“But where would it come down?  That’s the point!” cried Mrs. Bobbsey.  “If it came down in the lake——­”

“It’s on Hemlock Island, take my word for it!” growled out Captain Craig, in whose motor-boat the searching party was riding.  It was not because he was cross that his voice had a growling sound.  It was just naturally hoarse.  He was out on the water so much, often in the cold and rain, that he seemed to have an everlasting cold.  “We’ll find the balloon and the children, too, on Hemlock Island,” he went on.  “Half a dozen men I talked to, just before you came, said they saw something big and black, like an airship, swooping down on the island.  We’ll find ’em there, never fear!”

“How far are we from Hemlock Island?” asked Mr. Bobbsey of Captain Craig, when they had been in the motor-boat about fifteen minutes.

“Oh, a few miles—­just a few miles,” was the answer.

“And how long will it take to get there?” Mrs. Bobbsey asked.

“Well, that’s hard to say,” was the answer.  “It might take us a long while, and again it might not take us so long.”

“Why is that?” asked Mr. Bobbsey, wondering whether Bert and Nan would be all right, left to themselves as they were.  But then they would have their uncle, aunt, and cousin to look after them.

“Well,” went on Captain Craig, as he steered the boat to one side, “you see it’s getting thicker and thicker—­I mean the weather.  The rain is coming down harder and it’s getting foggy, too.  I can’t very well see where to steer, and I have to run at slow speed.  So it will take me longer to get to Hemlock Island than if it was a clear day and I could run as fast as my boat would go.”

“Well, get there as soon as you can,” begged Mrs. Bobbsey.  “I’m sure if Flossie and Freddie are on the island in all this rain they will be terribly frightened!”

“Well, they may be—­a little,” admitted Mr. Bobbsey.  “But Flossie and Freddie are brave children.  They’ll make the best of things I’m sure!”

The motor-boat went chug-chugging its way across the big lake, not running as fast as it could have done on a fair day.  The rain poured down, making a hissing sound in the water.  Those in the boat wore rubber coats, for Captain Craig had supplied them at his boathouse before starting out.  He owned a boat dock, and also a fishing pier, and supplied pleasure parties with nearly everything they needed for fair weather or stormy.

Suddenly Mrs. Bobbsey, who was straining her eyes to peer through the mist and rain, uttered a cry.

“There’s something!” she called out.

“Where?” asked her husband, and Captain Craig leaned forward, his hands gripping the spokes of the steering wheel.

“Right straight ahead,” went on Mrs. Bobbsey.  “Something black is looming up in the fog.  Maybe it’s the balloon!”

“We can’t be anywhere near the island yet,” said the captain.  “That is unless I’m away off my course.  But we’ll soon find out what it is.”