Then there came the whirring of very many electric fans, stirring up the air.

Then came the whirring of its propeller.

He was glad enough when Nellie knocked loudly at a door through which came the whirring of a sewing machine.

From the street outside came the whirring of a motor and the sound of Mary Rochefort's voice saying good-by to Pollen.

There was no answer, but a second later came the whirring again, and then a big bat flew into the light, just grazing Tom's face.