Fatuity: Noun: something foolish or stupid : a foolish or stupid quality

From the short story “The Yellow Wallpaper” by Charlotte Perkins Gilman. “Looked at one way each breadth stands alone, the bloated curves and flourishes — a kind of  “Debased Romanesque” and delirium tremens — go waddling up and down in isolated columns of fatuity.”

I now understand that she was saying that the lines in the wallpaper were moving up and down and basically all over the wall in a stupid or foolish way. Sort of like they had a violent delirium and shook allover with tremors thereby it looked like it was all over the place.