744 PROFESSOR THOMSON ON THE ELECTRO-DYNAMIC QUALITIES OF METALS. 
jecting part, FBKL, of the copper slip was bent round its middle line EG, so as to 
bring its edge, BK, close over the edge of the iron square lying over FC ; and to this 
edge, BK, in its new position (fig. 51), a second iron square, of the same dimensions 
and weight as the other, was soldered by one side, with its area lying in a position 
close to that of the former. The relative position of the two squares and the con- 
necting piece of copper will be understood by looking at fig. 52, which represents the 
iron squares as if soldered to the piece of copper before it was bent, and the iron 
square CDMH turned round its side CH, from the position close to the plane of the 
copper adjoining it, into a position in this plane continued across CH. If, now, we sup- 
pose the iron square CDMH to be turned down so as to lie below a square, FL'HC, 
of the copper ; this square of the copper to be bent sharp round its diagonal, FH, till 
the part FL'H lies over HCF; and, lastly, the part FL'KB projecting beyond FC to 
be bent downwards round EG with a less sharp bend ; the iron square, ABKL, will 
be brought close under the other one, CDMH, with the edges of the two which are 
connected to the edges of the copper perpendicular to one another, and the whole 
compound conductor will have exactly the position shown below in fig. 54. 
168. A convenient electrode was soldered along the edge of each iron square par- 
allel to the edge of the same square soldered to the connecting piece of copper ; so 
that a powerful electric current entering by one of those electrodes and carried away 
by the other would pass through the second-mentioned square of iron in lines exactly 
parallel to the side AB, through the connecting piece of copper in lines which were 
parallel to its length, BC, before it was bent ; and through the first-mentioned square 
in lines exactly parallel to its side CD, and therefore perpendicular to the lines along 
which it traverses the second square. The course of the current will be understood 
by looking at fig. 52, where the two squares and the copper connecting them are sup- 
posed to be opened out so as to throw the course of the current into a straight line. 
The order followed in constructing the compound conductor was not exactly the 
order of the description given above; but the connecting piece of copper was first 
cut and bent, and other pieces, to serve as electrodes (shown in the accompanying 
