OHM ON THE GALVANIC CIRCUIT. 407 



tended to a ring composed of any number of heterogeneous 

 parts, if each part be of itself homogeneous and of the same 

 thickness. I may here take as an example of this extension a 

 ring composed of two heterogeneous parts. Let this ring be 

 imagined as before open at one of its places of excitation and 

 stretched out to form the right line ABC (fig. 2), so that A B 

 and B C indicate the two heterogeneous parts of the ring. The 

 perpendiculars A F, B G, will represent by their lengths the 

 electrical forces present at the extremities of the part A B ; on 

 the other hand, B FI and C I, those present at the extremities of 

 the part B C ; accordingly A F + C I or F K will represent 

 the tension at the opened place of excitation, and G H the ten- 

 sion occurring at B at the point of contact. Now if we only 

 bear in mind the permanent state of the circuit, the straight 

 lines F G and H I will, from the reasons above mentioned, in- 

 dicate by their position the mode of separation of the elec- 

 tricity in the ring ; but whether the line A C Avill keep its place, 

 or must be advanced further up or down, remains uncertain, 

 and can only be found out in each distinct case by other se- 

 parate considerations. If, for instance, the point O of the cir- 

 cuit is touched abductively, and thus deprived of all electri- 

 city, ON would disappear; and therefore the line LM drawn 

 through N parallel with A C would in this case give the posi- 

 tion of A C required. It is hence evident, how sometimes this, 

 sometimes another, position of the line A C in the figure 

 F G H I, representing the separation of the electricity, may be 

 the one suited to the circumstances ; and herein we recognise 

 the source of the variability of galvanic phaenomena already 

 mentioned. 



It is, however, essentially requisite, in order to be able to 



[ judge thoroughly of the present case, to attend to a circum- 

 stance the mention of which has hitherto been puqiosely 



: avoided, that the various considerations might be separated 

 as distinctly as possible. The distances F K and G H are 



! indeed given by the tensions existing at the two places of ex- 

 citation, but the figure F G H I is not yet wholly determined 

 by this alone. For instance, the points G and H might move 

 down towards G' and H', so that G' H' would equal G H, 

 giving rise to the figure F G' H' I, which would indicate quite 



I a different mode of separation of the electricity, although the 



I individual tensions in it still retain their former magnitude. 



