Part 1
Science Primers. INTRODUCTORY.
BY
PROFESSOR HUXLEY, F.R.S.
=Toronto:=
CANADA PUBLISHING CO.,
(LIMITED.)
_Entered according to the Act of the Parliament of Canada, in the year One Thousand Eight Hundred and Eighty-one by_ MACMILLAN & CO., LONDON, _in the Office of the Minister of Agriculture_.
TABLE OF CONTENTS.
PART. SECT.
I. NATURE AND SCIENCE.
PAGE
1. 〃 Sensations and Things 5
2. 〃 Causes and Effects 5
3. 〃 The reason Why. Explanation 6
4. 〃 Properties and Powers 7
5. 〃 Artificial and Natural Objects. Nature 8
6. 〃 Artificial Things are only Natural Things shaped and brought together or separated by Men 8
7. 〃 Many Objects and Chains of Causes and Effects in Nature are out of our reach 10
8. 〃 The Order of Nature: nothing happens by Accident, and there is no such thing as Chance 10
9. 〃 Laws of Nature; Laws are not Causes 12
10. 〃 Knowledge of Nature is the Guide of Practical Conduct 14
11. 〃 Science: The Knowledge of the Laws of Nature obtained by Observation, Experiment, and Reasoning 16
II. MATERIAL OBJECTS.—(A.) MINERAL BODIES.
12. 〃 The Natural Object Water 19
13. 〃 A Tumbler of Water 20
14. 〃 Water occupies Space; it offers Resistance; it has Weight; and is able to transfer Motion which it has acquired; it is therefore a form of Matter 20
15. 〃 Water is a liquid 21
16. 〃 Water is almost incompressible 22
17. 〃 The meaning of Weight 24
18. 〃 Gravity and Gravitation 25
19. 〃 The cause of Weight: Attraction: Force 27
20. 〃 The Weight of Water is Proportioned to its Bulk 28
21. 〃 The Measuring of Weights. The Balance 29
22. 〃 The Weight of the same Bulk or Volume of Water is Constant under the same conditions. Mass. Density 30
23. 〃 Equal Volumes of Different Things under the same circumstances, have Different Weights: the Density of Different Bodies is Different 32
24. 〃 The Meaning of Heavy and Light—Specific Gravity 33
25. 〃 Things of greater Specific Gravity than Water sink in Water; Things of less Specific Gravity float 34
26. 〃 A Body which Floats in Water always occupies as much Space beneath the level of the Surface of the Water as is equal to the Volume of Water which weighs as much as that Body; in other words, it displaces its own Weight of Water 36
27. 〃 Water Presses in all Directions 37
28. 〃 The Transference of Motion by Moving Water: the Momentum of Moving Water 40
29. 〃 The Energy of Moving Water 43
30. 〃 The Properties of Water are Constant 47
31. 〃 Increase of Heat at first causes Water to Increase in Volume 48
32. 〃 Increase of Heat at length causes Water to become Steam 50
33. 〃 The taking away of Heat from Steam causes the Steam to change into Hot Water 51
34. 〃 When Water is changed into Steam, its Volume becomes about 1,700 times greater than it was at first 51
35. 〃 Gases or Elastic Fluids. Air 52
36. 〃 Steam is an Elastic Fluid or Gas 54
37. 〃 Gases and Vapours 55
38. 〃 The Evaporation of Water at ordinary Temperatures 56
39. 〃 When Hot Water is cooled, it Contracts to begin with, but after a time Expands 57
40. 〃 Water cooled still further becomes the transparent brittle solid Ice 58
41. 〃 Ice has less Specific Gravity than the Water from which it was formed 59
42. 〃 Hoar Frost is the Gaseous Water which exists in the Atmosphere, condensed and converted into Ice Crystals 60
43. 〃 When Ice is warmed it begins to change back into Water as soon as the Temperature reaches 32° 61
44. 〃 Ice the solid, Water the liquid, and Steam the gas, are three states of one natural object; the Condition of each State being a certain Amount of Heat 62
45. 〃 The Phenomena of Heat are the Effects of a rapid Motion of the Particles of Matter 63
46. 〃 The Structure of Water 65
47. 〃 Suppositions or Hypotheses; their Uses and their Value 67
48. 〃 The Hypothesis that Water is composed of Separate Particles (Molecules) 68
49. 〃 All Matter is probably made up either of Molecules or of Atoms 70
50. 〃 Elementary Bodies are neither destroyed nor is their Quantity increased in Nature 72
51. 〃 Simple Mixture 73
52. 〃 Mixture followed by Increase of Density; Alcohol and Water 74
53. 〃 Solution; Water Dissolves Salt 76
54. 〃 Quicklime and Water: Plaster of Paris and Water: Combination 79
55. 〃 Mineral bodies may take on definite shapes and grow, or increase in size, by the addition of like parts 82
(B.) LIVING BODIES.
56. 〃 The Wheat Plant and the substances of which it is composed 83
57. 〃 The common Fowl and the Substances of which it is Composed 85
58. 〃 Certain Constituents of the Body are very similar in the Wheat Plant and in the Fowl 86
59. 〃 Proteid Substances are met with in Nature only in Animals and Plants; and Animals and Plants always contain Proteids 87
60. 〃 What is meant by the word Living? 88
61. 〃 The Living Plant increases in Size, by adding to the Substances which compose its Body, like Substances; these, however, are not derived from without, but are manufactured within the Body of the Plant from simpler Materials 88
62. 〃 The Living Plant, after it has grown up, detaches part of its Substance, which has the Power of developing into a similar Plant, as a Seed 90
63. 〃 The Living Animal increases in Size by adding to the Substances which compose its Body, like Substances; these, however, are chiefly derived directly from other Animals or from Plants 90
64. 〃 The living Animal, after it has grown up, detaches part of its Substance, which has the Power of growing into a similar Animal, as an Egg 91
65. 〃 Living Bodies differ from Mineral Bodies in their Essential Composition, in the manner of their Growth, and in the fact that they are reproduced by Germs 91
III. IMMATERIAL OBJECTS.
66. 〃 Mental Phenomena 92
67. 〃 The order of Mental Phenomena: Psychology 93
SCIENCE PRIMERS.
_INTRODUCTORY._
I. NATURE AND SCIENCE.
1. =Sensations and Things.=
All the time that we are awake we are learning by means of our =senses= something about the world in which we live and of which we form a part; we are constantly aware of feeling, or hearing, or smelling, and, unless we happen to be in the dark, of seeing; at intervals we taste. We call the information thus obtained =sensation=.
When we have any of these sensations we commonly say that we feel, or hear, or smell, or see, or taste, something. A certain scent makes us say we smell onions; a certain flavour, that we taste apples; a certain sound, that we hear a carriage; a certain appearance before our eyes, that we see a tree; and we call that which we thus perceive by the aid of our senses a =thing= or an =object=.
2. =Causes and Effects.=
Moreover, we say of all these things, or objects, that they are the =causes= of the sensations in question, and that the sensations are the =effects= of these causes. For example, if we hear a certain sound, we say it is caused by a carriage going along the road, or that it is the effect, or the consequence, of a carriage passing along. If there is a strong smell of burning, we believe it to be the effect of something on fire, and look about anxiously for the cause of the smell. If we see a tree, we believe that there is a thing or object, which is the cause of that appearance in our field of view.
3. =The reason Why. Explanation.=
In the case of the smell of burning, when we find on looking about, that something actually is on fire, we say indifferently either that we have found out the cause of the smell, or that we know the =reason why= we perceive that smell; or that we have =explained= it. So that to know the reason why of anything, or to explain it, is to know the cause of it. But that which is the cause of one thing is the effect of another. Thus, suppose we find some smouldering straw to be the cause of the smell of burning, we immediately ask what set it on fire, or what is the cause of its burning? Perhaps we find that a lighted lucifer match has been thrown into the straw, and then we say that the lighted match was the cause of the fire. But a lucifer match would not be in that place unless some person had put it there. That is to say, the presence of the lucifer match is an effect produced by somebody as cause. So we ask why did any one put the match there? Was it done carelessly, or did the person who put it there intend to do so? And if so, what was his motive, or the cause which led him to do such a thing? And what was the reason for his having such a motive? It is plain that there is no end to the questions, one arising out of the other, that might be asked in this fashion.
Thus we believe that everything is the effect of something which preceded it as its cause, and that this cause is the effect of something else, and so on, through a chain of causes and effects which goes back as far as we choose to follow it. Anything is said to be explained as soon as we have discovered its cause, or the reason why it exists; the explanation is fuller, if we can find out the cause of that cause; and the further we can trace the chain of causes and effects, the more satisfactory is the explanation. But no explanation of anything can be complete, because human knowledge, at its best, goes but a very little way back towards the beginning of things.
4. =Properties and Powers.=
When a thing is found always to cause a particular effect, we call that effect sometimes a =property=, sometimes a =power= of the thing. Thus the odor of onions is said to be a property of onions, because onions always cause that particular sensation of smell to arise, when they are brought near the nose; lead is said to have the property of heaviness, because it always causes us to have the feeling of weight when we handle it; a stream is said to have the power to turn a water-wheel, because it causes the water-wheel to turn; and a venomous snake is said to have the power to kill a man, because its bite may cause a man to die. Properties and powers, then, are certain effects caused by the things which are said to possess them.
5. =Artificial and Natural Objects. Nature.=
A great many of the things brought to our knowledge by our senses, such as houses and furniture, carriages and machines, are termed =artificial things= or =objects=, because they have been shaped by the =art= of man; indeed, they are generally said to be made by man. But a far greater number of things owe nothing to the hand of man, and would be just what they are if mankind did not exist,—such as the sky and the clouds; the sun, moon and stars; the sea with its rocks and shingly or sandy shores; the hills and dales of the land; and all wild plants and animals. Things of this kind are termed =natural objects=, and to the whole of them we give the name of =Nature=.
6. =Artificial Things are only Natural Things shaped and brought together or separated by Men.=
Although this distinction between =nature= and =art=, between =natural= and =artificial= things, is very easily made and very convenient, it is needful to remember that, in the long run, we owe everything to nature; that even those artificial objects which we commonly say are made by men, are only natural objects shaped and moved by men; and that, in the sense of =creating=, that is to say, of causing something to exist which did not exist in some other shape before, man can make nothing whatever. Moreover, we must recollect that what men do in the way of shaping and bringing together or separating natural objects, is done in virtue of the powers which they themselves possess as natural objects.
Artificial things are, in fact, all produced by the action of that part of nature which we call mankind, upon the rest.
We talk of “making” a box, and rightly enough, if we mean only that we have shaped the pieces of wood and nailed them together; but the wood is a natural object and so is the iron of the nails. A watch is “made” of the natural objects gold and other metals, sand, soda, rubies, brought together, and shaped in various ways; a coat is “made” of the natural object, wool; and a frock of the natural objects, cotton or silk. Moreover, the men who make all these things are natural objects.
Carpenters, builders, shoemakers, and all other artisans and artists, are persons who have learned so much of the powers and properties of certain natural objects, and of the chain of causes and effects in nature, as enables them to shape and put together those natural objects, so as to make them useful to man.
A carpenter could not, as we say, “make” a chair unless he knew something of the properties and powers of wood; a blacksmith could not “make” a horseshoe unless he knew that it is a property of iron to become soft and easily hammered into shape when it is made red-hot; a brickmaker must know many of the properties of clay; and a plumber could not do his work unless he knew that lead has the properties of softness and flexibility, and that a moderate heat causes it to melt.
So that the practice of every art implies a certain knowledge of natural causes and effects; and the improvement of the arts depends upon our learning more and more of the properties and powers of natural objects, and discovering how to turn the properties and the powers of things and the connections of cause and effect among them to our own advantage.
7. =Many Objects and Chains of Causes and Effects in Nature are out of our reach.=
Among natural objects, as we have seen, there are some that we can get hold of and turn to account. But all the greatest things in nature and the links of cause and effect which connect them, are utterly beyond our reach. The sun rises and sets; the moon and the stars move through the sky; fine weather and storms, cold and heat, alternate. The sea changes from violent disturbance to glassy calm, as the winds sweep over it with varying strength or die away; innumerable plants and animals come in being and vanish again, without our being able to exert the slightest influence on the majestic procession of the series of great natural events. Hurricanes ravage one spot; earthquakes destroy another; volcanic eruptions lay waste a third. A fine season scatters wealth and abundance here, and a long drought brings pestilence and famine there. In all such cases, the direct influence of man avails him nothing; and, so long as he is ignorant, he is the mere sport of the greater powers of nature.
8. =The Order of Nature: nothing happens by Accident, and there is no such thing as Chance.=
But the first thing that men learned, as soon as they began to study nature carefully, was that some events take place in regular order and that some causes always give rise to the same effects. The sun always rises on one side and sets on the other side of the sky; the changes of the moon follow one another in the same order and with similar intervals; some stars never sink below the horizon of the place in which we live; the seasons are more or less regular; water always flows down-hill; fire always burns; plants grow up from seed and yield seed, from which like plants grow up again; animals are born, grow, reach maturity, and die, age after age, in the same way. Thus the notion of an =order of nature= and of a fixity in the relation of cause and effect between things gradually entered the minds of men. So far as such order prevailed it was felt that things were explained; while the things that could not be explained were said to have come about by =chance=, or to happen by =accident=.
But the more carefully nature has been studied, the more widely has order been found to prevail, while what seemed disorder has proved to be nothing but complexity; until, at present, no one is so foolish as to believe that anything happens by chance, or that there are any real accidents, in the sense of events which have no cause. And if we say that a thing happens by chance, everybody admits that all we really mean is, that we do not know its cause or the reason why that particular thing happens. Chance and accident are only _aliases_ of ignorance.
At this present moment, as I look out of my window, it is raining and blowing hard, and the branches of the trees are waving wildly to and fro. It may be that a man has taken shelter under one of these trees; perhaps, if a stronger gust than usual comes, a branch will break, fall upon the man, and seriously hurt him. If that happens it will be called an “accident,” and the man will perhaps say that by “chance” he went out, and then “chanced” to take refuge under the tree, and so the “accident” happened. But there is neither chance nor accident in the matter. The storm is the effect of causes operating upon the atmosphere, perhaps hundreds of miles away; every vibration of a leaf is the consequence of the mechanical force of the wind acting on the surface exposed to it; if the bough breaks, it will do so in consequence of the relation between its strength and the force of the wind; if it falls upon the man it will do so in consequence of the action of other definite natural causes; and the position of the man under it is only the last term in a series of causes and effects, which have followed one another in natural order, from that cause, the effect of which was his setting out, to that the effect of which was his stepping under the tree.
But, inasmuch as we are not wise enough to be able to unravel all these long and complicated series of causes and effects which lead to the falling of the branch upon the man, we call such an event an accident.
9. =Laws of Nature; Laws are not Causes.=
When we have made out by careful and repeated observation that something is always the cause of a certain effect, or that certain events always take place in the same order, we speak of the truth thus discovered as a =law of Nature=. Thus it is a law of nature that anything heavy falls to the ground if it is unsupported; it is a law of nature that, under ordinary conditions, lead is soft and heavy, while flint is hard and brittle; because experience shows us that heavy things always do fall if they are unsupported, that, under ordinary conditions, lead is always soft and that flint is always hard.
In fact, everything that we know about the powers and properties of natural objects and about the order of nature may properly be termed a law of nature. But it is desirable to remember that which is very often forgotten, that the laws of nature are not the causes of the order of nature, but only our way of stating as much as we have made out of that order. Stones do not fall to the ground in consequence of the law just stated, as people sometimes carelessly say; but the law is a way of asserting that which invariably happens when heavy bodies at the surface of the earth, stones among the rest, are free to move.
The laws of nature are, in fact, in this respect, similar to the laws which men make for the guidance of their conduct towards one another. There are laws about the payment of taxes, and there are laws against stealing or murder. But the law is not the cause of a man’s paying his taxes, nor is it the cause of his abstaining from theft and murder. The law is simply a statement of what will happen to a man if he does not pay his taxes, and if he commits theft or murder; and the cause of his paying his taxes, or abstaining from crime (in the absence of any better motive) is the fear of consequences which is the effect of his belief in that statement. A law of man tells what we may expect society will do under certain circumstances; and a law of nature tells us what we may expect natural objects will do under certain circumstances. Each contains information addressed to our intelligence, and except so far as it influences our intelligence, it is merely so much sound or writing.
While there is this much analogy between human and natural laws, however, certain essential differences between the two must not be overlooked. Human law consists of commands addressed to voluntary agents, which they may obey or disobey; and the law is not rendered null and void by being broken. Natural laws, on the other hand, are not commands but assertions respecting the invariable order of nature; and they remain laws only so long as they can be shown to express that order. To speak of the violation, or the suspension, of a law of nature is an absurdity. All that the phrase can really mean is that, under certain circumstances the assertion contained in the law is not true; and the just conclusion is, not that the order of nature is interrupted, but that we have made a mistake in stating that order. A true natural law is an universal rule, and, as such, admits of no exceptions.
Again, human laws have no meaning apart from the existence of human society. Natural laws express the general course of nature, of which human society forms only an insignificant fraction.
10. =Knowledge of Nature is the Guide of Practical Conduct.=