Very rare Massive Chinese Examination strength bow

Very rare enormous Chinese strength bow. These bows were made extra large and powerful, and were graded by lbs as a test for military archers. There were three grades of strength bow, this appears to be the second grade as possibly indicated by two marks at the top. The bow is almost double the size of a standard bow, the string is about 1 cm thick of twisted gut and was never intended to take an arrow, for the strength test was only to ensure the candidate could draw the bow back competently. Fabulous condition, and complete with the string a very rare find.19th century.