Ned was dressed in a dark business suit, so he was not likely to be observed from a distance, for it was a starless night. Half way to the end of the great yard he began to wonder if the light he had seen might not have been an hallucination.

He doubted very much if anybody was creeping about outside the fence. The boards were close together, with scarcely a crack half an inch wide anywhere. A light out there--

It flashed again. He was positive of it this time, and of its locality as well. It could be nobody who had any honest business about the Swift Construction Company's premises. It was not Koku, for ordinarily the giant would not use an electric torch.

Ned did not know where any of the watchmen were who were acting as sentinels. In fact, as it appeared later, three of them had been called off their beats by Tom himself to help in some necessary task inside the shed. The young inventor was getting ready to run the huge locomotive out upon the yard-track.

Remembering vividly the attempt which had been made some weeks before to blow up the Hercules 0001, it was only natural that Ned should suspect that the flash of light he had seen revealed the presence of some ill-conditioned person lurking just beyond the fence.

A man might be crouching there prepared to hurl an explosive bomb over the fence when the locomotive was brought around as far as that spot. Or was the villain foolish enough to attempt to enter the enclosure by surmounting the fence?

Ned, keeping close to the ground, crossed the rails in the fortunate shadow of one of the posts. There he found a place where, with his back to a pole-prop right at this curve in the trolley system, the shadow enfolded him completely.

Had his movements been marked by the person outside the fence? Ned waited several long and anxious minutes for some move from out there. Then something rather unexpected occurred. For the past ten minutes he had forgotten about the test of the Hercules 0001 which Tom had promised.

With a blast of its siren the huge electric locomotive burst out of the shed and thundered around the track. It smote Ned Newton's mind suddenly that the inventor was going to "take a chance" on this evening and try to get some speed out of the huge machine.

The electric headlight cast a broad cone of white and dazzling light across the yard. It suddenly struck full upon the spot where Ned Newton crouched; but the upright against which he leaned was broad enough to hide him completely.

Looking up at the top of the stockade at that moment of illumination, the young financial manager of the Swift Construction Company beheld a crawling figure nearing the wire entanglements on the summit of the fence.

The unknown man was climbing by means of a notched pole. Ned could not see that he bore any bulky object in his hands; indeed, he needed both of them to aid him to climb. But the man's right hand was reaching upward, above his head.

The Hercules 0001 came roaring on. Its cone of light passed beyond Ned's station. In a few seconds it reached the spot, and roared on. Ned had not made a move. It seemed to him that he could not move or speak.

The onrush of the electric locomotive all but swept the young fellow from his feet. It had come and gone in an instant!

"He's making more than fifteen or twenty miles an hour, all right," muttered Ned.

Then he flashed another glance up at the figure outside the fence. The man's cap showed above the top of the boards. He seemed to be dragging something up to him from below--something that hung and swung around and around a few feet from the ground.

Ned was about to dart out of concealment and hail the fellow. He was not armed, nor could he get out of the stockade near this point. He feared what the marauder intended, and he felt that he must frighten him away.

"Suppose that is a bomb and he means to fling it in front of Tom's locomotive?" thought the anxious Ned.

He again saw the stranger's right hand reach up above his head. But he had no bomb in his hand. Ned suddenly shrieked a word of warning! It had come to him what the man was doing and what the result of his act would be.

The wire-cutters bit on one of the copper wires. There followed a flash of blue flame, and the man screamed. He dropped the thing swinging below him and involuntarily grabbed at the wires with his left hand.

He was caught, then! The crackling intermittent shocks of electric fluid passed through his body in fiery sequence. His limbs writhed. He mouthed horribly, and croaking gasps came from between his wide open jaws.

The Hercules 0001 had rounded the enclosure and was coming down upon its second lap. The cone of white radiance from the headlight fell upon the writhing body of the victim on the wires. The locomotive siren emitted a blast that almost deafened Ned.

The monster ground to a stop. Tom swung himself half out of the cab window beside the controller.

"Who's that?" he yelled. Then he saw Ned below him. "Who is that fellow?"

"No friend of yours, Tom, I believe," returned his financial manager in a shaking voice.

"Where's Rad? Rad!" Tom shouted at the top of his voice.

"I's comm', Massa Tom," rejoined the colored man.

"Never mind coming here! Get a move on, and get to the switchboard. Turn the current out of the fence wires.

"Yis, sir, I'll go Massa Tom," declared the old man.

"Is he a spotter, Ned?" demanded the inventor.

"He's no friend. I am going out by the gate. He's got something there that means harm, I believe. Do you think he's killed, Tom?"

"Only ought to be. Not enough current to kill him. But he's badly burned and--and--well! I bet he won't care to fool around the works again."

Ned dashed away to an entrance. A watchman came running, opened the small gate, and followed Ned into the open.

Before they arrived at the vicinity of the accident Rad had got to the switchboard. The electricity was shut out of the stockade wires.

Ned uttered another shout. He saw the writhing body of the shocked man fall from the stockade. When he and the watchman got to the spot the fellow lay upon his back, groaning and sobbing; but Ned saw at once that he was more frightened than hurt.

"Well, you did it that time!" exclaimed the young financial manager. "And I hope you got enough."

"You--you demons!" gasped the man. "I'll have the law on you--"

"Sure you will," cackled the watchman. "You had every right in the world to try to cut those wires, of course, and get into the yard of the works. Sure! The judge will believe you all right."

Ned was, meanwhile, staring closely at the fallen man. Tom had come down from the locomotive and was close to the fence.

"Who is he?" demanded the inventor. "Not O'Malley?"

Ned stepped to the fence and whispered:

"It's the other fellow. The little chap with the Vandyke. He's dressed like a tramp, but it's the same man."

"Is he badly hurt?" demanded Tom.

"His temper is, Boss," said the watchman callously. "And say! I know this fellow. He works for the Blatz Detective Agency. I used to work for those folks myself. His name is Myrick--Joe Myrick."

"Ned," said Tom sternly, "go to the office and call the police. I'll make him tell why he was here. And I'll make the Blatz people explain, too. Hullo! what's that?"

Ned had seized the rope he had seen in Myrick's hand, and from a patch of weeds drew a two-gallon oil-can.

"What you got there, Ned?" repeated the young inventor.

"Whatever it is, I am going to be mighty easy with it. I think this scoundrel was trying to get it over the fence and into the way of the locomotive."

"You can't hang anything on me," said Myrick, suddenly. "I was just climbing up to the top of the fence to get a squint at that contraption you've built. You can't hang anything on me."

"He's evidently feeling better," said Tom, scornfully. "Nugent, don't let him get away from you. Go call the police, Ned. And take care of that can until we can find out what's in it."

Later, when the police had removed Joe Myrick and the mysterious can had been deposited in a tub of water in the open lot until its contents could be examined, Tom said to his chum:

"I was just working up some speed on the locomotive. The speedometer indicated fifty-five when I saw that fellow sprawling up there on the fence. I would not have dared go much faster in any case."

"Why, you weren't half trying, Tom!" cried the delighted Ned.

"She did slide around easy, didn't she? Fifty-five on an almost circular track is a good showing. I am not so scared as I was, my boy."

"You think that on a straight track you might accomplish what you set out to do?"

"It looks like it. At any rate, I shall risk a trial on the H. & P. A. tracks. I'm going to take her West. Be ready on Monday, Ned, for I shall want you with me," declared Tom Swift.