he dam had to be lengthened and the
guard fixed across a fresh pair of rails.

Taking the object from Jake, Dick examined it carefully. He thought he
recognized the dint where he had struck the iron, and then, turning it
over, noted another mark. This had been made recently, because the
surface of the iron was bright where the hammer had fallen, and a blow
there would loosen the clamp. He glanced at Jake, who nodded.

"It looks very suspicious, but that's all. You can't tell how long the
mark would take to get dull. Besides, we have moved the guard two or
three times in the last few days."

"That's true," said Dick. "Still, I wedged the thing up shortly before
the accident. It has stood a number of shocks; in fact, it can't be
loosened by pressure on the back. When do you _think_ the last blow was
struck?"

"After yours," Jake answered meaningly.

"Then the probability is that somebody wanted the truck to fall into the
hole and smash the block."

"Yes," said Jake, who paused and looked hard at Dick. "But I'm not sure
that was all he wanted. You were standing right under the block, and if I
hadn't been a little to one side, where the lights didn't dazzle me, the
smashing of a lot of concrete wouldn't have been the worst damage."

Dick said nothing, but his face set hard as he braced himself against the
unnerving feeling that had troubled him on the previous night. The great
block had not fallen by accident; it looked as if somebody had meant to
take his life. The cunning of the attempt daunted him. The blow had been
struck in a manner that left him a very slight chance of escape; and his
subtle antagonist might strike again.

"What are you going to do about it?" Jake resumed.

"Nothing," said Dick.

Jake looked at him in surprise. "Don't you see what you're up against?"

"It's pretty obvious; but if I ask questions, I'll find out nothing and
show that I'm suspicious. If we let the thing go as an accident, we may
catch the fellow off his guard."

"My notion is that you know more than you mean to tell. Now you began by
taking care of me, but it looks as if the matter would end in my taking
care of you. Seems to me you need it and I don't like to see you playing
a lone hand."

Dick gave him a grateful smile. "If I see how you can help, I'll let you
know. In the meantime, you'll say nothing to imply that I'm on the
watch."

"Well," said Jake, grinning, "if you can bluff Stuyvesant, you'll be
smarter than I