"Twig?" he said. "Master Percy has been showing off."

"Silly young a.s.s! Jolly lucky he hasn't wrecked 'em! I shall have to talk to him."

They rowed almost up to the boat, keeping clear of the sandbank.

"Hullo, old sports," said Pratt. "Really, Phil, you ought to carry a chart--an up-to-date one, you know, that would show all the coral reefs and other traps for the hapless navigator. The Admiralty ought to mark 'em with buoys or lightships or something, but you can never expect anything from the Government. There's no danger, of course. I a.s.sured the ladies that they needn't be the least bit nervous or frightened, but it's annoying to be pulled up when you don't want to be. I'm sure a 'bus conductor must get frightfully annoyed when the old 'bus is spanking along and somebody wants to get in or out. I dare say you've noticed it, Mrs. Crawshay; the conductor is so ratty at being interrupted that he simply won't see the umbrella you're waving at him from the kerb. Mrs. Crawshay and Miss Crawshay were kind enough to pay a call on us at the camp this afternoon. It was just after you had gone, and as it was far too early for tea, I thought it would be interesting--what they call a treat, you know"--Pratt's impetuous tongue had fairly run away with his _savoir faire_--"to take the ladies for a spin, especially as they had never been in a motor-boat before. I promised faithfully to bring them back to tea; you got some meringues and things, of course--and I have a distinct grudge against fate for making me out to be not a man of my word. There's no armour against----"

"Oh, Mr. Pratt, please!" Lilian Crawshay implored. "Mr. Warrender, can you get us off?"

"I have given up all hope of tea," said Mrs. Crawshay, good-temperedly.

"We have friends coming to dinner, and Mr. Pratt tells me that we must wait till the tide turns. Will that be long?"

"Three hours or so, I'm afraid," replied Warrender.

"Dear, dear! We shall be very late, Lilian," said Mrs. Crawshay.

"Can't you tug us off?" asked the girl.

"I'm sorry to say we haven't a hawser. But I think we could pull the dinghy near enough for you to get into it, if Mrs. Crawshay would venture?"

"I'll venture anything rather than wait here three hours," said the lady, "though Mr. Pratt has been most kind. I have really quite enjoyed it, but three hours more, you know----"

"It would be rather awful!" said Warrender, with a glance at Pratt, who having succeeded in his object, to prevent certain disclosures, was mopping his brow in the background. Now, however, he came forward.

"That's right, Phil," he said. "No nearer, or you'll run aground too."

He leapt overboard, and stood up to his knees in water. "I'll hold the boat's nose, Mrs. Crawshay. Or perhaps I might take you in my arms and----" "Bless the boy! You're getting your feet wet. No, no! I don't think you shall take me in your arms."

"Or try pick-a-back? Or shall I make myself into a gangway for you to walk over? I'd stand perfectly firm."

"If you would give me a hand! Lilian, my dear, jump in first. Then you can each give me a hand, and I shall manage very nicely. Dear me! What an adventure for an old woman!"

"Not at all," said Pratt. "I mean----"

"I am sure you do," said Mrs. Crawshay, interrupting. "Will you take my parasol?"

Pratt meekly relieved her of the parasol, then turned to help the girl into the dinghy. Lilian, however, sprang in without his aid, and between them the two boys a.s.sisted the mother, who gave a sigh of relief as she sank down upon the thwart.

[Ill.u.s.tration: "BETWEEN THEM THE TWO BOYS a.s.sISTED THE MOTHER"]

"We'll come back for you presently, Pratt," said Warrender, stiffly.

"Don't attempt to run up, mind."

"Good-bye, Mr. Pratt," said Mrs. Crawshay. "And thank you so much. When you come up to dinner, be sure to bring your banjo."

The two boys pulled off, Pratt climbing back into the motor-boat.

"What a clever, amusing person Mr. Pratt is," said Mrs. Crawshay to Armstrong, facing her. "So ready! And an excellent performer on the banjo! We could never be dull in his company. He talked most amusingly, then sang us song after song. Don't you think 'Two Eyes of Blue' very pretty, Mr.----"

"Rather sentimental, isn't it?" said Armstrong, blushing.

"All his songs are sentimental. He was playing a very funny tune, though, when you came round the bend. I was sure his voice was getting tired, and asked him just to play. The tune was quite unknown to me, but I thought it very cheering."

Meanwhile, at the other end of the boat, Lilian had been giving explanations to Warrender.

"He intended just to bring us to the mouth of the river, but seemed to have some difficulty in turning round. I think he said he wanted more sea-room. At any rate, he ran out to sea, and then we stuck on that wretched sandbank. He talked and sang to amuse us; he has quite a pleasant voice, but his songs are dreadfully sentimental, aren't they?"

"Frightful tosh!" returned Warrender.

"Well, it was very good of him, especially when he must have been much annoyed at the mishap, which, of course, wasn't his fault."

"No, of course not," said Warrender.

"You speak as if you thought it was."

"Oh, no. Any one might run on a hidden sandbank. But the fact is----"

"Yes?"

"You see, he was in charge of the camp."

"You mean he oughtn't to have come at all?"

"Naturally he thought it would please you and Mrs. Crawshay, but----"

"Oh!"

The girl said no more.

"She thought I was jealous, or huffy, or something," Warrender confided to Armstrong later. "I wonder what she'd have said if I'd told her that the idiot had never run a motor-boat before?"

CHAPTER XVII

THE TOPMOST ROOM

It was in the evening twilight that Armstrong and Warrender put off in the pram for their second expedition to the tunnel. On reaching the ruins, Warrender posted himself in one of the lower rooms, while Armstrong mounted to the upper floor, intent on discovering the source of the ghostly moans. Climbing out of the window opening, and pulling aside the ivy, he found that steps had been made in the brickwork of the crumbling wall, by means of which any one with a steady head might with ease ascend to the roof. And there, behind one of the gables, partly protected from the weather, he came upon a long metal organ pipe laid flat, and near it a large funnel-shaped object. A strong breeze was blowing from the south-west, but the organ pipe gave forth no sound.

Still puzzled as to the manner in which the sound was produced, and reflecting that Pratt would probably have jumped to it at once, Armstrong heard a low whistle from below. He scrambled hastily down, and had only just slipped into the eastern room when he heard lumbering footsteps upon the stairs. From the doorway he watched the man whom he had seen in the morning. A minute or two after the new-comer had entered the western room, the moaning broke out. Armstrong waited until the man had descended and all was quiet again, then once more climbed upon the roof. The mystery was solved. The funnel had been so adjusted as to catch the wind, and direct it with some force into the mouth of the organ pipe. It turned like a weather-c.o.c.k, so that the sound was independent of the veering of the wind.

Rejoining Warrender, Armstrong informed him of the discovery, and suggested that he should examine the contrivance for himself.

"I'll take your word for it," said Warrender, smiling. "I don't care about steeple-jack feats in half darkness. We'll wait a little before we follow that fellow through the tunnel. Let's go up and watch for the signal."

It was perhaps half an hour later when the light appeared above the tree-tops.