conomical methods
of duplication, including methods of shrinking a newly made copy to
facilitate its quick removal from the mold; methods of reaming, of
forming ribs on the interior, and for many other important and essential
details, which limits of space will not permit of elaboration. Those
mentioned above are but fair examples of the persistent and effective
work he has done to bring the phonograph to its present state of
perfection.

In perusing Chapter X of the foregoing narrative, the reader undoubtedly
noted Edison's clear apprehension of the practical uses of the
phonograph, as evidenced by his prophetic utterances in the article
written by him for the North American Review in June, 1878. In view of
the crudity of the instrument at that time, it must be acknowledged that
Edison's foresight, as vindicated by later events was most remarkable.
No less remarkable was his intensely practical grasp of mechanical
possibilities of future types of the machine, for we find in one of his
early English patents (No. 1644 of 1878) the disk form of phonograph
which, some ten to fifteen years later, was supposed to be a new
development in the art. This disk form was also covered by Edison's
application for a United States patent, filed in 1879. This application
met with some merely minor technical objections in the Patent Office,
and seems to have passed into the "abandoned" class for want of
prosecution, probably because of being overlooked in the tremendous
pressure arising from his development of his electric-lighting system.

IX. THE INCANDESCENT LAMP

ALTHOUGH Edison's contributions to human comfort and progress are
extensive in number and extraordinarily vast and comprehensive in
scope and variety, the universal verdict of the world points to his
incandescent lamp and system of distribution of electrical current as
the central and crowning achievements of his life up to this time. This
view would seem entirely justifiable when we consider the wonderful
changes in the conditions of modern life that have been brought about
by the wide-spread employment of these inventions, and the gigantic
industries that have grown up and been nourished by their world-wide
application. That he was in this instance a true pioneer and creator
is evident as we consider the subject, for the United States Patent No.
223,898, issued to Edison on January 27, 1880, for an incandescent lamp,
was of such fundamental character that it ope