ain line without attaining the desired result. "He
wanted to get a particular compound having definite qualities, and I had
tried in all sorts of ways to produce it but with only partial success.
He was confident that it could be done, and said he would try it
himself. In doing so he followed the same path in which I had travelled,
but, by making an undreamed-of change in one of the operations,
succeeded in producing a compound that virtually came up to his
specifications. It is not the only time I have known this sort of thing
to happen."

In speaking of Edison's method of experimenting, another of his
laboratory staff says: "He is never hindered by theory, but resorts to
actual experiment for proof. For instance, when he conceived the idea of
pouring a complete concrete house it was universally held that it would
be impossible because the pieces of stone in the mixture would not rise
to the level of the pouring-point, but would gravitate to a lower plane
in the soft cement. This, however, did not hinder him from making
a series of experiments which resulted in an invention that proved
conclusively the contrary."

Having conceived some new idea and read everything obtainable
relating to the subject in general, Edison's fertility of resource and
originality come into play. Taking one of the laboratory note-books,
he will write in it a memorandum of the experiments to be tried,
illustrated, if necessary, by sketches. This book is then passed on
to that member of the experimental staff whose special training and
experience are best adapted to the work. Here strenuousness is expected;
and an immediate commencement of investigation and prompt report are
required. Sometimes the subject may be such as to call for a long line
of frequent tests which necessitate patient and accurate attention to
minute details. Results must be reported often--daily, or possibly with
still greater frequency. Edison does not forget what is going on; but in
his daily tours through the laboratory keeps in touch with all the work
that is under the hands of his various assistants, showing by an instant
grasp of the present conditions of any experiment that he has a
full consciousness of its meaning and its reference to his original
conception.

The year 1869 saw the beginning of Edison's career as an acknowledged
inventor of commercial devices. From the outset, an innate recognition
of system dictated the desirability and wisdom of preserving reco