rom becoming
excessive upon any conductors, causing fire or other injury; also
switches for turning the current on and off; lamp-holders, fixtures, and
the like; also means and methods for establishing the interior circuits
that were to carry current to chandeliers and fixtures in buildings.

Here was the outline of the programme laid down in the autumn of 1878,
and pursued through all its difficulties to definite accomplishment in
about eighteen months, some of the steps being made immediately, others
being taken as the art evolved. It is not to be imagined for one moment
that Edison performed all the experiments with his own hands. The method
of working at Menlo Park has already been described in these pages
by those who participated. It would not only have been physically
impossible for one man to have done all this work himself, in view of
the time and labor required, and the endless detail; but most of the
apparatus and devices invented or suggested by him as the art took shape
required the handiwork of skilled mechanics and artisans of a high order
of ability. Toward the end of 1879 the laboratory force thus numbered at
least one hundred earnest men. In this respect of collaboration, Edison
has always adopted a policy that must in part be taken to explain his
many successes. Some inventors of the greatest ability, dealing with
ideas and conceptions of importance, have found it impossible to
organize or even to tolerate a staff of co-workers, preferring solitary
and secret toil, incapable of team work, or jealous of any intrusion
that could possibly bar them from a full and complete claim to the
result when obtained. Edison always stood shoulder to shoulder with his
associates, but no one ever questioned the leadership, nor was it ever
in doubt where the inspiration originated. The real truth is that Edison
has always been so ceaselessly fertile of ideas himself, he has had more
than his whole staff could ever do to try them all out; he has sought
co-operation, but no exterior suggestion. As a matter of fact a great
many of the "Edison men" have made notable inventions of their own, with
which their names are imperishably associated; but while they were with
Edison it was with his work that they were and must be busied.

It was during this period of "inventing a system" that so much
systematic and continuous work with good results was done by Edison in
the design and perfection of dynamos. The value of his contribu