DISCOURSE OF W. B. TAYLOR: NOTES. 377 



1,800 coils, (shortening the conductor to this extent,) the galva- 

 nometer now of 200 coils will begin to give notable deviations. If 

 we reduce it to 10 coils, the deflection will be considerably aug- 

 mented. Finally, if we reduce it to a single coil formed of a strip 

 of copper containing as much substance as the 200 coils, the deflec- 

 tion of the needle may amount to even 60 degrees. The quantity 

 of electricity produced in this experiment by the thermo-electric 

 pair is therefore evidently 2,000 times greater than that of the 

 above hydro-electric pair, since we obtain the same deviation with a 

 single coil as with the factitious quantity given by the reduplication 

 of the coils. On the other hand, in the first experiment the length 

 of the conducting wire was easily traversed by the hydro-electric 

 current; the inertia of the matter was overcome without difficulty 

 and without appreciable loss of the current : in the second experi- 

 ment this inertia could not be overcome ; the power of action was 

 insufficient and it was necessary to reduce the circuit to a very small 

 length for the electricity to be able to traverse it." From these 

 phenomena, Peltier argued that two very distinct conditions were 

 presented, which should not be confounded; an action of quantity 

 without resistance, and an action of intensity independent of quan- 

 tity, capable of overcoming considerable resistance.* 



In the same memoir however, Peltier took occasion to say that he 

 considered "dynamic intensity" an inappropriate expression for 

 electricity in movement; and that the term if retained should be 

 used to designate not a modification of the electric current, but a 

 particular disposition of the electro-motor. He discarded the idea 

 that intensity represents a peculiar quality in the current itself; but 

 considered the action as only the consequence of increased resistance 

 offered by the pile to a backward movement or return of the electric 

 flow: or in other words that intensity regarded as the power of 

 overcoming obstacles in the external path, results from the greater 

 obstacles presented by the battery to a neutralization by retrogra- 

 dation.f 



The designations under discussion have been largely superseded 

 in modern authorities by the mathematical treatment of the subject, 

 which takes cognizance alone of the ratio between electromotive 

 force and resistance differences in the circuits. Thus Professor 

 Jenkin, speaking of the two classes of batteries, remarks : " With a 

 short circuit of small external resistance, we can increase the cur- 

 rent by increasing the size of cells, or what is equivalent to this, by 

 joining several cells in multiple arc. With a long circuit of great 

 external resistance, large cells (or many of them joined in multijjle 



* Annales de Chimie et de Physique, 1836, vol. Ixiii. pp. 245, 246. 

 fSame work, p. 253. 



