On Apr 15, 6:11 am, (David Griffith) wrote:
When the key is down, the sounder clicks down. Let go and
it clacks up. So, a dot is "click-clack" and a dash is
"click-wait-clack".

With most sounders, the sound of the armature going down is different
from the sound going up, as you describe, so it's more than the time
spacing.

I think the Mark and Space stuff has to do with the
fact that the line was always kept energized, thus, an idle line would
hold the sounder arm down. That way you'd know immediately if there wa
s
a line fault.

Yes, but there were several reasons for the normally-energized series
line systems.

1) The first systems were powered by wet primary batteries called
"gravity" cells. (You can still make your own - all you need is
copper, zinc, copper sulphate, water and a jar). Unlike most other
kinds of cells, the gravity cells need a load for best results.

2) The primary cells required a lot of maintenance and care. With a
normally-energized system, line batteries were needed only at the ends
of a line; the telegraph offices in between would not need them
(except a cell or two for local loops). A typical line battery would
consist of 100 to 200 gravity cells (often half the cells would be at
each end) and permit operation over lines of 100 to 400 miles,
depending on the wire size and number of intermediate stations. (#9 or
#6 iron wire was commonly used for telegraph lines). So you can see
the advantage of not needing line batteries everywhere!

3) Besides making a line break obvious, operation up to a break could
be had by grounding the line at the last convenient point before the
break.

4) Normally energized circuits made duplexing, multiplexing and other
systems easier to implement.

The wire telegraph was more sophisticated than some folks give it
credit for being.

----

A telegraph story:

There was a railroad which had an important position open at the
division office. Applicants were told to show up on a certain day in
the outer waiting room, and wait to be called into the
Superintendent's private office for an interview.

The outer waiting room was a busy place, with a telegraph sounder
going continuously, various employees doing all sorts of tasks, and
the Superintendent inside his private office with the door shut.

A number of applicants showed up, most with years of experience. Each
handed their papers to the clerk, took a seat, and waited.

After all the chairs were occupied, a young man arrived - obviously
not nearly so experienced as the others. He paused for a moment,
papers in hand. Then he walked straight to the door of the
Superintendent's private office, opened it, and walked right in,
closing the door behind him!

The other applicants looked at each other in surprise and some
amusement. Barging in on the Division Superintendent was the best
guarantee of never getting any job! One waiting applicant said the
word "greenhorn" and the others all nodded.

But a few moments later, the door of the Superintendent's office
opened, and the Superintendent came out, followed by the young man.
The Superintendent said: "Thank you all for coming, but the position
has been filled." It was obvious that the young man had gotten the job
they all wanted.

Some of the applicants started to protest, but the Superintendent just
pointed to the telegraph sounder. It wasn't on an outside line. It was
playing the same message over and over:

"If you can read this, come into my office"

73 de Jim, N2EY

The