558 
ME. Gr. GOEE ON ELECTEOTOESION. 
1*23 mm., and of those yielded by an equal number of axial ones 3'18 mm., and of the 
two collectively 2*20. 
It would appear from these results that in iron the residuary torsional influence of 
the currents generally is about one tenth of that exerted by them during their conti- 
nuance*. In steel it would be a much greater proportion in consequence of the com- 
parative smallness of the torsions yielded by that substance with simultaneous currents 
(see Section 44). The general result in these cases would be considerably affected by 
variation of the relative strengths of the two currents, because, when alternate, the axial 
currents yielded torsions two and a half times the range of that yielded by the coil ones, 
and, when simultaneous, if one current was in excess it would only exert a part of its 
power effectively. To diminish this latter source of error I previously adjusted the 
currents as accurately as I was able in the way already described in Section 37. 
42. Effect of mechanical 'pull on torsions produced by simultaneous currents. 
With an iron wire 3*77 mm. thick, a current from six cells arranged as three, pro- 
ducing a north pole below, passed temporarily through the coil during the continuance 
of an upward current from a similar battery through the iron wire, produced a torsional 
movement of 3*5 mm. whilst a weight of 5-| kilogrammes was attached to the wire, and 
of 13*5 mm. in the opposite direction without the weight. As mechanical pull affects 
the magnitude of the torsions, both with alternate currents (see Section 22) and with 
simultaneous ones (see also Section 43), it is evident the weight of the pointer and its 
counterpoise exercised a similar effect in all the experiments. 
43. Melative magnitudes of torsions by different methods. 
The magnitudes of the torsions in all cases depended upon the advantageous applica- 
tion of the forces of the two currents. With an iron wire 3*77 mm. thick, supporting a 
weight of 5| kilogrammes, and a current from twelve Gkove’s cells arranged as three: — 
(A) Alternate axial currents in opposite directions gave torsional movements varying in 
magnitude from *5 to 3*25 mm. (B) Simultaneous and undivided currents from the 
same battery-arrangement gave movements varying in extent from 1*4 to 2*25 mm. 
(C) Simultaneous and divided currents, the coil one being from six cells arranged as 
three, and the axial one from the other six connected as three, yielded movements 
varying from 8 to 10 mm. in magnitude. (D) Similar divided currents, the axial ones 
being passed temporarily during the continuance of the coil ones, the torsional move- 
ments varied in extent from 1 to 6 mm. (E) Similar divided currents, with the axial 
ones continuous and the coil ones temporary, the movements ranged from 0 to 9 mm., 
and without the weight 13 mm. In these last experiments the coil-currents produced 
the largest torsions, but in some former experiments (see Section 39, p. 556) temporary 
axial currents passed during the continuance of coil ones produced the largest. The 
* As the amount of residuary axial effect is less than that of coil-influence, the proportion of the former 
would he less, and of the latter more, than one tenth. 
