With this brief practical production, we proceed to describe a few of
the simpler tricks with coins.

HEADS OR TAILS

You borrow a quarter, and spin it, or invite some other person to spin
it, on the table (which must be without a cloth). You allow it to spin
itself out, and immediately announce, without seeing it, whether it
has fallen head or tail upward. This may be repeated any number of
times with the same result, though you may be blindfolded, and placed
at the further end of the apartment.

The secret lies in the use of a quarter of your own, on one face of
which (say on the "tail" side) you have cut at the extreme edge a
little notch, thereby causing a minute point or tooth of metal to
project from that side of the coin. If a coin so prepared be spun on
the table, and should chance to go down with the notched side upward,
it will run down like an ordinary coin, with a long continuous
"whirr," the sound growing fainter and fainter till it finally ceases;
but if it should run down with the notched side downward, the friction
of the point against the table will reduce this final whirr to half
its ordinary length, and the coin will finally go down with a sort of
"flop." The difference of sound is not sufficiently marked to attract
the notice of the spectators, but is perfectly distinguishable by an
attentive ear. If, therefore, you have notched the coin on the "tail"
side, and it runs down slowly, you will cry "tail"; if quickly,
"head."

If you professedly use a borrowed coin, you must adroitly change it
for your own, tinder pretence of showing how to spin it, or the like.