bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Forces between Potential Wells Which Share a Particle
Authors: Chao Bella
Published: August 2005

The famous exchange forces arise in quantum mechanics from the uncertainty at any given time as to which of the two potential wells a particle, which is capable of leaking back and forth between the two wells, is occupying. This entirely quantum-theoretical result can be given an energetic explanation, and in fact be estimated quantitatively, by finding the possible energy eigenfunctions for the particle, which correspond to nearly-equal or to nearly-opposite probability amplitudes for the wave function in each of the two wells. The variation of system energy with the separation of the wells can be interpreted as a force. The present paper is an effort to give a much more intuitive account of the origin of these important forces. The force is here interpreted purely kinematically as the result of the fact that the particle bombards the well edges both from within and from without. The net attractive or repulsive force between the wells then arises from the fact that for one type of wave function the bombardment is more frequent on the inner, facing edges, and so the wells are forced together, and conversely for the other type. The ideas are generalized to wells other than the idealized square potential well, and compared quantitatively with more familiar treatments of the problem.
Vector Resultants Obtained Graphically through Centroids
Authors: Askovitz S. I.
Published: August 2005

A simple method is presented whereby the resultant of a set of vectors in a plane may be determined or checked by locating the centroid of the starting points of the vectors and the centroid of their endpoints.
The First Law of Thermodynamics for a Continuous Medium in Mass Motion
Authors: Grossman Lawrence M.
Published: August 2005

The integral form of the conservation of energy for a continuous medium in motion is derived from the usual differential expression of the first law of thermodynamics. Various special cases of this relation are considered, and in particular it is shown that the invariance of the sum of kinetic energy, potential energy, and e+p̄/ρ may be written for arbitrary dissipative motions under certain definitions of the boundary conditions of the system.
Summer Course in Physics for High School Teachers
Authors: Green John R.
Published: August 2005

A report is made on an upper-divison course in physics especially designed for secondary school teachers, given during the summer session of 1956 at the University of New Mexico. Both lecture and laboratory procedures are discussed.
Integrals over the Fermi Function
Authors: Blankenbecler R.
Published: August 2005

A formal device for evaluating integrals over the Fermi distribution function is presented. An expansion of the formal solution yields Sommerfeld's familiar result obtained in connection with the electron theory of metals. In special cases, the result can be expressed in closed form. One such case, the scattering form factor for the Fermi distribution, is presented. Application of the method to other integrals is indicated.
A Satisfying “Thick Lens” Experiment
Authors: Wood Thomas H.
Published: August 2005

An elementary experiment is described in which an object-image relationship for a thick lens is determined both by experiment and by calculations involving easily determined lens parameters. The two methods have over-all errors of less than 6% and agree quite well.
Computation Demonstration in Mechanics
Authors: Hoffmann Paul O. , Ramberg Eivind G. F.
Published: August 2005

A teaching method is discussed whereby students solve mechanics problems which can be verified experimentally in the classroom. The verification is done by means of very simple equipment.
Reminiscences in Physics from 1894 Onward
Authors: Satterly John
Published: August 2005

Professor Satterly recalls some of the incidents which have high-lighted a career of almost 60 years as a physicist and reminisces concerning the many famous physicists with whom he has studied and worked.
Note on the Principal Frequencies of a Double Spring-Mass System
Authors: Chen Henry S. C.
Published: August 2005

This paper gives an algebraic solution for the principal frequencies of a double spring-mass system. A comparison of numerical results is given.
What Kind of Cooperation with Colleges Do High School Physics Teachers Want?
Authors: Kruglak Haym
Published: August 2005

A questionnaire on college-high school cooperation was mailed to Michigan high school physics teachers. The percentage of responses on the relative merit of each proposal was tabulated. Additional proposals were also suggested by the respondents. The important problem of inter-school cooperation needs more intensive study by college physicists in close consultation with high school physics teachers.
Simple Expressions for the Two-Dimensional Maxwell Stress Distribution in Ideal Dielectrics
Authors: Power G.
Published: August 2005

By use of the complex variable, an attempt is made to obtain simple expressions for the Maxwell stress components in the case of two-dimensional electrostatic fields, when the dielectric material is homogeneous and effects of electrostriction can be neglected. Examples are given to illustrate how the results may be interpreted, with emphasis on the stress distribution at the interface separating two ideal dielectrics.
Split Sections and Learning in College Physics
Authors: Blumenthal Ralph H.
Published: August 2005

The influence of more than one instructor upon learning in college physics was determined statistically. Results indicated significant differences in student achievement with regard to the acquisition of factual physics knowledge, whereas no significant differences were evidenced with regard to the acquisition of physics problem-solving abilities.
Anniversaries in 1957 of Interest to Physicists
Authors: Barr E. Scott
Published: August 2005

During the year 1957 there will be two bicentennials, three sesquicentennials, and eight centennials of the birth or death of persons of interest to physicists. Brief biographical sketches of these persons are given here.
One-Year Introductory Course in a Liberal Arts College
Authors: Michels Walter C.
Published: August 2005

Prepared at the request of the AAPT Conference to illustrate how the recommendations of the Report may be applied in a small liberal arts college, this syllabus describes a one-year course for students majoring in science and mathematics, as well as for others not planning to major in those fields.
Some Simple Christiansen Filters
Authors: Auerbach Louis
Published: August 2005

A little-known demonstration in optics, the Christiansen filter, is described. A discussion of its merits and defects for demonstration or research work is included. Some new filter combinations for the visible region are described that are of special value for demonstration purposes. Special features of several are noted.
Coupled Oscillations
Authors: Kannewurf C. R. , Jensen Harald C.
Published: August 2005

A method of demonstrating coupled oscillatory motion between physical pendulums using a pair of selsyn motors as the coupling device is described. This type of electrical coupling makes possible the agreement of experimental and calculated values of the normal mode and energy transfer frequencies to better than 1%. Two methods for investigating the coupling as a function of the applied voltage are described and the results presented graphically.
“Ratio of the Specific Heats” and Thermodynamics
Authors: Hoxton L. G.
Published: August 2005

Attention is directed to certain adiabatic equations, which are deducible from definitions independent of thermodynamic principles. The facts appear to be little known; textbooks and other writings disagree about them. The very simple proofs discussed here result in economy of thought with attendant benefits to both student and instructor.
Derivation of the Energy-Distribution Formulas of Quantum Statistics
Authors: Cowan R. D.
Published: August 2005

The energy-distribution formulas of quantum statistics are derived in a way which treats all three cases (Bose-Einstein, Fermi-Dirac, and corrected Boltzmann) in a similar manner, so that the relationship of each case to the others is clear throughout the derivation. Stirling's formula for the factorial, which is of dubious applicability in the Fermi-Dirac case, is not required.
Weighing Atoms
Authors: Duckworth H. E.
Published: August 2005

This article is the text of a talk given by the author at the 1956 Summer Meeting of the AAPT. The audience included not only members of the Association plus other physicists, but also, as expected, a number of wives and even some children. For this reason the subject, “Weighing Atoms,” was presented at an elementary level in the hope both of instructing the lay element in the audience and of amusing the professional physicists who were present.
Nuclear Spin Echo Experiments and the Foundations of Statistical Mechanics
Authors: Rothstein Jerome
Published: August 2005

The problem of reconciling the irreversibility of thermodynamics with the completely reversible mechanics of the ultimate constituents of the thermodynamical system is examined from an operational viewpoint. The informational nature of entropy is demonstrated, and the famous paradoxes of statistical mechanics, due to Loschmidt and Zermelo, are resolved with its aid. Spin echo experiments are shown to realize the conditions of Loschmidt's reflection paradox, and used to illustrate how reversibility occurs only with perfect “memory” or information storage, while “forgetting” or loss of information implies irreversibility.
Liouville's Theorem and the Intensity of Beams
Authors: Arakengy Albert
Published: August 2005

The meaning of Liouville's theorem on the flow of points in phase space is discussed. The intensity for particles or for radiation is defined in the most general case. It is shown that the familiar theorem which states that an optical instrument cannot change the brightness of any object which it images is a special case of Liouville's theorem. The generalization of this result to classical particle- and radiation-handling systems of many kinds is discussed. The result holds even for situations in which the fields or refractive index distributions are arbitrarily varying in time, though in such situations the trajectories of “constant brightness” may move around by bending and distorting so that a stationary observer may thereby see some changes. The problem of point sources is considered. Simple examples of phase space motions are exhibited.
The Birth and Death of a Star
Authors: Sandage Allan
Published: August 2005

Astronomical studies of the life histories of the stars lead to speculation about our own future.
Representation of Effects of the Overhauser Type
Authors: Manley J. H.
Published: August 2005

A discussion of observations in magnetic resonance experiments and their relations to the processes involved involves consideration of the populations of magnetic states. By adding a population coordinate to an energy diagram a representation is obtained by which the time change of state population can be illustrated. Application is made to effects of the Overhauser type in solids, especially in semiconductors.
Atomic Energy: An Adventure in Learning
Authors: Clancy Edward P.
Published: August 2005

Some college students feel, by the time they reach their senior year, that they have in a sense been intellectually short-changed. Their views of important issues and ideas have been kept too narrow, and they have not been made aware of the relationships among the fields of knowledge.

An experimental program at Mount Holyoke College involving interdepartmental courses is discussed, and one of the courses—on atomic energy—is described. This course is taught by a staff which includes an economist, a political scientist, and a physicist. A sociologist gives considerable assistance.
Analysis of the Social Consequences of Scientific Discovery
Authors: Meier Richard L.
Published: August 2005

Present formulations of the responsibility of scientists for the social consequences of their efforts are not very helpful for the stabilization of society. More accurate estimates of the impact of a set of new developments can be generated if administrative scientists assigned a small group of specialists to the task while the ground-breaking research was still under way. An efficient procedure for such a group would be to (1) achieve an understanding of the scientific foundations of the impending innovation, (2) select those “futures” for the society for consideration which offer interesting changes in structure, and (3) develop ad hoc models for these futures into which the innovation may be introduced and exert changes. By such means a first approximation of the effects can be deduced. A more refined picture can be obtained by considering the relevant public decisions which have to be made, the convergence of the path of this innovation with others, and hypothetically “looking back” from some point in the future and describing the successive stages of the impact. These techniques are aimed at minimizing the surprise afforded at decision-making levels by developments in science.
Galvanometer Resistance and Linearity
Authors: Miller Bernard L.
Published: August 2005

The values of galvanometer resistance which are obtained by the two half-deflection methods (constant-voltage versus constant-current sources) are often found to differ because of nonlinearity in the galvanometer response. It is shown that the correct value is the geometric mean of the results of the two methods, if the initial deflections are the same in the two cases; also, the galvanometer resistance equals that value of the variable resistance in the two methods which gives the same second deflection. A new method which resembles the Kelvin method of obtaining the resistance of a galvanometer is reported. The source of the nonlinearity is apparently in the torsional response of the galvanometer coil suspension and not in a lack of uniformity in the magnetic field through which the coil turns.
Experiment on the Reflection and Absorption of Neutrons
Authors: Stephenson R. J. , Samsel T. F.
Published: August 2005

Fast neutrons from a radium-beryllium source were slowed down in paraffin and detected by a boron-trifluoride proportional counter. The absorption of the neutrons in aluminum and their reflection by paraffin blocks were measured using electronic amplifying and counting equipment.
Hidden Variables in Quantum Mechanics
Authors: Zinnes I. I.
Published: August 2005

The hidden variable theorem due to von Neumann is deduced in a physically transparent manner. As a result it is clear that the theorem is correct only if one requires that these hidden variables merely enlarge the set of observables employed at present in quantum mechanics. The theorem cannot be interpreted to mean that one cannot introduce such additional variables in order (1) to specify a state with classical completeness and (2) to define the usual observables as statistical parameters.
Study of Collisions. Part II. Survey of the Textbooks
Authors: Barnes George
Published: August 2005

A survey of physics and engineering textbooks indicates that there is lack of agreement among the authors on the subject of impact and the coefficient of restitution as well as disagreement between the textbook authors and the writers of the articles in the periodicals. The confusion arises primarily because of (1) the way in which the coefficient of restitution ε is so often defined, (2) the nature of the usual discussions of it, and (3) the reason given for ε being less than unity for most collisions between objects of ordinary size. Ways of eliminating the difficulty are discussed.
An Advanced Laboratory Project: Construction of a Wilson Cloud Chamber
Authors: Tanner Raymond L.
Published: August 2005

A 6-in. diameter Wilson Cloud Chamber was constructed by six senior students as a project in an atomic and nuclear physics course. The planning and actual machine work were student performed and several good pictures of alpha tracks were made using the apparatus.
On the Use of the Optical Path Concept in the Study of Spherical Surfaces
Authors: Douglas D. G.
Published: August 2005

The author believes that the optical path method should be used more widely than it is at present in the teaching of geometrical optics. As illustrations of the use of the method, spherical aberration and astigmatism of a spherical surface are discussed.
Increase of Surface Tension of Certain Solutions when Brought into Contact with Hot Gases
Authors: Skogen N.
Published: August 2005

The effect may be demonstrated by a flame of coal gas directed toward a surface of a soap solution. A rapid flow of surface layer toward the flame, a surface elevation of several millimeters, and a downward current under the elevation will occur. Rough measurements of the tension by means of drop methods (1) at room conditions and (2) near a flame show an increase from 29 to 57 dyne/cm for a certain solution. The effect of the hot gases may be to restore the conditions of the surface to those of clean water.
New Approach to the Teaching of Electrostatics in General Physics Courses
Authors: Rekveld J.
Published: August 2005

After a few remarks about the necessity of adapting our teaching method to the rationalized mks system of units, a short analysis of the objections to the use of Coulomb's law as a basic, introductory law is given. A new approach is suggested which introduces Gauss' law by means of Faraday's ice-pail experiment.
Centroids, Vectors, and Least Squares
Authors: Askovitz S. I.
Published: August 2005

A mechanical model is presented which corresponds to the mathematical problem of determining the straight line best fitting a series of points according to the least squares criterion. The model consists essentially of a bar in equilibrium under the action of suitably arranged springs. By applying certain relationships between centroids of points and vectors in equilibrium, two points can be located which determine the correct line. A graphic method can thereby be developed for drawing the line without any calculations. The technique is illustrated for the case of three points.
Design and Uses of a Light-Water-Moderated Subcritical Assembly
Authors: McDaniel E. W. , Elliott T. A.
Published: August 2005

The utility of subcritical assemblies in the development of nuclear reactors and as educational tools is discussed, and a detailed description of the light-water-moderated, natural uranium assembly at Georgia Tech is presented.
Aristotle and the Physics Student
Authors: Wood John K.
Published: August 2005

The difficulty encountered by a beginning science student is discussed in terms of the ability to build abstract models. Aristotle was unable to do this in some instances, able to do it in others, depending on his background knowledge. A student must be trained to perform mental, abstract, “experiments” to get an understanding of the technique of problem solving in science.
Unified Approach to Physics at the University Level
Authors: Shepanski J. R. , Pollard H. F. , Parry L. G.
Published: August 2005

Repeated criticisms have been made recently of conventional university physics courses. A brief discussion is given of these criticisms followed by a summary of different methods of teaching physics. A proposal is then put forward giving the design of a course which, it is contended, should offer advantages over conventional courses. This is achieved by departing from the “compartmentalized” division of the subject and replacing it by a unified treatment. Such a course should provide the undergraduate with an all-round knowledge of fundamental principles and allow easy incorporation of new developments in physics. The suggested course may conveniently follow the sequence: mechanics, field phenomena, and matter.
Elliptic Polarimeter for the Student Laboratory: “Specimens” of Elliptically Polarized Light
Authors: Brown Thomas B.
Published: August 2005

The elliptic polarimeter here described for use in the advanced undergraduate laboratory is simple and inexpensive, yet its precision approaches that of a research instrument. Experiments with it are simplified by providing the student with “specimens” of elliptically polarized light made by binding together with suitable orientation a Polaroid and a birefringent plate of approximately quarter-wave retardation. Precision is attained by means of an improved form of analyzer. The errors encountered with a compensator plate that does not produce exactly quarter-wave retardation are analyzed and a method for taking data is developed which reduces the final errors to small second-order terms.
Meta-Derivatives and Anticommutators
Authors: Freistadt Hans , Struik Ruth Rebekka
Published: August 2005

A functional operation, (called meta-differentiation) suitable for representing quantum-mechanical momenta in terms of the coordinates to which they are conjugate, is constructed explicitly from the commutation or anticommutation relations. In the case of commutation relations, one is led to a slight generalization of the conventional derivative. The operation to be used in the case of anticommutation relations is: take the odd part of the function and divide by the independent variable.
Elementary Derivation of the Multicomponent Diffusion Equation
Authors: Williams F. A.
Published: August 2005

It is demonstrated that the multicomponent diffusion equation can be derived from elementary kinetic-theory considerations without employing the results of the mathematical theory of nonuniform gases. By using the approach described by Furry, elementary expressions for the binary diffusion coefficients are also obtained. The advantage of the concept of the equivalence of partial pressure gradients and momentum gradients is thereby emphasized.
Summer Session Course in Demonstration Experiments for High School Physics Teachers
Authors: Miller Julius Sumner
Published: August 2005

This paper describes the preparation and modus operandi of a course in demonstration experiments in physics given during the summer of 1957 at the University of California, Los Angeles, supported by the Department of Physics and the National Science Foundation. The writer's philosophy of demonstrations is briefly narrated and the summer program appraised.
Explicit Expression for Spherical Harmonics
Authors: Schmid L. A.
Published: August 2005

A general expression for spherical harmonics as an explicit function of the angle coordinates is derived using standard methods of group-representation theory. This expression is more useful to physicists than a corresponding expression available in the mathematical literature for two reasons: (1) Its normalization is the one most commonly used by physicists, rather than one of several other normalization conventions used mainly by mathematicians. (2) Its form is especially convenient for use in the operator equations which occur in quantum mechanics. Furthermore, the derivation serves the pedagogical purpose of providing a simple illustration of the methods of group-representation theory.

A set of relations useful in solving the Dirac equation are listed, both because their verification provides an example of the utility of the expression derived, and because the form in which these relations are stated in the literature is apt to result in confusion stemming from the various different normalization conventions in use.
AEC Grants to Educational Institutions for Purchase of Certain Kinds of Equipment
Authors:   Report of the AAPT Committee on Apparatus for Educational Institutions
Published: August 2005

The Atomic Energy Commission has announced a policy permitting the AEC to make grants and contributions to nonprofit educational institutions for the acquisition of teaching aids, demonstration apparatus, and student laboratory equipment. This report reviews procedures which must be followed in making application for such grants.
Clock Paradox and the Physics of Discontinuous Gravitational Fields
Authors: Leffert C. B. , Donahue T. M.
Published: August 2005

The motion of the clocks as represented in a solution of the clock paradox offered by C. Mo/ller is studied in detail. It is found that in the noninertial rest frame of the accelerated clock the free clock suffers discontinuities in velocity whenever the “gravitational field” in that frame abruptly changes. Although these discontinuities occur at points of discontinuity of the metric tensor, examination of a case in which the gravitational field is turned on smoothly reveals that the effect is a real one within the framework of the general theory of relativity. By the principle of equivalence it follows that even in a real gravitational field when that field changes in time velocity-dependent terms in the acceleration of a particle exist. These become impulsive for abruptly changing fields and can even cause acceleration in the direction “opposite” to the field.
Chemistry and the Atomic Nucleus
Authors: Libby Willard F.
Published: August 2005

An informal account is given of the development of the Berkeley school of science and radiochemistry, followed by a summary of the results of radiocarbon dating measurements in relation to archaeological problems. A few suggestions are made as to future potential uses of radioisotope techniques in science and in industry.
Laws of Conservation: Parity and Time Reversal
Authors: Wu Ta-You
Published: August 2005

The concept of conservation of parity is explained, and the reason for the usual transformation laws for electric charge, electric field, magnetic pole, and magnetic field as scalar, vector, pseudo-scalar, and pseudo-vector, respectively (or, alternatively, as p.s.; p.v; s; v, respectively) is traced to the requirement that the laws of electromagnetism be invariant under inversion. The work of Lee, Yang, Wu et al. is then briefly summarized. The usual canonical transformations in classical dynamics are extended to include time reversal by extending the usual conditions for canonical transformations. Thus upon time reversal the Poisson brackets undergo a change of sign. If the behavior of the quantum Poisson brackets upon time reversal is analogously defined, it seems to provide an alternative view to the invariance of the Schrödinger or Heisenberg equations in quantum mechanics under the Wigner time reversal.
New Version of Edwards' Ampere Balance
Authors: Williamson Charles
Published: August 2005

Professor R. L. Edwards' design of the ampere balance has been modified as follows. Our balance is made from 38-in. aluminum tubing, not bent to shape but cut and soldered. It has two pairs of parallel fixed conductors, 61 cm long and 3 cm apart. The moving conductor, rectangular in plan view, is gabled in vertical view, and made with a dihedral angle of 150° so that its center of gravity is near the axis of rotation. Steel balls rolling on horizontal glass plates are used as pivots. The mercury cups are apart from the pivots. The moving conductor bears a central Lucite cross rod perpendicular to the fixed conductors. This rod carries a small mirror and two threaded brass rods with adjustable bobs for horizontal and vertical balancing of the moving system. To provide the counterbalancing torque short pieces of fine copper wire or analytical weights are laid on Lucite plugs fitted into the open ends of the moving conductor. The damping device is an aluminum vane in a beaker of machine oil. A beam arrest is provided. With a telescope and scale at a distance of two meters the ampere balance has a weight sensitivity of 5 mg/cm and a current sensitivity of 2amp2/cm. An ammeter indicating a current of 5 amp can be calibrated with this balance to somewhat better than 1%.
Newton and the Cause of Gravity
Authors: Evans Melbourne G.
Published: August 2005

Newton attempted to explain the force of gravity on two hypotheses: the existence of a medium, or ether, and action at a distance. The first hypothesis he rejected as being physically absurd, the second as contrary to reason. Newton had, therefore, no theory of gravity. However, his long and sustained effort to understand gravity was not without at least one serious consequence. For involvement in the ether theory obscured from Newton the universal character of the inverse-square relation, and delayed for twenty years his final formulation of the law of gravity.
Radio Propagation Research at the National Bureau of Standards
Authors: Brown F. W.
Published: August 2005

The Central Radio Propagation Laboratory is the central agency of the U. S. Government for obtaining, analyzing, and disseminating information on the propagation of radio waves at all frequencies along the surface of the earth, in the atmosphere, and in the space. In order to carry out its responsibility, this Laboratory conducts research on the nature of radio waves, the nature of the media through which radio waves are transmitted, the interaction of the waves with the media, and the nature of radio noise and interference effects. This article describes some of that research and summarizes the historical background leading to the present framework for carrying out the research. To the best of the author's knowledge, no completely comprehensive general summary of the Laboratory's history, objectives, and research programs has previously been published.
On the Formation of Quantum-Mechanical Operators
Authors: Shewell John Robert
Published: August 2005

A number of rules for forming operators corresponding to classical quantities are investigated. Spin and relativistic effects are excluded from consideration. The two rules which are in agreement with the customary interpretation of quantum mechanics are ambiguous in that they do not yield unique operators. The other rules considered yield unique operators but are in disagreement with the customary interpretation of quantum mechanics. It is shown that any symmetrization rule is in this category. All the rules investigated are linear, but no attempt is made to formulate a nonlinear rule. It is indicated that additional experimental evidence is necessary to clarify the question of quantum-mechanical operators.
Observations on the Acoustical Characteristics of the English Flute
Authors: Herman Robert
Published: August 2005

A discursive presentation is given of the English flute or recorder as a serious musical instrument including remarks based on acoustical theory and experiment, concerning such matters as intonation, partial content, blowing pressure, and some possible criteria for the “good” recorder, among other subjects.
On the Retardation of a Satellite
Authors: Bacon Ralph Hoyt
Published: August 2005

As the satellite is slowed down by the tenuous upper atmosphere, its period is shortened; the greater the energy losses, the greater the shortening of the period. This surprising result is due to the fact that at the vertices of the elliptic path, the loss of potential energy alone is greater than the loss of total energy caused by any single retarding impulse; a retarding impulse at any point of the satellite's path, therefore, produces at some other point of the path a gain of kinetic energy greater than the loss of total energy at the point at which the impulse was received.
Problems on Artificial Satellites of the Earth Fizika V Shkolye 18, 80–84 (May–June, 1958)
Authors: Kruglak Haym
Published: August 2005

Problems on artificial satellites are proposed by four physics teachers in the USSR.
Twin Paradox in Special Relativity
Authors: Romer Robert H.
Published: August 2005

The familiar “traveling twin paradox” is discussed in a particularly simple manner, using special relativity only. The asymmetrical aging of the twins is predicted using only the relativistic definition of simultaneity and the relativistic time dilatation. Possible objections to such a treatment are discussed.
Gamma Rays of Low Energy in the Cosmic Radiation at Sea Level
Authors: D'Angelo N.
Published: August 2005

A study of the cosmic gamma rays of low energy at sea level by means of a NaI crystal spectrometer is described. No gamma-ray lines of direct atmospheric origin are found in the energy region investigated.
Summer Physics Program for Talented High School Students
Authors: Day J. W.
Published: August 2005

A report on the physics course offered at Texas Technological College during the summer of 1958 for especially gifted high school students. This course was sponsored by the Texas Education Agency and financed by a grant from the Fund for the Advancement of Education.
Moments of Inertia of Skeleton Figures and Shells
Authors: Satterly John
Published: August 2005

By a skeleton figure is meant the figure composed of the edges of all the plane surfaces of the figure. Thus a skeleton triangle is just the three sides of the triangle and the skeleton cube is just the twelve edges. Theoretically a skeleton figure can have no mass but for purposes of calculation the edges are assumed to have uniform linear density. Skeleton triangles are considered first followed by a summary for skeleton rectangles, polygons, polyhedra, hollow cones, spherical caps, anchor rings, and ellipsoids. The formulas quoted have been checked by experiments with models.
Michelson on Measurement
Authors: Lagemann Robert
Published: August 2005

At various times A. A. Michelson attributed to an unnamed physicist the remark “… the future truths of Physical Science are to be looked for in the sixth place of decimals.” The circumstances surrounding this famous comment are related, and the hypothesis is offered that it was Maxwell, or possibly Kelvin, whom Michelson was quoting.
Anniversaries in 1959 of Interest to Physicists
Authors: Barr E. Scott
Published: August 2005

During the year 1959 there will be major anniversaries of birth or death for 22 men who have contributed importantly to the development of physics. Brief accounts of their lives and contributions are presented here.
Recent Advances in Physics
Authors: Park David
Published: August 2005

This is an elementary review covering recent experimental and theoretical developments in three areas: liquid helium, superconductivity, and properties of elementary particles. Under the last heading are discussions of the nucleon form factors and possible excitation states, and of the universal Fermi interaction.
Inexpensive Recording Microdensitometer
Authors: Purbrick R. L.
Published: August 2005

A simple recording microdensitometer constructed largely from government surplus property is described.
On a Generalization of the Lagrange Function
Authors: Borneas M.
Published: August 2005

Some mechanical aspects of a generalization with s-order derivatives of the Lagrange function are examined. The fundamental equations of a generalized Lagrangian mechanics are established
Accident and Professor Röntgen
Authors: Romer Alfred
Published: August 2005

Though his own paper is wonderfully clear, the circumstances under which Röntgen discovered x-rays are completely obscure. Contemporary accounts are few, uninforming, and unreliable. It is certain that Röntgen was working with Lenard rays in the summer of 1894, but he seems to have made little use of Lenard's special equipment when working with x-rays in the autumn of 1895. Röntgen's discovery amounts to more, however, than the observation of the rays; it includes also his thorough exploration of their properties.
Presentation of the Concept of Mass to Beginning Physics Students
Authors: Jackson Herbert L.
Published: August 2005

It is suggested that beginning students be introduced to the concept of mass by means of a discussion of the various phenomena in which it plays an essential role rather than via a formal definition.
Harmonic Oscillator Wave Packets
Authors: Epstein Saul T.
Published: August 2005

Time-dependent operators are used to find harmonic oscillator wave packets which oscillate without change in shape. The results are in agreement with those of Senitzky and others. Some useful averages are computed for these packets and some comments are made on the classical limit.
Graduate Schools for Physicists
Authors: Weller Richard I.
Published: August 2005

Factors affecting the choice of graduate schools are outlined. A quantitative ranking of graduate schools offering doctoral programs in physics is presented.
Relativistic Mechanics of a Particle
Authors: Park David
Published: August 2005

The dynamics of a particle in special relativity can be developed in a form analogous to that of Newtonian mechanics. One starts with the observation that the four-vector generalization of the Newtonian momentum and the Lorentz transformation are two complementary but equivalent means for describing the behavior of a body in motion. This suffices to determine the four-vector unambiguously, and the laws of dynamics are conveniently expressed by the assertion that this vector satisfies a conservation law. Whether or not a particle's rest mass is conserved in an interaction is undecided by this principle, but is shown to be determined by the nature of the interaction involved.
Spinor Theory and Relativity. II
Authors: Payne W. T.
Published: August 2005

The various kinds of second-rank spinors are defined; geometric representations are given for two special cases; and the applications of spinor theory to relativistic quantum mechanics and to electromagnetic theory are studied.
Angular Momentum in Sphero-Conal Coordinates
Authors: Spence R. D.
Published: August 2005

Angular momentum eigenfunctions obtained by separation of variables reflect the symmetry of the coordinate system in which the variables are separated. The sphero-conal angular momentum eigenfunctions lack the z axis symmetry of their spherical counterparts and are therefore particularly useful in dealing with certain physical problems which exhibit the same lack of symmetry. The theory of the sphero-conal eigenfunctions is outlined. Graphs of the eigenfunctions and eigenvalues for l = 1, 2, 3, 4 are given. The eigenvalues are interpreted in terms of certain operators and semiclassical pictures of the motion of the angular momentum vector. Applications considered are the energy levels of the asymmetric top molecule and a nucleus with an electric quadrupole moment in an electric field gradient.
Effect of the Earth's Magnetic Field on the Motion of an Artificial Satellite
Authors: Jefimenko Oleg
Published: August 2005

The effect of the earth's magnetic field on the motion of an artificial satellite moving in a circular orbit in the plane of the magnetic equator of the earth is discussed. Approximate formulas for the current induced in the satellite and for the resulting induction drag are obtained. The current in a conducting satellite of an average size at an altitude of several hundred kilometers is estimated to be of the order of milliamperes. The induction drag may exceed the friction drag for satellites of large dimensions and for elongated satellites.
Equipment for the Determination of Magnetic Susceptibilities
Authors: McMillan J. A.
Published: August 2005

Equipment for the determination of magnetic susceptibilities by the Gouy method utilizing an electromagnet and a Westphal specific gravity balance is described. Using Mohr's salt as a standard, the paramagnetism of salts like pentahydrated copper sulphate can be determined within 4%. The diamagnetism of some substances, such as water, can also be measured to one significant figure. Experimental results are given.
Note on the Dual Natures of Light and of Matter
Authors: Ikenberry Ernest
Published: August 2005

L. de Broglie's heuristic interpretation of the equations E = hν, p = h/λ is applied in deriving Planck's radiation law and to the Schrödinger and Dirac equations.
On the Physics of Fluids
Authors: Seeger Raymond J.
Published: August 2005

In connection with the concept of the “physics of fluids” as part of a broad, interdisciplinary field, the historical development of the concept of the fluid itself is outlined. The three major fields are hydrostatics, hydrodynamics, and aerodynamics. The use of the fluid concept in physics generally is mentioned. The paper concludes with modern fluids, i.e., the understanding of real fluids under the major headings of (1) ordinary fluids, involving stability, anomalous viscosity, and free surfaces; (2) fluids under unusual conditions, such as high-speed, high-temperature, low-density, and quantum fluids; (3) large-scale phenomena involving fluids, those that are local in character, such as planetary atmosphere, and those that are cosmic, such as magnetohydrodynamics. Attention is called to the use of high-speed computing machines and the understanding of real fluids.
On Colleagues and Clients
Authors: Kirkpatrick Paul
Published: August 2005

Teaching physicists will do well to overcome their present conditioned attitude of automatic opposition to professional educationists. We are still teaching by traditional methods which lack scientific justification; the eventual establishment of rational procedures in instruction will require sympathetic collaboration between teachers in the several fields and scholars concerned with the philosophy, psychology, and techniques of instruction in general. Although instruction and research operate as an established partnership in our universities there are many aspects of competition and interference between them. The growth of research to its present status as a dominant university activity was in part at the expense of the teaching function. It is no longer necessary to nurture research by depressing the interests of instruction, and it would be well for the universities and their students if the place of preference which research has been enjoying were now to be yielded, at least temporarily, to the teaching activity. A crying defect in science instruction is the use of untrained and inexperienced graduate students as instructors, a practice employed by universities but to a lesser degree by liberal arts colleges and scarcely paralleled at all in the public school system. Increasing enrollments are threatening the personal relationship between teacher and student, particularly the teacher's detailed comprehension of his students as individuals in need of specific and nonidentical services.
Heisenberg's Contracting Wave Packets
Authors: Landé Alfred
Published: August 2005

The discontinuous contraction of a wave packet preceded and followed by a continuous expansion controlled by Schrödinger's equation is a much discussed difficulty in the quantum theory of measurement. It is shown to rest on a mistaken interpretation of Schrödinger's equation as a “process equation” and on two different usages of the word “state,” first as a subjective expectation state of an observer, then as the physical state of the object, and finally as a subjective expectation state again, with a sudden change of word meaning which of course has no place in a physical theory.
Who Was Earnshaw?
Authors: Scott William T.
Published: August 2005

The originator of the theorem that stable equilibrium is impossible for a particle under inverse-square forces alone is identified as the Rev. Samuel Earnshaw (1805–1888), and the original reference is located [Trans. Cambridge Phil. Soc. 7, 97–114 (1842)].
Physical Sciences in Our Secondary Schools
Authors: Powers Samuel Ralph
Published: August 2005

This paper covers early recognition of physical sciences; two guiding objectives; development of uniform college entrance courses; trends in enrollments; textbook and laboratory manuals; methods in teaching; supporting claims for present courses; the teacher's education; suggested new developments in physical science courses and in the preparation of teachers with proper education and specialization for success in their work.
Graduate Examinations in Physics
Authors: Strandberg M. W. P. , Gokhale B. V.
Published: August 2005

The extensive and intensive character and the number of graduate level examinations for doctoral candidates in physics are discussed in relation to the probable objectives which the examinations are intended to serve. Results of a recent survey of graduate examination procedures in universities in the United States are presented.
Simple Microwave Resonance Spectrometer
Authors: Gravlin E. S. , Cowen J. A.
Published: August 2005

A relatively simple and inexpensive apparatus for the observation of electron paramagnetic resonance at microwave frequencies is described. The apparatus is designed for the undergraduate laboratory but, with some modification, may be used as a research tool.
Résumé of Atomic Constants
Authors: Bearden J. A. , Thomsen John S.
Published: August 2005

Some of the more interesting conclusions of a 1955 survey of atomic constants were the following. (1) Most familiar experiments described in general physics courses now carry negligible weight. (2) Probable errors in values of the constants are of the order of 10 ppm. (3) Use of x-ray “h/e experiments” has been a source of error in previous evaluations; theoretical interpretation of these results involves considerable uncertainty. (4) Electrochemical values of the Faraday are now in fair agreement, but their mean differs significantly from the value obtained by electromagnetic experiments. (5) There is still some evidence for variation of the velocity of light with frequency; however, the negative case appears stronger and is further strengthened by newer data.

Recent developments are discussed and the authors' analysis compared with the 1955 study of Cohen, DuMond, Layton, and Rollett. Recommended values for principal constants are given. These include a correction for an error in the Karplus and Kroll calculation of the anomalous moment of the electron, but do not reflect any experimental data reported since 1955.
Large Amplitude Motion of a String
Authors: Keller Joseph B.
Published: August 2005

The motion of a string is investigated without assuming that the amplitude of the motion is small or that the motion is purely transverse. By assuming a special stress-strain law for the string material, we find that the three components of motion are independent and that each component satisfies the usual linear wave equation. The derivation of these exact results seems to be simpler than the usual approximate derivations. It is also shown that the special stress-strain law employed is the only one for which purely transverse motion is possible.
Dislocation Theory of the Formation of Small-Angle Boundaries
Authors: Atwater H. A.
Published: August 2005

The elastic interaction energy of some simple arrays of edge dislocations is calculated as a function of position of one member of the array on its glide plane. The resulting energy relations are interpreted as binding potentials for the capture of a dislocation by the array. This mechanism is assumed to be operative in the formation of small-angle grain boundaries in crystals.
Two Contrasting Theories of Capillary Action
Authors: Chapin Ernest K.
Published: August 2005

Two theories regarding the mechanism of the rise of a liquid in a capillary tube appear in current textbooks of physics and physical chemistry. In one theory the rise is attributed to hydrostatic pressure; in the other, the liquid is drawn up the tube by a climbing meniscus. Evidence is presented in favor of the latter theory.
Early Development of Particle Accelerators
Authors: Livingston M. Stanley
Published: August 2005

Professor Ernest O. Lawrence of the University of California conceived the idea of the cyclotron in 1929 and reported the principle in Science in 1930. The first successful experimental demonstration of cyclotron resonance was by Livingston in a Doctorate thesis completed in April, 1931, using a 4-in. pole magnet and producing H2+ ions of 80 000 ev energy. By late 1931 Lawrence and Livingston completed an 11-in. cyclotron which produced H+ ions of 1.2 Mev, and which was used with others in the laboratory for disintegration experiments. By late 1932 the “27-in.” cyclotron was completed and was in service for research experiments; the energy and intensity were steadily increased during 1933 and 1934 and both H2+ and D+ ions of up to 5 Mev energy became available. During these early years many young scientists joined the group to do research on disintegration reactions, neutron properties, and induced radioactivity, under the stimulating leadership of Professor Lawrence.