Abstract
THIS is a most interesting introduction to Maxwell's theories about electromagnetic actions. The whole question of generalised coordinates is introduced by means of models that enable the student to make a concrete picture to himself of a particular case of what he is studying. Some people may prefer to study subjects in the most general form, but the majority find very great difficulty in working out any advance on what they are taught by others without the assistance of some concrete case. In the case of most students it certainly helps them very much indeed to be provided with simple examples. Models may often do even more than facilitate the path of the student, they have before now pointed the way for the discoverer. As the mathematical part of Maxwell's theory is so largely an application of the principles of generalised coordinates this introduction to his theory is eminently interesting and suggestive. It is perhaps more suited to the state of scientific development on the Continent than in England. German and French electrical ideas had been so bound up with Coulomb and Ampère's laws of action at a distance that even the formulæ of Weber and Clausius which postulated propagation in time did not shake their faith in action at a distance, attracting and repelling electricities and currents and poles. Even yet Poincaré cannot get over the Coulomb law foundation of electrostatics. To such ideas a dynamical foundation such as Boltzmann has given should give a new direction. The whole process by which the electric current, the electrification, the magnetic pole, appear as generalised coordinates is brought out. The only objection that can be raised to the method from a British point of view is that the method is not drastic enough. It panders to the weaknesses of those who look upon the electric current as the important thing. It almost neglects the medium. It does not emphasise the connection of electric force and displacement, magnetic force and induction. It does not go even so far as Maxwell in formulating a theory as to the nature of the medium. It is too content with symbols. It introduces the propagation of the action through the medium almost as indirectly as Maxwell does. The forces and the displacements should be the foundations of electromagnetic theory and not the equation in generalised coordinates
Vorlesung über Maxwell's Theorie der Electericität und des Lichtes.
By Dr. Ludwig Boltzmann. Part I. pp. 139. (Leipzig: Johann A. Barth.)
Article PDF
Rights and permissions
About this article
Cite this article
Our Book Shelf. Nature 48, 435 (1893). https://doi.org/10.1038/048435a0
Issue Date:
DOI: https://doi.org/10.1038/048435a0