ITO M. Oersted ow the connectlbn between 
The action of the uniting wire upon the needle may be trans- 
mitted without any diminution of its effect, through gldss^ me- 
tals^ woody watery rosin, earthen-ware and stones. Even when 
these various substances are interposed at the same time, they 
scarcely seem to diminish the effect. A disc of the electro- 
phorus, plates of porphyry, a stone-ware vessel full of water, 
were interposed with as little effect, and the influence of the uni- 
ting wire continued the same when the needle was shut up in a 
brass box filled with water. As the ordinary galvanic and elec- 
trical influence has never been transmitted through these sub- 
stances, the effects^'which take place in the conflict of elec- 
tricity are totally different from those which belong to electri- 
cal attractions and repulsions. 
Needles of brass, glass and gum lac were substituted in place 
of the magnetic needle ; but they were not influenced by the 
action of the uniting wire. 
In extending his electro-magnetic researches, M. Oersted has 
obtained several additional results of a very interesting nature. 
He found that the electro-magnetic effects do not depend 
upon the intensity of the electricity, but solely on its quantity. 
A plate of zinc of six inches square, immersed into a vessel 
of copper containing the dilute acid, produces a considerable 
electro-magnetic effect; but when the plate has 100 square 
inches of surface, it acts upon the needle with such force, that the 
effect ''upon it is sensible at the distance of three feet. The 
effect is diminished, rather than increased, when forty troughs, 
similar to this single one, ore united in one battery 
In comparing the effect of a single galvanic arc with that of 
«an apparatus composed of several, M. Oersted supposes Fig. 6* 
of Plate III. to represent a galvanic arc composed of one piece of 
zinc z, a piece of copper c, a metallic wire a b, and a fluid con- 
ductor I, The zinc always communicates a portion of its posi^ 
* M. Oersted found, that the discharge of a strong electric battery, transmit- 
ted through a metallic wire, produced no deviation in the needle ; ^neither did a 
series of uninterrupted sparks produce any other effect than the ordinary attrac- 
tions and repulsions. A galvanic pile of 100 discs of two inches square each, and 
cf paper moistened with salt-waterj is also destitute of any sensible effect. 
