Humboldt H-3250 Length Comparators - Manual (Page 5)

Reading Instructions for H-3250.3 Dial Gauge
The gauge shown above has a total range of .400". This is indicated by the
upper small scale, which goes to 4. The gauge has a accuracy of .0001", which
is measured on the large outer scale. Each gradation of the outer scale is equal
to .0001"
One full revolution of the gauge’s large hand on the outer scale is equal to .010"
One full revolution of the hand on the small, lower scale is equal to .100"
Every full revolution of the hand on the small, lower scale is recorded on the
upper small scale, up to the maximum of 4.
Example:
Large hand is on 84,
the small, lower scale’s hand is between 4 and 5 on the scale,
the small, upper scale’s hand is between 2 and 3
.
2484
reading from the large outer scale
reading from small upper scale
reading from small lower scale
figure 1