Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. Excerpt from book: Section 3mutual action of two electric currents, was led, by means of calculation, to connect with the same principle the action of magnets upon each other, and the mutual action of electric currents and magnets. Having realised by experiment certain cases of equilibrium, to which he had been led by mathematical analysis, he succeeded in finding the elementary law of the mutual action of two infinitely small portions of electric currents, and in establishing, with M. Savary, the identity between a magnet and a solenoid, that is to say, an assemblage of closed( electric currents, all moving in the same direction, and perpendicular to a common rectilinear or curvilinear axis. Ampere's theory, however, failed in certain points of direct experimental demonstration. M. Weber succeeded in filling up this gap, demonstrating by certain experiments, which were as accurate as they were delicate, the complete identity between the laws that regulate the mutual action of two solenoids, and those to which the mutual action of two magnets is subject. This important result has been the means of removing all doubts, that might still have remained, as to the accuracy of Ampere's theory, and consequently has given to it a degree of probability, which approaches almost to certainty. Weber's apparatus is composed of two rings, formed of copper-wires covered with silk, and arranged with perfect regularity. The interior of one of the rings contains a space sufficiently large for the other to move freely within it. When an electric current is sent through the wire of each of the two rings, the fixed one, which is the outer of the two, tends to make the inner and movable one turn with a force that is at its maximum when their two centres coincide and the planes of their currents are perpendicular to each other. The diameter of the two...