（解説文要約）
明治時代の、坑内から巻場の運転手への連絡方法を描いたものです。
左側の男性は坑内からワイヤーを使って巻揚げ機を操作する人に信号を送っています。
体重を乗せてワイヤーを引っ張って離すと、受信装置が音を出します。
1つは止めろ、二つは巻け、三つはおろせ、四つはゆっくり巻け、五つはゆっくりおろせ

といった具合に合図を送っていました。

中央に描かれているのは巻揚げ機の説明です。

 

 

This is a painting explaining how coal miners sent signals to the winch machine driver on the ground level around 1900.
The miner in the left of this painting is pulling on a wire to send a signal to the winch machine driver illustrated on the right side of this painting.
The miner uses his body weight to pull down on the wire and let go--this rings a bell connected to the wire on the ground level.
The number of rings specified a certain action. 
For example,one ring of the bell meant “Stop." Two rings meant, “Winch up." Three rings meant “Winch down." Four rings meant “Winch up slowly,” and five rings meant “Winch down slowly."
The illustration in the middle of this painting is an explanation of a winch machine.