84 Electro-Magnetic Experiments made by 
poles (points consequent ) as the turns of the spirals changed 
their direction. 
4. A brass spiral wire was used as in the 1st and 2d experi- 
ments ; but instead of placing the needle in a glass-tube, within 
the windings of the spirals, it was wound in paper, and fastened 
externally on the spiral, parallel to its axis. When a right- 
hand spiral was used, the needle was magnetic after the discharge, 
and its north pole turned to the positive side. 
5. The same experiment as the former, but the spiral is left- 
handed. The north pole is now turned against the negative side. 
In this and in the former experiments, the poles of the needle 
were in an inverted direction, as in the 1st and 2d experiments. 
This may be rendered more striking, by^ putting in the same ex- 
periment a needle in glass or paper ivithin the spiral, and at- 
taching another also in paper on the outside of the spiral. On 
transmitting tile discharge, both needles will be magnetic, but 
their poles inversely situated. This experiment was, we believe, 
first made by some Italian philosophers, but with galvanic electri- 
city : we doubted its correctness on making it the first time, but 
we found it ta answer afterwards. 
6. Round a glass-tube was twisted a spiral of soft iron. In 
the tube was a brass-wire connected with the battery. In this 
way the battery was discharged through the brass-wire. Then, 
taking away both the tube and the brass-wire, the steel spiral wire 
was found magnetic. If its turns went to the right, its north pole 
was towards the negative side, but if to the left, to the positive 
side of the battery. The ends of this curious spiral magnetic 
needle, being brought together, it shewed of course no magnetism, 
but when loosened again,, its magnetism appeared. 
7. A small glass-plate was placed on a straight copper-wire. 
On the glass, at right angles with the brass-wire, was laid a 
needle. The electric discharge being thrice passed through the 
brass, the needle was found strongly magnetic. The needle’s 
north pole was turned to the left hand, the observer facing the 
side of the battery^ 
8. The same experiment repeated, with this difference, that 
now the needle was under the glass-plate, and the brass-wire 
above it. The poles of the needle were now in an inverted si- 
tuation, the north pole to the right of a person with liis face to 
the positive side of the battery. 
