Glasgow
University the surprising records that he obtained. His official report
closes thus: "The electromagnetic shunt with soft iron core, invented
by Mr. Edison, utilizing Professor Henry's discovery of electromagnetic
induction in a single circuit to produce a momentary reversal of the
line current at the instant when the battery is thrown off and so cut
off the chemical marks sharply at the proper instant, is the electrical
secret of the great speed he has achieved. The main peculiarities of Mr.
Edison's automatic telegraph shortly stated in conclusion are: (1) the
perforator; (2) the contact-maker; (3) the electromagnetic shunt; and
(4) the ferric cyanide of iron solution. It deserves award as a very
important step in land telegraphy." The attitude thus disclosed toward
Mr. Edison's work was never changed, except that admiration grew as
fresh inventions were brought forward. To the day of his death Lord
Kelvin remained on terms of warmest friendship with his American
co-laborer, with whose genius he thus first became acquainted at
Philadelphia in the environment of Franklin.

It is difficult to give any complete idea of the activity maintained at
the Newark shops during these anxious, harassed years, but the statement
that at one time no fewer than forty-five different inventions were
being worked upon, will furnish some notion of the incandescent activity
of the inventor and his assistants. The hours were literally endless;
and upon one occasion, when the order was in hand for a large quantity
of stock tickers, Edison locked his men in until the job had been
finished of making the machine perfect, and "all the bugs taken out,"
which meant sixty hours of unintermitted struggle with the difficulties.
Nor were the problems and inventions all connected with telegraphy.
On the contrary, Edison's mind welcomed almost any new suggestion as a
relief from the regular work in hand. Thus: "Toward the latter part of
1875, in the Newark shop, I invented a device for multiplying copies of
letters, which I sold to Mr. A. B. Dick, of Chicago, and in the years
since it has been universally introduced throughout the world. It is
called the 'Mimeograph.' I also invented devices for and introduced
paraffin paper, now used universally for wrapping up candy, etc."
The mimeograph employs a pointed stylus, used as in writing with a
lead-pencil, which is moved over a kind of tough prepared paper placed
on a finely grooved steel plate. T