Abstract:Mr. H. W. Tang, a British reader, asked for advice after reading the article 'Men-guang Ruler' written by Mr. Lu Chang In the sixth general issue of Ancient Architecture and Garden Technology. This paper gives a reply one by one on the analysis of the contents of the literature, the use method of combining the Men-guang ruler with the Ying-zao ruler and the calculation method of the Men-guang ruler proposed by Mr. H. W. Tang.