| 摘要 |
An elongated body is provided including opposite side portions removably secured together by transverse threaded fasteners. One set of corresponding ends of the side portions include relieved areas opening toward each other defining a cavity opening outwardly of the corresponding end of the body and along one longitudinal edge thereof. A protractor arm is pivotally mounted within the notch for movement between a retracted position received within the cavity and extending along the one edge and an extended position disposed at substantially 90 DEG relative to the elongated body. The body and protractor arm include coacting structure for adjustably limiting angular displacement of the protractor arm to the extended position and the ends of the opposite side portions of the body remote from the protractor arm include two pairs of opposing sockets formed therein in which spirit level supporting annular bodies are mounted. The bodies are angularly adjustable in the corresponding sockets and clamped in adjusted angularly displaced positions between the body opposite side portions. The body side portions including windows registered with the spirit levels and a first form of the invention incorporates worm wheel teeth on the annular bodies and worm gear shafts journaled between the body side portions and meshed with the worm wheels. In a second form of the invention, the body side portions are notched and the annular bodies include a peripheral recess registered with the notches with which a lever tool may be engaged through the notches.
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