[ I I I 1 I . I I I I M DiBimitr* 



Figure 17. — Serrin's modele Suisse arc-light 

 regulator. From Bulletin de la Societe d'En- 

 couragement pour P Industrie Nationale, 1861, vol. 

 8, pi. 234. 



could electrolyze water and was a great improve- 

 ment over Faraday's." 



In the month following his Sorbonne demon- 

 stration Ampere reported how Pixii had built a much 

 larger generator than before and had modified 

 Ampere's commutator switch so that it could be 



2- Jean N. P. Hachette, "Nouvelle Construction d'une ma- 

 chine electromagnetique," Annates de chimie et de physique, 

 1832, vol. 50, pp. 322-324, and "De I'Action chimique produite 

 par rinduction electrique; decomposition de I'eau," Annates de 

 chimie et de physique, 1832, vol. 51, pp. 12-1 A; Charles Jackson, 

 "Notice of the Revolving Electric Magnet of Mr. Pixii of 

 Paris," American Journal of Science, 1833, vol. 24, pp. 146-147; 

 Gehler's physikatisches Woerterbuch, Leipzig, 1836, new ed., 

 Band 6/2, pp. 1177-1180. 



used with the generator (fig. 22).^^ A cam on the 

 axis of the armature actuated the commutator that 

 reversed the directions of the alternations at the 

 appropriate time so as to obtain a more or less unidi- 

 rectional current. The magneto now provided a 

 current similar to that from the chemical cell, and 

 the gases resulting from the electrolysis of water 

 were in the correct proportions. 



Since it was also possible to rotate the coils making 

 up the armature and to keep the magnets stationary, 

 such modifications soon appeared. One of the first 

 of these was described in a report given by the Rev. 

 William Ritchie in March 1833 on a magnetoelectric 

 generator (fig. 23) that he had worked out during the 

 previous summer.-^ Ritchie's armature, in the form 

 of a disk that rotated about an axis perpendicular to 

 its plane, consisted of four coils, 90° apart, that were 

 mounted between two wheels with the axes of the 

 coils parallel to the axis of the supporting wheels. 

 When the armature was rotated, the coils passed in 

 succession between the poles of a permanent magnet 

 and produced an alternating current. In order to 

 obtain a unidirectional or direct current from the 

 rotating armature, Ritchie devised a commutator 

 switch that was mounted directly on the axis of the 

 armature. 



Other, more practical forms of the Pixii magneto 

 generator were devised a few years later by instrument- 

 makers Joseph Saxton of Washington and Edward 

 Clarke of London.-* Their magnetos became quite 

 popular for laboratory demonstrations and for medical 

 experiments. Saxton modified Pixii's generator by 



23 Andre M. Ampere, "Note de M. Ampere sur une experience 

 de M. Hippolyte Pixii, relative au courant produit par la 

 rotation d'un aimant, ^ I'aide d'un appareil imagine par M. 

 Hippolyte Pixii," Annates de chimie et de physique, 1832, vol. 51. 

 pp. 76-79. 



-^ VViUiam Ritchie, "Experimental Researches in Electro- 

 Magnetism and Magneto-Electricity," Philosophical Transac- 

 tions, 1833, vol. 123, pp. 313-321. 



25 Joseph Saxton, "Description of a Revolving Keeper 

 Magnet, for Producing Electrical Currents," Journal of the 

 Franklin Institute, 1834, vol. 13, pp. 155-156; Edward M. 

 Clarke to the editors. Philosophical Alagazine, 1836, vol. 9, 

 pp. 262-266; "A Description of a Magnetic Electrical Ma- 

 chine," Annals of Electricity, 1837, vol. 1, pp. 145-155; "Reply 

 of Mr. E. M. Clarke to Mr. J. Saxton," Philosophical Magazine, 

 1837, new ser., vol. 10, pp. 455-459; "Account of a Series of 

 Experiments Made with a Large Magneto-Electrical Machine," 

 Transactions and Proceedings oj the London Electrical Society, 1837— 

 1840, vol. 1, pp. 73-76. 



346 



BULLETIN 228: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



