[GreenKeys] Telephoto machines?

[Richard Knoppow]

      The term Sonograph reminded me of another device not related but 
the name tickled my memory.   This was a sound spectrograph developed at 
Bell Laboratories sometime around the mid-1940s and used for the 
analysis of speech.   A book was published describing the method and 
discussing some of the results under the title _Visible Speech_  Potter, 
Kopp and Green   (1948) D. van Nostrand and Company.   I thought the 
machine might have used Teledeltos paper but it seems to have used 
photographic paper.   A machine for "reading" the graphs was also 
designed.  I remember seeing a film or program about this research on 
television when I was a kid.  Perhaps available at Archive org or You 
Tube, I have not yet looked. Although pretty far removed from Teletype 
machines or even FAX machines I think it may be of some interest to 
those on this list. Note that Mellville Bell, Alexander Bell's father, 
devised a phonetic alphabet also called Visible Speech, many years 
before this spectrum analyzer.   Unfortunately the book does not seem to 
be available as a PDF on the web.   I believe several related papers 
were published in the BSTJ and in the Journal of the Acoustical Society 
of America but do not have specific citations.

On 6/30/2015 10:10 AM, Lester Veenstra wrote:
> And also use in the SONOGRAPH, a device well known to CTTs and CTMs.
>
>
> Lester B Veenstra  MØYCM K1YCM W8YCM
> lester at veenstras.com
>
>> -- Chris Elmquist N?JCF
>      No, it was called Teledeltos paper.   It's a simple resistive
> coating (carbon plus copper thiocyanate in the final version)
> which is burned off by power from the writing stylus.  It's
> not electrostatic; that puts something onto the paper. This takes it
> off.
>
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-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL