Shaku Ruler with Bachiru

This ruler is made of ivory. The surface was dyed red, and then the pattern was brought out by shaving down certain dyed areas to bring out the white of the ivory. The upper half of the top of the ruler is separated into five sections, each delineating a length of one sun, or around three cm. The images within the sections alternate between imaginary flowers and mandarin ducks standing atop lotus blossoms. The lower half of the ruler has the images of four birds, but no measurement marks. The reverse side of the ruler is decorated with flowers and mandarin ducks. The Shōsōin Imperial Repository in Nara has an ivory ruler similar to this one. However, because the design of this one is simpler, one hypothesis suggests that the Shōsōin example was imported while this ruler was made in Japan in imitation of it.

The ruler was made to be one shaku in length. It is 29.6 centimetres long, which makes it consistent with the length of one shaku in Tang China at the time. At Hōryūji, it is said that this ruler was used by Prince Shōtoku when he created Buddhist sculptures and priests’ garments. This ruler measures one shaku, which was approximately 29.7 cm during the Nara period (710–794). The design in the upper half seems to create five graduations for measuring objects. Bachiru refers to a technique in which ivory is dyed and then carved with designs to reveal the contrasting white color underneath. This ruler was dyed red and then engraved with mandarin ducks and floral motifs.

— Museum description: Tokyo National Museum (CC BY 4.0), via ColBase / Japan Search.