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HOW TO STUDYILLUSTRATED THROUGH PHYSICSBy

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HOW TO STUDYIllustrated through Physicsy BYFERNANDO SANFORD

FORMERLY PROFESSOR OF PHYSICS,LELAND STANFORD UNIVERSITY

H2eto gorfeTHE MACMILLAN COMPANY

1922All rights reserved


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Copyright, 1922,By THE MACMILLAN COMPANY.

Published February, 1922.

CI.A653985

PRINTED IN THE UNITED STATES OF AMERICA

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INTRODUCTIONNearly everywhere the principal emphasis in

instruction is on knowledge. Tests or examina-tions on knowledge are the basis of ratings andpromotions, and therefore the goal both of pri-vate study and of class work. While method isa frequent subject of discussion, it is the methodrather of the teacher than of the learner, andeven it is judged by the extent to which it leadsto acquisition of knowledge. The fact that youngpeople have a method of their own, that itsquality is of vital importance, and that it needsgreat improvement is generally overlooked; forit is unrelated to tests.A very different conception of teaching isrepresented in this monograph. Physical Scienceis shown to owe its progress to improvement inthe method of studying it; and as a result of suchimprovement a single day now brings a greateradvance in knowledge of the physical world thandid the first thousand years of the Christian era.

Since method has been the secret of themarvelous progress, the principal object of in-struction in Physics should not be merely the

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IV INTRODUCTIONcomprehension of a lot of facts or even laws, butrather the control of the method of investigationthat has proved so fruitful in the discovery ofthose facts and laws. Furthermore,, Physicsshould be primarily a study of scientific method,because skill in that method has a much broaderapplication than knowledge of subject matter inthat field.The implications for general Education in this

point of view are far-reaching. If the idea issound, the principal object of instruction in someor possibly all other subjects might well begreatly modified, and the method of the learnermight be brought into prominence. And sincePhysics offers the most nearly perfect exampleof the scientific method, it might be taken asthe standard for the other subjects; they differfrom it rather in degree than in kind.How sound are such implications? Certainlymodern Education is moving toward this pointof view. For illustration, during the last fewyears the pupil's method of reading has beenextensively studied by educational specialists andin many schools improvement in that method hasalready become a prominent purpose in the teach-ing of Reading. The method of the learner isslowly receiving recognition.There are several reasons. The child's enjoy-


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INTRODUCTION Vment of school is very dependent upon his skillin study ; so also is his real digestion of any sub-ject studied. But even more important is thethought that method in any given field, just asin Physics, has a far wider application to life'sproblems than subject matter; that control ofmethod is largely the same as mental discipline, orpower. In consequence, students should beexamined and rated at least as much on theirmethod of procedure as upon their knowledge ofsubject matter.Thus there are large possibilities suggested in

these pages. But one should understand thatmovement toward realization of these possibilitiesmust be very slow. The demand is that one shalllearn to think, independently and skilfully, ineach field studied. That is not only a radical, itis a revolutionary demand; for thinking is a verydifferent thing from acquisition of knowledge.Many curricula and textbooks of the presenttime fail even to meet the conditions that allowgood thinking; they must be made over beforea good start can be made toward thinking.Also, since the pupil or student is the one thatis to be taught to thinkto propose the questionsas well as to find their answersteachers mustlearn to keep still in the classroom much morethan at present, while, at the same time, stimu-


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VI INTRODUCTIONlating activity. In short, since emphasis onmethod of study requires subordination of bothsubject matter and teacher to the learner, aradical change in the teacher's point of view, inthe very purposes of instruction, is involved. Atpresent not one teacher in one hundred woulddare attempt to give demonstration lessons show-ing how to do good thinking in the lessons as-signed; and a great majority of teachers couldnot now show the difference between memorizinga text and good thinking.

It will be a long time, therefore, before thevarious studies in school and college will followthe lead of Physics in the emphasis on methodsuggested in this monograph. Yet that is nottoo discouraging. We see the direction we haveto travel; and if the road is long, it is high timethat the journey be commenced.

Frank M. McMurry,Teachers College,

December 15, 1921.


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HOW TO STUDYILLUSTRATED THROUGH PHYSICS


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HOW TO STUDY:ILLUSTRATED THROUGH PHYSICSThe influence of purpose in method of study.It is plain that any study may be pursued from

a variety of motives, and that each one of thesemotives may influence to a greater or less degreethe method of study to be adopted. Thus one maystudy history in order to pass a prescribed ex-amination, he may study it in order to appear in-telligent and well informed in society, he maystudy it in order to apply its lessons in politics orsocial matters, he may study it in order to gain alivelihood by teaching it to others, or he may studyit simply because he wants to know. Any ofthese motives may influence his selection of sub-ject matter and his method of pursuing the study.What has been said of the variety of motives

which may lead to the study of history is just astrue of the reasons which may be given for study-ing physics,, and in this case, since there are moremethods of study open to the student of physicsthan to the student of history, the method of


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2 how to study:study will be determined by the motive much morein the case of the former than of the latter.

Thus, consider the single case of preparingfor an examination in physics. The questionsasked may refer merely to the statement of gen-eral laws (and these may frequently be statedeither in words or in mathematical formulae)or they may require a knowledge of how to applythese laws to a specific case. They may be quali-tative, that is, they may require a descriptiveanswer, or they may be quantitative and require anumerical answer. They may, and often do, re-quire an experimental demonstration. If the can-didate for examination knows beforehand whichkinds of questions are likely to be asked,, he willdo wisely to so modify his methods of study as toget the best possible preparation for the comingexamination with the least amount of effort. Hemay prepare for one examination by the studyof a single textbook, while in another case it maybe necessary for him to get his preparation in a*library or in a laboratory.

If the student of physics has some other aimthan the mere passing of a set examination, hispossible methods of study may be still morenumerous. Accordingly, before a student is qual-ified to decide for himself upon a method of


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ILLUSTRATED THROUGH PHYSICS 3studying physics, it is highly important for him tobe informed in regard to the possible methods ofstudying this science which are open to him, andto have a tolerably clear comprehension of theaims which he hopes to accomplish by the study.

There are, in general, two partially distinctmethods of science study which may, to some ex-tent, be contrasted with each other. One of theseis the method which is usually most encouragedin our schools and colleges, and which leads towhat we know as scholarship. It consists largelyin learning what has been known and what hasbeen thought by the men whom the world hasrecognized as leaders in scientific thinking, and intrying to comprehend their thoughts and to thinkthem over again as if they were our own. Thus,for more than a thousand years approved scholar-ship in science throughout Europe consisted inaccepting and in comprehending more or less per-fectly the teaching of Aristotle. At the presenttime, it consists largely in accepting and in tryingto comprehend the teachings of a few recognizedleaders in each department of science.The other method of science study results fromthe attempt on the part of the student to acquire

not only the knowledge which has been left to usby our masters of a previous age, but to cultivate


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4 how to study:the mental habits which enabled these men tobecome leaders of scientific thinking in their gen-erations.The dependence of progress on the purpose

adopted.As a result of the greater prevalenceof the training for scholarship than for scientificleadership, a few men in each generation are stillcompelled to do the real thinking for the wholeworld, while the rest of us are content to bemerely their disciples. In this respect there hasbeen but little improvement in recent times. Thusthe following paragraph, which was written byJoseph Priestley in 1767, would be just as true ifit were written to-day

Priestley says:I think that the interests of Science have

suffered by the excessive admiration andwonder, with which several first rate philoso-phers are considered; and that an opinion ofthe greater equality of mankind, in point ofgenius,, and powers of understanding, wouldbe of real service in the present age. Itwould bring more labourers into the commonfield; and something more, at least, wouldcertainly be done in consequence of it. Forthough I by no means think that philosoph-ical studies are at a stand, I think the prog-ress might be quickened if studious andmodest persons, instead of confining them-selves to the discoveries of others, could be


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ILLUSTRATED THROUGH PHYSICS 5brought to the idea that it was possible tomake discoveries themselves.

If it is true, as Priestley believed, that there isa greater mental equality of mankind than theresults of science study in the past seem to indi-cate,, so that it is possible for studious andmodest persons'' to make original discoveries forthemselves, a much nobler motive for the studentof science is suggested than the mere desirefor scholarship. Let us, before discussing thispossibility, inquire more fully into the generalnature of science study, and particularly into thespecial character of the science of physics.Reason for the many divisions of the field ofscience.All science study results from theattempts of human beings to comprehend the uni-verse of which they are themselves a part.The universe is so great and so complex thatall attempts at understanding it as a whole have

failed; but by concentrating a great amount ofthought and labor upon some small part of it at atime many things of great value have beenlearned.

Since by this method of acquiring knowledgeeach investigator must work in a very limitedfield, the study of the universe has been under-taken along a great number of special lines whichhave come to be regarded as distinct sciences.


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b how to study:It should be remembered, however, that thesedivisions have been made by man merely forconvenience in applying the principle of divisionof labor upon which most of his other work isbased. To a mind capable of a complete compre-hension of the universe there would be but onescience.Advantages for study that the physical sci-ences enjoy.The division and classificationof scientific knowledge into separate sciences hasgenerally been based upon certain obvious dis-tinctions between the things about us. One ofthese distinctions is between living and nonlivingthings. The differences between these two classesof things are very great. Since we, ourselves, areliving beings, our interest in living things is nat-urally very much greater than in nonliving, orinanimate, things. Unfortunately, the complexchanges which are constantly going on in livingbodies are much more difficult to comprehendthan are the changes which are taking place ininanimate bodies. Besides, many of the methodswhich are employed in the study of inanimatebodies cannot be applied to the study of livingbodies without destroying life. For these rea-sons, much greater progress has been made inunderstanding the relations between the changesin nonliving than in living bodies.


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ILLUSTRATED THROUGH PHYSICS JSince most of the changes which are going on

in nonliving bodies are also taking place in livingbodies, we may learn much about the latter by astudy of the former. In fact, almost the onlyphenomena of living bodies for which satisfac-tory explanations have been found are thosewhich are also common to nonliving bodies.The special purpose of physics.The scienceof physics has to do wholly with nonliving bodiesand their relations to one another. The changeswhich are continually taking place in and betweenthese bodies are very numerous, and some of themare very complex. It is the purpose of the scienceof physics to determine under what conditionsand, if possible, why certain changes alwaysoccur. When these conditions are known, theyenable us to predict or to bring about desirablechanges.Our slowness in accomplishing this purpose.It is only within the past three hundred years

that mankind has begun to learn how to predictwith certainty the physical changes which willoccur under specified conditions. Before thattime such knowledge was usually acquired acci-dentally, if at all. Once every few hundred yearssome man was born who seemed to have a specialinsight into the workings of nature, and such aman always made important discoveries; but he


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8 how to study:did not succeed in teaching other men how tomake the same kinds of discoveries, and he wasgenerally looked upon as a very superior or as avery dangerous person. Other men came to ac-cept his merest opinions as authority in mattersof science, or to look upon him as in league withthe Devil. Often both opinions concerning himwere held at the same time by different people.

It has thus come about that a very few menhave done nearly all the important scientific think-ing of the world. Most of what has passed forscientific study has resulted from the attempts ofother men to find out what these few leaders havethought and, if possible, to think the samethoughts over after them.The attempt to do even as much as this did not

come early in our civilization. It has always beenthe tendency of human beings in the state ofintellectual infancy to attribute the movements ofmaterial bodies to acts of will on the part ofsome being superior to themselves. It is in thisway that most of the religions of the world havearisen. Accordingly, although the Greeks wereapparently the earliest people to look for physicalcauses for natural phenomena, it has been saidthat the Greeks of Homer's time would not havethought of asking the cause of rain or thunder


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ILLUSTRATED THROUGH PHYSICS 9or earthquakes, but instead, who rains, or whothunders, or who shakes the earth.The discovery that has made physical sciencepossible.The fact that many of the changeswhich take place in nonliving bodies in our uni-verse depend upon some kind of relation betweenthe bodies themselves, and not upon the wills ofgods or demons or other spiritual beings, is oneof the greatest discoveries ever made by thehuman mind. Until this discovery was made allphysical science was impossible; for if a givenphenomenon might be caused by one god or onespiritual power at one time and by some othergod or spiritual power at another time, it wouldbe impossible to tell when this phenomenon wasgoing to occur, or what means to take to bring itabout or to prevent its occurrence. Accordingly,it was not until it was recognized that there is apart of the universe in which spiritual powersseem to play no direct part, and in which everyaction or change taking place is the inevitableconsequence of some previous action or change,that it was possible to have a physical science.That part of the universe in which mental or

spiritual powers never intervene is known as thephysical universe. The main purpose of the studyof physical science is to acquire a comprehension


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IO HOW to study:of the relations which lead to inevitable changesin the physical universe. It is upon our knowl-edge of these relations that our mastery of thephysical universe depends.Meaning of Natural Law.When these in-

variable relations between physical phenomenahave been discovered and described they areknown as natural laws. Thus it has always beenobserved that a heavy body when unsupported byanother body falls to the earth, or continues tofall until it is supported by another body. Wecan accordingly say that it is a law of naturethat an unsupported body falls toward the earth.No one knows why it falls. We have learned howfar it will fall in each second that it is free andhow great its speed will be at the end of eachsecond of falling. These facts, when combinedinto an intelligible statement, constitute what isknown as The law of falling bodies.

It will be seen that the word law is not hereused with its customary meaning. In the mostcommon usage, a law means a decree or enact-ment by a ruler or a governing body. Such alaw may be obeyed or disobeyed. Generally apenalty is prescribed for disobedience, but thispenalty is not always enforced.

Another common meaning of the word law isthat of a usage or custom. Thus a law of gram-


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ILLUSTRATED THROUGH PHYSICS IImar or spelling is merely the statement of whathas come to be a customary usage. These lawshave not, in general, been decreed, and when cer-tain decrees have been announced by some or-ganized body, as, for example, The SimplifiedSpelling Board, the body issuing the decree hasno authority to enforce it.A natural law differs from a decree or usagein that it is a statement of a universal, and henceinevitable, order of events. A decree may bedisobeyed, regardless of consequences. Theusages upon which the laws of grammar andspelling rest are very far from being universal,and are generally incapable of being so statedthat there are not many exceptions to them. Buta law of nature is not subject to a single excep-tion. If a single heavy body could be liftedwithout the expenditure of energy or if it couldremain unsupported above the earth, then wouldour whole present science of physics be over-thrown.

Importance of our knowledge of naturallaws.Huxley has given one of the best state-ments of our reasons for wishing to acquire aknowledge of natural laws. He says

It is a very plain and elementary truththat the life, the fortune and the happinessof every one of us and, more or less, of those


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12 HOW TO study:who are connected with us, do depend uponour knowing something of the rules of agame infinitely more difficult and compli-cated than chess. It is a game which hasbeen played for untold ages, every man andwoman of us being one of the two playersin a game of his or her own. The chessboard is the world, the pieces are the phe-nomena of the universe, the rules of thegame are what we call the laws of nature.

Education is learning the rules of thismighty game. In other words, education isthe instruction of the intellect in the laws ofnature, under which name I include notmerely things and their forces, but men andtheir ways ; and the fashioning of the affec-tions and the will into an earnest and lovingdesire to move in harmony with those laws.

Huxley seems to suggest that it is possible tobe out of harmony with nature's laws, and inanother place he speaks of the penalty of dis-obedience to natural laws ; but in the strict sensea disobedience of nature's laws is an impossibility.A man who leaps from a high cliff is not punishedfor disobeying any law of nature; on the con-trary, he obeys the law of falling bodies andtakes the consequences. The so-called penaltywhich he pays is only an additional proof of theinvariableness of natural law. The same thing


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ILLUSTRATED THROUGH PHYSICS 13may be said of a man who contracts a contagiousdisease or indulges in the excessive use of alcoholor deprives himself of necessary food; he doesnot disobey the laws of naturehe merely exem-plifies them in his own person.Our knowledge of the laws of nature accord-

ingly will not shield us from disobedience to them,,because the very existence of a law precludes anypossibility of disobedience to it; but while we can-not disobey a natural law if we would, we may,by understanding these laws,, often avoid theunpleasant results of certain relations betweenourselves and external things. If we thoroughlyunderstand the rules of the game, we may predictthe consequences of our moves before we makethem.Two methods of learning natural laws.How, then, shall we learn the rules of this mightygame ? Attention has already been called to twogeneral methods which we may designate for ourpurpose as the method of the scholar and themethod of the scientist. The former, we haveseen, consists in learning from books and lectureswhat other men have thought about the laws ofnature and in trying to think their thoughts overafter them. This method leaves all the realthinking to a few men, while the rest becomemerely their disciples.


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14 how to study:As has already been said, much the greater

part of the physics teaching of the schools isbased upon this method. We are given theopinions of Galileo and Newton and Faraday asto what constitute the rules of the game. Welearn the stock arguments in favor of theseopinions and we perform experiments and solveproblems in order that we may have a clear un-derstanding of the opinions which we accept; butwe are given no opportunity of forming an inde-pendent opinion on the basis of our own seeingand thinking; and, what is still more to be de-plored, we are given no training in the method ofscience study which made Galileo and Newtonand Faraday our scientific authorities, and which,though used by but few men, has completely revo-lutionized our civilization in only three hundredyears.And yet the method of the scientist is not neces-sarily more difficult than the method of thescholar, for it is sometimes more difficult to un-derstand the laborious and involved thinking ofsome of the leaders whom custom has selected asour guides to scholarship than it is to get, by ourown efforts, a much clearer understanding ofthe relations which they are trying to explain.Let us, then, consider the method of the scien-tist.


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ILLUSTRATED THROUGH PHYSICS 1Modern physical science compared with the

old natural philosophy.It is more than twothousand years since it was recognized by Grecianphilosophers that the changes which take place inthe physical universe are not merely the arbitraryacts of some god or demon, but are the inevitableconsequences of physical conditions. Since thisdiscovery was made, many of the keenest mindsof the world have been devoted to the discoveryof natural laws and a comprehension of their re-lations to each other. Down to the year 1600these efforts were almost wholly without suc-cess. Previous to this time the human racehad apparently reached its highest possibleachievements in many lines of intellectual en-deavor. In religion, in philosophy, in logic, in art,in music, in architecture,, in literature, people stillturn to the old masters for their models andtheir inspiration. In science there were no oldmasters.

Yet in the three hundred years that haveelapsed since 1600 the whole character of ourcivilization has been revolutionized and most ofour habits of thought have been changed by themarvelous development of physical science. It issafe to say that during any day of the year justpassed greater scientific advancement was madethan in the first thousand years of the Christian


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1 how to study:Era. It would seem that a method of study whichhas led to such tremendous achievement in even asingle line of thought would be immediatelyadopted by at least all the workers in that par-ticular field, even though it could not be appliedelsewhere; but the painful admission must bemade that the scientific method of study, likemany well-known virtues, is highly commendedand seldom practiced.

Yet it must be true that if there is a peculiarmethod of studying physical science, the use ofwhich has so greatly modified our civilization, theacquisition of this method of study and of think-ing should be the most important aim of oureducation. It is when we undertake to explainthis scientific method that the really hard partof this discussion begins. It is easy to writeabout textbook methods and lecture methods andlaboratory methods, but it is very difficult tospecify clearly what we mean by these methods.This is especially true of the so-called laboratorymethods. It is difficult to find any considerablenumber of textbooks the authors of which woulduse the physical laboratory from the same mo-tives. To a less degree,, the same may be said ofthe different uses made of textbooks and lectures.

However, it is possible to show important


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ILLUSTRATED THROUGH PHYSICS 1differences between the Greek methods of study-ing natural philosophy which prevailed down tothe year 1600, and the methods of studyingphysics to-day. The Greeks gave a great deal ofthought to Natural Philosophy, but, as we haveseen, they made very little progress in the in-terpretation of nature. This appears to have beentrue partly because they made very inaccurateobservations, and partly because they tried tosettle questions in physical science in the sameway that we now try to settle questions in whatwe call the political and social sciences, namely, byarguing about them. It should be rememberedthat the reason why a question may be argued isbecause the true answer to it has not been found.So it happened that while the Greeks were thebest debaters and the keenest logical reasonersthat the world has produced, they could make noprogress in physical science.

Another reason for failure in the science studyof the ancients lies in the fact that in those daysmen tried to discover what has been called theessence of things ; that is, they tried to find somegeneral principle from which all the phenomenaof the physical universe could be logically de-duced, instead of trying to find out merely therelations between these phenomena.


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1 how to study:Perhaps a fair characterization of the common

method of the natural philosophy of those daysmay be put in this way: the ancients tried toimagine the nature of the first cause from whichthe universe sprang or of the deity by whom itwas created; then from their conception of thisfirst cause or deity they drew their conclusions asto what kind of universe must have resulted ormust have been created.A similar point of view, which was held bysome ancient philosophers as well as by a con-siderable number of more modern ones, is thatthe human mind is but the duplication on asmaller scale of the mind of the Creator; andthat consequently we may, when undisturbed byexternal conditions, think over again the thoughtsof the Creator, and thus arrive at a comprehen-sion of the physical universe. Unfortunately,this method has never given an interpretation ofthe universe which even remotely coincided withobserved relations.Method of Roger Bacon and Leonardo da

Vinci.But even in the days when these fruit-less methods of studying the universe were al-most invariably adopted, an occasional man ap-peared who seemed to have some peculiar insightinto natural phenomena. It may be worth whileto inquire how these men studied physics.


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ILLUSTRATED THROUGH PHYSICS 19One such man was Roger Bacon, a learned

monk, who lived in England seven hundred yearsago. Bacon wroteWe have three means of arriving at

knowledge: authority, reason, experiment.Authority has no value if its basis is not un-derstood ; it teaches nothing, but merely callsout our assent. By reason we may distin-guish a sophism from a demonstration, whilewe may test our conclusions by experiment.

It will be seen that Bacon suggests experiment,instead of argument, as a means of testing con-clusions. However, his suggestion seems to havehad no influence upon the scientific method of histime.

Three hundred years later there was living inItaly one of the famous men of history. Leonardoda Vinci was celebrated as a painter, sculptor,architect, engineer, anatomist, botanist, astrono-mer, poet, and musician, and he was also thegreatest physicist of his time. It would seem thatDa Vinci must have had superior methods ofstudy in order to accomplish so much, no matterhow great his genius. Fortunately, he has toldus something of his method of studying physics.He says:

In undertaking scientific investigations, Ifirst plan a few experiments, because it is my


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20 HOW to study:design to base the problem on experience andthen to determine why the bodies in questionare constrained to act in a given manner.This is the method that one must adopt inall researches. It is true that nature beginswith reason and ends in experience, but,nevertheless, we must choose the oppositeway; we must, as I have already said, beginwith experience and through its means strivefor a recognition of the truth. 1

Thus Da Vinci suggests that before attemptingto find an explanation of a phenomenon by rea-soning about it, it is necessary to observe verycarefully the relations to be explained. But hissuggestions were not adopted by the other scien-tific men of his day, and it was not until a hundredyears later that another physicist appeared inItaly.The change introduced by Gilbert and

Galileo.The year 1600 may be regarded as aturning point in the methods of scientific study.In that year Dr. William Gilbert published one ofthe great physical monographs of the world, inwhich he not only laid the foundation for thesciences of magnetism and electricity, but pro-posed and exemplified a new method of physicalstudy. He says in his preface

1 Translated from Gerland's Geschichte der Physik.


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ILLUSTRATED THROUGH PHYSICS 21To you alone, true philosophers, ingenu-

ous minds, who not only in books but inthings themselves look for knowledge, have Idedicated these foundations of magnetic sci-encea new style of philosophizing. But ifany see fit not to agree with the opinionshere expressed and not to accept certain ofmy paradoxes; still let them note the greatmultitude of experiments and discoveriesthese it is chiefly that cause all philosophy toflourish ; and we have dug them up and dem-onstrated them with much pains and sleep-less nights and great money expense.

To the English speaking world, Gilbert may beregarded as the father of physical science. Inhis writings he constantly refers to the impor-tance of experiments.At the present time no physicist will give any

consideration to physical interpretations whichare not based upon experimental evidence, but thiswas not true of the philosophers of Gilbert's day,nor is it true of the average man of the presentday.The greatest scientific man of ancient times

was the Greek philosopher, Aristotle. His writ-ings were the chief textbooks of Europeanscholars for more than a thousand years. Hisstudies covered all the lines of thought of theancient world, and determined what men should


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22 HOW TO STUDY:think during the middle ages. Throughout allthis time approved scholarship consisted in tryingto comprehend and adopt the opinions ofAristotle.

Aristotle taught, among other things, thatbodies of different weight fall with differentvelocities, and that the speed of fall is propor-tional to the weight. Thus, a ten-pound ballshould fall ten times as fast as a one-pound ball.Everybody accepted this opinion, and no onetested it experimentally for two thousand years.Then, when Galileo dropped two cannon balls ofunequal weight from the leaning tower of Pisaand invited the multitude to see that they bothreached the pavement at the same time, the scien-tists'' of that day believed that what they hadapparently seen was a mortal error, and still ac-cepted the teaching of Aristotle in preference tothe evidence of their own senses.The four necessary steps in the scientificmethod.What has been said should beenough to make it plain that any study of physicsshould be based upon experiment, but it is plainthat experiments may be used in various waysand for various purposes. For example, someteachers introduce them for the purpose ofmanual training, some use them as a means ofillustrating or verifying the statements of text-


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ILLUSTRATED THROUGH PHYSICS 23book or lecture; and many, apparently, use themas a sort of busy work, to keep their studentsoccupied. None of these methods is what isknown as the method of science. Da Vinci tellsus that he used experiments before beginning thestudy of a problem so that he might understandclearly the phenomena which he was undertakingto interpret. Roger Bacon says we may testour conclusions by experiment. ,, Here are twodistinct uses that may be made of experiment;namely, to enable us to understand clearly howthe actions which we wish to explain actuallytake place, and to test our final conclusions as tothe cause of the actions.

Between these two appeals to experiment thereare apparently two distinct mental processesnecessary. In the first place, after getting a clearunderstanding from our first experiments of thecharacter of the actions which we wish to explain,we make a guess at the probable explanation ; thatis, we guess that a certain relation exists betweenthe phenomenon which we are studying and someother phenomenon with which we are already ac-quainted. This guess is called an hypothesis or ageneralization. The mental process concerned inits production is commonly known as induction.Then we say, If our guess is correct, certain

other phenomena which we have not yet observed


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24 HOW to study:must be produced by conditions which we canspecify. That is, we may predict new phe-nomena which have never been observed. Thisis logical thinking, or the mental process com-monly known as deduction. If our predictionshave to do with the magnitude or the intensity ofthe expected result or with geometrical relationswe may use mathematics in making our deduction.This is the only step in the scientific method inwhich mathematics comes into play.The fourth step in our scientific method is the

testing of our predictions by experiment. Untilthis step is taken our scientific process is incom-plete ; after it is taken we can go no further exceptby making other predictions and testing them byexperiment. If all our predictions stand the testof experiment we may conclude that our hypothe-sis is actually a natural law. Later, some moreadvanced thinker may find a logical deductionfrom it which does not stand the test, and thendoubt is cast upon the validity of the law, and itsstatement must be changed to fit the new con-dition.An illustration of the difference between thescientific method and the method of argument.To make our description of the scientific proc-ess as plain as possible, let us imagine a concreteexample. Let us suppose that a traveler who has


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ILLUSTRATED THROUGH PHYSICS 2been accustomed to modern conditions in civilizedcommunities is walking in an uninhabited wilder-ness at night when suddenly he sees in front ofhim two long shadows of himself stretching for-ward nearly parallel to each other. Let us sup-pose his first thought to be that an automobile isapproaching him from the rear. This, then, ishis hypothesis.

If he uses the methods of the old Natural Phil-osophy, he will begin at once to argue with himselfas to the probability or the improbability of anautomobile's being in the wilderness. He will dis-cuss the possibility of its traveling over the routewhich he has followed. He may think of theswamps and rivers which he has crossed and ofthe mountains which he has climbed. He mayrecall all that he has learned from other explorersas to the presence or absence of human habita-tions and roads in the surrounding country.From all these data he will probably reach a con-clusion as to the probability or improbability ofan automobile's being behind him, and if he is amathematician he may state this probability as apercentage of all the possibilities which occur tohim. Meantime, while following out all theselines of argument, he has stood with his back tothe lights.On the other hand, if the traveler has been


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26 HOW to study:trained in the methods of modern science, whilehe may start with the same hypothesis, his de-ductions from it and his experimental tests ofthem may be somewhat as follows:

i. Since the shadows are cast in front of him,the lights which cast them must be behind himand must be visible. To test this deduction, heturns and looks for the lights.

2. If the lights are moving and are attachedto an automobile,, the engine of the machine mustbe running; he accordingly listens for the engine.

3. If the lights are approaching, the automo-bile, if such it is, must soon overtake him ; and hewill wait for it and determine its character.

4. If the lights are at rest, the machine, ifthere be one, has stopped; and he at once startsfor it, meanwhile being guided by the lights. Inthe end, though his mental processes may be muchsimpler than those of the other traveler, he willknow certainly whether or not the shadows arecast by the headlights of an automobile.A noted historical example of this difference.In order that the foregoing comparison maynot seem too much like a caricature, let us con-

sider an historical instance of the manner inwhich two of the world's great men attempted toexplain the same concrete and fairly simple phe-


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ILLUSTRATED THROUGH PHYSICS 27nomenon. Just two hundred years ago Newtonpublished a treatise on Optics. One of the firstexperiments he describes consisted in making asmall hole in the window shutter of a darkenedroom and in placing a three-cornered glass prismin the path of the beam of sunlight which enteredthrough the hole and formed a spot of light onthe opposite wall. Newton observed two im-portant changes due to the passing of the lightthrough the prism. In the first place, he saw thatthe path of the beam of light was bent where itpassed through the prism, so that the spot oflight on the wall appeared in a new position, andin the second place he saw that what had beforebeen a round patch of sunlight on the wall wasnow a band of rainbow colors.There seemed to be two possible hypotheses as

to the cause of the colors. One was that theywere already in the sunlight and had in some waybeen separated in passing through the prism ; theother was that the light in passing through theprism took something from the glass which gaveit the colors. Newton chose the former hypothe-sis for trial. He guessed that all the colors of therainbow were already in the sunlight, and thatwhile all of them were bent aside in passingthrough the pr;sm, some of them were turnedaside more than others. Looking at his band of


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28 HOW to study:light he saw that the blue end was farthest fromthe position originally occupied by the spot oflight on the wall and that the red end was nearestto this position. So he concluded that if the bandof colors was due to the bending of beams ofdifferent colored light by his prism, it must followthat a prism would cause a greater bending ofblue light than of red light. This was the logicaldeduction from his hypothesis. To test this de-duction, he placed another glass prism in thebeam of light which had passed through the firstone, but placed it at right angles to the first andso that the red light would pass through it nearone end and the blue light near the other end. Hesaw, as he had guessed, that the colored bandwas again turned aside in passing through thesecond prism,, and that the blue end of it wasturned aside more than the red end. His deduc-tion was verified by experiment.Then he argued that if light is turned aside in

passing through a prism, objects seen through aprism would appear displaced from their true po-sition, and that blue objects would appear moredisplaced than red objects. So he painted twosquares side by side on a black screen, one blueand the other red, and looked at them through aprism. The squares appeared separated, and the


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30 how to study:Ninety years after the publication of Newton's

Optics, the German poet, Goethe, undertook tointroduce another theory of colors based upon thehypothesis that the light in passing through theglass prism took up some unknown substance fromthe prism which combined with ordinary light toproduce color. Goethe's fundamental experimentconsisted in looking through a prism at a whitewall, apparently expecting it to be seen in rain-bow colors. When he saw it white, except for anarrow band of red on one side and of blue on theother side, he at once decided that he had over-thrown Newton's theory of colors. His friendsamong scientific men tried to point out to himthat what he had seen was exactly what might bepredicted from Newton's theory, since if the wallwere divided into narrow strips and the lightfrom each strip were dispersed into the rainbowcolors, these bands of colors would fall upon theneighboring strips in such a way that all thestrips except those nearest to one edge would re-ceive all the colors of ordinary light. Along thisedge the red light would be least deviated, so thatthis edge of the wall would be bounded by a redband. Along the opposite edge of the wall all thecolors would appear displaced beyond the trueedge of the wall, but since blue light is displacedmore than the other colors it would extend be-


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ILLUSTRATED THROUGH PHYSICS 3yond all the other colors, and the wall would seemto be bounded on this side by a blue band.Goethe was apparently unable to reason to thisdeduction. In fact, he seems to have been almostincapable of using the logical process at all. Hisgreat countryman Helmholtz, in referring to thisweakness of Goethe, says:

But this step into the region of abstractconceptions, which must necessarily be takenif we wish to penetrate to the causes of phe-nomena, scares the poet away.

For Goethe was a poet, and a poet, as a poet,has no use for the logical method of drawing de-ductions from hypotheses. The poet's generaliza-tions are not intended as hypotheses to be testedby the methods of science.

Lowell tells us that Poetry is not made outof the understanding/' and Goethe was a poet.So he wrote a book on the theory of color, whichwas largely made up of repeated statements ofhis own beliefs and of declamation against whathe calls the disgusting Newtonian white of thenatural philosophers. Helmholtz says of thisattempt at the discovery of scientific truth byintuitionWe must look upon his color theory as a

forlorn hope, as a desperate attempt to rescuefrom the attacks of science the belief in the


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32 HOW to study:direct truth of our sensations. And this willaccount for the enthusiasm with which hestrives to elaborate and to defend his theory,,for the passionate irritability with which heattacks his opponent, for the overweeningimportance which he attaches to these re-searches in comparison with his otherachievements, and for his inaccessibility toconviction or compromise.

When Goethe found that, while his theory ofcolor was received with some favor by the in-tuitional philosophers of his day, it failed to con-vince anyone trained in the use of the scientificmethod, he wrote a second volume, devoted inpart to a reiteration of his theory, but mostly toan indecent attack upon Newton, who was, ofcourse, long since dead. In this attack he callsNewton's reasoning incredibly impudent/' sayshis theory might be admirable for school chil-dren in a go-cart, and accuses Newton of fre-quently lying about his experiments, though all ofthem had been repeated many times by otherphysicists.Now that almost a century has passed since

the publication of Goethe's theory of color, New-ton's interpretations of the phenomena of lightand color are more firmly believed than ever,while their author is universally regarded as thegreatest interpreter of nature that the world has


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ILLUSTRATED THROUGH PHYSICS 33ever known. Goethe is still regarded as thegreatest of German poets, but his venture into thefield of physical science is deplored by all his ad-mirers who know anything about it.How skill in the different steps of the scien-tific method has varied.Not all physicistshave been so expert in the steps of the scientificprocess as Newton seems to have been; andmany of them have been much more skillful insome of the steps than in others. Accordingly, ithas sometimes happened that part of the processleading to an important discovery has been car-ried through by one man and another part of theprocess by another man. This was true in thecase of the discovery of the barometer and themeasurement of atmospheric pressure.For hundreds of years the disciples of Aristotle

had taught that the reason water can be raised bysuction is because Nature abhors a vacuum/'We find the same opinion still expressed by peoplewho tell us that the warm air in a chimney risesand the cold air rushes in to take its place. Aftertwo thousand years, the students of Galileo foundthat a vacuum may apparently exist in a closedtube above a column of water thirty-four feethigh, and hence that nature's abhorrence of avacuum does not extend above thirty-four feet.Torricelli, in 1643, tried the experiment with a


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34 how to study:column of mercury, instead of water, and foundthat a vacuum could exist above a columnof mercury only thirty inches high. Torricelliknew that a column of mercury thirty inches highweighs as much as a similar column of waterthirty-four feet high. He guessed that the liquidcolumn was in both cases held up by the pressureof the atmosphere, which must accordingly be asgreat as that of a layer of water thirty-four feetdeep or a layer of mercury thirty inches deep.This was the hypothesis,the second step in thescientific process.

Torricelli was apparently unable to carrythrough the process. He did not know how totest his hypothesis, so he merely argued about it.But Pascal saw the next step. He said that if theatmosphere were a fluid pressing down upon theearth, its pressure would be less at an elevationthan at sea level. So he carried a Torricelliantube of mercury to the top of a church steeple inParis and thought that the mercury column stoodlower than when on the ground. He then wroteto his brother-in-law, who lived near a moun-tain, to carry the tube to the top of themountain and observe the effect. The brother-in-law did so, and the mercury column stood threeinches lower on the top of the mountain than atits base. The scientific process was completed,


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ILLUSTRATED THROUGH PHYSICS 35and the mercurial barometer has ever since beenused to measure the pressure of the atmosphereupon the earth.The contributions of different men in the

discovery of universal gravitation.While inthe case just mentioned it took the work of twomen to carry the scientific process through tocompletion, the establishment of a discovery inscience sometimes involves the work of severalmen, each of whom carries through but a smallpart of the whole process. This was true of thediscovery of universal gravitation.Three hundred and fifty years ago TychoBrahe established the first astronomical observa-

tory, and made a great number of measurementsof the relative positions of the stars and planetsat different times. He undertook to decide be-tween the theory of Ptolemy, which made theearth the center of the universe with the sun,moon, and stars revolving around it, and a theorythat had been proposed but a short time beforeby Copernicus, which made the sun the center ofthe solar system, with the earth and the otherplanets revolving around it.

Tycho was a skillful observer and made veryaccurate measurements, though the telescope hadnot then been invented; but he was unable toapply the scientific process to the facts which


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36 HOW TO study:he had discovered, and he finally decided in favorof the theory that the earth is the center of theuniverse. Years later he accepted as a student ayoung man named John Kepler, who proved to bea much abler scientific thinker than his master.Kepler, by using the measurements which Tychohad made, was able to compute with great ac-curacy the orbits of the planets about the sun andof the moon about the earth. He showed that allthe planets move in elliptical orbits with the sunat one focus of the ellipse.So far the work of Tycho and Kepler was

descriptive, though Tycho's work involved meas-urements which still command the admiration ofastronomers, and Kepler's work involved some ofthe most famous mathematical calculations of theworld. Neither gave any explanation of why theplanets all moved in similar orbits about the sun,or even why they moved about the sun at all.It was sixty years later before an hypothesis ex-plaining these facts was proposed by Newton.Meanwhile, Galileo had experimented upon freelyfalling bodies and bodies rolling down inclinedplanes, and had made the discoveries which werelater collected by Newton under the name of thelaws of falling bodies. Galileo had also intro-duced the hypothesis of forces into mechanics,and had supposed that all bodies near the earth


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ILLUSTRATED THROUGH PHYSICS ^7are pulled toward it by a force which came to beknown as the attraction of gravitation.Newton, while still a very young man, under-took to calculate under what conditions one bodywould move in an elliptical orbit about anotherbody placed at one focus of the ellipse. He knewthat when a heavy body is fastened to one end of astring and whirled around the hand which holdsthe other end of the string the hand must con-stantly pull upon the string or the body will notmove in a curved path around the hand, but willcontinue to move in a straight path exceptas it is pulled toward the earth. His computa-tions told him that to make the body move in anelliptical path with the hand at one focus of theellipse the pull upon the string must be greaterwhen the weight is near the hand and less whenit is farther away, and that the pull must increasejust as fast as the square of the distance of themoving body decreases. This is called the law ofthe inverse square of the distance. Its calculationat that time was one of the great mathematicalfeats of the world.

It seemed to Newton that the moon revolvingabout the earth must be pulled toward the earthby a force varying in this way. Then it occurredto him that this might be the same force whichpulls all falling bodies to the earth. This was his


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38 how to study:hypothesis. He proceeded to calculate how farthe moon must fall in one second toward the earthfrom its straight path if a body near the earthfalls sixteen feet in one second and if gravitationdecreases as the square of the distance betweenthe falling body and the earth increases. Thedistance from the center of the earth to its sur-face and to the moon had both been calculatedfrom astronomical measurements. Using thesedistances,, Newton calculated how far the moonshould fall toward the earth in one second, andhe found that it did not fall as far as it shouldif it were pulled by gravitation. Instead of fall-ing five and one-half hundredths of an inch, asit should from his computations, it falls only fourand two-thirds hundredths of an inch in a second;hence he concluded that his deduction was notverified and, consequently, that his hypothesiswas not sustained.As a consequence, Newton did not even tell

any one of his hypothesis, much less attempt todefend it by argument; but accepted the test ofhis deduction. He says that he laid aside at thattime any further thought of the matter. So hewent on with his investigations in optics,, his in-vention of the reflecting telescope and the sextant,and his work on the differential calculus that has


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ILLUSTRATED THROUGH PHYSICS 39been such a powerful tool in the hands of mathe-maticians since that time.Twenty years later a new measurement of the

curvature of the earth was made by Pickard,which gave the radius of the earth as about fourthousand miles, instead of 3436 miles, the dis-tance used by Newton in calculating how muchthe pull of gravitation should be at the dis-tance of the moon. Newton had found that themoon falls toward the earth one thirty-six hun-dredth as far in a second as does a body at thesurface of the earth, and the new measurementof the earth's radius made it one-sixtieth of themoon's distance. Since the square of sixty isthirty-six hundred, the pull of the earth at thedistance of the moon should be one thirty-sixhundredth as great as at its surface, and New-ton's deduction was finally verified.Newton seemed at that stage to have proved

that the same gravitation which makes the applefall from the tree extends as far as the moon,and falls off with the inverse square of the dis-tance. But if gravitation may extend from theearth to the moon, why not to the sun? Theearth moves about the sun in the same kind ofcurved path in which the moon moves about theearth. There should accordingly be a force which


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40 how to study:varies with the inverse square law between theearth and the sun, and Newton saw the wholesolar system moving according to one general law.

But this was, again, a new hypothesis, or ratheran extension of his original hypothesis beyondthe limits for which it had been verified. So New-ton inquired if there might not be some effect ofthe moon's gravitation on the earth which wouldenable him to test whether the sun produced asimilar effect. There was. The tides wereknown to follow the apparent movement of themoon around the earth, and Newton was able toexplain these by the difference in intensity of themoon's gravitation on the side of the earth near-est it and the side farthest from it. If the effectof the sun's gravitation reached the earth, itshould also produce tides. Newton was able topoint out these tides and show that they were ofthe proper magnitude, and hence that his hypothe-sis as to the extension of gravitation throughoutthe solar system was justified. Such was thescientific method of Newton.And such is the method by which scientificknowledge has always been acquired. It is thescientific method. It can be used in its entiretybetter in the study of physics than in the studyof any other science. That is why physicshas developed so much more rapidly than any


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ILLUSTRATED THROUGH PHYSICS 41other science. It is also the reason why one canacquire facility in the use of the scientific methodbetter in studying physics than in studying anyother subject.Importance of the scientific habit of thinking.Is it important to acquire facility in the scien-

tific habit of thinking? Let Professor JohnDewey answer this question. He says

One of the only two articles that remainin my creed of life is that the future of ourcivilization depends upon the wideningspread and the deepening hold of the scien-tific habit of mind; and that the problem ofproblems in our education is therefore howto discover and how to mature and makeeffective this scientific habit. Mankind sofar has been ruled by things and by words,not by thought, for till the last few momentsof history humanity has not been in posses-sion of the conditions of secure and effectivethinking.

Again, Professor Dewey says of the scientificmethod

It represents the only method of thinkingthat has proved truthful in any subjectthatis what we mean when we call it scientific.It is not a peculiar development of thinkingfor highly specialized ends ; it is thinking sofar as thought has become conscious of its


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42 HOW TO study:proper ends and of the equipment indis-pensable for success in their pursuits.

If it is true that the mental process which wehave called the method of science is the onlymethod of thinking that has proved truthful inany subject, it would seem that a training in thismethod should surpass in importance any otherkind of mental training. It is true that themethod cannot be used in its entirety in any otherfield of knowledge ; but it is likewise true that inany field where it cannot be applied, we cannothope to attain to the same degree of certainty thatwe may in physical science.

Significance of the scientific method in otherfields than physics.This, at least, it may dofor us in other fieldsit may teach us thatopinions formed upon other matters are justas truly hypotheses until logically made deduc-tions from them have been verified as they are inphysical science. It is here that argument has itsproper place, which is, principally, to assist us inthe formation of a clearer understanding of whatmay be involved in our hypothesis. Argumentis commonly used to convert another to our hy-pothesis, rather than to test the hypothesis. Anargument usually consists in a series of logicaldeductions from the hypothesis under considera-tion, but if such deductions are incapable of ex-


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ILLUSTRATED THROUGH PHYSICS 43perimental test they can be of value only whenthey lead to some relation which is known to exist,or when they lead to an absurdity. If the lattercase should happen in a single instance the hy-pothesis must be abandoned or reconstructed sothat it will avoid the absurdity.The mental attitude necessary.Thus wemay learn to approach the investigation of othersubjects in much the same attitude of mind as wewould begin the investigation of a question inphysical science. This mental attitude has beenvery clearly described by Faraday in his lectureon The Education of the Judgment. Faradaysays:

I believe that in the pursuit of physicalscience, the imagination should be taught topresent the subject investigated in all pos-sible, and even in impossible views ; to searchfor analogies of likeness and (if I may sayso) of oppositioninverse or contrastedanalogies ; to present the fundamental idea inevery form, proportion, and condition; toclothe it with suppositions and probabilities,that all cases may pass in review, and betouched, if needful, by the Ithuriel spear ofexperiment. But all this must be under gov-ernment, and the result must not be given tosociety until the judgment, educated by theprocess itself, has been exercised upon it.Let us construct our hypotheses for an hour,


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44 how to study:or a day, or for years ; they are of the utmostvalue in the elimination of truth which isevolved more freely from error than fromconfusion; but above all things let us notcease to be aware of the temptation theyoffer, or, because they gradually becomefamiliar to us, accept them as established.

This is a description of a kind of argumentwhich may be applied in other fields as well as inphysical science, and it suggests the value of dis-cussion with others ; for it is seldom that a singleperson is able to present all the possible, not to saythe impossible, views of a very simple question.The danger of discussion is that we may have amuch greater predilection for the points of viewwhich we present ourselves than for equally sig-nificant points of view when presented by another,and the love for truth may easily be lost in thepleasure of successful combat or the struggle tomaintain an hypothesis merely because it is one'sown. Above all, it must not be forgotten that theestablishment of truth is a mental, not a vocal,process.The danger from prejudice.The tendency

to a warping of the judgment through prejudiceor through the expectation of a particular resultis one of the most difficult things to overcome,even when our expectation is in no way influenced


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ILLUSTRATED THROUGH PHYSICS 45by our desires. It is much more so when the mat-ter under consideration has a personal bearingupon ourselves or our friends, or when it is con-cerned with a belief which has been inculcated byprevious education. To overcome this dangerthe investigator in physical science usually triesto work out the experimental tests of his deduc-tions without knowing until they are finishedwhat their bearing upon his hypothesis will be.Thus, a chemist may balance his sample to beanalyzed by another body of unknown weight, sothat he may remain ignorant of the proportionswhich he should obtain if his hypothesis is to beverified. Not until his analysis is complete willKe weigh his counterpoise and compute the quan-tities which his hypothesis leads him to predict.

Faraday, in the lecture already referred to,calls especial attention to the danger of havingour judgment warped by prejudice, and we havealready seen a deplorable example of this in thecase of the poet Goethe. Faraday says:

The inclination we exhibit, in respect toany report or opinion that harmonizes withour preconceived notions, can only be com-pared in degree with the incredulity we en-tertain towards everything that opposesthem; and these opposite and apparently in-compatible, or at least inconsistent, conditions


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46 how to study:are accepted simultaneously in the most ex-traordinary manner. At one moment a de-parture from the laws of nature is admittedwithout the pretence of a careful examina-tion of the proof; and at the next, the wholeforce of these laws, acting undeviatinglythrough all time, is denied, because the testi-mony they give is disliked.

/ will simply express my strong belief,that that point of self-education which con-sists in teaching the mind to resist its desiresand inclinations, until they are proved to beright, is the most important of all, not only inthings of natural philosophy, but in everydepartment of daily life.

Suggestions for overcoming prejudice.Itwould appear from the above considerations thatsomething more than a knowledge of the scientificmethod of procedure is necessary to one whowould become an independent investigator ofphenomena,,that the mental traits which aregenerally included under the term, character arequite as important in scientific work as in otherfields of endeavor. It would seem to follow that acomplete discussion of how to study should atleast advise one as to how the mind can be taughtto resist its desires and inclinations until theyare proved to be right.

This is more difficult than to describe the scien-tific method of thinking. The question is, How


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ILLUSTRATED THROUGH PHYSICS 47may one form a habit of developing hypothesesand of deducing their logical consequences with-out being influenced by the bearing which his con-clusions may have upon himself or upon otherpeople ? In the opinion of the present writer, thishabit may be acquired most easily in a field of in-vestigation where the personal applications arenot appreciable. Thus, in the beginning, one isperfectly indifferent as to whether a suspendedmagnet sets north and south or east and west, orwhether a free body falls sixteen feet or twentyfeet in one second. His only concern is to de-termine the truth. If he continues to work withthis sole end in view,, the determination of truthwill gradually become a more and more importantmotive, and it may finally become so important as )to be stronger than his prejudices and desires.

Thus, the habit of seeking only the truth, com-bined with the fact that the scientific investigatorwho misrepresents the results of an investigationimmediately receives the contempt of all men ofscience throughout the world, becomes a powerfulcorrective of prejudice and helps the investigatorto be always upon honor with himself.

In this connection, Professor Tyndall has saidof the study of physics

It requires patient industry, and anhumble and conscientious acceptance of what


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48 how to study:nature reveals. The first condition of suc-cess is an honest receptivity and a willing-ness to abandon all preconceived notions,however cherished,, if they be found to con-tradict the truth. And if a man be notcapable of this self-renunciationthis loyalsurrender of himself to Naturehe lacks, inmy opinion, the first mark of a true philoso-pher. Thus the earnest prosecutor of sci-ence, who does not work with the idea ofproducing a sensation in the world, who lovesthe truth better than the transitory blaze ofto-day's fame, who comes to his task with asingle eye, finds in that task an indirectmeans of the highest moral culture. Andalthough the virtue of the act depends uponits privacy, this sacrifice of self, this uprightdetermination to accept the truth, no matterhow it may present itselfeven at the handsof a scientific foe, if necessarycarries withit its own reward. When prejudice is putunder foot, and the stains of personal biashave been washed awaywhen a man con-sents to lay aside his vanity and to becomeNature's organhis elevation is the instantconsequence of his humility.

The kind of problem suitable for training inscientific method.Thus far these pages havebeen devoted largely to an attempted descriptionof the methods of the scientist as distinct fromthe methods of the scholar. It was stated in the


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ILLUSTRATED THROUGH PHYSICS 49beginning that there are two partially distinctmethods which may, to some extent, be contrastedwith each other. It is true, however, that it wouldbe very difficult if not impossible to follow thescientific method to the exclusion of the other,,except as a mere matter of training. It would notbe difficult to select for purposes of training a listof scientific problems which a student could betaught to solve by the scientific method withoutknowing what had, or had not, been done byothers. So long as the purpose is training only,it is a matter of no consequence whether theanswer of the question which is being put tonature is already known to others or not. How-ever, a teacher in putting such questions shouldknow whether they are capable of being answeredthrough the knowledge and skill already acquiredby his pupil, and he can know this only if thequestion has already been answered, and if he isfamiliar with the process by which the answerhas been obtained. Thus, for purposes of earlytraining, a teacher is virtually compelled to con-fine himself to problems the answers to which healready knows; but it is necessary, if the studentis to be trained in the scientific method of interro-gating nature, that he shall not know beforehandthe answer which he is seeking.To the learner, any scientific question to which


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50 how to study:he does not know the answer may serve as aproblem upon which to try his skill, but the dangeris that the beginner will select a problem sodifficult that no one has been able to solve it. Ininterrogating nature it is necessary to go veryslowly, taking a single step at a time, and it isvery difficult to break up the complex problemswhich seem to us nearest and most important intothe simple problems of which they are built up.The most difficult task of a leader of investigationis to analyze the complex relations which existeverywhere in nature into simple relations whichlend themselves to scientific investigation. Usu-ally there are not more than two or three menin the world working in physical science who arecapable of making this analysis, and such meninevitably become world leaders in investigation.A man who belongs to this class must have bothscientific insight and scholarship. De Morgansays:

New knowledge, when to any purpose,must come by contemplation of old knowl-edge, in every matter which concernsthought; mechanical contrivance sometimes,not very often, escapes this rule. All themen who are now called discoverers in everymatter ruled by thought, have been menversed in the minds of their predecessors,


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ILLUSTRATED THROUGH PHYSICS 5and learned in what had been before them.There is not one exception.

The need of studying the methods of formerscientists.It should be noted that De Morganlays stress upon the fact that a successful investi-gator should be versed in the minds of hispredecessors,not merely acquainted with theknowledge which they have possessed. This isequivalent to saying what has already been said inthese pages,, that the way to learn the successfulmethod in science is to study the methods of themen who have been the most successful investi-gators. This knowledge can only be acquired byreading the original descriptions of the investiga-tions as given by their authors ; it cannot be gainedby reading second-hand descriptions compiled byother writers. To one who wishes to learn howto investigate physical phenomena, Tyndall'sSound or his Heat: A Mode of Motion is worthmany textbooks on physics; and Faraday's Ex-perimental Researches in Electricity is of morevalue than all the libraries of scientific knowledgewhich have ever been compiled.

Results of the scientific method.We havealready seen that until about three hundred yearsago the human race had made little more prog-ress in its conquest of the physical universe than


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52 how to study:it had in other lines of human endeavor. Sincethat time we have made comparatively little prog-ress in the acquisition of knowledge concerningmen and their ways, while each decade nowcarries us farther than the preceding century inour comprehension of physical laws.Why have we not also made progress in ourcomprehension of things of the spirit? Withinthe possible span of a single life the physicisthas taught the little whirligig of Hiero to dothe work of millions of men, and thus to banishhuman slavery from the earth; he has re-leased the spirit that was imprisoned in theamber and made it his mighty servant and mes-senger of light; he has compelled the faithlesswings of Icarus to bear him at will over moun-tains or sea; but the student of Literature, ofMusic, of Art, of Philosophy, of Morality, ofman's relations to his Maker, must still go for hisinspiration to the old masters. When only a fewyears ago a popular magazine took a vote of theleading thinkers of the world on the questionWhat are the seven wonders of the modernworld? six of the seven selected were achieve-ments of modern physics, and the seventh a re-cent achievement of an allied science.And we have seen why this is so. In the year1600, Dr. Gilbert announced to the world a new


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ILLUSTRATED THROUGH PHYSICS S3method of discovering the laws of the physicaluniverse, and proved the accuracy of his methodby discovering more of the laws of magnetism andof electricity than had all his predecessors sincethe beginning of time. That same year GiordanoBruno was burned at the stake in the streets ofRome for daring to defy the authority of thechurch in matters of the intellect ; and the youngprofessor, Galilei Galileo, was risking a similarfate in dropping iron balls from the tower of Pisato see if they would really fall with a speed pro-portional to their weight,, and in daring to recog-nize through his home-made telescope the spots onthe sun, though ecclesiastical authorities hadwarned him that the sun must have no spots. Forthe first time in the history of our race men hadbegun to test their conclusions by experiment andto cross-question Nature experimentally to com-pel her to yield her secrets. It is this method ofGilbert and Galileo which has come to be calledthe scientific method, and it is due to the employ-ment of this method by a few individuals in eachgeneration that our era has come to be known asThe Age of Science.

Responsibility of teachers for centering at-tention on scientific method.It would seemthat it is only in the possession of this one methodof learning the rules of the game that the hu-


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54 how to study:man mind is more competent than it was in thedays of Aristotle or Socrates. And when we re-member that this method of science which has,within the memory of living man, so transformedour earth has been acquired by only a few indi-viduals among the many millions now living, werecognize the tremendous responsibility of theteachers who are chosen to guide beginners in themethod of science. For the beginner, unless hebe one of the world's great geniuses, must beguided by one who has learned to find his wayabout. No one travels in an unknown land bythe aid of guide books,he must depend ratherupon his knowledge of physiography, his train-ing in woodcraft and his ability to supply his ownnecessities from the natural resources of thecountry. Until he has acquired these necessaryaccomplishments he must rely upon a guide whohas acquired them. It will depend upon his use ofthe knowledge which he acquires from this guidewhether he will ever be able to find his way aboutwithout assistance. And the teacher to whom isintrusted the training of the young men andyoung women who aspire to scientific attainmenthas not faithfully discharged his responsibilityuntil he has given them a mastery of the onlymethod of investigation which has ever been sue-


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ILLUSTRATED THROUGH PHYSICS 55cessfully employed by human beings to compelNature to surrender her secrets for the benefitof mankind.Even the most enlightened members of our

race still know very little about the physical uni-verse. They are pioneers who have only recentlylanded upon the shores of an unknown world.They have blazed a few trails into the surround-ing wilderness, and have ascended a few conspicu-ous mountain peaks. To some of these outlooksthey have built easy roads, and have invitedothers to look out with them over the unknowncountry. They know that this country containsmany wonderful mountains and fertile valleyswhich have never yet been trodden by the foot ofman. It is the ambition of the pioneers of sci-ence first to blaze trails and then to find practicalroutes for roads into these delectable moun-tains. It is the duty of the teacher of scienceto give the young men and young women whocome to him a sufficient training so that theymay at least be able to step aside from thebeaten trails to gather the flowers and fruitswhich grow so profusely along them. Many willnever venture far from the trail, but once in along time will come a student with the courageand instincts of the pioneer, who wishes to go


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56 HOW TO STUDYbeyond the landmarks of other men, and him thetrue teacher welcomes, not as a pupil, but as acompanion and brother.

It is these stalwart ones, who play their gameof life single handed and away from their fel-lows, to whom the human race owes all it hasachieved in the conquest of the physical universe.They are little known or heeded by the great un-thinking mass of their fellows, but no greaterhappiness can come to the true teacher of sciencethan to stand as a guide and companion to a fewof these chosen ones.


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