e Strand and asked if
he had a powerful battery. He said he hadn't; that all that he had was
Tyndall's Royal Institution battery, which he supposed would not
serve. I saw it--one hundred cells--and getting the price--one hundred
guineas--hurried to Gouraud. He said 'Go ahead.' I telegraphed to the
man in Liverpool. He came on, got the battery to Liverpool, set up and
ready, just two hours before the test commenced. One of the principal
things that made the system a success was that the line was put to earth
at the sending end through a magnet, and the extra current from this,
passed to the line, served to sharpen the recording waves. This new
battery was strong enough to pass a powerful current through the magnet
without materially diminishing the strength of the line current."

[Footnote 4: The sand battery is now obsolete. In this type,
the cell containing the elements was filled with sand, which
was kept moist with an electrolyte.]

The test under these more favorable circumstances was a success. "The
record was as perfect as copper plate, and not a single remark was made
in the 'time lost' column." Edison was now asked if he thought he could
get a greater speed through submarine cables with this system than with
the regular methods, and replied that he would like a chance to try
it. For this purpose, twenty-two hundred miles of Brazilian cable then
stored under water in tanks at the Greenwich works of the Telegraph
Construction & Maintenance Company, near London, was placed at his
disposal from 8 P.M. until 6 A.M. "This just suited me, as I preferred
night-work. I got my apparatus down and set up, and then to get a
preliminary idea of what the distortion of the signal would be, I sent a
single dot, which should have been recorded upon my automatic paper by
a mark about one-thirty-second of an inch long. Instead of that it was
twenty-seven feet long! If I ever had any conceit, it vanished from my
boots up. I worked on this cable more than two weeks, and the best I
could do was two words per minute, which was only one-seventh of what
the guaranteed speed of the cable should be when laid. What I did
not know at the time was that a coiled cable, owing to induction, was
infinitely worse than when laid out straight, and that my speed was as
good as, if not better than, with the regular system; but no one told me
this." While he was engaged on these tests Colonel Gouraud came down
one night to visit him at