current passes clockwise as you look upon the plane of the loop, it
will be drawn into the loop. Reversing the position of the needle or
of current will show repulsion.

Clerk Maxwell's method of stating the fact is that "every portion of
the circuit is acted on by a force urging it across the lines of
magnetic induction, so as to include a greater number of these lines
within the embrace of the circuit."[2]

[Footnote 2: Electricity and Magnetism, Maxwell, p. 137, §§ 489,
490.]

If the horizontal loop is used (Fig. 14a), the needle tries to
assume a vertical position, with the N or S end down, according to the
direction of the current.

If it is desired to show that if the magnet is fixed and the loop
free, the loop will be attracted or repelled, a special support is
needed.

[Illustration: Fig. 15]

A strip (Fig. 15) of brass, J, having two iron mercury cups, K_{1}
K_{2}, screwed near the ends, one insulated from the strip, is
fastened upon the horizontal arm of the ring support, Fig. 9, already
described. The cups may be given a slight vertical motion for accurate
adjustment. Small conductors (Figs. 16, 17, 18), which are circles,
rectangles, solenoids, etc., may be suspended from the top of the
plate by unspun silk, with the ends dipping into the mercury. The
apparatus is therefore an Ampere's stand, with the weight of the