120' Sparks: Tesla's own words

(Terry, let me know if the formatting in this message gets too mangled.  My
last one was almost illegible.  I can repost this with word wrapping turned
off if it helps. -Charles) <<<looks fine to me - T. >>>

Hi everyone!

Before Terry kills the "Tesla's Energy Transmission"  thread and puts it to
a well deserved rest, I felt the master himself, Nikola Tesla should be
heard from regarding the supposed 120' spark length that comes up so often.
There have been a lot of other bogus numbers in this discussion as well.
Tesla kept meticulous notes, so anyone with a serious interest in his
Colorado Springs system should read them along with Richared Hull's
excellent analysis (if it's still available...try Amazon).  Forget the hype
in some of the Tesla bios and just go to the source!

Anyway here is an excerpt from the Colorado Springs notes in which Tesla is
describing a series of photographs that had just been shot of his system:

Colorado Springs Notes December 31, 1899

IX. " This photograph illustrates again the extra coil with streamers and
sparks from a pointed wire placed towards the camera"
"The longest streamers reached the side of the building and even the
corners sometimes.  One of them reached the photographer Mr. Alley in the
corner of the building, while another one struck me as I was operating the
switch in another corner.  They were so feeble at that distance, however,
that they did not cause any injury or pain.  Another struck the camera but,
as subsequently found, did not spoil the plate.  These streamers were about
the longest produceable in the present building, with the roof closed,
measuring from 31-32 feet in a straight line from origin to end.  Taking
into account the curiously curved path the length was probably more than
twice this, so that taking the discharge from tip to tip of these longest
streamers, the actual path of the discharge through the air was from, say,
124-128 feet!  If the building would permit I think that the present
apparatus, by putting  about two to three times the copper in the
oscillator a discharge extending through approximately twice this distance
would be obtained, and by overcoming some defects of the present type of
oscillator a further gain of about 50% could still be effected, so that I
can certainly expect to reach, measured in this way, a length from 372 to
384 feet from end to end."

Read this closely.  He is saying that the maximum spark length he could
achieve with his sytem in its existing building was 31-32 feet.  Since the
spark is sinuous, he then estimates how long the actual path through the
air is (i.e. if you stretched it out) and comes up with the 128 foot
figure.  He guesses that his present system could ouput twice this distance
if you measured it in this stretched out fashion.  If you look at this as a
point to point spark which is how we measure them now, he is saying that he
achieved 31-32 linear feet, and thinks he could do maybe 64 feet if he were
in a bigger building and lowered the frequency of his system a bit.  It's
no wonder that this 128 foot figure became part of the Tesla myth.  Even a
32 foot spark was an incredible feat for 1899 when you consider the
equipment available at the time. Note also that these are sparks inside the
building.  Tesla did not get huge sparks from his mast.  There was simply
not enough clearance in the roof opening, and he had problems with arcing
from the mast to supporting structures.  All that said,  a 32 foot spark
was an amazing achievement for 1899 considering the equipment Tesla had to
work with.

Lastly regarding the destruction of one of the generators at the Colorado
Springs power plant, no suprise here.  Tesla was sending huge HV transients
down the AC supply line (I believe he was arcing the transmission line to
ground at the time).  The generator was simply not designed to withstand
that sort of overvoltage and arced internally.  Much of this was hashed out
last February on this list in the thread "Tesla Coil Operation - Myths"
which can be found by searching pupman-dot-com

Hope everyone has a great holiday with lots of arcs & sparks!


Charles Brush