4. You should always maintain contactbetween the leveling screw shoes and the footplate.5. You should not disturb the setup of theinstrument until you are certain that all observa-tions at that point are completed and roughlychecked. You should move the instrument fromthat setup only after checking with the party chief.6. Before the transit is moved or taken up,you should center the instrument on the footplate, roughly equalize the height of the levelingscrews, clamp the upper motion (the lowermotion may be tightened lightly), and point theMeasuring Horizontal AnglesThe transit contains a graduated horizontalcircle, referred to as the horizontal limb. Thehorizontal limb may be graduated clockwise from0° through 360°, as shown in figure 13-9, viewA, or clockwise from 0° through 360° and alsoin quadrants, as shown in figure 13-9, view B; orboth clockwise and counterclockwise from 0°through 360°, as shown in figure 13-9, view C.The horizontal limb can be clamped to stayfast when the telescope is rotated (called clampingthe lower motion), or it can be released fortelescope vertically upward and also lightly tightenrotating by hand (called releasing thethe vertical motion clamp.motion).lowerFigure 13-9.-Three types of horizontal limb graduations.13-9
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