of an Electric Current by Magnetic Action. 131 
Let Zin fig. 8 represent an equipotential line in a strip of 
metal through which an electric current is flowing, the metal 
eing in a normal condition. Be 
In fig. 4, 7 represents the corresponding equipotential line 
when the metal strip is acted upon by a powerful magnetic 
force in a direction perpendicular to the plane of the paper. 
If now a and b be connected by means of a wire, a current 
will flow from a to 3 through the wire. If a’ and be con- 
nected in the same way, a weaker current will flow from a’ to} 
through the wire. 
3, 6. 
a 
' a5 Tne 
4. b 
Roh ar ff ti 
oy a 
4 wile 7 e <_ 
5. aes é <— 
i 
~> ft pare 
Fig. 5 represents a metal strip having along its middle a slit 
longer than the diameter of the magnetic poles between which 
the slit is Placed, 7 and 7 being corresponding equipotential 
lines when the strip is in its normal unstressed condition. 
et a magnetic force act as before. Hach of the lines J, Z in 
fig. 5 is rotated about its center through the samie angle as / in 
8 Sand 4. The result is shown in fig. 6. 
tf now a and 6 be connected by means of a wire & gurrent 
Will flow from atobthrough the wire. If a’ and b be con- 
to in same way a current will flow from 6’ toa through 
€ Wire, 
To get Mr. Bidwell’s case, imagine a narrow bridge of metal 
‘0 be left Crossing the slit te! a’ and 0’. Such a ee 
Would serve as a shunt to the wire which we have imagine 
Fontecting a’ and 4/ but would not reverse the relative poten- 
'S Of these two points. The lines J, 4, as Sir Wm. re : 
ER ak at the Philadelphia sie would now e 
Something like that shown in at j 
AS the bridge across the slit becomes wider such lines as : 
me more nearly straight till finally the ort o 
the © represented in fig. 4 will be practically reproduced. ak 
© other hand if the slit in fig. 5, were short compared 
