The works of Sakubei Yamamoto
Drainage and Ventilation

Air Bridge Used since the Meiji Era (1868-1912): Underground Ventilation
March 1965

Meiji yori Fukyo: Konai Tsuki
[Air Bridge Used since the Meiji Era (1868-1912): Underground Ventilation]
38.2 x 54.3 cm Painting in Watercolors and Ink

Air bridges had to be built where return air ways and other roadways were crossed. Large-scale coal mines like those run by Nittetsu installed large-sized elliptical pipes made of steel plates of 1/16 inch in thickness on the roofs of their roadways. However, small and middle-scale coal mines used air bridges of cedar boards instead of pipes. But large-scale coal mines did not have small and narrow single coalfaces called tancho-shiki kirihas, and they did not have many air bridges for ventilation.
It was very expensive for coal mines with hard roof rocks to install air bridges. Such coal mines needed a lot of money for roof-rock cutting and timbering.

Text at the Top Right
Ventilation fans or pipes were sometimes used.

Words in the Inset
honsen makioroshi: main slope
haiki oroshi: return air way
fukyo: air bridge
shomon: small gate
bira: curtain or canvas (canvas door)
itabari matawa shomon: wooden fence or small gate
tanchu: coal pillar

Translation Assisted by Mr. Nathan Johndro

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