Figure 40. — Schweigger's multiplier. From 

 Schweigger's Journal Jiir Chemie mid Physik, 

 1821, vol. 31, pi. I (after p. 114). 



Figure 41. — Sturgeon's first electromagnet. 

 From Transactions of the Society jor the En- 

 couragement oj the Arts, Manufactures and 

 Commerce, 1824, vol. 43, pi. 3. 



[n the early portion of his studies of the Oersted 

 effect — which led to the foundation of the science of 

 electrodynamics ''* — Andre-Marie Ampere pointed out 



Figure 42. — Sturgeon's later electromagnet. 

 From Philosophical Magazine, 1832, vol. II, 

 p. 201. 



that the combination of a wire and a magnetic needle 

 was an indicator of an electric current and was in 

 contrast to the (electrostatic) electrometer that 

 detected an electrical tension or voltage. Although 

 it was not the first device so called, Ampere proposed 

 that this new combination of a wire and a magnetic 

 needle be called a galvanometer." Independently 

 of Ampere and of one another, Schweigger and 

 Poggendorff, repeating Oersted's experiments, found 

 they could increase the effect of the current on the 

 needle by rolling the wire into a coil and placing the 

 needle inside. Schweigger called his coil a "Ver- 

 staerker" or multiplier (fig. 40),'^'' while Poggendorff 

 named his a "Condensator" or condenser.^' 



"* A. M. Ampere, Theorie des phenomenes eleclro-dynamiqnes, 

 uniquement deduite de I' experience , Paris, 1826. 



^i- Journal de Paris, September 18, 1800, vol. 8, no. 368. 

 A. M. Ampere, "De raction mutuelle de deux courants elec- 

 triques," Annates de chimie et de physique, 1820, vol. 15, pp. 59-76. 



66 J. S. Schweigger, "Zusaetze zu Oersted's elekbro-mag- 

 netische Versuchen," Allgemeine Literatur-Zeitung, 1820, no. 296, 

 cols. 622-624; "Noch einige Worte iiber diese neuen elektro- 

 magnetischen Phanomene," Schweigger's Journal, 1821, vol. 

 31, pp. 35-41. 



67 J. C. Poggendorff, "Account of the New Galvano-Mag- 

 netic Condenser," Edinburgh Philosophical Journal, 1821, vol. 5, 

 pp. 112-113. 



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