On Sun, 03 Apr 2011 16:20:08 +0100
Oli Glaser <oli.glaser@talktalk.net> wrote:

> I think it's probably just to make sure of this, like the old turntable=20
> strobes (for speed tuning) which generally had more than one line of=20
> dots which were slightly offset. This would be similar for the string,=20
> one point being slightly offset from the other which should make it=20
> easier to detect relative movement.

The turntables (at least the ones I had) had different line for each
speed - 33 1/3, 45 and 78. They looked offset, but in fact did have
different number of blocks.

John
--=20
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