cted machine and records now so widely known all over the
world. From among these many inventions, however, we will select two
or three as examples of ingenuity and importance in their bearing upon
present perfection of results.

One of the difficulties of reproduction for many years was the trouble
experienced in keeping the stylus in perfect engagement with the
wave-like record, so that every minute vibration would be reproduced. It
should be remembered that the deepest cut of the recording tool is only
about one-third the thickness of tissue-paper. Hence, it will be quite
apparent that the slightest inequality in the surface of the wax would
be sufficient to cause false vibration, and thus give rise to distorted
effects in such music or other sounds as were being reproduced. To
remedy this, Edison added an attachment which is called a "floating
weight," and is shown at A in the illustration above.

The function of the floating weight is to automatically keep the
stylus in close engagement with the record, thus insuring accuracy of
reproduction. The weight presses the stylus to its work, but because
of its mass it cannot respond to the extremely rapid vibrations of the
stylus. They are therefore communicated to the diaphragm.

Some of Edison's most remarkable inventions are revealed in a number of
interesting patents relating to the duplication of phonograph records.
It would be obviously impossible, from a commercial standpoint, to
obtain a musical record from a high-class artist and sell such an
original to the public, as its cost might be from one hundred to several
thousand dollars. Consequently, it is necessary to provide some way by
which duplicates may be made cheaply enough to permit their purchase by
the public at a reasonable price.

The making of a perfect original musical or other record is a matter
of no small difficulty, as it requires special technical knowledge and
skill gathered from many years of actual experience; but in the exact
copying, or duplication, of such a record, with its many millions
of microscopic waves and sub-waves, the difficulties are enormously
increased. The duplicates must be microscopically identical with the
original, they must be free from false vibrations or other defects,
although both original and duplicates are of such easily defacable
material as wax; and the process must be cheap and commercial not a
scientific laboratory possibility.

For making duplicates it was o