The Hairy Ape by Eugene O'Neill

The stokehole. A few minutes later.

The stokehole. In the rear, the dimly-outlined bulks of the furnaces and boilers. High overhead one hanging electric bulb sheds just enough light through the murky air laden with coal dust to pile up masses of shadows everywhere. A line of men, stripped to the waist, is before the furnace doors. They bend over, looking neither to right nor left, handling their shovels as if they were part of their bodies, with a strange, awkward, swinging rhythm. They use the shovels to throw open the furnace doors. Then from these fiery round holes in the black a flood of terrific light and heat pours full upon the men who are outlined in silhouette in the crouching, inhuman attitudes of chained gorillas. The men shovel with a rhythmic motion, swinging as on a pivot from the coal which lies in heaps on the floor behind to hurl it into the flaming mouths before them. There is a tumult of noise -- the brazen clang of the furnace doors as they are flung open or slammed shut, the grating, teeth-gritting grind of steel against steel, of crunching coal. This clash of sounds stuns one's ears with its rending dissonance. But there is order in it, rhythm, a mechanical regulated recurrence, a tempo. And rising above all, making the air hum with the quiver of liberated energy, the roar of leaping flames in the furnaces, the monotonous throbbing beat of the engines.