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Re: Tesla's CS Coil Data from ScanTesla and all....

Original poster: "Bart B. Anderson" <bartb@xxxxxxxxxxxxxxxx>

And it doesn't take a lot of thought to understand why Tesla and all should account for all the "path lengths" rather than a point to point discharge, except of course, way too much approximation and interpretation evolves. For most measurement purposes of today's coiler "goals", point to point is perfectly valid. If measuring the voltage, current, and all the other misc. of how far an arc can propagate in an atmosphere, then certainly the entire path length should be measured, but always by interpretation of a photograph (that's the problem).

Take care,

Tesla list wrote:

Original poster: Charles Brush <cfbrush@xxxxxxxxxxxxx>

<huge snip>

John, are you, well, absolutely certain on this? The reason is I have read the "120 foot" (40 meter) figure so many times. Please understand I'm just double checking with you; this is the first time I personally have seen the 33 feet number. Again, I am not arguing with you, I am just very surprised!

This is a bit like finding out who Santa Claus really is! ... :-(


This gets hashed out every few years here. It seems the 120' number did come from Tesla himself, but he was estimating the length of his 32' sparks if you stretched them out so that they had no twists and turns. He no doubt preferred the larger number when talking to reporters or seeking financial backing from the wealthy industrialists of the time. Sadly few biographers seem to have actually read the guy's notes which explain it all pretty clearly. Here is the section from the CSN. Read it closely and you'll see where the numbers came from. At the end he guesses how the output could be improved with a larger building, bigger resonator, etc :

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 producible 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."

It's too bad that an incredible accomplishment like 32 foot sparks in 1899 has gotten obscured by sensationalistic and fictional accounts.


Charles Brush