Over this main trunk, and most of the other canals and rivers, are a great variety of bridges, some with arches that are pointed not unlike the gothic, some semicircular, and others shaped like a horse-shoe: some have the piers of such an extraordinary height that the largest vessels, of two hundred tons, sail under them without striking their masts. Some of their bridges, of three, five, and seven arches[21], that cross the canal, are extremely light and beautiful to the eye, but the plan on which they are usually constructed does not imply much strength. Each stone, from five to ten feet in length, is cut so as to form a segment of the arch, and as, in such cases, there is no key-stone, ribs of wood fitted to the convexity of the arch are bolted through the stones by iron bars, fixed fast into the solid parts of the bridge. Sometimes, however, they are without wood, and the curved stones are morticed into long transverse blocks of stone, as in the annexed plate, which was drawn with great accuracy by Mr. Alexander. [21] A bridge with ninety-one arches will be noticed in a subsequent chapter. In this Plate, No. 1. Are stones cut to the curve of the arch 10 feet long. 2. An immense stone, 2 feet square, of the whole depth of the arch. 3. Curved stones, 7 feet long. 4. Ditto, 5 feet. 5. Ditto, 3-1/2 feet. 6. Ditto, 3 feet. 7. Ditto, 3 feet. 8.8. Stones similar to No. 2. being each one entire piece running through the bridge, and intended, it would seem, to bind the fabric together as the pillars 9.9. are morticed into them. [Illustration: _Construction of the Arch of a_ CHINESE BRIDGE _Pub. May 10^th., 1804, by Cadell, & Davies Strand._ _Neele sc. 352, Strand._]