They saw the three men working over it for a while, and finally push it overboard again so the boat could tow it.
When this was done the light craft was rowed down the river and the detectives lost track of it altogether.
They felt rather disappointed.
"What the deuce were they doing?" Harry asked.
"Blessed if I could tell," replied Old King Brady, in perplexity.
"Let's go back to Mason's house and wait for him to come back."
Old King Brady assented.
They returned to the West Thirty-sixth street residence.
An hour later, as they stood on the corner, the man they suspected as Mason came along, and Old King Brady stepped in front of him.
"Hold on there, my friend!" he remarked.