（解説文要約）
炭鉱労働者たちは、炭坑直営の売店や指定の店で買い物をしていました。
この炭坑直営の売店を売勘場といい、市価より高く売っていたようです。
売勘場の番頭は、巧妙な手口で、米などを少なめに計って売っていたようです。
現金の代わりに支払われていた炭券では他の店で買うことができません。
文句を言うと売ってもらえず、泣き寝入りをするほかありませんでした。
Coal miners shopped for their daily supplies at colliery-owned or affiliated shops.
They made their payment by Tanken, vouchers issued by the colliery company for their salary, instead of cash.
The shops were called Urikanba, and they charged higher prices than shops outside the mine.
In order to make a profit, shrewd head clerks at rice shops would often measure less rice than the miners were actually paying for.
Seeing as Tanken were only valid at the Urikanba, miners had no choice but to give in and accept the amount of rice they were given.