Frank took the helm and watched his companion as he shook the big sail out all over the boat, after which he led a rope fastened to one corner of it through a block at the end of a long spar that lay along the deck. He thrust this out over her side and made its inner end fast to the foot of the mast.

"A spinnaker boom always goes forward of the shrouds and you lead the guy aft outside them," he said. "Get hold of it and stick fast. It's easy so far, but in a minute the circus will begin. You want two pairs of hands to set a spinnaker in a breeze of wind."

Frank glanced at the short seas which surged by, glittering in the moonlight flecked with wisps of snowy froth, and it struck him by the way the boat swung over them with the foam boiling about her that she was carrying sufficient canvas in her mainsail. Then Harry, calling to him to mind his steering, hauled on a halliard and a mass of thrashing canvas rose up the mast. It blew out like a half-filled balloon, lifting up the boom, which was run out on the opposite side to the mainsail, and seemed bent on soaring skyward over the masthead. After that the boom swung forward with a crash, the mast strained and rattled, and Frank feared that the great loose sail would tear it out of the boat. He saw Harry lifted off his feet and flung upon the deck, after which the forward part of the boat was swept by flying ropes and billowy folds of canvas, among which his companion seemed to be futilely crawling to and fro. Presently his voice reached Frank hoarse and breathless.

"Haul on the guy!" he cried. "She'll pitch me over or whip the mast out if this goes on."

Frank dragged at the rope with all his might, but he could not get an inch of it in, and he dared not take his right hand off the tiller for fear of bringing the big mainboom over upon the spinnaker, which would probably have caused a catastrophe. Indeed, he fancied that one was inevitable already, since it seemed impossible that Harry could control the big loose sail which was now wildly hurling itself aloft.

"I can't move it!" he shouted.

Harry came aft with a jump and grasped the guy.

"Now," he said, "together! Get both hands upon it. Hold the tiller with your elbow."

For the next half minute there was a furious struggle, and as the boom went up again Frank felt that they were beaten. His companion, however, hung on desperately, panting hard, and by degrees the boom swung down and back across the boat and the sail flattened out.

"Make fast!" cried Harry breathlessly. "I can manage the sheet."