mena that are produced by currents and electric discharges, and on the application of which these properties of electricity are susceptible. Finally, there is the study, that is being prosecuted at once by many philosophers, of the sources of electricity, and of the laws by which they are regulated. Every day there are new names, introducing into the science of electricity their contingent of discoveries; and old names which are far from ceasing to furnish theirs. There is Becquerel continually reappearing with the results, as various as they are numerous, which he derives from his galvanometer; there is Faraday astonishing the scientific world, after his induction currents, with diamagnetism, and all the other productions of his creative genius.

This very imperfect and rapid sketch of the features that would be presented by a chronological exposition of the theories on the phenomena with which electricity has been enriched during the past century, is sufficient to show the confusion that would be created in the best organized brain, by this mode of studying. In order, therefore, that this study may be conducted in an intelligent and sound manner, it is indispensable to introduce into it a methodical classification, which, by grouping under the same head phenomena of the same order, facilitates the explanation of them and their retention in the memory. To the attainment of this end, have my endeavours been directed.

The examination of electric phenomena very soon leads us to discover two very distinct points of view; one of which comprehends the general laws to which electricity is subjected, whether in a state of rest or in a state of motion; and of which the other comprehends the various effects that arise from the action of different bodies upon electricity, and the action of electricity upon these bodies. In the first point of view, as the ponderable substance only serves for the manifestation of the general properties

of the electric agent, its particular nature is of no importance; it is sufficient that it be an insulating or a conducting body. In the second point of view, the body plays the principal part; consequently its physical and chemical constitution exercise a preponderating influence over its relation with electricity. From these two very different objects, under which the study of electricity may be viewed, arises evidently the necessity of studying separately the facts that appertain to the one, and those that are comprehended under the other. The sources and the applications of electricity also form two parts, that are very distinct from each other, and from the preceding. These few words will suffice to explain the division that I have been very naturally led to adopt.

A First Part, which serves as an introduction, contains a general exposition of fundamental phenomena, and to a description of the principal instruments that are employed, either in producing or in detecting and measuring electricity. The theoretical aud complete explanation of these apparatus, it is true, can only be given further on; but it is quite necessary to become acquainted with them at the very outset of the descriptive part, on account of the services that are constantly being required of them.

The Second Part, entitled Static Electricity, is devoted to the exposition of general phenomena, that is to say, the laws presented by electricity in the state of rest or tension, ―attraction and repulsion, distribution, induction, disguised electricity, theories on the nature of electricity.

The Third Part comprises the general laws of electricity in motion, which constitutes Electro-Dynamics and Magnetism, which is considered to be nothing more than a particular form of dynamic electricity. Different chapters are successively devoted to magnetism, properly so called, to the mutual action of magnetism and dynamic electricity, to magnetization by electricity, to electro-dynamic in

duction, and to the action of magnetism and of dynamic electricity upon all bodies. A distinct chapter is appropriated to magnetic galvanometers, on account of the importance of being well acquainted with these instruments, and of knowing how to manage them, employed as they so frequently are in the physical sciences.

The Fourth Part includes under the title of Transmission of Electricity through different Media, first the description of the phenomena, relating to the mode itself of the propagation of electricity in the interior of bodies, of conductibility, &c. ; then a detailed study of the calorific, luminous and chemical effects that accompany this propagation; and finally the examination of the physiological phenomena, to which it gives rise in organized bodies.

The Fifth Part has for its objects the Sources of Electricity; a subject which can only be conveniently treated of after the study of the general laws which regulate electricity, whether static or dynamic, and of the various phenomena, by which it manifests its passage through bodies. The successive examination of the different physical, mechanical, and chemical actions, which liberate electricity is preceded by a glance into the general causes that produce this liberation, and is followed by a theoretic explanation of electromotor apparatus. The natural sources are studied in their turn, both in their origin and in their effects; animal electricity, atmospheric electricity, terrestrial electricity, which comprehends terrestrial magnetism, are the three forms, under which nature of itself produces electricity; and they consequently form three distinct chapters in this part of the Treatise. Each source is considered not only in respect to the development of the electricity to which it gives rise, but also in the relations that unite it with effects analogous to the producing cause, and which effects the electricity itself is capable of originating; a connection that leads to general consider

ations on the forces of nature, which are replete with interest. Thus heat, chemical action, physiological action are at once the cause and the effect of electricity; and this double form, under which electricity manifests its relation with these three great forces, is a proof of the intimate union by which they are connected both with electricity itself and with each other.

Finally, the Sixth and last Part is devoted to all the various applications of which electricity is susceptible; — electro-chemical applications (gilding, galvanoplastic, &c.), electro-magnetic applications (telegraphy, clocks, &c.), electro-calorific and electro-luminous applications, electrophysiological applications to medicine.

The simple enumeration I have been making of the different points that are treated in my work, though dry and abridged as it may be, is sufficient to enable every mind that is in the least degree inspired with a love of philosophic truths, to perceive the vast extent that electricity occupies in the domain of the physical sciences. It may seem matter for surprise, therefore, to find no place assigned in my division to the study of the great questions which concern the constitution of matter, and the nature of physical forces; and the more so as electricity appears to be the most general form, under which is presented the link that exists between ponderable bodies and immaterial forces. But considerations of that kind, which are more metaphysical than physical, could not be treated with that development which they command in a work of this kind. However, although I have not devoted to them a separate chapter, I have not failed to enter upon that subject, whenever an opportunity presented itself; convinced as I am that, independently of the interest which they offer of themselves, they possess the immense advantage of elevating the mind, by bringing it nearer to the Almighty, whose power is more fully recog

nized, in proportion as we examine more closely the works of creation.

Geneva, November, 1852.

P. S.-Private circumstances had occurred to the author, which compelled him to suspend his labours for a very long time, whence it happened that the printing of his work was interrupted; on which account it has been decided no longer to delay the publication of the first volume, which has been printed for upwards of a year. The publication of the second volume shall not be delayed, and will take place in the spring at the latest.

The French manuscript of this volume was entrusted to the care of Mr. Charles V. Walker, by whom the present translation has been made, and who has carried the work through the press. He will translate the second volume.