Hi, In several recent articles, I have seen the angular rotation of
records reported to four significant figures.   While I was tempted to
dismiss these figures as obviously over-precise, I suspect that Glenn
or someone else has made a serious and earnest effort to define the
speed used as carefully as possible.  So I am interested to see how it
was done.  Could a couple of the folks who have done so tell us the
process??

The only way I was able to figure out was to assume that Caruso and the
orchestra performed at a precise pitch and then adjust the record
player until the pitch matched and record the RPM.

Craig Smith

 [ A discerning ear can detect a pitch error of less than 1%, so
 [ three significant digits is reasonable.  The 'four-digit' speed,
 [ 78.26 rpm, synchronizes with a 92-line stroboscope disc illuminated
 [ with light flashing at 120 Hz, from 60 Hz mains.  Of course, this
 [ is useless if you have 50 Hz mains!  -- Robbie