Phenomena of continuous Rotation, arising from the mutual Magnetisation of soft Iron by Electric Currents Vibratory Movements and molecular Effects determined in Magnetic Bodies by the Influence of Electric Currents Electro-dynamic Induction produced by Electric Discharges 403 Influence that is exercised upon Induction by Metal Masses principally Magnetic, placed in the Interior of Bobbins, and ACTION OF MAGNETISM UPON ALL BODIES. Notions relative to an Action of the Magnet upon all Bodies, other than that arising from Induction Distinction of Bodies into Magnetic and Diamagnetic Theories of Diamagnetism, and diamagnetic Polarity Influence of Magnetism upon Flames and Gases, and upon Magnetic Properties of Crystals, and the Magneto-crystalline Action of transparent Bodies, subjected to Magnetic Influence, Determination of the magnetic rotatory Power of different Examination of the Nature and of the Cause of the rotatory Note relative to the Measure of magnetic Forces 533 § 1. General Expression of the Effect of Terrestrial Magne- § 2. Laws of the Movement of the Needle, when compelled P. 437. 1. 19. ERRATUM AND ADDITION. Instead of inductive read induced. P. 321. At the end of Chap. III., add “M. Wertheim has shown that the torsion and detorsion of a bar of soft iron, magnetized by an electric current, produce a change in this magnetization; sometimes an increase, at other times a decrease, according as they occur in the direction in which the bar has been already twisted, or in a contrary direction. These experiments prove the fact that magnetization and demagnetization are accompanied by a molecular change in the iron; and that there is an intimate relation between the magnetization of this metal and the arrangements of its particles." TREATISE ON ELECTRICITY IN THEORY AND PRACTICE. PART I. PRELIMINARY NOTIONS. CHAPTER I. MANIFESTATION OF ELECTRICITY. Electricity developed by Friction. WHEN a stick of wax, a piece of amber, or a glass rod, is rubbed with very dry cloth, these bodies are observed, by the effect of the friction, to acquire the property of attracting small fragments of paper, small balls of elder pith, and light substances in general which are placed in their neighbourhood. This attraction occurs at a distance; and the substances upon which it is exercised remain adhering to the surface of the rubbed body by which they are attracted; or rather are alternately repelled and attracted by this body (Fig. 1.). The bodies, upon which the friction has developed the property that we have just explained, are said to be electrised; and the property itself, and the agent to which it is supposed to be due, is named electricity. This name electricity is derived from the Greek word eтpov, signifying amber, the first substance, it is said, upon which electrical properties were observed. Fig. 1. 3 |