Here the Count d’Artigas stole a rapid and meaning glance at Captain Spade, who responded with a gesture which said plainly enough:  “I understand.”  And had any one observed the captain during the visit, they could not have failed to remark that he examined with the greatest minuteness that portion of the park surrounding Pavilion No. 17, and the different paths leading to the latter—­probably in view of some prearranged scheme.

The garden of the pavilion was near the high wall surrounding the property, from the foot of which on the other side the hill sloped gently to the right bank of the Neuse.

The pavilion itself was a one-story building surmounted by a terrace in the Italian style.  It contained two rooms and an ante-room with strongly-barred windows.  On each side and in rear of the habitation were clusters of fine trees, which were then in full leaf.  In front was a cool, green velvety lawn, ornamented with shrubs and brilliantly tinted flowers.  The whole garden extended over about half an acre, and was reserved exclusively for the use of Thomas Roch, who was free to wander about it at pleasure under the surveillance of his guardian.

When the Count d’Artigas, Captain Spade, and the director entered the garden, the first person they saw was the warder Gaydon, standing at the door of the pavilion.  Unnoticed by the director the Count d’Artigas eyed the attendant with singular persistence.

It was not the first time that strangers had come to see the occupant of Pavilion No. 17, for the French inventor was justly regarded as the most interesting inmate of Healthful House.  Nevertheless, Gaydon’s attention was attracted by the originality of the type presented by the two visitors, of whose nationality he was ignorant.  If the name of the Count d’Artigas was not unfamiliar to him, he had never had occasion to meet that wealthy gentleman during the latter’s sojourn in the eastern ports.  He therefore had no idea as to who the Count was.  Neither was he aware that the schooner Ebba was then anchored at the entrance to the Neuse, at the foot of the hill upon which Healthful House was situated.

“Gaydon,” demanded the director, “where is Thomas Roch?”

“Yonder,” replied the warder, pointing to a man who was walking meditatively under the trees in rear of the pavilion.

“The Count d’Artigas has been authorized to visit Healthful House,” the director explained; “and does not wish to go away without having seen Thomas Roch, who was lately the subject of a good deal too much discussion.”

“And who would be talked about a great deal more,” added the Count, “had the Federal Government not taken the precaution to confine him in this establishment.”

“A necessary precaution, Count.”

“Necessary, as you observe, Mr. Director.  It is better for the peace of the world that his secret should die with him.”

After having glanced at the Count d’Artigas, Gaydon had not uttered a word; but preceding the two strangers he walked towards the clump of trees where the inventor was pacing back and forth.