due credit should be given to Henry, and that whenever Morse had the
opportunity he would gladly accord to that eminent man the discoveries
which were his. There never was a true second edition of Vail's book, but
in 1847 a few more copies were struck off from the old plates and the
date was, unfortunately, changed from 1845 to 1847. Henry, naturally,
looked upon this as a second edition and his resentment grew.

Morse's opportunity to do public honor to Henry came in 1848, when
Professor Sears C. Walker, of the Coast Survey, published a report
containing some remarks on the "Theory of Morse's Electro-Magnetic
Telegraph." When Professor Walker submitted this report to Morse the
latter said: "I have now the long-wished-for opportunity to do justice
publicly to Henry's discovery bearing upon the telegraph. I should like
to see him, however, previously, and learn definitely what he claims to
have discovered. I will then prepare a paper to be appended and published
as a note, if you see fit, to your Report."

This paper was written by Morse and sent to Professor Walker with the
request that it be submitted to Professor Henry for his revision, which
was done, but it was not included in Professor Walker's report, and this
naturally nettled Morse, who also had sensitive nerves, and so the breach
was widened. In this paper, after giving a brief history of electric
discoveries bearing on the telegraph, and of his own inventions, Morse
sums up:--

"While, therefore, I claim to be the first to propose the use of the
_electro-magnet for telegraphic purposes_, and the _first_ to _construct
a telegraph on the basis of the electro-magnet_, yet to Professor Henry
is unquestionably due the honor of the _discovery of a fact in science_
which proves the practicability of exciting magnetism through a long coil