NavList:

To me, brought up to make always make a rough estimate first, Vernier scales provide a ‘second opinion’ (no pun intended) along the lines of:  "Looks like 41.30.6 to me.  Vernier agrees" – warm fuzzy feeling.  "Vernier says 41.30.8 – better have another look and decide which to believe".  Unfortunately, my Hughes Mates Three Circle has a 0-60 second Vernier on the drum, marked with six ten second intervals, which kind of knocks that possibility on the head unless you’re good at dividing by 60.  DaveP