Part 6/9:
The book "Surveying for Engineers" also covers how large-scale maps are created, especially in the UK, where the Ordnance Survey maps are based on a Transverse Mercator projection. This projection models Earth's curved surface onto a flat map, inherently introducing distortions.
The maps use a scale factor to adjust measurements taken on the map to real-world distances at various locations. The fact that the scale factor varies across the map further confirms that a uniform flat map cannot accurately represent Earth's surface. Instead, the need for variable correction factors indicates Earth's roundness, as flat Earth models would not require such adjustments.