this day in my laboratory over forty years later."

It was at Stratford that Edison's inventiveness was first displayed. The
hours of work of a night operator are usually from 7 P.M. to 7 A.M., and
to insure attention while on duty it is often provided that the operator
every hour, from 9 P.M. until relieved by the day operator, shall send
in the signal "6" to the train dispatcher's office. Edison revelled in
the opportunity for study and experiment given him by his long hours
of freedom in the daytime, but needed sleep, just as any healthy youth
does. Confronted by the necessity of sending in this watchman's signal
as evidence that he was awake and on duty, he constructed a small wheel
with notches on the rim, and attached it to the clock in such a manner
that the night-watchman could start it when the line was quiet, and at
each hour the wheel revolved and sent in accurately the dots required
for "sixing." The invention was a success, the device being, indeed,
similar to that of the modern district messenger box; but it was soon
noticed that, in spite of the regularity of the report, "Sf" could not
be raised even if a train message were sent immediately after. Detection
and a reprimand came in due course, but were not taken very seriously.

A serious occurrence that might have resulted in accident drove him soon
after from Canada, although the youth could hardly be held to blame for
it. Edison says: "This night job just suited me, as I could have the
whole day to myself. I had the faculty of sleeping in a chair any time
for a few minutes at a time. I taught the night-yardman my call, so I
could get half an hour's sleep now and then between trains, and in case
the station was called the watchman would awaken me. One night I got an
order to hold a freight train, and I replied that I would. I rushed out
to find the signalman, but before I could find him and get the signal
set, the train ran past. I ran to the telegraph office, and reported