In my lecture of September 16th, I showed that Oersted’s results depend, not on the voltaic cell, but only on the connecting circuit. The principle I have used for amplification of the effects, for the construction of an electromagnetic battery as it were, was the winding of wire around the compass, and I now present to the Society a bow-pattern of multiple-wound, wax-insulated wire, Figure 3. [There were no illustrations with Schweigger’s first paper.] While a single wire, using the weak electric circuit here, deflects the magnetic needle only 30° or 40°, if the compass is placed in one of the openings of this pattern, the needle is deflected 90° to the east, or in the other opening 90° to the west, using the same weak electric circuit....
The “bow-pattern” device has novelty interest only, adding nothing to the elucidation of the multiplier phenomenon. The same is true of Schweigger’s next proposal, shown in figure 4. “... I will now add another apparatus, which is just an extension of the previous one, whereby the needle can take up any angle from 0° to 180°.” A short length of circular glass tubing, of inside diameter large enough to contain a compass needle, stands with its axis vertical and has single or multiple loops of wire wound on it in vertical diametral planes. In the illustration, successive plane coils are inclined at 30° to one another. “... the electric current flows through the whole wire, and the needle moves under all of these currents, and coming always into another loop can take any desired angle.”
With much further theorizing about “the correlation of magnetism with the cohesion of bodies,” Schweigger states again his evaluation of his discovery: “Oersted succeeded in electromagnetic research by using a spark-producing cell, which could make a wire glow. My amplifying electromagnetic device needs only a weak circuit of copper, zinc, and ammonium chloride solution.”[24]
Figure 4.—Schweigger made this peculiar construction of wire coils, wound endwise on a short vertical section of glass tubing with a compass needle inside, merely to startle his Halle audience with the fact that the compass needle could rest in any of several stable positions. (From Journal für Chemie und Physik.)
Figure 5.—Schweigger’s suggestion of one possible design for an amplifying electromagnetic indicator. The components are wooden rods and insulated wire. Position b referred to in the text is at the bottom of the diagram between the letters a and c. (From Journal für Chemie und Physik.)
“FURTHER WORDS ABOUT THE NEW MAGNETIC PHENOMENA”
[This was presumably written between November 4, 1820, and the January 1, 1821, publication date of his Journal.]
These wonderful new electrical effects[25] are most easily rendered perceptible with the help of the previously described wire loops. To focus attention on just one of the windings of Figure 3, we sketch a new drawing, Figure 5.... Since it is of major importance that these loops be made of silk-covered wire lying evenly on one another, it is convenient to wind the loops on two small slotted sticks of wood, although it is also possible to hold the wires together with wax or shellac, or to tie them together in an orderly manner with silk thread....