Rev. H. C. Du Bose, Chin. Rec., xix., 1888, p. 207 (Google Books ⧉, Amazon ⧉, Bookshop ⧉)

The Travels of Marco Polo

“Within the city there are, generally speaking, six canals from North to South, and six canals from East to West, intersecting one another at from a quarter to half a mile… ” (Rev. H. C. Du Bose, Chin. Rec., xix., 1888, p. 207).