“Not so.”  Mr. Mortimer tapped his brow.  “An idea occurs to me—­if you will spare me a moment to consult with my—­er—­partner.  A Primrose Fete, you said?  I am no politician, Mr. Holly, but I understand the Primrose League exists—­primarily—­or ultimately—­to save our world-wide empire.  And how shall an empire stand without its Shakespeare?  Our tent and appliances will just load your wagon.  As the younger Dumas observed, ’Give me two boards, two trestles, three actors’—­but the great Aeschylus did with two—­’two actors,’ let us say—­’and a passion’—­provided your terms are not prohibitive . . .  Hi, Smiles!  Approach, Smiles, and be introduced to Thespis.  His charge is three shillings.  At the price of three shillings behold, Smiles, the golden age returned!  Comedy carted home through leafy ways shall trill her woodnotes—­her native woodnotes wild—­in Henley-in-Arden!”

The wagon had been packed and had departed, Mrs. Mortimer perched high on a pile of tent cloths, and Mr. Mortimer waving farewells from the tail-board.

The two children, left with instructions to keep near the boat and in hiding, had made a nest for themselves among the stalks of loosestrife, and sat watching the canal for sign of a moorhen or a water-rat.  The afternoon was bright and very still, with a dazzle on the water and a faint touch of autumn in the air—­the afterglow of summer soon to pass into grey chills and gusts of rain.  For many minutes neither had spoken.

“Look!” said Tilda, pointing to a distant ripple drawn straight across the surface.  “There goes a rat, and I’ve won!”

The boy said—­

“A boat takes up room in the water, doesn’t it?”

“0’ course it does.  But what’s that got to do with rats?”

“Nothing.  I was thinking of Sam’s puzzle, and I’ve guessed it.  A boat going downwards through a lock would want a lock full, all but the water it pushes out from the room it takes up.  Wouldn’t it?”

“I s’pose so,” said Tilda doubtfully.

“But a boat going up will want a lock full, and that water too.  And that’s why an empty boat going downhill takes more water than a loaded one, and less going up.”

To Tilda the puzzle remained a puzzle.  “It sounds all right,” she allowed.  “But what makes you so clever about boats?”

“I’ve got to know about them.  Else how shall we ever find the Island?”

She thought for half a minute.

“You’re sure about that Island?” she asked, a trifle anxiously.

Arthur Miles turned to her with a confident smile.

“Of course I’m sure.”

“Well, we’ll arsk about it when we get to Stratford-on-Avon.”

She was about to say more, but checked herself at sight of a barge coming down the canal—­slowly, and as yet so far away that the tramp of the tow-horse’s hoofs on the path was scarcely audible.  She laid a hand on ’Dolph’s collar and pressed him down in the long grass, commanding him to be quiet, whilst she and the boy wriggled away towards an alder bush that stood a furlong back from the bank.