on electromagnetism by the celebrated M. Erman 

 published very shortly after its discovery, bet imi 

 known to many scientists before that of M. Schweigger. 

 Tliis is the reason for the same apparatus carrying 

 differenl nami 

 The same confusion is well illustrated by the paper 



(o which (lilhcrt attached his confessional footnote 

 mentioned above. Written by Professor Raschig of 



Dresden, on April 3, 1821, tin' paper is entitled 



"Experiments with the Ele< tro-magnetii Multiplier," 

 hut the device, throughoul the paper, is repeatedly 



referred to ill the phrase "PoggendorPs condenser. 



.11 lather multiplier," an awkward combination that 

 suggests editorial intervention. " 



The work of James Cumming at Cambridge is 

 described in two papers which he read to the Cam- 

 bridge Philosophical Society in 1821, which were 

 then duly published in the Transactiom of thai So; iety . 

 The fust, "On the Connexion of Galvanism and 

 Magnetism," was read April'-'. IM'_' I, 22 and the second, 

 "( )n the Application of Magnetism as a Measure of 

 Electricity ," was read a few weeks later on May 21st. 23 



Though he quotes some unrelated 18th-century 

 experiments by Hitter in Germany, an 1807 publica- 

 tion of ( )ersted's, and electromagnetic experiments 

 with solenoids performed by AragO .\m\ Ampere in 

 late 1820, Cumming makes no mention ol Schweig- 

 ger or Poggendorf, and never uses the word 

 '•multiplier." It, therefore, seems probable that his 

 work was done without knowledge of the German 

 publications or inventions. 



Original Electromagnetic Multipliers 



Of the three sets of instruments made, respectively, 

 by Schweigger, Poggendorf and Cumming, those of 

 Schweigger are the most elementary, and the leasl 



realistic from a practical point of view, lie makes 

 little effort to investigate the eil'eet of any design 

 parameters, hut presents some odd conductor con- 

 figurations that involve unimportant variations of 

 tin- basic principle. The following extracts from his 

 lnsi three papers 1 ' contain the major references to 

 his conception, construction, and use of his multiplier. 



II C. Ot Rsn i). "Sur le Multiplier electro-magm tiqui d< 

 M. Schweigger, et sur quelques applications qu'on en a faites," 

 Annates </<■ Chimit el i / 1823 vol pp 



-' "Versuche mitdem electrisch-magnetist hen Multiplii 

 Annalen det Physik (1821 ), vol. 67, pp. 127 I 16. 



reactions of the Cambridge Philosophic :al vol. 1, 



I J 7!!. 

 Ip. cit. (footnote 8). 



PAPER READ IN HALLE, SEPT] Mill K l6, iSlO 



Ih.n a powerful voltaii pile is required foi th< i 

 periments mi Oersted) I have confirmed in my physics 

 III hue,, using .in electric pile thai was mi stroi 

 would easily produce potassium metal the second and 



third day alter it was built. However, I mj.hi saw that 



the electromagnetic effect was related, ma to die pile, 

 hut io die simple circuit, ami I was thereby led to 

 perform the experiment with much greatei sensitivity. 

 to implify these electromagnetic phenomena of the 

 simple circuit it seemed in me necessary in adopt a 

 differenl an om that initiated by Volta, in 



order that die ele< trical p ol his simple i in mi 



might he raised to a higher deg 



sime ,i reversal of the effect occurs a. li 



whether the connecting-wire lies ovei ot undei the 

 needle, and likewise according to whether die wire 

 leads from the positive or negative pole, thence I say 

 ii is ai\ easy inference thai a doubling of die effe< i is 

 attainable, w hit h i- vet ified in prat dee 



I present to the So iety the simple "doubling appa- 

 ratus" [Verdoppelungs-Apparat], where the compass is 

 placed between two wins passing around it. \ multi- 

 plication of the effect is easily obtained when the wire 

 is not just once hut many limes wound around. A 

 single nun suffices, however, to demonstrate Oersted's 

 experiments, using small strips ol zinc and coppet dipped 

 in ammonium-chloride solution. 



Amid innumerable, rambling theorizations (such 



as, that "hydros-nation affects magnetism as oxida- 

 tion affects gal\ anisni." or "sulphur, phosphorous and 

 carbon are especially significant in magnetism, since 

 iron in combination with any of these inflammable 

 materials becomes a magnet-material"), Schw 

 announces that In the reactive force of the 



needle dm lie- i oiinectiii'; wire in the simple ( )ersted 



experiment, and that he used his "amplifying 

 paratus" to look foi magnetic effects from an i li 

 static machine, hut without success in both i 

 He suggests that he will continue with mam 



1 1' i • i ii ri nents because "w ith the use 

 of the doubling-apparatus, the needle, instead of 

 needing for excitation a cell capable of generating 

 sparks, approaches more closely the sensitivity ol 

 a twitching nerve." However, "additional special 

 experiments are required to find to what limits the 

 amplification can be increased l>v the method I have 

 created in the construction of this doubling-apparatus, 

 using multiple turns of w ire " 



PAPER 38: EARLIEST EI. EC I R( i\l \< .\l IK INSTRUMENTS 



12" 



