Nick lost his balance and would have fallen had he not thrown up his hands to save himself ; as he did so, he grasped a two-by-four inch timber which looked as though it had been placed there for additional support to the stairs.
The timber was not stationary, however. It came loose in his hand, but with sufficient difficulty to save him from falling.
Leaping down, he rearranged the box and again mounted it.
The necessity for searching was, however, ended.
The removal of the stick of wood disclosed an ordinary staple and hook which fastened the movable stairs in place. He removed the hook, and the stairs worked Just as he had expected them to.
A person could go from the cellar to the parlor-floor without having to pass through a door.
The discovery was one which filled Nick with pleasure, and there only remained now to find an equally easy way into the street.
But hour after hour passed, and found him still searching
At last he turned away, noticing, as he did so, that one of the stays which supported the floor above, was out of place.
It did not occur to him that he could straighten it, and yet he put out his hand and gave it a sharp pull.
What was his surprise to find that it was loose at the top.
As he pulled there was resistance enough to satisfy him that the support acted as a lever, while behind him he heard a slight grating noise as of something moving on small iron wheels.
Turning, he flashed his light along the wall, but saw nothing.
Nevertheless he pulled the lever away -over, and then placed a weight upon it to hold it down while he searched for the aperture of which he felt certain it was the instrument.
"Ah!"
He paused with the glad exclamation on his lips.
Before him, close to the wall, was an opening in the cellar-floor.
One of the stones, with which the floor was paved, had settled down nearly five feet, leaving an opening quite large enough to admit him, and when he flashed his light along, the underground gallery that he saw, he discovered that it led toward the street, and was, without doubt, the secret entrance for which he had been searching.
Nick took the precaution to put more weight upon the lever before descending into the forbidding opening that it had revealed.
Then with his dark-lantern in hand, he entered.
The passage way was not high enough for him to stand upright, and was only sufficiently wide to accommodate his body.
It led him about twenty feet, diagonally in the direction of the street, and then abruptly ended.
He looked up.
Over his head were the stone steps which led to the front door of the house.
"More stairway doors," he muttered. "This will not be so well concealed."
Nor was it.
There was an ordinary bolt such as are used for fastening doors, which he easily moved, noticing, as he did so, that the bolt was so arranged that it could be worked from the outside.
That is, a portion of the next toe piece had been chipped off, leaving a space through which a small steel rod could be thrust, to move the fastening.
First, he tried to push the stone up, but in vain.
Then he endeavored to pull it down toward him, but it refused to move.
There was but one way left and that was to slide it away lengthwise.
The effort met with instant success.
The stone slid along easily, offering little or no resistance, and thus afforded an- opening sufficiently large for an ordinary-sized man to squeeze through.
A means by which a murderer could have entered and left the house when Eugenie La Verde was choked to death was now found.
That portion of the case was no longer a mystery.
It was still daylight in the street, and Nick hastily closed the aperture, having studied out how he could open it from the outside if necessary.
He returned to the cellar and removed the weights that he had placed upon the lever.
It remained down, as, indeed, he had expected it would.
Then once more to the secret passage-way.
There, he raised the stone and put it in place.
On the underside was a handle.
He grasped that, pulled upon it, and the stone came down in his grasp.
The secret was now entirely his.
He could go either way through the hidden passage without any trouble.
The mystery was a mystery no longer.
"I have only to satisfy myself, now, that Tony is the murderer, and then the whole story is in my possession. But I must find a motive," he thought. "Why did those men want Eugenie La Verde out of the way? There is another mystery still, to solve."
The flat stone which covered the opening in the cellarfloor, was worked by the lever, by means of a long steel rod and two cog-wheels.
It was a clever mechanical device, and whoever planned it must have had a strong incentive.
"There is nothing more to do here now," he thought. "I will go home."
He had been at home about an hour when he rose and went to the window, whistling softly to himself, and lost in thought.
Suddenly he started.
Darkness was just settling over the city, and half concealed in the door way of a vacant house opposite was Tony, the strangler.
"I had forgotten all about him," mused Nick. "it won't do to let that fellow run at large. I think I will arrest him, cobra and all, and take him down to headquarters. If he gets a chance, he'll fill the house with snakes, and I don't want that, particularly in my absence."
Nick remained at the window several moments, lost in thought.
Suddenly he smiled. A good idea had occurred to him.
He went to the telephone and called up Inspector Byrnes.
"I am going to bring you a man whom I want you to hold for me till called for," he said, as soon as they were in communication.
"All right," replied the officer. "What do you know about him?"
"I know he is a murderer although perhaps not the murderer."
"He will do to keep, anyhow."
"Rather. Say!"
"Hello."
"This fellow is a snake-charmer, and in order to take him in, I have got to kill a cobra which he carries around with him. Will you have two men on the corner of Mott and Bleecker for me, in an hour?"
"Yes. How will they know you?"
"Easily. They will see me knock my man down first. Then they will see a cobra stick its head out of the fellow's coat after which, it they look sharp, they will see me shoot the cobra."
"Good; but don't kill the man instead of the cobra."
"I guess not."
"How are you going to get him there?"
"He's outside now, waiting for me."
"Waiting for you to take him in?"
"Yes. He's in the shadow business. He's made a contract to strangle me' to death with a cord, and is on my trail now."
"Ah! Well, fetch him in; I'd like to have a look at him."
"All right. Good-by."
"Good-by."
Nick hung up the ear-piece and hastily made-a few changes in his appearance.
Then he started out to lead Tony to the Central Office of the police, where he proposed to keep him out of mischief by locking him up in a cell.
"Now, my gentle Tony, come along," murmured Nick, as he ran down the steps. "I can't keep on with this case and feel easy about matters at home unless I put you where you will be out of mischief, and since you are kind enough to follow me, I'll show you the way."
In order to make it perfectly easy for the strangler to keep track of him, Nick avoided the elevated road, and took a surface car.
Bleecker street and the Bowery were duly reached by Nick with Tony a close second.
There the detective dismounted from the car and walked leisurely westward, purposely going slowly so that the strangler could gain upon him without the appearance of haste.