The Talking Machine Forum — For All Antique Phonographs & Recordings

Dave is right. ⅛" in 4" is 1:32. My problem has been that I recalled ⅛" per foot, which is the information from the later article and which had been picked upon by others and which is not borne out by measuring a machine. Edison's original letter makes it clear. 1:32 it is!

Thanks

Keith

....and then when one starts measuring a bunch of
mandrels to get the actual results, one finds out that
it's more like 1 in 32.5 instead of 1 in 32.

So, we have some early indications of the ideal design
taper, and then we have the measurements of what actually
exists.