e eighties and early nineties. Improvement of the lamp was constantly
in his mind all those years, and besides the vast amount of detail
experimental work he laid out for his assistants, he carried on a great
deal of research personally. Sometimes whole books are filled in his
own handwriting with records of experiments showing every conceivable
variation of some particular line of inquiry; each trial bearing some
terse comment expressive of results. In one book appear the details of
one of these experiments on September 3, 1891, at 4.30 A.M., with the
comment: "Brought up lamp higher than a 16-c.p. 240 was ever brought
before--Hurrah!" Notwithstanding the late hour, he turns over to the
next page and goes on to write his deductions from this result as
compared with those previously obtained. Proceeding day by day, as
appears by this same book, he follows up another line of investigation
on lamps, apparently full of difficulty, for after one hundred and
thirty-two other recorded experiments we find this note: "Saturday 3.30
went home disgusted with incandescent lamps." This feeling was evidently
evanescent, for on the succeeding Monday the work was continued and
carried on by him as keenly as before, as shown by the next batch of
notes.

This is the only instance showing any indication of impatience that the
authors have found in looking through the enormous mass of laboratory
notes. All his assistants agree that Edison is the most patient,
tireless experimenter that could be conceived of. Failures do not
distress him; indeed, he regards them as always useful, as may be
gathered from the following, related by Dr. E. G. Acheson, formerly one
of his staff: "I once made an experiment in Edison's laboratory at Menlo
Park during the latter part of 1880, and the results were not as looked
for. I considered the experiment a perfect failure, and while bemoaning
the results of this apparent failure Mr. Edison entered, and, after
learning the facts of the case, cheerfully remarked that I should not
look upon it as a failure, for he considered every experiment a success,
as in all cases it cleared up the atmosphere, and even though it failed
to accomplish the results sought for, it should prove a valuable lesson
for guidance in future work. I believe that Mr. Edison's success as
an experimenter was, to a large extent, due to this happy view of all
experiments."

Edison has frequently remarked that out of a hundred experiments he