560 THE POPULAR SCIENCE MONTHLY. 



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 Man- 

 chester 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 cor- 

 responding 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 Elec- 

 trical Force without the Use of Permanent Magnetism." ^ On the 14th 

 of February a paper from Sir Charles Wheatstone was received, bear- 

 ing the title, " On the Augmentation of the Power of a Magnet by the 



' Pa"-e and Moio-no had previously shown that the magneto-electric current could 

 produce powerful electro-magnets. 



2 Mr. Wilde's paper is published in the "Philosophical Transactions " for 1867, p. 

 89. My opmion regarding Wilde's machine was briefly expressed in a report to the 

 Elder Brethren of the Trinity House on the I'Zth of May, 1866 : " It gives me pleasure to 

 state that the machine is exceedingly effective, and that it far transcends in power all 

 other apparatus of the kind." 



2 A paper on the same subject, by Dr. Werner Siemens, was read on the lYth of 

 January, ISGV, before the Academy of Sciences in Berlin. In a letter to "Engineering," 

 No. 622, p. 45, Mr. Robert Sabine states that Professor Wheatstone's machines were 

 constructed by Mr. Stroh in the months of July and August, 1866. I do not doubt Mr. 

 Sabine's statement ; still it would be dangerous in the highest degree to depart from the 

 canon, in asserting which Faraday was specially strenuous, that the date of a discovery 

 is the date of its publication. Toward the end of December, 1866, Mr. Alfred Varley 

 also lodged a provisional specification (which, I believe, is a sealed document) embody- 

 ing the principles of the dynamo-electric machine, but some years elapsed before he made 

 anything public. His brother, Mr. Cromwell Varley, when writing on this subject in 

 1867, does not mention him ("Proceedings of the Royal Society," March 14, 1867). It 

 probably marks a national trait that sealed communications, though allowed in France, 

 have never been recognized by the scientific societies of England. 



