what kind of success does Rainford's first trap have ?

Rainsfords first trap merely wounds Zaroff. None-the-less, Zaroff is impressed.

Even as he touched it, the general sensed his danger and leaped back with the agility of an ape. But he was not quite quick enough; the dead tree, delicately adjusted to rest on the cut living one, crashed down and struck the general a glancing blow on the shoulder as it fell; but for his alertness, he must have been smashed beneath it. He staggered, but he did not fall; nor did he drop his revolver. He stood there, rubbing his injured shoulder, and Rainsford, with fear again gripping his heart, heard the general's mocking laugh ring through the jungle.

"Rainsford," called the general, "if you are within sound of my voice, as I suppose you are, let me congratulate you. Not many men know how to make a Malay mancatcher. Luckily for me I, too, have hunted in Malacca. You are proving interesting, Mr. Rainsford. I am going now to have my wound dressed; it's only a slight one. But I shall be back. I shall be back."