The Electrical review Volume 6 - Softcover

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1878 edition. Excerpt: ...circuit forms a coil round a small core of soft iron fastened to the end of a steel magnet. Now, lines of magnetic force pass more freely through iron than through any other substance. They will go out of their way in order to pass through iron instead of air. Hence a large proportion of the lines of force belonging to the magnet pass through the iron core and, therefore, through the coil, even though there is no iron beyond the core, so that they have to complete their circuit through air. But if another piece of soft iron is placed near the end of the core, 1t will afford greater facilities for lines which have passed through the core to complete their circuit; and so the lines belonging to the magnet will crowd still closer together, to take advantage of an easy passage through the core and the iron beyond it. If, then, the iron is moved nearer to the core, there-will be an increase in the number of such lines, and, therefore, a negative current in the circuit. If it is moved away there will be a diminution in the number of lines, and a positive current in the circuit. This principle was employed by Page in the construction of one of the earliest magneto-electric machines, but it was reserved for Professor Bell to discover that the vibrations of a tinned iron plate, set in motion by the voice, would produce such currents in the circuit as to set in motion a similar tin plate at the other end of the line. (To be continued.) Expose des Applications delelectricite. Par Le Comtb Du Moncel, &c., &c. Tome V. Applications Industrielles. Paris: Eugene Lacroix, 54, Rue des Saints-Peres. In the work before us the indefatigable Comte du Moncel brings his arduous undertak1ng to a close. The five volumes with which he has enriched scientific...