Figure 22. — Pixii magneto generator with 

 Ampere's commutator, whiich is shown 

 enlarged at the bottom of the figure. From 

 H. W. Dove and L. Moser, Repertorium der 

 Physik, Berlin, 1837, vol. i, pi. 2. 



by Daniel Davis, of Boston, beginning in the spring 

 of 1838.2" 



Most of the preceding instruments of the 1830"s 

 were essentially laboratory instruments constructed 

 for experimental purposes. One of the earliest 

 commercial applications of magneto generators was 

 made by John S. Woolrich of Birmingham, England, 

 in the following decade. In his patent application of 

 1841, Woolrich described how Saxton generators 

 could be modified for electroplating, and his method 

 seemed feasible enough to be tried by the Elkington 



26 Charles Page, "New Magnetic Electrical Machine of 

 Great Power, with Two Parallel Horse-Shoe Magnets, and 

 Two Straight Rotating Armatures, Affording Each, in an 

 Entire Revolution, a Constant Current in the Same Direction," 

 American Journal of Science, 1838, vol. 34, pp. 163-169; Daniel 

 Davis, Manual oj Magnetism, Boston, 1847, ed. 2, pp. 277-282. 



Figure 23. — Ritchie's magneto generator. The 

 armature was shaped in the form of a disk, 

 in which the coils (r) passed in succession 

 between the poles of the magnet (M). The 

 commutator is at ijgh. From William 

 Ritchie, "Experimental Researches in 

 Electro-Magnetism and Magneto-Elec- 

 tricity." Philosophical Transactions, 1833, ^°1- 

 123, pi. 7 (opposite p. 316). 



firm in Birmingham, the same English firm that had 

 already pioneered in electroplating." 



Three years later Woolrich designed a more am- 

 bitious generator (fig. 29) that was basically similar to 

 Ritchie's. Coils and magnets were added to the 

 Ritchie apparatus so that now a disk armature of 

 eight uniformly spaced coils rotated between the poles 

 of four magnets spaced 90° apart. The whole was 

 built in a wooden framework that was 5 feet 4 inches 

 high, 6 feet wide, and 2 feet deep. Faraday is said to 

 have inspected Woolrich's generator and to have been 

 delighted with this application of electromagnetic 

 induction. The device was sold to the Prime Plating 

 Company, of Birmingham, who used it for many 

 years. 2* 



2' British patent 9431 (August 1, 1841); Mechanics Magazine 

 1843, vol. 38, pp. 145-149. 



2S Industrial Britain, November 1938, no. 74, p. 1 ; J. Hamel, 

 "Colossalc magneto-elektrische Maschine zum Versilbern, und 

 Vergolden," Journal Juer practische Chemie, 1847, vol. 41, pp. 

 244-255. 



350 



BULLETIN 228: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



