A COURSE IN PHYSICS FOR ENGINEERING

STUDENTS.

BY W. S. FRANKLIN,

Professor of Physics, Lehigh University.

There is too much of a tendency in our technical schools to curtail elementary instruction in the sciences, and to expect our students to get a general insight into elementary physics and chemistry by a study of the more elaborate technical subjects which rest upon these sciences. This is exemplified in the degree to which courses in elementary mechanics and heat are abbreviated in our schools and by the inclusion of what are intended to be advanced courses in applied mechanics and thermodynamics of a great deal of elementary instruction. The objections to this arrangement are, first, that the elementary aspects of a subject are almost sure to be obscured by the excess of detail that is always involved in the advanced courses, and second, that the more advanced instruction is nearly always given without an accompaniment of laboratory and lecture demonstration work of the kind that is required to accentuate the fundamental principles of the subjects.

Character of Instruction in Elementary Physics.We are now passing through a formative period in the establishing of a satisfactory course in elementary physics for technical students, and it seems that there are three questions in particular which are now up for solution: First, as to a clearer line of division

between instruction in the elementary sciences and in the applied sciences; second, as to the character of the instruction in the elementary sciences and third, as to the time to be devoted to elementary physics and chemistry in our technical schools. Many engineering instructors feel that present courses in elementary physics are more or less ineffective, and we see evidences in a number of institutions of an attempt to rectify this matter by the establishment of professorships of physics especially for engineering students. Many of our teachers of physics are certainly inclined to turn away from the exacting method of presenting this subject, and to lean towards a popular presentation in which the striking phenomena and the fascinating descriptive phases of the subject are allowed to monopolize the attention of the student. An exacting mode of presentation must eventually prevail, and too much stress cannot be laid upon the development of the simpler parts of physical theory and upon a thorough drill in numerical calculations.

In the teaching of physics a clearly and concisely written text-book should be used; explanatory lectures of such character as to appeal properly to the student's imagination should be given, theoretical lectures in fact, illustrated by the simplest kind of experiments; the student should be required to perform a large amount of numerical calculation; and he should be provided with laboratory work from the beginning to the end of the course.

Time to be Given to Elementary Physics.-Two full years of work in elementary physics is not an unreasonable amount to include in our technical courses.

In the first year, one lecture and two recitations every week and one laboratory period every two weeks should be devoted to mechanics and heat. In the second year, one lecture, two recitations and one laboratory period per week should be given to electricity and magnetism and to light and sound. The laboratory work of the second year should, however, consist in part of a continuation of the work in mechanics and heat.

Elementary Mechanics.-Effective instruction in elementary mechanics, with emphasis upon the physical aspects of the subject, is the most important element in technical education. Without this firm foundation nothing can be accomplished in the other branches of physics, and but little can be done in any other line of technology. A detailed discussion of the teaching of elementary mechanics is given in a paper to be presented at this meeting. An outline of a suggested laboratory course in elementary mechanics is given at the end of this paper.

Heat. So far as one is able to judge, it seems that problem work in elementary physics is too much confined to mechanics, not, indeed, that the amount of problem work in mechanics is greater than might be desired, but that the possibility of problem work in heat and perhaps also in electricity and magnetism is unduly limited thereby. At one institution, for example, provision is made for about five and a half term-hours of problem work in simple statics and in the dynamics of translatory motion, and but one-half of a term-hour is available for problem work in the dynamics of rotatory motion, elementary elasticity,

hydrostatics, hydraulics, thermometry, calorimetry, and changes of state. Criticism is unnecessary. Thorough instruction in heat is quite as important as thorough instruction in elementary mechanics.

Instruction in heat should cover the following topics: thermometry; calorimetry; changes of state; conduction, convection and radiation; the properties of gases; and a simple discussion of thermodynamics. The fundamental ideas of thermodynamics might be insisted on as the rational essence of the whole subject of heat. Some of our deepest-seated physical intuitions can, by a proper suggestive handling of them, be transformed into the rational structure of thermodynamics, so as to give to the second law (often spelled with capitals because, perhaps, nearly every one remains unconvinced) the same unquestioned dominion over every physical argument that is now universally conceded to the first law of arithmetic, namely, that two and two are four.*

Electricity and Magnetism.-It is high time for some one to undertake to develop the logical structure of this branch of physics in contempt of the tremendously over-emphasized system of absolute measurements. Not one student in a hundred ever gets a clear idea of that long chain of ordered operations which forges the ampere out of the meter, the kilogram, and the mean solar day; indeed, every electrical engineer ignores this chain of operations on the recommendation of several International Congresses and defines his ampere as so much silver-plating per second, by the watch!

* See a brief paper on "The Intuitive Aspects of the Second Law of Thermodynamics," Electrical Review, September 8, 1906.

That part of the subject of electricity and magnetism which precedes the ampere is always a nightmare, and the subsequent development of the subject, which is as simple and concrete as one could wish, is spoiled. I have held more than one serious argument to justify what seems to be to some extent a teaching innovation of mine in beginning the teaching of electricity and magnetism at the electric-current end rather than at the electrostatics end; and yet I know of but one electrical engineer who has clear ideas of the more or less obscure phenomena that like a mist surround the electrostatics end of the subject, whereas every school boy has some substantial knowledge of the electric current. When will we learn to teach physics according to our doings?

Elementary laboratory work in electricity and magnetism has heretofore been limited to too narrow a field, and it is very important that the experiments be chosen to cover as wide a range of phenomena as possible.

Light and Sound.-Very little need be said regarding the teaching of this branch of physics except to insist on the importance to any engineer of a clear understanding of optical instruments and of some understanding of the phenomena of wave motion and oscillatory motion, which are nowhere so prominently exhibited as in the phenomena of light and sound.

LABORATORY COURSE IN ELEMENTARY PHYSICS.
Mechanics.

First year.

One period every two weeks.

1. Practice with the simple vernier, use of vernier

caliper and barometer.