It's actually the sine scale wrapped around twice.
If you use the inner sine scale, you need to add .0 to the front of the digits shown. Otherwise (if the angle is larger than 5° 50´), just place the decimal point in front.
I guess you could use the inner scale for extremely small windspeeds! But for most winds just use the large numbers.
The old workbook is out of print, but there is another........ as Yoda says
If you're interested, there will be a CR-3 android app out very soon!
Phil