insertion of Tables containing the names of the new Asteroids, and of those of their discoverers, with the date of each discovery.

Among the additions will be found descriptions and illustrations of McCormick’s Reaper; Sharps’ Rifle; Printing Presses; House’s Printing Telegraph; Manufacture of Percussion Caps; The Organ; Monochord; Hygrometer; Harmonicon; Air-Gun; Dipping Needle, and much new matter on Electro-Magnetism.

The questions, in this edition, are numbered, to correspond

VI

PREFACE.

with those of the paragraphs ; and nearly all the old cuts have been re-engraved, and about fifty new ones added.

And, finally, perhaps the author will- be excused for adding, that besides the circulation of this work in England, Scotland, and Prussia, there have been printed, and sold more than half a million copies in this country.

J. L. C.

Hartford, April, 1852.

NATURAL PHILOSOPHY, &c.

Chapter I. The Properties Of Bodies

Natural Philosophy, or the Science of Nature, has for its objects the investigation of the properties of all natural bodies and their mutual action on each other. The term Physics has a similar meaning.

1. A Body is any substance of which we can gain a knowl¬ edge by our senses. Hence , air , water , and earth , in all their modifications , are called bodies .

2. There are certain properties which are common to all bodies. These are called the essential properties of bodies. They are Impenetrability , Extension , Figure , Divisibility , In¬ ertia, and Attraction.

3. Impenetrability. — By impenetrability, is meant that two bodies can not occupy the same space at the same time, or, that the ultimate particles of matter can not be penetrated. Thus, if a vessel be exactly filled with water, and a stone or any other substance heavier than water, be dropped into it, a quantity of water will overflow, just equal to the size of the heavy body. This shows that the stone only separates or displaces the parti¬ cles of water, and therefore that the two substances can not ex¬ ist in the same place at the same time. If a glass tube open at the bottom, and closed with the thumb at the top, be pressed down into a vessel of water, the liquid will not rise up and fill the tube, because the air already in the tube resists it ; but if the thumb be removed, so that the air can pass out, the water will instantly rise as high on the inside of the tube as it is on

What are the objects of natural philosophy 1 ]. What is a body? 2. Mention several bodies. What are the essential properties of bodies 7 3. What is meant by impenetrability 7 How is it proved that air and water are impenetrable 7

PROPERTIES OF BODIES.

the outside. This shows that the air is impenetrable to the water.

4. If a nail be driven into a board, in common language, it is said to penetrate the wood, but in the language of philoso¬ phy, it only separates , or displaces the particles of the wood. The same is the case, if the nail be driven into a piece of lead ; the particles of the lead are separated from each other, and crowded together, to make room for the harder body, but the particles themselves are by no means penetrated by the nail.

5. When a piece of gold is dissolved in an acid, the parti¬ cles of the metal are divided, or separated from each other, and diffused in the fluid, but the particles of gold are supposed still to bb entire, for if the acid be removed, we obtain the gold again in its solid form, just as though its particles had never been separated.

6. Extension. — Every body , however small, must have length , breadth , and thickness , since no substance can exist without them. By extension , therefore , is only meant these qualities. Exten¬ sion has no respect to the size , or shape of a body.

7. The size and shape of a block of wood a foot square is quite different from that of a walking-stick. But they both equally possess length, breadth, and thickness, since the stick might be cut into little blocks, exactly resembling in shape the large one. And these little cubes might again be divided until they were only the hundredth part of an inch in diameter, and still it is obvious that they would possess length, breadth, and thickness, for they could yet be seen, felt, and measured. But suppose each of these little blocks to be again divided a thou¬ sand times, it is true we could not measure them, but still they would possess the quality of extension, as really as they did . be¬ fore division, the only difference being in respect to dimensions.

8. Figure or form is the result of extension, for we cannot conceive that a body has length and breadth, without its also having some kind of figure, however irregular.

9. Some solid bodies have certain or determinate forms which are produced by nature, and are always the same, wherever they are found. Thus, a crystal of quartz has six sides, while a garnet has twelve sides, these numbers being in¬ variable. Some solids are so irregular, that they can not be

4. When a nail is driven into a board or piece of lead, are the particles of these bodies penetrated or separated 7 5. Are the particles of gold dissolved, or only separated by the acid 7 6. What is meant by extension? 7. In how manv directions do bodies possess extension 7 8. Of what is figure or form the result 7 Do all bodies possess figure 7 9. What solids are regular in their forms 7

PROPERTIES OF BODIES.

compared with any mathematical figure. This is the case with the fragments of a broken rock, chips of wood, fractured glass, &c. ; these are called amorphous .

10. Fluid bodies have no determinate forms, but take their shapes from the vessels in which they happen to be placed.

11. Divisibility. — By the divisibility of matter , we mean that a body may be divided into parts, and that these parts may again be divided into other parts.

12. It is quite obvious, that if we break a piece of marble into two parts, these two parts may again be divided, and that the process of division may be continued until these parts are so small as not individually to be seen or felt. But as every body, however small, must possess extension and form, so we can conceive of none so minute but that it may again be di¬ vided. There is, however, possibly a limit, beyond which bodies can not actually be divided, for there may be reason to believe that the atoms of matter are indivisible by any means in our power. But under what circumstances this takes place, or whether it is in the power of man during his whole life, to pulverize any substance so finely, that it may not again be broken, is unknown.

13. We can conceive, in some degree, how minute must be the particles of matter, from circumstances that every day come within our knowledge.

14. A single grain of musk will scent a room for years, and still lose no appreciable part of its weight. Here, the particles of musk must be floating in the air of every part of the room, otherwise they could not be every where perceived.

15. Gold is hammered so thin, as to take 282,000 leaves to make an inch in thickness. Here, the particles still adhere to each other, notwithstanding the great surface which they cover, — a single grain being sufficient to extend over a surface of fifty square inches.

16. Indestructibility. — This term means that nothing is destroyed. The ultimate particles of matter, however widely they may be diffused, are not individually destroyed, or lost, but under certain circumstances, may again be collected into a body without change of form. Mercury, water, and many other substances, may be converted into vapor, or distilled in

9. What bodies are irregular? 11. What is meant by divisibility of matter? Is there any limit to the divisibility of matter ? 12. Are the atoms of matter divisible ? 14. What examples are given of the divisibility of matter ? 15. How many leaves of gold does it take to make an inch in thickness? How many square inches may a grain of gold be made to cover ? 16. Under what circumstances may the particles of matter again be collected in their original form ?

1*

PROPERTIES OF BODIES.

close vessels, without any of their particles being lost. In such cases, there is no decomposition of the substances, but only a change of form by the heat, and hence the mercury and water assume their original state again on cooling.

17. Where bodies suffer decomposition or decay, their ele¬ mentary particles, in like manner, are neither destroyed nor lost, but only enter into new arrangements or combinations with other bodies.

18. When a piece of wood is heated in a close vessel, such as a retort, we obtain water, an acid, several kinds of gas, and there remains a black, porous substance, called charcoal. The wood is thus decomposed, or destroyed, and its particles take a new arrangement, and assume' new forms, but that nothing is lost, is proved by the fact that if the water, acid, gases, and charcoal, be collected and weighed, they will be found exactly as heavy as the wood was before distillation.

19. Bones, flesh, or any other animal substance, may in the same manner be made to assume new forms, without losing a particle of the matter which they originally contained.

20. The decay of animal or vegetable bodies in the open air, or in the ground, is only a process by which the particles of which they were composed, change their places and assume new forms.

21. The decay and decomposition of animals and vegetables on the surface of the earth form the soil, which nourishes the growth of vegetables ; and these, in their turn, form the nu¬ triment of animals. Thus is there a perpetual change from life to death, and from death to life, and as constant a succes¬ sion in the forms and places, which the particles of matter as¬ sume. Nothing is lost, and not a particle of matter is struck out of existence. The same matter of which every living ani¬ mal, and every vegetable was formed since the creation, is still in existence. -As nothing is lost or annihilated, so it is proba¬ ble that nothing has been added, and that we, ourselves, are composed of particles of matter as old as the creation. In time, we must, in our turn, suffer decomposition, as all forms have done before us, and thus resign the matter of which we are composed, to form new existences.

22. Inertia. — Inertia means passiveness or want of power.

i7. What is meant by indestructibility ? 18. When bodies suffer decay are their nrnhnhiS 19‘ WJlat becomes of the particles of bodies which decay 21 Is it

or *<“«!, since the flS cretionl wnat is said of the particles of matter of which we are made 1

PROPERTIES OF BODIES.

Thus , matter is, of itself , equally incapable of putting itself in motion, or of bringing itself to rest when in motion .

23. It is plain that a rock on the surface of the earth never changes its position in respect to other things on the earth. It has of itself no power to move, and would, therefore, forever lie still, unless moved by some external force. This fact is proved by the experience of every person, for we see the same objects lying in the same positions all our lives. Now, it is just as true, that inert matter has no power to bring itself to rest, when once put in motion, as it is that it can not put itself in motion when at rest, for having no life, it is perfectly passive, both to motion and rest; and therefore either state depends entirely upon cir¬ cumstances.

24.. Common experience proving that matter does not put itself in motion, we might be led to believe, that rest is the nat¬ ural state of all inert bodies ; but a few considerations will show that motion is as much the natural state of matter as rest, and that either state depends on the resistance, or impulse, of ex¬ ternal causes.

25. If a cannon-ball be rolled upon the ground, it will soon cease to move, because the ground is rough, and presents imped¬ iments to its motion ; but if it be rolled on the ice, its motion will continue much longer, because there are fewer impediments, and consequently, the same force of impulse will carry it much further. We see from this, that with the same impulse, the distance to which the ball will move must depend on the im¬ pediments it meets with, or the resistance it has to overcome. But suppose that the ball and ice were both so smooth as to re¬ move as much as possible the resistance caused by friction, then it is obvious that the ball would continue to move longer, and go to a greater distance. Next, suppose we avoid the friction of the ice, and throw the ball through the air, it would then continue in motion still longer with the same force of projection, because the air alone presents less impediment than the air and ice, and there is now nothing to oppose its constant motion, ex¬ cept the resistance of the air, and its own weight, or gravity.

26. If the air be exhausted, or pumped out of a vessel by means of an air-pump, and a common top, with a small, hard point, be set in motion in it, the top will continue to spin for

22. What does inertia mean 7 24. Is rest or motion the natural state of matter 7 25 Why does the ball roll farther on the ice than on the ground ? What does this prove? Why, with the same force of projection, will a ball move further through the air than on the ice ? 26. Why will a top spin, or a pendulum swing, longer in an exhausted vessel than in the air ?

PROPERTIES OF BODIES.

hours, because the air does not resist its motion. A pendulum, set in motion, in an exhausted vessel, will continue to swing, without the help of clock-work, for a whole day, because there is nothing to resist its perpetual motion but the small friction at the point where it is suspended, and gravity.

27. We see, then, that it is the resistance of the air, of fric¬ tion, and of gravity, which cause bodies once in motion to cease moving, or come to rest, and that dead matter, of itself, is equally incapable of causing its own motion, or its own rest.

28. We have perpetual examples of the truth of this doc¬ trine, in the moon, and other planets. These vast bodies move through spaces which are void of the obstacles of air and fric¬ tion, and their motions are the same that they were thousands of years ago, or at the beginning of creation.

29. Attraction. — By attraction is meant that property or quality in the particles of bodies , which makes them tend toward each other.

30. We know that substances are composed of small atoms or particles of matter, and that it is a collection of these, united together, that form all the objects with which we are ac¬ quainted. Now, when we come to divide, or separate any sub¬ stance into parts, we do not find that its particles have been united or kept together by glue, little nails, or any such me¬ chanical means, but that they cling together by some power, not obvious to our senses. This power we call Attraction , but of its nature or cause, we are entirely ignorant. Experiment and observation, however, demonstrate that this power pervades all material things, and that under different modifications, it not only makes the particles of bodies adhere' to each other, but is the cause which keeps the planets in their orbits as they pass through the heavens.

3 1 . Attraction has received different names, according to the circumstances under which it acts.

32. The force which keeps the particles of matter together, to form bodies, or masses, is called Attraction of cohesion. That which inclines different masses toward each other, is called Attraction of gravitation. That which causes liquids to rise in tubes, is called Capillary attraction. That which forces

27. What are the causes which resist the perpetual motion of bodies 7 28. Where have we an example of continued motion without the existence of air and friction i 29. What is meant by attraction 7 30. What is known about the cause of attraction 1 Is attraction common to all kinds of matter, or not 7 What effect does this power have upon the planets 7 31. Why has attraction received different names 7 32. How many kinds of attraction are there 7 How does the attraction of cohesion operate 7 What is meant by attraction of gravitation 7 What by capillary attraction 7

PROPERTIES OF BODIES.

the particles of substances of different kinds to unite, is known under the name of Chemical attraction. That which causes the needle to point constantly toward the poles of the earth, is Magnetic attraction; and that which is excited by friction in certain substances, is known by the name of Electrical at¬ traction.

33. The following illustrations, it is hoped, will make each kind of attraction distinct and obvious to the mind of the student.

34. Attraction of Cohesion acts only at insensible distances , as when the particles of bodies apparently touch each other.

35. Take two

pieces of lead, Fig. fig. i.

1, of a round form, an inch in diame¬ ter and two inches long ; flatten one end of each and Cohesion.

make through it

an eye -hole for a string. Make the other ends of each as smooth as possible, by cutting them with a sharp knife. If now the smooth surfaces be brought together, with a slight turning pressure, they will adhere with such force that two men can hardly pull them apart by the two strings.

36. In like manner, two pieces of plate glass, when, their surfaces are cleaned from dust, and they are pressed together, will adhere with considerable force. Other smooth substances present the same phenomena.

37. This kind of attraction is much stronger in some bodies than in others. Thus, it is stronger in the metals than in most other substances, and in some of the metals it is stronger than in others. In general it is most powerful among the particles of solid bodies, weaker among those of liquids, and probably entirely wanting among elastic fluids, such as air and the gases.

38. Thus, a small iron wire will hold a suspended weight of many pounds, without having its particles separated; the particles of water are divided by a very small force, while, those of air are still more easily moved among each other. These different properties depend on the force of cohesion with which the several particles of these bodies are united.

32. What by chemical attraction? What is that which makes the needle point toward the pole ? How is electrical attraction excited ? 53. Give an example of cohe¬ sive attraction ? 37. In what substances is cohesive attraction the strongest? In what substances is it the weakest ? 38. Why are the particles of fluids more easily separated than those of solids?

PROPERTIES OF BODIES.

39. When the particles of fluids are left to arrange them¬ selves according to the laws of attraction, the bodies which they compose assume the form of a globe or ball.

40. Drops of water thrown on an oiled surface, or on wax, — globules of mercury, — hailstones, — a drop of water adhering to the end of the finger, — tears running down the cheeks, and dewdrops on the leaves of plants, are all examples of this law of attraction. The manufacture of shot is also a striking illustra¬ tion. The lead is melted and poured into a sieve, at the height of about two hundred feet from the ground. The stream of lead, immediately after leaving the sieve, separates into round globules, which, before they reach the ground, are cooled and become solid, and thus are formed the shot used bv sports¬ men.

41. To account for the globular form in all these cases, we have only to consider that the particles of matter are mutually attracted toward a common center, and in liquids being free to move, they arrange themselves accordingly.

42. In all figures except the globe or ball, some of the parti¬ cles must be nearer the center than others. But in a body that is perfectly round, every part of the outside is exactly at the same distance from the center.

43. Thus, the corners of a cube, or square, are at much greater distances from the center than the sides, while the circumference of a circle or ball is every where at the same distance from it. This difference is shown by Fig. 2, and it is quite obvious, that if the parti¬ cles of matter are equally attracted to¬ ward the common center, and are free to arrange themselves, no other figure could possibly be formed, since then every part of the outside is equally at¬ tracted.

FIG. 2.

Globular form.

44. The sun, earth, moon, and indeed all the heaven y bodies, are illustrations of this law, and therefore were probably in so soft a state when first formed, as to allow their particles freely to arrange themselves accordingly. J

39- *°rm do fluids take> when their particles are left to their own arrant

menu 40. G.ve examples of this law. 41. How is the globular form which liS assume accounted for ? If the particles of a body are free to move, and are eaual ly attracted toward the center, what must be its figure 1 43. Why must the figure be a globe 1 44. What great natural bodies are examples of this law 1 ®

PROPERTIES OF BODIES.

FIG. 3.

Adhesion between solids and liquids.

45. Adhesion. — The attraction between solids and liquids is termed adhesion. This is well illustrated by means of Fig. 3.

First, very nice¬ ly balance the plate of copper,

C, by means of weights in the cup, A, and then slide the vessel of water, B, un¬ der the copper, pouring in more of the fluid un¬ til the metal just touches it. Now

on placing weights in A, it will be found that the metal ad¬ heres to the water with so much force, that if the plate has an area of about seven inches, it will require a weight of more than 1000 grains to raise it from the surface of the water.

46. Attraction of Gravitation. — As the attraction of cohesion unites the particles of matter into masses or bodies , so the attraction of gravitation tends to force these masses toward each other , to form those of still greater dimen¬ sions. The term gravitation, does not here strictly refer to the weight of bodies, but to the attraction of the masses of matter toward each other, whether downward, upward, or horizontally.

47. The attraction of gravitation is mutual, since all bodies not only attract other bodies, but are themselves attracted.

48. Two cannon-balls, when suspended by long cords, so as to hang quite near each other, are found to exert a mutual attraction, so that neither of the cords are exactly perpendicular, but they approach each other as in Fig. 4.

49. In the same manner, the heavenly bodies,

when they approach each other, are drawn out of the line of their paths, or orbits, by mutual IP W attraction. Attraction.

FIG. 4.

45. What explanation can you give of Fig. 3? 46. What is meant by attraction of gravitation ? 47. Can one body attract another without being itself attracted ?

48. How is it proved that bodies attract each other 1

PROPERTIES OF BODIES.

FIG. 5.

50. The force of attraction increases in proportion as bodies approach each other, and by the same law it must diminish in proportion as they recede from each other.

51. Attraction, in technical language^ is inversely as the squares of the distances between the two bodies. That is, in proportion as the square of the distance increases, in the same proportion attraction decreases, and so the contrary. Thus, if at the distance of 2 feet, the attraction be equal to 4 pounds, at the distance of 4 feet, it will be only 1 pound ; for the square of 2 is 4, and the square of 4 is 16, which is 4 times the square of 2. On the contrary, if the attraction at the dis¬ tance of 6 feet be 3 pounds, at the distance of 2 feet it will be 9 times as much, or 27 pounds, because 36, the square of 6, is equal to 9 times 4, the square of 2

52. The law of attraction in masses is very sat¬ isfactorily shown by the two little cork balls in Fig.

5. They are cover¬ ed with varnish, or beeswax, to re¬ pel the water.

Two such balls placed on the surface of a dish of water, two or -three inches apart, and not near the side of the dish, will soon begin to approach each other; their velocities being m proportion to their sizes, and increasing as their distances di-

theyhad^ife ^ rUsh to£etlier as though

. Tlie ^tensity of light is found to increase and diminish m the same proportion. Thus, if a board a foot square, be placed at the distance of one foot from a candle, it will be found to hide the light from another board of two feet square at the distance of two feet from the candle. Now a board of two feet square is just four times as large as one of one foot square, and therefore the light at double the distance being spread over four times the surface, has only one fourth the in¬ tensity. J

Attraction of cork balls.

PROPERTIES OF BODIES.

54. The force of the attraction of gravitation, is in proportion to the quantity of matter the attracting body contains.

55. Some bodies of the same bulk contain a much greater quantity of matter than others : thus, a piece of lead contains about twelve times as much matter as a piece of cork of the same dimensions, and therefore a piece of lead of any given size, and a piece of cork twelve times as large, will attract each other equally.

56. Capillary Attraction. — The force by which small tubes , or porous substances , raise liquids above their levels , is called capillary attraction.

57. If a small glass tube be placed in water, the water on the inside will be raised above the level of that on the outside of the tube. The cause of this seems to be nothing more than the ordinary attraction of the particles of matter for each other. The sides of a small orifice are so near each other as to attract the particles of the fluid on their opposite sides, and as all at¬ traction is strongest in the direction of the greatest quantity of matter, the water is raised upward, or in the direction of the length of the tube. On the outside of the tube, the opposite surfaces, it is obvious, can not act on the same column of water, and therefore the influence of attraction is here hardly percep¬ tible in raising the fluid. This seems to be the reason why the fluid rises higher on the inside than on the outside of the tube.

58. Height and size of the bore. — The height to which the fluid wilj rise, seems to depend, not on the specific gravity of the fluid, but on the size of the bore.

59. Thus, if the four glass tubes, shown by Fig. 6, are respectively the 10th, 20th, 40th, and 80th of an inch in diameter, then the height of the fluid in each will be inversely as their several diameters.