126 Proceedings of Boy at Society of Edinburgh. 
wire was gently lowered without rotation by means of a screw until 
the weight came to rest on a shelf. The wire was then sharply cut 
a little above its lower end, the glass tube slipped over it, and a 
second severance made near its upper end. The glass tube with 
contained wire was next inserted into the magnetising coil, and the 
ends carefully clamped after the manner already indicated. In the 
following table the results of one experiment with the iron are given. 
The word “ current ” means the current along the wire ; the word 
“field” means the longitudinal magnetising force to which the 
wire was subjected. A current is positive when it flows in the 
direction of the lines of force, of what is conventionally taken as 
the positive field — that is, in the experiments under consideration, 
towards the east. Under the column headed “ range ” is given the 
range of scale readings corresponding to the cyclic variation of field 
under the circumstances indicated. The column headed “ polarity ” 
contains the mean of the extreme scale readings. 
For Iron Wire of Diameter 0*94 mm. 
Current. 
Field. 
Range. 
Polarity. 
0 
± 
324 
-6 
+ 2*2 
3 J < 
175 
-7-5 
-2-2 
5 5 
180 
-7 
0 
J 5 
317 
-4-5 
0 
321 
-2-5 
+ 1*47 
> 5 
208 
-5 
-1*47 
206 
-4 
0 
325 
-7-5 
+ 0-83 
275 
-5-5 
-0-83 
5 > 
277 
-6-5 
+ 0-5 
287 
-6*5 
-0-5 
” 
282 
-7 
Here, the only apparent effect of passing a current along the wire 
is to decrease the range of intensity due to a given cyclic variation 
of field. The susceptibility is markedly diminished, and the more 
so as the current is taken stronger. There is not the least evidence 
of an accumulated polarity changing sign with the current, as de- 
scribed in my first note. 
In the next series of experiments the wire (current and field being 
both zero) was twisted right-handedly through an angle of 10° in a 
