"Bravo, Minerva!" cried Mr. Howbridge. "You should have been a lawyer. I shall call you Portia for a change."

"Don't, please!" she begged. "You have enough nicknames for me now."

"Very well then, we'll stick to the old ones. And, meanwhile, if you are all ready I'll give the word to Hank to start his mules. There is no hurry on this trip, as the man to whom I am to deliver this boat has no special need for it. But we may as well travel on."

"I'll be glad when I can start the gasoline motor," remarked Neale.

"Which will be as soon as we get off the ca.n.a.l and into the river," said the lawyer. "I'd use the motor now, only the ca.n.a.l company won't permit it on account of the wash of the propeller tearing away the banks."

The tow-line tauted as the mules leaned forward in their collars, and once more the _Bluebird_ was under way.

Life aboard the houseboat was simple and easy, as it was intended to be.

There was little housework to do, and it was soon over, and all that remained was to sit on deck and watch the ever-changing scenery. The changes were not too rapid, either, for a boat towed on a ca.n.a.l does not progress very fast.

"It's like a moving picture, isn't it?" remarked Agnes. "It puts me in mind of some scenes in foreign countries--rural scenes, I mean."

"Only the moving pictures move so much faster," returned Ruth, with a smile. "They show you hundreds of miles in a few minutes."

"Gracious, I wouldn't want to ride as fast as that," exclaimed Tess.

"We'd fall off or blow away sure!"

It just suited the Corner House girls, though, and Neale extracted full enjoyment from it, though, truth to tell, he was rather worried in his mind. One matter was the finding of his father, and the other was a suspicion concerning Hank and the ring.

This was a suspicion which, as yet, Neale hardly admitted to himself very plainly. He wanted to watch the mule driver for a time yet.

"It may not have been one of Ruth's rings, to begin with," reasoned Neale. "And, if it is, I don't believe Hank had anything to do with taking it, though he may know who did. I've got to keep on the watch!"

His meditations were interrupted, as he sat on the deck of the boat, by hearing Hank cry:

"Lock! Lock!"

That meant the boat was approaching one of the devices by which ca.n.a.l craft are taken over hills. A ca.n.a.l is, of course, a stream on a level.

It does not run like a river. In fact, it is just like a big ditch.

But as a ca.n.a.l winds over the country it comes to hills, and to get up or down these, two methods are employed. One is what is called an inclined plane.

The ca.n.a.l comes to the foot of a hill and stops. There a sort of big cradle is let down into the water, the boat is floated into the cradle, and then boat, cradle and all are pulled up over the hill on a sort of railroad track, a turbine water wheel usually furnishing the power. Once over the brow of the hill the cradle and boat slide down into the water again and the journey is resumed.

The other means of getting a ca.n.a.l boat over a hill is by means of a lock. When the waterway is stopped in its level progress by reaching a hill, a square place is excavated and lined with rocks so as to form a water-tight basin, the open end being closed by big, wooden gates.

The _Bluebird_ was now approaching one of these locks, where it was to be raised from a low to a higher level. While Hank managed the mules, Neale steered the boat into the stone-lined basin. Then the big gates were closed behind the craft, and the mules, being unhitched, were sent forward to begin towing again when the boat should have been lifted.

"Now we can watch!" said Dot as she and Tess took their places at the railing. Going through ca.n.a.l locks was a novelty for them, as there were no locks near Milton, though the ca.n.a.l ran through the town.

Once the _Bluebird_ was locked within the small stone-lined basin, water was admitted to it through gates at the other and higher end. These gates kept the body of water on the higher level from pouring into the lower part of the ca.n.a.l. Faster and faster the water rushed in as the lock keeper opened more valves in the big gates. The water foamed and hissed all around the boat.

"Oh, we're going up!" cried Dot. "Look, we're rising!"

"Just like in an elevator!" added Tess.

And, indeed, that is just what it was like. The water lifted the _Bluebird_ up higher and higher. As soon as the water had raised it to the upper level, the other gates were opened, and the _Bluebird_ moved slowly out of the lock, having been raised about fifteen feet, from a lower to a higher level. Going from a higher to a lower is just the reverse of this. Sometimes a hill is so high that three sets of locks are necessary to get a boat up or down.

Once more the mules were hitched to the tow-line, and started off. As the boat left the lock another one came in, which was to be lowered. The children watched this as long as they could, and then turned their attention to new scenes.

It was toward the close of the afternoon, during which nothing exciting had happened, except that Tess nearly fell overboard while leaning too far across the rail to see something in the water, that Neale, looking forward toward the mules and their driver, saw a man leading a lone animal come out of a shanty along the towpath and begin to talk to Hank.

Hank halted his team, and the _Bluebird_ slowly came to a stop. Mr.

Howbridge, who was talking to Ruth and Agnes, looked up from a book of accounts he was going over with them and inquired:

"What's the matter?"

"Oh, Hank has met a friend, I imagine," ventured Neale. "It's a man with a lone mule."

"Well, he shouldn't stop just to have a friendly talk," objected the lawyer. "We aren't hiring him for that. Give him a call, Neale, and see what he means."

But before this could be done Hank turned, and, making a megaphone of his hands, called:

"Say, do you folks want to buy a good mule cheap?"

"Buy a mule," repeated the lawyer, somewhat puzzled.

"Yes. This man has one to sell, and it might be a good plan for us to have an extra one."

"I never thought of that," said the lawyer. "It might be a good plan.

Let's go up and see about it, Neale."

"Let's all go," proposed Agnes. "It will rest us to walk along the towpath."

The _Bluebird_ was near sh.o.r.e and there was no difficulty in getting to the path. Then all save Mrs. MacCall, who preferred to remain on board, walked up toward the two men and the three mules.

The man who had stopped Hank was a rough-looking character, but many towpath men were that, and little was thought of it at the time.

"Do you folks want to buy a good mule?" he asked. "I'll sell him cheap,"

he went on. "I had a team, but the other died on me."

"I'm not much of an authority on mules," said Mr. Howbridge slowly.

"What do you say, Neale? Would you advise purchasing this animal if he is a bargain?"

Neale did not answer. He was carefully looking at the mule, which stood near the other two.

"Where'd you get this mule?" asked Neale quickly, looking at the stranger.

"Oh, I've had him a good while. He's one of a team, but I sold my boat and--"

"This mule never towed a boat!" said the boy quickly.

"What makes you say that?" demanded the man in an angry voice.