length. This stick is known as Jacob’s staff, as shownin figure 15-38. For rough work, you may ignore theuse of a stick and merely use the height of your eyeabove the ground in your normal standing position.The hand level is used for checking grade duringthe rough or early part of a construction project and isnot used at distances greater than about 50 feet or evenlesser distances if an accuracy of more than 2 or 3tenths is required.DUMPY LEVELThe dumpy level (fig. 15-39) has its telescoperigidly attached to the level bar, which supports anadjustable, highly sensitive level vial. The cross hairsare brought into focus by rotation of the eyepiece andthe focusing knob. The telescope can be exactlytrained on the level rod by lightly tightening theazimuth clamp and manipulating the azimuth tangentscrew. Depending on atmospheric conditions, thedumpy level can be used to measure vertical distancesaccurately at distances of 300 feet or less. When usedfor alignment, it is accurate at distances up to 1,000feet.SELF-LEVELING LEVELThe self-leveling level (fig. 15-40) is a precise,time-saving leveling instrument and is equipped witha small bull’ s-eye level and three leveling screws. Theleveling screws, which are on a triangular foot plate,are used to center the bubble of the bull’ s-eye level.The line of sight automatically becomeshorizontal andbubble remainsremains horizontal as long as theapproximately centered. A prismaticFigure 15-40.—Self-leveling level.15-23
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