| 摘要 |
A spirit level having an I-beam type frame with an opening in the web for mounting a vial assembly for viewing a bubble vial from the side. The vial assembly includes a dummy portion and a vial holding portion. An opening in a flange of the frame is adapted to provide a window for vertical viewing of the vial. A window element includes elongated upper and lower windows, with the upper window extending into the opening in the I-beam flange and the lower window being received by a recess in the vial assembly. A pair of locating ledges are disposed between the upper and lower windows and extend outwardly from the peripheries thereof. The ledges are separated by end slots which receive a cut-out web portion of the I-beam frame. When the upper window is disposed in the I-beam flange opening, the dummy portion of the vial assembly is positioned on one side of the web and holds the window element tightly in position against the flange. However, when the vial holder is placed on the opposite side of the web, a slight space is provided between the vial holder and adjacent ledge, thus permitting rocking adjustment of the vial holder before it is tightened to the web.
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