Blake.  And Blake was an English name!  He looked about as much like an Englishman as he, Whistler, looked like Dinkelspiel!

“I have seen plenty of Britishers,” thought the young fellow, “and not one of them ever looked like this chemist, or whatever he is.  And he’s a stranger—­worked here only a month.

“He was not tapping rocks or getting botanical specimens over here when we fellows came along the Upper Road.  His interest was in this dam—­if it was at long distance.  I wonder if we ought to report him to the marshal’s office.

“And get him, if he’s innocent of any wrongdoing, into hot water,” Whistler added, wagging his head.  “Say! that won’t do.  We fellows came near getting poor Seven Knott into trouble, thinking him a German spy,” he added, referring to an incident mentioned in “Navy Boys After the Submarines.”

Thus meditating he drew nearer to the place where the flashboard was down and the water poured into the rocky river bed.  There were stepping stones here, so it was easy for an agile person to get across the stream.

A blue haze of spray rose from the foaming water on the rocks, and there sounded a pleasant murmur from the falling water.  Birds darted in and out of this spray, fluttering their pinions in the bath thus provided.

On this side of the waterfall Whistler could discover nothing on the face of the dam nor along its foot that seemed in the least suspicious.  The masonry was perfect.

He crossed the river bed, leaping from stone to stone, and stepped up so close to the falling water that the spray splashed him.  It was somewhere about here, he thought, that the man, Blake, had focused his field-glass from the roadside.

There was absolutely nothing out of the way here that he could see.  The brush was kept cleared out at the foot of the dam for a dozen feet or so; there seemed to be no cover here.  Not a stone had been overturned along this cleared path.

The water splashed and bubbled at the foot of the fall.  Did it seem to splash more vigorously just here at the edge of the pool, hidden by the spray in part, and partly by the overhang of a great rock on which Whistler stood?

The observant youth stooped, then knelt beside the stream.  The rock was wet and his garments were fast becoming saturated.  But he paid no attention to this.

There was something down there in the pool, at its edge, struggling beneath the surface.  Not a fish, of course!

Suddenly he thrust in his hand, wetting his sleeve to the elbow.  Quickly he made sure that his suspicion was correct.  There was some kind of water wheel whirling down there.

He moved a flat stone which seemed to have lain for ages in its present position.  Yet under that stone was the end of the wheel’s axle with cogwheels rigged to pass on the power engendered by the wheel to some mechanical contrivance not yet placed.

Whistler returned the flat rock back to its former position, and moved slowly back from the place on hands and knees.  Then he stood up and looked all around to see if he had been observed.  Particularly did he look through the break in the trees toward the spot where Blake, the stranger, had stood when Whistler and his friends had first spied him.