68 Report of Chemistry and Experimental Philosophy. [Feb. 1, 



3. If we suppose a second conjunctive attempt was made by several philosoplier.--, 

 ■wire parallel to, and similarly situated with, to influence the magnetic needle, by piaciug- 

 t he first, as in this figure, those wires will it in the open , galvanic circuit, but no effect 



P I ~" IK was perceptible; and it occurred to Mr. 



^ Oersted to make theexperiment vvhenthegul- 



P l ~ — ■ in^i vauic circle was complete. He immediately 



«(fr..f.t o„,.i> „.!, . , . c '■ -'^ found that the magnetic needle was moved 



fvirlhl f 7J V 'f °"^ ^o"Junc(.ve from its position ; but as his apparatus was 

 dirpn.i .! ^^ ;'*" ?■ "''^ '"'^^""-" '^""^ ■" °°^ feeble, and the results not strongly marked, 

 direction, and another in an opposite direc- ^e associated himself with his friend M. Es- 

 ti on. as m the following wood-cut, those mark, councillor to the King, and provided a 

 "' I M":"''""'" app;iratus,cousisiing of twenty cop- 



per troughs, each of which was 12 inches 

 ]P Siju.Tre, with a breadth of about 2§ inches. — 

 Each trough was furnished with two plates 

 of copper, disposed so as to support the rod 

 of copper w hich sustains the zinc plate iu 

 the fluid of the next trough. The conduct- 

 inu; fluid consisted of pure water, containing 

 J^th of its weight of sulphuric acid, and as 

 much nitric acid. The portion of each zinc 



N[ 



Wires Will rej.el each other. In this circui.. 



stance, the dissimilarity of the cleetio-mag- 



Betic and of simple electric phenomeuu is 



observed ; for boilies similarly electrified 



repel each other, and, dissimilarly electrified, 



attract each other ; ^ but here the horizontal 



wires, similarly electro-magnetized, niiracf; 



and, dissimilarly electro-magnetized, repel plate immersed iu (he fluid is a square whose 



each other.— AI. Ampere. side is about ten inches long. A less pow-. 



4. The shock of a Leyden jar, or batlery, erfu! battery will be sunicieiit, provided 

 passed through u wire, confers upon it, 'at that it is able to make a metallic wire red 

 the moment of its passage, properties pre- hot. The opposite extremities of the pile 

 cisely similar to those of the voiiaio appa- are joined by a metallic wire, called the 

 f"'"^' Uniting iVire, and the name of the Electric 



To render a steel bar magnetic, it is not Conflict was given to the effect which took 

 necessary that it should /oj(c/i the conjunctive place in the uniting wire, and iu the space 

 Wire, to which it is attached at riuht angles, around it. 



or theelectio-magnetic influence is conveyed 1. Above a magnetic needle, well sus- 



to some distance, and is not excluded bv the pended, and in eriuilibrio in the magnetic 

 interposition of a plate of a glass, of metal, meridian, is placed a straight part of the 

 or of water. — Sir H.Davy, uniting wire, so as to be horizontal and pa- 



5. The phenomena, exhibited by the elec- 



tro-magnetic, or conjunctive wire, niav be 

 explained upon the supposition of an electro- 

 magnetic current passing round the axis of 

 the conjunctive wire, its direction depending 

 upon that of the electric current, or upon 

 the poles of the battery with which it is con- 

 nected.— Dr. WOI.LASTON, 



In the above figure, such a current is re- 

 presented in two sections at right angles to 

 the axis of the wires, when similarly elec- 

 trified, from which it will be apparent that 

 the north end south powers meeting, will at- 

 tract each other. 



rallel to the needle, which may be done by 

 bending it near its eflicaeious part. When 

 this is dune, the needle will be found to de- 

 viate from its position ; — the pole which is 

 nearest thp negative end of the battery will 

 move to the westward, and if the distance of 

 the needle from the uniting wire does not ex- 

 ceed three-fourths of on inch, the declina- 

 tion of the needle will be 45". At greater 

 distances the declination decreases propor- 

 tionally ; and thedistance remaining the same 

 the declination varies with the strength of 

 the battery. 



If the uniting wire is placed below, in- 

 stead of above, the needle, the effects will be 

 inverted, and the pole which is nearest the 

 negative end of th"* battery will move to the 

 eastward . 



2. Hence it follows, in general, that if 

 ne^a^tce electricity enters aftoye the pole of 



In the following figure, the sections of the **"* "^edle, it will decline to the west, and if 



it enters below, it will decline to the east. 

 „sjiS,^^ If the uniting wire is made to turn in n 



tN \^, /y xiX horizontal plane, so as to deviate gradually 



from the magnetic meridian on either side, 

 the declination of theneedle will increase, if 

 3^y^ >^ — -^ the wire approaches the needle, and will di- 



minish if it recedes from it. 

 3. If, when the magnetic needle is ren- 

 wire are shown dissimilarly electrified, by dered horizontal by a counterpoise, we place 

 which similar magnetic powers meet, and the uniting wire in the same horizontal 

 consequently occasion a repulsion. plane, and parallel with it, no declination 



Some years ago, says Professor Brewster, takes place, but the needle dips, so that the 

 in the Journal of Natural Philosophy, an pole where the 7iegative electricity enters, 



