| 摘要 |
An instrument for indicating levels above an irregular surface. A liquid reservoir of uniform internal cross section, having a scale on a transparent side wall indicating distances above and below a zero mark, is connected by a flexible duct with the bottom of an elongated transparent tube mounted on an elongated rod, the latter having a scale indicating distances above the bottom thereof. A pair of endless tapes is mounted for movement along the length of the tube. The tube is flat in cross section. The cross sectional area of the reservoir is larger than that of the tube, the ratio being an integer greater than one, and the ratio of the divisions on the scales on the reservoir and on one of the movable tapes is spaced in inverse ratio. The rod carries a movable guide which can be set to different positions to enable an operator to indicate positions at predetermined levels.
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