Take two pieces of white cotton _cord_, precisely alike in length;
double each of them separately, so that their ends meet; then tie
them together very neatly, with a bit of fine cotton _thread_, at the
part where they double (_i. e._ the middle). This must all be done
beforehand.
When you are about to exhibit the sleight, hand round two other pieces
of cord, exactly similar in length and appearance to those which you
have prepared, but not tied, and desire your company to examine them.
You then return to your table, placing these cords at the edge, so that
they fall (apparently accidentally) to the ground behind the table;
stoop to pick them up, but take up the prepared ones instead, which you
have previously placed there, and lay _them_ on the table.
Having proceeded thus far, you take round for examination three ivory
rings; those given to children when teething, and which may be bought
at any of the toyshops, are the best for your purpose. When the rings
have undergone a sufficient scrutiny, pass the prepared double cords
through them, and give the two ends of one cord to one person to hold,
and the two ends of the other to another. Do not let them pull hard, or
the thread will break, and your trick be discovered. Request the two
persons to approach each other, and desire each to give you one end of
the cord which he holds, leaving to him the choice. You then say, that,
to make all fast, you will tie these two ends together, which you do,
bringing the knot down so as to touch the rings; and returning to each
person the end of the cord next to him, you state that this trick is
performed by the rule of contrary, and that when you desire them to
pull hard, they are to slacken, and _vice versâ_, which is likely to
create much laughter, as they are certain of making many mistakes at
first.
During this time, you are holding the rings on the fore-finger of
each hand, and with the other fingers preventing your assistants from
separating the cords prematurely, during their mistakes; you at length
desire them, in a loud voice, to slacken, when they will pull hard,
which will break the thread, the rings remaining in your hands, whilst
the strings will remain unbroken: let them be again examined, and
desire them to look for the springs in the rings.