that he had seen young Armstrong strike the fatal blow--had seen
him distinctly by the light of a bright moon. Lincoln made him
repeat the statement until it seemed as if he were sealing the
death-warrant of the prisoner. Then Lincoln began his address to
the jury. He was not there as a hired attorney, he told them, but
because of friendship. He told of his old relations with Jack
Armstrong, of the kindness the prisoner's mother had shown him in
New Salem, how he had himself rocked the prisoner to sleep when
the latter was a little child. Then he reviewed the testimony,
pointing out how completely everything depended on the statements
of this one witness; and ended by proving beyond question that
his testimony was false, since, according to the almanac, which
he produced in court and showed to judge and jury, THERE WAS NO
MOON IN THE SKY THAT NIGHT at the hour the murder was committed.
The jury brought in a verdict of "Not guilty," and the prisoner
was discharged.

Lincoln was always strong with a jury. He knew how to handle men,
and he had a direct way of going to the heart of things. He had,
moreover, unusual powers of mental discipline. It was after his
return from Congress, when he had long been acknowledged one of
the foremost lawyers of the State, that he made up his mind he
lacked the power of close and sustained reasoning, and set
himself like a schoolboy to study works of logic and mathematics
to remedy the defect. At this time he committed to memory six
books of the propositions of Euclid; and, as always, he was an
eager reader on many subjects, striving in this way to make up
for the lack of education he had had as a boy. He was always
interested in mechanical principles and their workings, and in
May, 1849, patented a device for lifting vessels over shoals,