The flooding billows were spilled from the big tank at the top of the scaffold and the boat rocked in obedience to the tugging of a rope--tugged from the shore by a crew of helpers--that ran to the top of its mast.

Thus had the storm been produced.
A spidery, youngish man from one of the platforms built out from the scaffold, now became sharply vocal through a megaphone to assistants who were bending the elements to the need of this particular hazard of Hortense.

He called directions to the men who tugged the rope, to the men in control of the lights, and to another who seemed to create the billows.

Among other items he wished more action for the boat and more water for the billows.

"See that your tank gets full-up this time," he called, whereupon an engine under the scaffold, by means of a large rubber hose reaching into the pool, began to suck water into the tank above.
The speaker must be Miss Baxter's director, the enviable personage who saw her safely through her perils.