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Explanation: 「垂直出し」とは下げ振り定規（plumb rule）やレーザ鉛直器（laser plummet instrument）などを使って水平面・地平面に対して直角の方向を示すことです。
The maximum pumping height for showing the vertical line is one meter.
Beeton's Dictionary of Industries and Commerce - Google ブック検索結果Samuel Orchart Beeton著 p261
A weight of lead attached to a string, used by builders and other artificers for the purpose of showing the vertical line.