| 摘要 |
A perpetual lunar gauge consisting of a disc upon which there are arranged (49) equally spaced radial marks around the perimeter, another disc within this one around which there are arranged (32) equally spaced radial marks, and within this, another moveable disc with phases of the moon indicated upon it where a whole lunation corresponds to a concentric arc of approximately 216.96 degrees. An index arm or indicator placed upon this is used to align with any particular angle on the gauge. A central axle securing these together, allows each piece to be turned relative to the others.
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