but it was also
an integral part of his great and complete system of lighting, to every
part of which it bore a fixed and definite ratio, and in relation to
which it was the keystone that held the structure firmly in place.

The work of Edison on incandescent lamps did not stop at this
fundamental invention, but extended through more than eighteen years
of a most intense portion of his busy life. During that period he was
granted one hundred and forty-nine other patents on the lamp and its
manufacture. Although very many of these inventions were of the utmost
importance and value, we cannot attempt to offer a detailed exposition
of them in this necessarily brief article, but must refer the reader,
if interested, to the patents themselves, a full list being given at
the end of this Appendix. The outline sketch will indicate the principal
patents covering the basic features of the lamp.

The litigation on the Edison lamp patents was one of the most determined
and stubbornly fought contests in the history of modern jurisprudence.
Vast interests were at stake. All of the technical, expert, and
professional skill and knowledge that money could procure or experience
devise were availed of in the bitter fights that raged in the courts for
many years. And although the Edison interests had spent from first to
last nearly $2,000,000, and had only about three years left in the
life of the fundamental patent, Edison was thoroughly sustained as to
priority by the decisions in the various suits. We shall offer a few
brief extracts from some of these decisions.

In a suit against the United States Electric Lighting Company, United
States Circuit Court for the Southern District of New York, July 14,
1891, Judge Wallace said, in his opinion: "The futility of hoping to
maintain a burner in vacuo with any permanency had discouraged prior
inventors, and Mr. Edison is entitled to the credit of obviating the
mechanical difficulties which disheartened them.... He was the first
to make a carbon of materials, and by a process which was especially
designed to impart high specific resistance to it; the first to make a
carbon in the special form for the special purpose of imparting to it
high total resistance; and the first to combine such a burner with the
necessary adjuncts of lamp construction to prevent its disintegration
and give it sufficiently long life. By doing these things he made a lamp
which was practically operative and successful,