For the freshman and sophomore, two lectures per week are sufficient for this type of instruction. In these exercises the student should give his undivided attention to what is presented by the lecturer. The taking of notes is to be discouraged rather than encouraged, for it results in dividing the attention between what is presented and the mechanical work of writing. To take the place of the usual lecture notes, students of this grade had better be provided with a suitable text, definite chapters in which are assigned for reading in connection with each lecture. The text thus serves for purposes of review, and also as a means for inculcating additional details which cannot to advantage be presented in a lecture, but are best studied at home by perusing a book, the contents of which have been illuminated by the experimental demonstrations, the explanations on the blackboard, the charts, lantern slides, and above all the living development and presentation of the subject by the lecturer. The lectures should in no case be conducted primarily as an exercise in dictation and note taking. If the lectures do not give general orientation, illumination, and inspiration for further study in laboratory and library, they are an absolute failure and had better be omitted entirely. On the other hand, when properly conducted the lectures are the very life of the course.

The laboratory work should be well correlated with the lectures, especially during the first year. The experiments to be performed by the student should be carefully chosen and should not be a mere repetition of the lecture demonstrations. The laboratory experiments should be both qualitative and quantitative in character. They should on the one hand illustrate the peculiar properties of the substances studied and the typical concomitant changes of chemical action, but on the other hand a sufficient number of quantitative exercises in the laboratory should be introduced to bring home to the student the laws of combining weights and volumes, thus giving him the idea that chemistry is exact and that quantitative relations always obtain when chemical action takes place. At the same time the quantitative exercises lay the basis for the proper comprehension of the laws of combining weights and volumes and the atomic and molecular theories. At least three periods of two consecutive hours each should be spent in the laboratory per week, and the laboratory exercises should be made so interesting and instructive that the student will feel inclined to work in the laboratory at odd times in addition if his program of other studies permits. The laboratory should at all times be, as its name implies, a place where work is done. Order and neatness should always prevail. Apparatus should be kept neat and clean, and in no case should slovenly habits of setting up apparatus be tolerated. The early introduction of a certain amount of quantitative experimentation in the course makes for habits of order and neatness in experimentation and guards against bringing up "sloppy" chemists.

The laboratory notebook should be a neat and accurate record of the work in the laboratory. To this end the entries in the notebook should be made in the laboratory at the time when the experiment is actually being performed. The writing of data on loose scratch paper and then finally writing up the notebook later at home from such sheets is not to be recommended, for while thus the final appearance of the notebook may be improved, it is no longer a first-hand record such as every scientist makes, but rather a transcribed one. The student, in making up such a transcription, is only too apt to draw upon his inner consciousness to make the book appear better; indeed, when he has neglected to transcribe his notes for several days, he is bound to produce anything but a true and accurate record, to say nothing about being put to the temptation to "fake" results which he has either not at all obtained in the laboratory, or has recorded so imperfectly on the scratch paper that he can no longer interpret his record properly. The only true way is to have the notes made directly in the permanently bound notebook at the time when the experiment is actually in progress. The student ought not to take the laboratory notebook home at all without the instructor's knowledge and permission. Each experiment should be entered in the notebook in a brief, businesslike manner. Long-winded, superfluous discussions should be avoided. As a rule, drawings of apparatus in the notes are unnecessary, it being sufficient to indicate that the apparatus was set up according to Figure so-and-so in the laboratory manual or according to the directions given on page so-and-so. The student should be made to feel that the laboratory is the place where careful, purposeful experimentation is to be done, that this is the main object of the laboratory work, and that the notebook is merely a reliable record of what has been accomplished. To this end the data in the notebook should be complete, yet brief and to the point, so that what has been done can be looked up again and that the instructor may know that the experiment has been performed properly, that its purpose was understood by the student, and that he has made correct observations and drawn logical conclusions therefrom. While in each case the notes should indicate the purpose of the experiment, what has actually been done and observed, and the final conclusions, it is on the whole best not to have a general cut-and-dried formula according to which each and every experiment is to be recorded. It is better to encourage a certain degree of individuality in this matter on the part of each student. Notebooks should be corrected by the teacher every week, and the student should be asked to correct all errors which the teacher has indicated. A businesslike atmosphere should prevail in the laboratory at all times, and this should be reflected in the notebooks. Anything that savors of the pedantic is to be strictly avoided. Small blackboards should be conveniently placed in the laboratory so that the instructor may use them in explaining any points that may arise. Usually the same question arises with several members of the class, and a few moments of explanation before the blackboard enable the instructor to clear up the points raised. This not only saves the instructor's time, but it also stimulates interest in the laboratory when explanations are thus given to small groups just when the question is hot.

It is, of course, assumed that the necessary amount of apparatus, chemicals, and other supplies is available, and that the laboratory desks, proper ventilation of the rooms, and safeguards in the case of all experiments fraught with danger have received the necessary painstaking attention on the part of the instructor, who must never for a moment relax in looking after these matters, which it is not the purpose to discuss here. At all times the student should work intelligently and be fully aware of any dangers that are inherent in what he is doing. It need hardly be said that a beginner should not be set at experiments that are specially dangerous. Having been given proper directions, the student should be taught to go ahead with confidence, for working in constant trepidation that an accident may occur often creates a nervous state that brings about the accident. Too much emphasis cannot be laid upon proper, definite laboratory instructions, especially as to kinds and amounts of materials to be used. Such directions as "take a little phosphorus," for example, should be strictly avoided, for the direction as to amount is absolutely indefinite and may in the case where phosphorus or any other dangerous substance is used lead to dire accidents. The student should be given proper and very definite directions, and then he should be taught to follow these absolutely and not use more of the materials than is specified, as the beginner is so apt to do, thus often wasting his time and the reagents as well. Economy and the correct use of all laboratory supplies should be inculcated indirectly all the time. A fixed set of printed rules for the laboratory is generally neither necessary nor desirable when students are properly directed to work intelligently as they go, and good directions are given in the laboratory manual. Thus a spirit of doing intelligently what is right and proper, guarding against accidents, economizing in time and materials of all kinds will soon become dominant in the laboratory and will greatly add to the efficiency of the workers. Minor accidents are almost bound to occur at times in spite of all precautions, and the instructor should be ready to cope with these promptly by means of a properly supplied first-aid kit.

For students of the first year quizzes or recitations should be held at least twice a week. In these exercises the ground covered in the lectures and laboratory work should be carefully and systematically reviewed. The quiz classes should not be too large. Twenty-five students is the upper limit for a quiz section. The laboratory sections too should not be larger than this, and it is highly desirable that the same instructor conduct both the recitation and the immediate laboratory supervision of the student. Lecture classes can, of course, be very much larger in number. In most colleges the attendance upon classes in chemistry is so large that it is not possible for the professor to deliver the lectures and also personally conduct all of the laboratory work and recitations. It is consequently necessary to divide the class up into small sections for laboratory and quiz purposes. It is highly desirable that the student become well acquainted with his individual instructor in laboratory and quiz work, and therefore it would be unfortunate to have one instructor in the laboratory and still another instructor in the quiz. It might be argued that it is a good thing to have the student become acquainted with a number of instructors, but in the writer's experience such practice results to the disadvantage of the student, and is consequently not to be recommended.

In the recitations the student is to be encouraged to do the talking. He is to be given an opportunity to ask questions as well as to answer the queries put by the teacher. Short written exercises of about ten minutes' duration can be given to advantage in each of these recitations. In this way the entire class writes upon a well-chosen question or solves a numerical chemical problem and thus a great deal of time is saved. The quiz room should be well provided with blackboards which may be used to great advantage in the writing of equations and the solution of chemical problems just as in a class in mathematics. The textbook, from which readings are assigned to the student in connection with the lectures, should contain questions which recapitulate the contents of each chapter. When such questions are not contained in the book, they ought to be provided by the teacher on printed or mimeographed sheets. When properly conducted, the recitation aids greatly in clarifying, arranging and fixing the important points of the course in the mind of the student. Young instructors are apt to make the mistake of doing too much talking in the quiz, instead of encouraging the student to express his views. In these days, when foreign languages and mathematics are more or less on the wane in colleges, the proper study of chemistry, particularly in the well-conducted quiz, will go far toward supplying the mental drill which the older subjects have always afforded.

If the work of the first year has been properly conducted, it will have given the student a general view of the whole field of chemistry, together with a sufficient amount of detail so securely anchored in careful laboratory work and practical experience as to form a basis for either more advanced work in chemical lines or in the pursuance of the vocations already mentioned in which a knowledge of chemistry is basal. It is hardly necessary to add that if well taught, the student will at the end of such a course have a desire for more chemistry.

The work of the second year of chemistry in college generally consists of quantitative analysis, though the more intensive study of the compounds of carbon, known as organic chemistry, is also frequently taken up at this time, and there is much to be said in favor of such practice.

In the quantitative analysis, habits of neatness and accuracy must be insisted upon. It is well to give the general orientation and directions by means of lectures. One or two such exercises per week will suffice. There should also be recitations. When two lectures per week are given, it will suffice to review the work with the student in connection with such lectures, provided the class is not too large for quiz purposes. Intelligent work should characterize a course in quantitative analysis. To this end the student should be taught how to take proper representative samples of the material to be analyzed. He should then be taught how to weigh or measure out that sample with proper care. The manipulations of the analytical process should be carried out so that each step is properly understood and its relations to the general laws of chemistry are constantly before the mind. In carrying out the process, the various sources of error must be thoroughly appreciated and guarded against. The final weighing or measuring of the form in which the ingredient sought is estimated should again be carried out with care, and in the calculation of the percentage content due regard should be had for the limits of error of experimentation throughout the entire analytical process. The student feels that a large number of the exercises in quantitative analysis are virtually cases of making chemical preparations of the highest possible purity, thus connecting his previous chemical experience with his quantitative work. The course in quantitative analysis should cover the determination of the more important basic and acid radicals, and should consist of both gravimetric and volumetric exercises.

The choice of the exercises is of great importance. It may vary, and should vary considerably in different cases. Thus a student in agriculture is naturally interested in the methods of estimating lime, phosphorus, nitrogen, potash, silica, sulphur, etc., whereas a student in engineering would be more interested in work with the heavy metals and the ingredients which the commercial samples of such metals are apt to contain. Thus, analytical work on solder, bearing metal, iron and steel, cement, etc., should be introduced as soon as the student in engineering is ready for it. It is quite possible to inculcate the principles of quantitative analysis by selecting exercises in which the individual student is interested, though, to be sure, certain fundamental things would naturally have to be taken by all students, whatever be the line for which they are training. A few exercises in gas analysis and also water analysis should be given in every good course in quantitative analysis that occupies an entire year. Careful attention should be given to the notebook in the quantitative work, and the student should also be made to feel that in modern quantitative analysis not only balances and burettes are to serve as the measuring instruments, but that the polariscope and the refractometer also are very important, and that at times still other physical instruments like the spectroscope, the electrometer, and the viscometer may prove very useful indeed.

The quantitative analysis offers a splendid opportunity for bringing home to the student what he has learned in the work of the first year, showing him one phase of the application of that knowledge and making him feel, as it were, the quantitative side of science. This latter view can be imparted only to a limited degree in the first year's work, but the quantitative course offers an unusual opportunity for giving the student an application of the fundamental quantitative laws which govern all chemical processes. It is not possible to analyze very many substances during any college course in quantitative analysis. The wise teacher will choose the substances to be analyzed so as to keep up the interest of the student and yet at the same time give him examples of all the fundamental cases that are commonly met in the practice of analytical work. A careful, painstaking, intelligent worker should be the result of the course in quantitative analysis. Toward the end of the course, too, a certain amount of speed should be insisted upon. The student should be taught to carry on several processes at the same time, but care should be taken not to overdo this.

In the course in organic chemistry, lectures, laboratory work, and recitations, arranged very much as to time as in the first year, will be found advantageous. If the intensive work in organic chemistry is postponed to the third year in college, there are certain advantages. For example, the student is more mature and has had drill and experience in the somewhat simpler processes commonly taught in general and analytical chemistry. On the other hand, the postponing of organic chemistry to the third year has the disadvantage that the student goes through his basal training in quantitative analysis without the help of that larger horizon which can come to him only through the study of the methods of organic chemistry. The general work of the first year, to be sure, if well done compensates in part for what is lost by postponing organic chemistry till the third year, but it can never entirely remove the loss to the student. Teachers will differ as to whether the time-honored division of organic chemistry into the aliphatic and aromatic series should be maintained pedagogically, but they will doubtless all agree that the methods of working out the structure of the chemical compound are peculiarly characteristic of the study of the compounds of carbon, and these methods must consequently constitute an important point to be inculcated in organic chemistry. The derivation of the various types of organic compounds from the fundamental hydrocarbons as well as from one another, and the characteristic reactions of each of these fundamental forms which lead to their identification and also often serve as a means of their purification, should naturally be taught in a thoroughgoing manner. The numerous practical applications which the teacher of organic chemistry has at his command will always serve to make this subject one of the deepest interest, if not the most fascinating portion of the entire subject of chemistry. No student should leave the course in organic chemistry without feeling the beautiful unity and logical relationship which obtains in the case of the compounds of carbon, the experimental study of which has cast so much light upon the chemical processes in living plants and animals, processes upon which life itself depends. The analysis of organic compounds is probably best taught in connection with the course in organic chemistry. It is here that the student is introduced to the use of the combustion furnace and the method of working out the empirical formulæ of the compounds which he has carefully prepared and purified. The laboratory practice in organic chemistry generally requires the use of larger pieces of apparatus. Some of the experiments also are connected with peculiar dangers of their own. These facts require that the student should not approach the course without sufficient preliminary training. Furthermore, the teacher needs to exercise special care in supervising the laboratory work so as to guard the student against serious accidents.

The historical development of organic chemistry is especially interesting, and allusions to the history of the important discoveries and developments of ideas in organic chemistry should be used to stimulate interest and so enhance the value of the work of the student. The practical side of organic chemistry should never be lost sight of for a moment, and under no condition should the course be allowed to deteriorate into one of mere picturing of structural formulæ on the blackboard. All chemical formulas are merely compact forms of expression of what we know about chemical compounds. There are, no doubt, many facts about chemical compounds which their accepted formulas do not express at all, and the wise teacher should lead the student to see this. There is peculiar danger in the course in organic chemistry that the pupil become a mere formula worshiper, and this must carefully be guarded against.

The applications of organic chemistry to the arts and industries, but especially to biochemistry, will no doubt interest many members of the class of a course in organic chemistry if the subject is properly taught. This will be particularly the case if the teacher always holds before the mind of the pupil the actual realities in the laboratory and in nature, using formulation merely as the expression of our knowledge and not as an end in itself.

Physical chemistry, commonly regarded as the youngest and by its adherents the most important and all-pervading branch of chemistry, is presented very early in the college course by some teachers, and postponed to the junior and even the senior year by others. Just as a certain amount of organic chemistry should be taught in the first year, so a few of the most fundamental principles of physical chemistry must also find a place in the basal work of the beginner. However, in the first year's work in chemistry so many phases of the subject must needs be presented in order to give a good general view, that many details in either organic, analytical, or physical chemistry must necessarily be omitted. What is to be taught in that important basal year must, therefore, be selected with extreme care. Moreover, so far as physical chemistry is concerned, it is in a way chemical philosophy or general chemistry in the broadest sense of the word, and consequently requires for its successful pursuit not only a basal course, but also proper knowledge of analytical and organic chemistry, as well as a grounding in physics, crystallography, and mathematics. At the same time a certain amount of biological study is highly desirable. A good course in physical chemistry postulates lectures, laboratory work, and recitations. In general, these should be arranged much like those in the basal course and the course in organic chemistry. If anything, more time should be put upon the lectures and recitations; certainly more time should be devoted to exercises of this kind than in the course in quantitative analysis, which is best taught in the laboratory. At the same time it would be a mistake to teach physical chemistry without laboratory practice. Indeed, laboratory practice is the very life of physical chemistry, and the more of such work we can have, the better. However, since physical chemistry, as already stated, delves into the philosophical field, discussions in the lecture hall and classroom become of peculiar importance.

Many colleges now give additional courses in chemical technology. These would naturally come after the student has had a sufficient foundation in general chemistry, chemical analysis, and organic and physical chemistry. As a rule such applied courses ought not to be given until the junior or senior year. It is a great mistake to introduce such courses earlier, for the student cannot do the work in an intelligent manner.

In all the courses in chemistry, interest and enthusiasm are of vital importance. These can be instilled only by the teacher himself, and no amount of laying out courses on paper and giving directions, however valuable they may be, can possibly take the place of an able, devoted, enthusiastic teacher. Chemistry deals with things, and hence is always best taught in the laboratory. The classroom and the library should create interest and enthusiasm for further laboratory work, and in turn the laboratory work should yield results that will finally manifest themselves in the form of good written reports.

Original work should always be carried on by the college teacher. If he fails in this, his teaching will soon be dead. There will always be some bright students who can help him in his research work. These should be led on and developed along lines of original thought. From this source there will always spring live workers in the arts and industries as well as in academic lines. Lack of facilities and time is often pleaded by the college teacher as an excuse for not doing original work. There is no doubt that such facilities are often very meager. Nevertheless, the enthusiastic teacher is bound to find the time and also the means for doing some original work. A great deal cannot be expected of him as a rule because of his pedagogical duties, but a certain amount of productive work is absolutely essential to any live college teacher.

The importance of chemistry in daily life and in the industries has been increasing and is bound to continue to increase. For this reason the subject is destined to take a more important place in the college curriculum. If well taught, college chemistry will not only widen the horizon of the student, but it will also afford him both manual training and mental drill and culture of the highest order.

Louis Kahlenberg
University of Wisconsin

VI

If culture means the subjective transformation of information into a philosophy of life, can culture be complete unless it has included in its reflections the marvelously simple yet intricate interrelations of natural phenomena? The value of this intricate simplicity as a mental discipline is equaled perhaps only in the finely drawn distinctions of philosophy and in the painstaking statements of limitations and the rapid generalizations of pure mathematics; and let us not forget the value of discipline, outgrown and unheeded though it be in the acquisitive life of the present age.

The professional student, continually increasing in numbers in our colleges, either of science or in certain branches of law, finds a broad familiarity with the latest points of view of the physicist not only helpful but often indispensable. Chemistry can find with difficulty any artificial basis for a boundary of its domain from that of physics. Certainly no real one exists. The biologist is heard asking about the latest idea in atomic evolution and the electrical theories of matter, hoping to find in these illuminating points of view, he tells us, some analogy to his almost hopelessly complex problems of life and heredity. Even those medical men whose interest is entirely commercial appreciate the convenience of the X-ray and the importance of correctly interpreting the pathological effects of the rays of radio-activity and ultra-violet light. One finds a great geologist in collaboration with his distinguished colleague in physics, and from the latter comes a contribution on the rigidity of the earth. Astronomy answers nowadays to the name of astrophysics, and progressive observatories recognize in the laboratory a tool as essential as the telescope. In a word, the professional student of science not only finds that the subject matter of physics has many fundamental points of contact with his own chosen field, but also recognizes that the less complex nature of its material allows the method of study to stand out in bolder relief. Training in the method and a passion for the method are vital to a successful and an ardent career.

In the teaching of physics, then, the aim might at first sight appear to be quite varied, differing with different classes of students. A careful analysis of the situation, however, will show, we think, that this conclusion can with difficulty be justified: that it is necessary to conduct college instruction in a fashion dictated almost not at all by the subsequent aims of the students concerned. In the more elementary work, certainly, adherence to this idea is of great importance. The character, design, and purpose of an edifice do not appear in the foundations except that they are massive if the structure is to be great.

Not infrequently this seems an unnecessary hardship to a professional student anxious to get into the work of his chosen field. If such is the case, let him question perhaps whether any study of physics should be attempted, as this query may have different answers for different individuals. But if he is to study it at all, there is but one place where the analysis of physical phenomena can begin, and that is with fundamentals—space, time, motion, and inertia. How can one who is ignorant of the existence and characteristics of rotational inertia understand a galvanometer? How can waves be discussed unless in terms of period, amplitude, frequency, and the like, that find definition in simple harmonic motion? How does one visualize the mechanism of a gas, unless by means of such ideas as momentum interchange, energy conservation, and forces of attraction?

Let us emphasize here, lest we be misunderstood, that we are considering collegiate courses. We do not doubt that descriptive physics may be given after one fashion to farmers, quite differently to engineers, and from still a third point of view to medical students. Unfortunately some collegiate courses never get beyond the high school method. Our aim is not to discuss descriptive courses, but those that approach the subject with the spirit of critical analysis, for these alone do we deem worthy of a place in the college curriculum.

The problem of the descriptive course is the problem of the high school. Because of failure there, too often we see at many a university courses in subfreshman physics. These are made necessary where entrance requirements do not demand this subject and where subsequent interest along related lines develops among the students a tardy necessity of getting it. From the point of view of the collegiate course it often appears as if the subfreshman course could be raised to academic rank. This is because familiarity with the material must precede an analysis of it. Credit for high school physics on the records of the entrance examiner, unless this credit is based on entrance examination, is often found to stand for very little. Consequently the almost continual demand for the high school work under the direct supervision of a collegiate faculty. The number of students who should go into this course instead of the college course is increasing at the present time in the immediate locality of the writer.

As contributory testimony here, witness the number of colleges that do not take cognizance at all of high school preparation and admit to the same college classes those who have never had preparatory physics with those who have had it. We are told the difference between the two groups is insignificant. Perhaps it is. If so, this fact reflects as much on the college as on the high school. If we are looking for a solution of our problem in this direction, let us be undeceived; we are looking backwards, not forward.

No one will affirm that to a class of whose numbers some have never had high school physics a course that is really analytical can be given. Wherever a rigorous analytic course is given those who have been well trained in descriptive physics do well in it in general. Let us not beg the question by giving such physics in a college that does not require high school preparation. The college curriculum is full enough as it is without duplication of high school work, and any college physics course that is a first course is essentially a high school course.

Let us rather put the responsibility squarely where it lies. The high school will respond if the urgency is made clear. Witness some of them in our cities already attempting the junior college idea, an idea that has not been unsuccessful in some of our private schools. If it is made clear that a thoroughgoing course in descriptive physics is a paramount necessity in college work and that no effort will be spared on the part of the university to insure this quality, the men will be found and the proper courses given.

We favor a comprehensive examination plan in all cases where the quality of the high school work is either unknown or open to question.

Familiarity, likewise, with the most elementary uses of mathematics should be insured. It would be highly desirable that a course of collegiate grade in trigonometry should immediately precede the physics. This is not because the details of trigonometry are all needed in physics. In fact, a few who have never had trigonometry make a conspicuous success in physics. These, however, are ones who have a natural facility in analysis. To keep them out because of failure to have had a prerequisite course in trigonometry often works an unnecessary hardship. We would argue, therefore, for a formal prerequisite on this subject, reserving for certain students exemption, which should be determined in all cases, if not by the instructor himself, at least by his coöperation with some advisory administrative officer.

Nor is it sufficient with regard to the mathematical preparation or the knowledge of high school physics in either case to go exclusively by the official credit record of the student. It is our firm conviction from several years' experience where widely different aims in the student body are represented that above and beyond all formal records attention to the individual case is of prime importance. The opening week of the course should be so conducted that those who are obviously unequipped can be located and directed elsewhere into the proper work. How this may best be accomplished can be determined only by the circumstances in the individual school, we imagine. Daily tests covering the simplest descriptive information that should be retained from high school physics and requiring the intelligent use of arithmetic, elementary algebra, and geometry will reveal amazing incapacity in these things. Tuttle, in his little book entitled An Introduction to Laboratory Physics (Jefferson Laboratory of Physics, Philadelphia, 1915), gives on pages 15-16 an excellent list of questions of this sort. Any one with teaching experience in the subject whatever can make up an equally good one suited for his special needs and temperament. It should not be assumed that all who fail in such tests should be dropped. Some undoubtedly should be sent back to high school work or its equivalent; others may need double the required work in mathematics to overcome their unreadiness in its use. Personal contacts will show that some are drifting into a scientific course who have no aptitude for it and who will be doomed to disappointment should they continue. In a word, then, we are convinced that the more carefully one plans the work of the first week or so the more smoothly does the work of the rest of the year follow. The number of failures may be reduced to a few per cent without in any way relaxing the standard of the course.

With regard to the organization of the college courses in physics there seems to us to be at least one method that leads to a considerable degree of success. This is not the lecture method of instruction; neither is it a wholly unmitigated laboratory method.

To kindle inspiration and enthusiasm nothing can equal the contact in lectures with others, preferably leaders in their profession, but at least men who possess one of these qualities. Such contacts need not be frequent; indeed, they should not be. The speaker is apt to make more effort, the student to be more responsive, if such occasions are relatively rare. Even thus, although real information is imparted at such a time, it is seldom acquired. However, perspective is furnished, interest stimulated, and the occasion enjoyed.

For the real acquisition of scientific information, the great method is the working out of a laboratory exercise and pertinent problems, with informal guidance in the atmosphere of active study and discussion engendered among a small group,—the laboratory method. Taken alone, it is apt to become mechanical and uninteresting and the outlook to be obscured by details. Lectures, especially demonstration lectures, are needed to vitalize and inspire. Moreover, many of the most vivid illustrations of physical principles that occur on every hand to focus the popular attention are never met with in the college course because they are unsuited for inexperienced hands or not readily amenable to quantitative experimentation. The more informally such demonstrations can be conducted, the more enthusiastically they are received.

With regard to laboratory work, accuracy in moderate degree is important, but too great insistence upon it is apt to overshadow the higher aim; namely, that of the analysis of the phenomena themselves. A determination of the pressure coefficient of a gas to half a per cent, accompanied by a clear visualization of the mechanism by which a gas exerts a pressure and a usable identification of temperature with kinetic agitation, would seem preferable to an experimental error of a tenth per cent which may be exacted which is unaccompanied by these inspiring and rather modern points of view. Especially in electricity is a familiarity with the essentials of the modern theories important. Here supplementary lectures are of great necessity, for no textbook keeps pace with progress in this tremendously important field. Problem solving with class discussion is absolutely essential, and should occupy at least one third of the entire time. In no other way can one be convinced that the student is doing anything more than committing to memory, or blindly following directions with no reaction of his own.

The incorporation recently of this idea into the courses at the University of Chicago has been very successful. Five sections which are under different instructors are combined one day a week at an hour when there are no other university engagements, for a lecture demonstration. This is given by a senior member of the staff whenever possible. The other meetings during the week are conducted by the individual instructors and consist of two two-hour laboratory periods and two class periods that usually run into somewhat over one hour each. These sections are limited to twenty-five, and a smaller number than this would be desirable. The responsibility for the course rests naturally upon the individual instructors of these small sections. These men also share in the demonstration work, since each is usually an enthusiast in some particular field and will make a great effort in his own specialty to give a successful popular presentation of the important ideas involved. The enthusiasm which this plan has engendered is very great. Attendance is crowded and there is always a row of visitors, teachers of the vicinity, advanced students in other fields of work, or undergraduates brought in by members of the class. These latter especially are encouraged, as this does much to offset current ideas that physics is a subject of unmitigated severity. The particular topics put into these demonstrations will be discussed in paragraphs below, which take up in more detail the organization of the special subdivisions of the material in a general physics course.

Mechanics is a stumbling block at the outset. As we have indicated above, it must form the beginning of any course that is analytic in aim. There is no question of sidestepping the difficulty: it must be surmounted. A judicious weeding during the first week is the initial part of the plan. Interest may be aroused at once in the demonstration lectures by mechanical tricks that show apparent violations of Newton's Laws. These group around the type of experiment which shows a modification of the natural uniform rectilinear motion of any object by some hidden force, most often a concealed magnetic field. The instinctive adherence of every one to Newton's dynamic definition, that acceleration defies the ratio of force to inertia, is made obvious by the amusement with which a trick in apparent defiance of this principle is greeted. Informality of discussion in such experiments, questions on the part of the instructor that are more than rhetorical, and volunteer answers and comment from the class increase the vividness of the impressions. A mechanical adaptation of the "monkey on the string" problem, using little electric hoists or clockworks, introduces interesting discussion of the third law in conjunction with the second. A toy cannon and target mounted on easily rolling carriages bring in the similar ideas where impulses rather than forces alone can be measured.

There follow, then, the laboratory experiments of the Atwood machine and the force table, where quantitative results are demanded. It is desirable to have these experiments at least worked by the class in unison. Whatever may be the exigencies of numbers and apparatus equipment that prevent it later, these introductions should be given to and discussed by all together. In the nature of things, fortunately, this is possible. A single Atwood machine will give traces for all in a short time under the guidance of the instructor. The force table experiment is nine-tenths calculation, and verifications may be made for a large number in a short time. Searching problems and discussion are instigated at once, and the notion of rotational equilibrium and force moments brought in. Because of the very great difficulty seeming to attach to force resolutions, demonstration experiments and problems using a bridge structure, such as the Harvard experimental truss, will amply repay the time invested. Another experiment here, which makes analysis of the practice of weighing, is possible, although there will be divergence almost at once due to the personality of the instructor and the equipment by which he finds himself limited. The early introduction of moments is important, however, because it seems as if a great amount of unnecessary confusion on this topic is continually cropping out later. At this point, if limitations of apparatus present a difficulty, a group of more or less independent experiments may be started. Ideas of energy may be illustrated in the determination of the efficiency and the horse power of simple machines, such as water motors, pulleys, and even small gas or steam engines.

In discussion of power one should not forget that in practical problems one meets power as force times velocity rather more frequently than as rate of doing work, and this aspect should be emphasized in the experiments. Conservation of energy is brought out in these same experiments with reference to the efficiencies involved. In sharp contrast here the principle of conservation of momentum may be brought in by ballistic pendulum experiments involving elastic and inelastic impacts. Most students are unfamiliar with the application of these ideas to the determination of projectile velocities, and this forms an interesting lecture demonstration. Elasticity likewise is a topic that may be introduced with more or less emphasis according to the predilection of the instructor. The moduli of Young and of simple rigidity lend themselves readily to quantitative laboratory experiments. Any amount of interesting material may be culled here from recent investigations of Michelson, Bridgman, and others with regard to elastic limits, departures from the simple relations, variations with pressure, etc., for a lantern or demonstration talk in these connections.

By this time the student should have found himself sufficiently prepared to take up problems of rotational motion. The application of Newton's Laws to pure rotations and combinations of rotation and translation, such as rolling motions, are very many. We would emphasize here the dynamic definition of moment of inertia, I ═ Fh/a rather than the one so frequently given importance for computational purposes, Σmr². Quantitative experiments are furnished by the rotational counterpart of the Atwood machine. Lecture demonstrations for several talks abound: stability of spin about the axis of greatest inertia, Kelvin's famous experiments with eggs and tops containing liquids, which suggest the gyroscopic ideas, and finally a discussion of gyroscopes and their multitudinous applications. The book of Crabtree, Spinning Tops and the Gyroscope, and the several papers by Gray in the Proceedings of the Physical Society of London, summarize a wealth of material. If one wishes to interject a parenthetical discussion of the Bernouilli principle, and the simplest laws of pressure distributions on plane surfaces moving through a resisting medium, a group of striking demonstrations is possible involving this notion, and by simple combination of it with the precession of a rotating body the boomerang may be brought in and its action for the major part given explanation.

Rotational motion leads naturally to a discussion of centripetal force, and this in turn is simple harmonic motion. This latter finds most important applications in the pendulum experiments, and no end of material is here to be found in any of the textbooks. The greatest refinement of experimentation for elementary purposes will be the determination of "g" by the method of coincidences between a simple pendulum and the standard clock. Elementary analysis without use of calculus reaches its culmination in a discussion of forced vibrations similar to that used by Magie in his general text. Many will not care to go as far as this. Others will go farther and discuss Kater's pendulum and the small corrections needed for precision, for here does precision find bold expression.

It is not our purpose to give a synopsis of the entire general physics course. We have made an especially detailed study of mechanics, because this topic is the one of greatest difficulty by far in the pedagogy. It is too formally given in the average text, and seems to have suffered most of all from lack of imagination on the part of instructors.