(2) If the instrument is slightly out of adjustment, the index mark may point halfway between the

circle marks and cause confusion. In this case, obtain a reading by locating the degree graduation to the

left of the index and counting to the right from the 4-minute subdivisions until reaching the diametrically

opposite degree mark on the upper, inverted circle image. Multiply the number of these subdivisions by

one-half their value to obtain the proper number of minutes read by the index.

(3) One method of reading the minute value of the horizontal circle uses both the upper and

lower circles. If both circles are used, as shown in Figure 3-8, the number of divisions or graduations

from the degree mark on the lower circle to the degree mark diametrically opposite (180,) on the upper

circle, when multiplied by 2, gives the value of minutes.

When the 10-percent mark on the lower circle coincides with the 190, mark on the upper circle,

the minute value is 0. Counting to the right from the 9, mark on the lower circle to the 189, mark on the

upper circle, there are 30 divisions. The actual value is *1000' *which is equal to *9*60'. Therefore, in 60

minutes, which is the minute value from 9, there are 3 divisions. The minute value of each graduation