nciples of a true
system--that system which has since been put into practical use all over
the world, and whose elements do not need the touch or change of more
modern scientific knowledge.

These patents were not by any means all that he applied for in the
year 1880, which it will be remembered was the year in which he was
perfecting the incandescent electric lamp and methods, to put into the
market for competition with gas. It was an extraordinarily busy year for
Mr. Edison and his whole force, which from time to time was increased
in number. Improvement upon improvement was the order of the day. That
which was considered good to-day was superseded by something better and
more serviceable to-morrow. Device after device, relating to some
part of the entire system, was designed, built, and tried, only to
be rejected ruthlessly as being unsuitable; but the pursuit was not
abandoned. It was renewed over and over again in innumerable ways until
success had been attained.

During the year 1880 Edison had made application for sixty patents, of
which thirty-two were in relation to incandescent lamps; seven covered
inventions relating to distributing systems (including the two above
particularized); five had reference to inventions of parts, such
as motors, sockets, etc.; six covered inventions relating to
dynamo-electric machines; three related to electric railways, and seven
to miscellaneous apparatus, such as telegraph relays, magnetic ore
separators, magneto signalling apparatus, etc.

The list of Mr. Edison's patents (see Appendices) is not only a monument
to his life's work, but serves to show what subjects he has worked on
from year to year since 1868. The reader will see from an examination
of this list that the years 1880, 1881, 1882, and 1883 were the most
prolific periods of invention. It is worth while to scrutinize this list
closely to appreciate the wide range of his activities. Not that his
patents cover his entire range of work by any means, for his note-books
reveal a great number of major and minor inventions for which he has
not seen fit to take out patents. Moreover, at the period now described
Edison was the victim of a dishonest patent solicitor, who deprived him
of a number of patents in the following manner:

"Around 1881-82 I had several solicitors attending to different classes
of work. One of these did me a most serious injury. It was during
the time that I was developing my electric-lighting sys