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The overwhelming majority of important papers in physics are written by physicists. But the physician Julius Robert Mayer (1814-1878, see photo) did a valid theoretical calculation of the mechanical equivalent of heat just before Joule reported on his results from his well-known paddle-wheel experiments. Joule is well-known to physics people and Mayer is a relatively obscure and unknown name. Joule was part of the physics establishment; Mayer was not. Joule's paddle-wheel experiments were easy to understand, and physics people appreciated the painstaking manner in which he made corrections in his experiments. The fame of Joule is well-deserved. On the other hand, Mayer's work is not traditional and there will almost certainly never be a Mayer physics laboratory experiment. We can admire the tenacity with which Mayer pushed his priority case, but that is all.

Francois Arago brought the news of Oersted's discovery of the effect of a current-carrying wire on a magnet to Paris on September 4, 1820. Andre-Marie Ampere and the team of Jean-Baptiste Biot and Felix Savart quickly set to work to establish a quantitative law for this effect. Their approaches were quite different. This paper describes the experiments of Blot and Savart and their results. It also briefly discusses the approach of Andre-Marie Ampere, who coined the name 'electrodynamics' and whose fundamental formula gave the force between two infinitesimal current elements. Ampere's formula fell into disuse after the advent of Maxwell's field approach. Biot and Savart's experimental law, in the modern form of the differential magnetic field due to a current element, became the standard starting point for calculating the magnetic field due to steady currents.

A course requiring more intuitive and historical study of physics, rather than mathematical problems, is offered to liberal art students at the College of Staten Island, New York. A laboratory closely follows classroom studies of Ptolemy and Copernicus, Galileo and telescopic discovery, the role of scientific discovery and the church, and studies by Christiaan Huygens and Newton.

Christiaan Huygens was probably the first person to solve the problem of elastic collisions. He did this in the 1650s when he was only in his early twenties. The first formal publication of his general rule for the outcome of a head-on hard collision was in March 1669 in the Journal des Scavans. Our present paper describes in detail Huygens' work on elastic collisions. We focus particularly on how Huygens' instinct for symmetry led him to a solution in the center-of-gravity reference frame. He readily transformed this solution to other frames using what we now call the Galilean velocity transformation. Huygens' symmetry approach is quite different from the modern description of collisions using Newtonian action and reaction forces.

Christiaan Huygens was the first person to discover the general formula for the center of oscillation length of a physical pendulum. He was motivated to do this work by his interest in constructing accurate pendulum clocks. It is remarkable that Huygens arrived at his brilliant solution about a quarter of a century before the publication of the first edition of Newton's Principia. This paper analyzes Huygens' little-known derivation in detail. We take particular note of Huygens' ingenious idea of having the moving physical pendulum 'theoretically explode' into constituent pieces which then rise until their kinetic energy is exhausted.

Newton's concept of force was developed over a period of time, starting with a collisional model in his Waste Book, and culminating in his measure of the centripetal force at a point found in De Motu and again in Principia, Book I, Prop. VI. Newton kept developing his force concept, adding to it and making it many faceted. This rich concept of force has often posed difficulties for historians of science [for example, R. S. Westfall, Force in Newton's Physics (MacDonald and American Elsevier, New York, 1971) and J. Herivel, The Background to Newton's Principia (Oxford U.P., New York, 1965)] and others. These difficulties are related to at least six things as follows: (1) lack of understanding that Newton's 'motive force' is an abbreviation for 'motive quantity of a force,' so that Newton's 'motive force' and his 'foce' are not two different types of force. Motive force (motive quantity) is used to quantify force; (2) lack of understanding of Newton's model for instantaneous impulses; (3) lack of understanding that although Newton's motive force has directionality Newton added it as a scalar in his analysis of uniform circular motion; (4) lack of understanding of Newton's polygon model; (5) lack of understanding that Newton's measure of the motive value of a force, the motive force, was always used to obtain a comparative measure of forces in his early mechanics; and (6) lack of understanding that Newton's Prop. VI measure of centripetal force at a point permitted Newton to bring the time dimension into his motive force concept, thus developing it into something very close to our modern definition of force. This paper analyzes Newton's development of his motive force concept, and discusses the difficulties that some scholars have had with various aspects of this concept.

In his letter of 6 January 1679/80 Hooke wrote to Newton 'in truth I agree with You that the Explicating the Curve in which a body Descending to the Center of the Earth, would circumgyrate were a Speculation of noe Use yet' [The Correspondence of Isaac Newton, edited by H. W. Turnbull (Cambridge U.P., Cambridge, 1960), Vol. 2, p. 309]. In these words, Hooke referred to a hypothetical problem which he was discussing in a correspondence with Newton. The problem was that of determining the orbit of a body moving inside a narrow cut made centrally across the Earth. This was perhaps the very first inverse central force problem to be attacked by Newton. Newton seems to have used his instantaneous impulse technique to provide a drawing of a solution that was almost exact. This paper explores this fascinating early solution of an inverse central force problem.

The Ampere Circuital Law was not developed by Ampere. The law, which is correlated with field theoretic concepts, is a misnomer. Arguably, it was formulated by Maxwell who based it on the works of Ampere. The naming of the law was probably the result of a desire to associate a critical law of magnetism with someone considered as the historical father of electrodynamics which was Ampere.

The involvement and contributions of Kelvin with the laying of the trans-Atlantic cable are described.

Presbyopia refers to receding of the near point of the eye due to old age. For this condition, usage of inexpensive reading glasses is a good option from a pharmacy, which in turn purchases it from diopters. The glasses are purchased based on the strength of the lens needed for the particular presbyopic eye.

'Maxwell to Einstein and Beyond', a course designed for liberal-arts students to study the ideas of major contributors in the field of physics is demonstrated.

A collision experiment originally carried out by Isaac Newton is discussed. The experiment was conducted with spheres attached to two pendulums and then released to collide into each other.

This article presents the numerical solution for the magnetic field of a current-carrying circular turn at any point. Textbook solutions usually confine themselves to the solution on the axis of the turn because the on-axis Biot-Savart law integration is easy to do in closed form. As the knowledge and use of hand-held calculators and computers has increased, the numerical solution of this problem for off-axis points has become possible by students in the introductory calculus-based course. A good way to do this problem is in the physics laboratory where actual measurements can be compared with the values obtained from a numerical solution.