juxtaposition that Ampere quickly gave the narro oi 

 galvanometer. 11 It cannot be said thai the scientists 

 of the day agreed thai this instrument detected 01 

 measured "electric current," however. Volta him- 

 seli had referred to the "current" in his original 

 circuits, and Ampere used the word freely and con- 

 fidently in his eleptrodynamu irM-.inii.soi 1820 1822, 

 !>ni ( tersted did nol use it first and many of the 

 German physicists who followed up his work avoided 

 it for several years. As late as l!;i'_\ I'aradav could 

 make onl) the rather noncommittal statement: "B\ 

 current I mean anything progressive, whethei il I" a 

 fluid of electricity or vibrations or generall) pro- 

 gi essh e for© 



Nevertheless, whatever the winds or concepts the) 

 used, experimenters agreed that Oersted's apparatu 

 provided a method ol monitoring the "strength" of a 

 voltaic circuit and a means of comparing, foi example, 

 one voltaic batter) or circuil with another. 



It was perfectly clear, from Oersted's pamphlet, 



that if a compass needle w as del Ire ted clockwise when 



tin wire of a particular voltaic circuil la) above it in 

 the magnetic meridian, the same needle would also 

 he deflected clockwise if the wire was turned end- 

 for-end and placed below the compass needle, 

 without changing the rest of the circuit. Anyone 

 perceiving this fact might deduce, as a matter of 

 Ionic, that if the wire of the circuit was first passed 

 above the needle, in the magnetic meridan, then 

 folded and returned in a parallel path below tin 

 needle, the deflecting effect on the needle would be 

 repeated, and a more sensitive indicator would result, 

 assuming tint an) additional wire introduced has not 

 affected the "'circuit'' excessively. 



Since 1821, historical accounts of the origins of 

 electromagnetism seem to have limited their credit 

 assignments lot tin- conception and observation of 

 this electromagnetic "doubling" effect (or "multi- 

 plying" effect, if the folding is repeated) to three 



" A. M. Ampere, Annates de Chimie et de Physiqui (1820) 

 \ul 15, p. 67. The word "galvanometer" had been used 



mm li earlier l>v Bisiiimi. "On Galvanism and its Medical 

 Applications," The Medical and Physical jituimil (180'J), vol 7, 

 p. i29, for a form of goldleal electroscope shown here in 



figure '-'. but tliis use of the word dues not seem to have been 



adopted by others. 



'- ( )p. cit. (footnote 6), paragraph 283, dated January 18 I I. 

 A similar attitude was expressed in the same scar l>v Christie, 

 Philosophical Transactions oj the Royal Societ) oj London I 18 I 1 1, vol, 

 123, p. 96: "1 adopt the word current as a convenient mode of 

 expression. . . . but I would not he considered as adopting 

 any theoretical views on the subject. . . ." 



persons. Almost without exception, however, these 

 accounts have given no specifii information as to 

 pre< isel) what ea< h ol th< si thn t at i omplished, what 

 physical form their respective creations took, what 

 experiments they performed, and what functional 

 understanding the) apparentl) had of the sii 

 The usual statement is simpl) thai a compass needle 

 was placed in a coil of w ire. " The mam purpose ol 

 the present review is to recounl some ol these details 



The follow tng are the three candidates whose 

 ii \ nioiislv associated with the "invention" ol the 

 in -i 1 1 a ist i in ted electromagnetic instrument, or "mul- 

 tiplier," or primitive galvanometer. 



1 1 HI v\\ SALOMO ( I li' is n n ii Schweigcer (1779 

 1857) in 1820 had alread) been editor for several 

 years of the Journal fib Chemii und /' . • ind was 

 professor of chemistr) .it the I niversit) of Halle. 



J oh ann Christian Poggendori (1796 1877) in 

 1820 had onl) recently entered the Universit) ol 

 Berlin as a student following several years as an 

 apothecary's apprentice and a brief period as an 

 apothecary, lour years later, he succeeded Gilbert 

 as editor of the influential Annalen a P \ a posi- 

 tion he held foi more than "ill veils. 



I wii s t i \i\n\i. i I 77 1 1861) in 1820 was professoi 

 of chemist] y at < ami n idge I nivei sit) , 



Chronology and Priority 



The earliest established date iu the "multiplier" 

 record is September H>. 1820, when Schweiggei read 

 his first paper to the Natural Philosoph) S« iet) of 

 Halle. There seems to be no reason to doubt that 

 this report justifies the frequentl) used label "Schweig- 

 ger's multiplier." 



In an exuberant support of Schweigger's position, 

 Speter " with no mention of Cumming and no hint 

 of "invention" details, shows that Poggendoifin 1821 

 admitted Schweigger's priority, but suffered some 

 lapse of memory 40 years later when writing sections 

 of his biographical dictionary, leaving a distinct 



Some prominent examples of this brevity of treatment are 

 in E. Hoppe, Geschichte der Elektrizitat (Leip I Mahr, 



Geschichllichf Einzeldarstellungen aus der Elrktrotrthmk (Berlin, 

 I'll i i ; K S, \\ uii'i'i i . "1 he Evolution ol the Galvonoi 

 Journal oj Scientific Instruments ( 1934 I, vol. 7. pp. 17 I ! . Wii i i wi 

 Sturci * r.niv. 1850); \ W.Humphreys, 



"The Development of the Conception and Measurement of 

 Electric Current," Annals oj Sciena 1937 . vol. -!. pn 164—178. 



'* M. Speter, "KiSrung da Multiplikator-Pri 

 Schweigger-Poggendorf," JJ Ischi fiii Instrumentenkunde (1937 

 vol. 57, pp. 29 



PAPER 38: I \KI IKST ELECTROMAGNETIC INSTRUMENTS 



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