Page:Popular Science Monthly Volume 14.djvu/578

560 Faraday's discovery, which opens out the prospect of our being able to apply the electric light to public use.

In 1866 a great step in the intensification of induced currents, and the consequent augmentation of the magneto-electric light, was taken by Mr. Henry Wilde. It fell to my lot to report upon them to the Royal Society, but before doing so I took the trouble of going to Manchester to witness Mr. Wilde's experiments. He operated in this way: Starting from a small machine like that worked in your presence a moment ago, he employed its current to excite an electro-magnet of a peculiar shape, between whose poles rotated a Siemens armature; from this armature currents were obtained vastly stronger than those generated by the small magneto-electric machine. These currents might have been immediately employed to produce the electric light; but instead of this they were conducted round a second electro-magnet of vast size, between whose poles rotated a Siemens armature of corresponding dimensions. Three armatures therefore were involved in this series of operations: 1. The armature of the small magneto-electric machine; 2. The armature of the first electro-magnet, which was of considerable size; and, 3. The armature of the second electro-magnet, which was of vast dimensions. With the currents drawn from this third armature, Mr. Wilde obtained effects, both as regards heat and light, enormously transcending those previously known.

But the discovery which, above all others, brought the practical question to the front is now to be considered. On the 4th of February, 1867, a paper was received by the Royal Society from Mr. William Siemens, bearing the title, "On the Conversion of Dynamic into Electrical Force without the Use of Permanent Magnetism." On the 14th of February a paper from Sir Charles Wheatstone was received, bearing the title, "On the Augmentation of the Power of a Magnet by the