Futa Yasunosuke

was a village chief and also an architect in Kumamoto Prefecture, Japan. He built an aqueduct, Tsujun Bridge, which improved the fertility of the land.

History Futa inherited the post of village chief at the age of twenty-three. At the age of thirty, he was entrusted to extend rice fields and was provided with the funds to do so. He became a full-fledged village chief at the age of thirty-two. Within that same year, he was awarded a prize for successfully keeping nationwide famine away from his village. Futa undertook the construction of the notable Tsujun Bridge, which was completed on July 29, 1854. He was recognized and lauded for his contributions to the village, particularly by Lord Hosokawa for the bridge. He remained village chief until he died on 3 April 1873, at the age of seventy-one.

Tsujun Bridge

Tsujun Bridge is an aqueduct in Yabe, Kumamoto. Completed in 1854, it is an arch bridge 84 meters long, with an arch that spans 27.3 meters. It is the largest stone aqueduct in Japan. The aqueduct was 6meters lower than the upper part of the waterway, and because of this, a reversed siphon mechanism works when water is allowed to flow through the aqueduct. The stone aqueduct was made watertight with mortar. In order to keep the aqueduct in good working condition, and for the safety of viewers such as tourists, water is poured into the river once in a while. This estimate is based on the direct cost of 710 Kan; this is roughly the same as 800 Kan, which was the direct cost of Lord Shigekata Hosokawa's traveling with a little less than 1000 followers to Osaka for Sankin kotai (alternate attendance).

Economical effectiveness of the aqueduct Futa was very clever in stating that he would open 42 Cho (1 Cho = 99.17 a) of rice fields; the real number of rice fields opened was 73 Cho, making a difference of 31 Cho more than he had promised. This meant that the money he could use would be very great.

Technology Futa observed a rotten rainwater pipe which blew out water, and it gave him the idea for the reversed siphon system, a method of sending water to higher land. He made three waterways and a bridge to let water cross a river to higher land. The water pressure was too high for wood, so the construction material was changed to stone. Special mortar was developed to make the waterways tight. On the day of completion, Futa stood in a spot where, if the bridge failed, he would die.