In fact, they could not misunderstand Dingo’s intention.

“Then was Samuel Vernon alone when he left the sea-coast of the Congo?” ask Dick Sand.

“That I know not,” replied Captain Hull.  “However, it is probable that he would take a native escort.”

At that moment Negoro, leaving his post, showed himself on the deck.  At first no one remarked his presence, and could not observe the singular look he cast on the dog when he perceived the two letters over which the animal seem to mount guard.  But Dingo, having perceived the master-cook, began to show signs of the most extreme fury.

Negoro returned immediately to the crew’s quarters, not without a menacing gesture at the dog’s skill having escaped him.

“There is some mystery there,” murmured Captain Hull, who had lost none of this little scene.

“But, sir,” said the novice, “is it not very astonishing that a dog should know the letters of the alphabet?”

“No!” cried little Jack.  “Mama has often told me the story of a dog which knew how to read and write, and even play dominoes, like a real schoolmaster!”

“My dear child,” replied Mrs. Weldon, smiling, “that dog, whose name was Munito, was not a savant, as you suppose.  If I may believe what has been told me about it, Munito would not have been able to distinguish the letters which served to compose the words.  But its master, a clever American, having remarked what fine hearing Munito had, applied himself to cultivating that sense, and to draw from it some very curious effects.”

“How did he set to work, Mrs. Weldon?” asked Dick Sand, whom the history interested almost as much as little Jack.

“In this way, my friend.”  When Munito was ‘to appear’ before the public, letters similar to these were displayed on a table.  On that table the poodle walked about, waiting till a word was proposed, whether in a loud voice or in a low voice.  Only, one essential condition was that its master should know the word.”

“And, in the absence of its master—­” said the novice.

“The dog could have done nothing,” replied Mrs. Weldon, “and here is the reason.  The letters spread out on the table, Munito walked about through this alphabet.  When it arrived before the letter which it should choose to form the word required, it stopped; but if it stopped it was because it heard the noise—­imperceptible to all others—­of a toothpick that the American snapped in his pocket.  That noise was the signal for Munito to take the letter and arrange it in suitable order.”

“And that was all the secret?” cried Dick Sand.

“That was the whole secret,” replied Mrs. Weldon.  “It is very simple, like all that is done in the matter of prestidigitation.  In case of the American’s absence, Munito would be no longer Munito.  I am, then, astonished, his master not being there—­if, indeed, the traveler, Samuel Vernon, has ever been its master—­that Dingo could have recognized those two letters.”