I thoroughly enjoyed Thomas Henden's analysis of the stroboscopic
effect.  I am a great fan of strobes.

Sorry, but I guess I should have kept my tongue out of my cheek
and asked the proper question:  Could the stroboscopic effect account
for the paper appearing to move bottom to top?

I don't think so, but as soon as I can repair my 40-year-old
stroboscope I will check it out !

I also own 1-1/2 Strobo-Conn tuners, the one with the adjustable
tuning fork oscillator driving 12 strobe wheels, and an amplifier
lighting a large neon bulb behind the wheels.

Anyone working around moving machinery should be aware of the strobo-
scopic effect.  With a fluorescent light above my table saw I thought
the blade had come off the motor shaft as it appeared to stop!

I held the work with one hand and reached for the master switch with
the other.  Out went the lights, and I was in the dark with a rotating
blade half through the work.  As it slowed to a stop I realized what
had happened.

John Spradley

 [ Mike Ames pointed out to me that the old Conn Strobotuner with the
 [ spinning strobe disc is about the only way to test the tuning of a
 [ xylophone.  The tone decays so quickly that an ordinary frequency
 [ 'counter' can't measure it.  -- Robbie