Afterword to the compilation of the topographic wall map of the Republic of China

This article explains the objectives, source base, and technical principles underlying the compilation of the Topographic Wall Map of the Republic of China. Unlike small-scale wall maps intended chiefly to convey a general geographical overview, this map sought a comparatively precise representation of national relief, drainage, transportation networks, and settlements. Its compilers assembled maps at diverse scales from central and provincial survey agencies, hydraulic and railway authorities, geological institutions, foreign mapping organizations, and travelers, evaluating each source according to its date, survey control, methodology, and reliability. The article argues that a nationwide map cannot be produced by mechanically joining existing sheets. Geodetic, astronomical, and triangulation controls must be examined, while coordinate origins, datums, elevation systems, and projections must be converted into a unified framework. Deflection of the vertical, discrepancies in position, and the depiction of contours should be treated in accordance with the precision of the underlying evidence. Conflicts between adjoining sources are to be resolved by comparing scale, survey method, date, and corroborating railway, hydraulic, geological, and field records; transfer to the new projection may employ control points and triangular subdivision. Relief, drainage, place names, transport routes, administrative boundaries, symbols, and colors must balance accuracy, generalization, legibility, and suitability for viewing at a distance. Because the quality of surveying varied greatly across China, poorly documented regions could only be represented cautiously, without creating a false impression of precision. The map is therefore presented not as a definitive solution, but as a systematic synthesis of available knowledge and a foundation for continuing revision through triangulation, leveling, aerial photography, and future field surveys.