The works of Sakubei Yamamoto
Disasters and Lynchings

Pits (Yama) in the Meiji (1868-1912) and Taisho (1912-1926) Eras: Rock Pressure (Ni) and Pillars
June 1966

Meiji Taisho: Juatsu (Ni) to Hashira
[Pits (Yama) in the Meiji (1868-1912) and Taisho (1912-1926) Eras: Rock Pressure (Ni) and Pillars]
38.1 x 54.2 cm Painting in Watercolors and Ink

Text at the Top right
Slopes with ceilings and bottoms consisting of glutinous shale would not easily collapse even when rock pressure grew stronger. However, points which had small-scale fault scarps or were near faults in slopes like the above were dangerous. Before slopes collapsed, wedges on pillars cracked and the knotted or weak points of pillars broke with cracking sounds. Props stood improperly (tatemae no warui hashira) fell toward the inclined sides of slopes (kata). In such cases, it was dangerous for every miner if they did not escape from the slopes no matter how seasoned the worker was. These phenomena sometimes continued for dozens of minutes or several hours. Miners could be buried alive if they did not escape from slopes with small-scale fault scarps. Miners (yamabito) used to say, "Ni ga kita" when these phenomena occurred.
After the cracking ceased, the height of slopes decreased because the roofs lowered or the bottoms swelled. Also the coal of coalfaces became softer because of increased rock pressure. Additionally, if there were coal pillars in haulage ways, their side walls swelled by about 30 centimeters thick and were in danger of crumbling away. Miners robbed these coal pillars (uwame o kuru), scraping coal away with their four-bladed rakes (ganzume) without using their pickaxes (tsurubashi).

Text at the Bottom Left
Creator's Notes
Tatemae no Warui Hashira [Props Stood Improperly]
It was a pillar which was not erected at an angle of 90 degrees against the inclination of the slope or vertically against the level, and was also called a yodomeki bashira.

Uwame Kuru [Robbing Coal Pillars of Coal]
It means to rob coal pillars of coal, though mining them for coal was prohibited. It also means to skimp every job, such as timbering or marking on the slopes which they repaired or drove. Uwame (to cheat) in pit dialect was regarded as a more vicious behavior than aburauri (to idle) among surface workers.

It was very dangerous to depend on pillars erected not according to the inclination of slopes like the one with red marks in the center of this painting, which sometimes fell down.
They did not bear growing rock pressure. Inexperienced hewers (sakiyama) often erected such pillars.

Translation Assisted by Mr. Nathan Johndro

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