Thomas Roch paid no attention to them.  He appeared to be oblivious of their presence.

Meanwhile, Captain Spade, while being careful not to excite suspicion, had been minutely examining the immediate surroundings of the pavilion and the end of the park in which it was situated.  From the top of the sloping alleys he could easily distinguish the peak of a mast which showed above the wall of the park.  He recognized the peak at a glance as being that of the Ella, and knew therefore that the wall at this part skirted the right bank of the Neuse.

The Count d’Artigas’ whole attention was concentrated upon the French inventor.  The latter’s health appeared to have suffered in no way from his eighteen months’ confinement; but his queer attitude, his incoherent gestures, his haggard eye, and his indifference to what was passing around him testified only too plainly to the degeneration of his mental faculties.

At length Thomas Roch dropped into a seat and with the end of a switch traced in the sand of the alley the outline of a fortification.  Then kneeling down he made a number of little mounds that were evidently intended to represent bastions.  He next plucked some leaves from a neighboring tree and stuck them in the mounds like so many tiny flags.  All this was done with the utmost seriousness and without any attention whatever being paid to the onlookers.

It was the amusement of a child, but a child would have lacked this characteristic gravity.

“Is he then absolutely mad?” demanded the Count d’Artigas, who in spite of his habitual impassibility appeared to be somewhat disappointed.

“I warned you, Count, that nothing could be obtained from him.”

“Couldn’t he at least pay some attention to us?”

“It would perhaps be difficult to induce him to do so.”

Then turning to the attendant: 

“Speak to him, Gaydon.  Perhaps he will answer you.”

“Oh! he’ll answer me right enough, sir, never fear,” replied Gaydon.

He went up to the inventor and touching him on the shoulder, said gently:  “Thomas Roch!”

The latter raised his head, and of the persons present he doubtless saw but his keeper, though Captain Spade had come up and all formed a circle about him.

“Thomas Roch,” continued Gaydon, speaking in English, “here are some visitors to see you.  They are interested in your health—­in your work.”

The last word alone seemed to rouse him from his indifference.

“My work?” he replied, also in English, which he spoke like a native.

Then taking a pebble between his index finger and bent thumb, as a boy plays at marbles, he projected it against one of the little sand-heaps.  It scattered, and he jumped for joy.

“Blown to pieces!  The bastion is blown to pieces!  My explosive has destroyed everything at one blow!” he shouted, the light of triumph flashing in his eyes.