More than four months had passed since the contract had been signed, when Tom made his first yard-test of the Hercules 0001. For a month nothing had been seen or heard of Andy O'Malley, whose identity as the spy, set by Montagne Lewis to cripple Tom's attempt to help the Hendrickton & Pas Alos Railroad, had been determined beyond any doubt.

The private inquiry agent that Tom had engaged to find O'Malley had been unsuccessful in his work. The spy had disappeared from Shopton and the vicinity. Nevertheless, the inventor did not for a moment overlook the possibility that the enemy might again strike.

Every night the electric current was turned into the wires that capped the stockade of the Swift Construction Company enclosure. Koku beat a path around the enclosure at night, getting such short sleep as he seemed to need in the forenoon.

"Dat crazy cannibal," grumbled Rad, "got it in his haid dat he's gwine to he'p Massa Tom by walkin' out o' nights like he was dis here Western, de great sprinter, Ma lawsy me! Koku ain't got brains enough to fill up a hic'ry nut shell. Dat he ain't."

Nothing anybody else could do for Tom ever satisfied Rad. The colored man fully believed that he was the only person really necessary for Tom's success and peace of mind. In fact, Rad thought that even Ned Newton's duties as financial manager of the firm were scarcely of as much importance.

When he heard that Tom was going West, after a time, with the electric locomotive, to try it out on the tracks of the H. & P. A., Rad was quite sure that if he did not go along, the test would not come out right.

"O' course yo'll need me, Massa Tom," he said, confidently. "Couldn't git along widout me nohow. Yo' knows, sir, I allus has to go 'long wid yo' to fix things."

"Don't you think father will need you here, Rad?" Tom asked the faithful old fellow. "You're getting old--"

"Me gittin' old?" cried, the colored man. "Huh! Yo' don't know 'bout dis here chile. I don't purpose ever to git old. I been gray-haided since befo' yo' was born; but I ain't old yit!"

Mr. Damon chanced to be present at this conversation, and he was highly amused, yet somewhat impressed, too, by the colored man's statement.

"Bless my own antiquity!" he exclaimed. "I agree with Rad, Tom. It's us old fellows who know what to do when an emergency of any kind arises. Experience teaches more than inspiration."

"Oh," said Tom, laughing, "I do not deny the value of old friends at any stage of the game."

"Bless my roving nature! I am glad to hear you say that. For I tell you right now, Tom, I want to be out there when you make your final test of the locomotive."

"Do you mean that you will go West when I take out the Hercules Three-Oughts-One?" cried Tom.

"It's just what I want to do. Bless my traveling bag, Tom! I mean to be present at your final triumph."

"What will happen to your buff Orpingtons while you are gone?" asked the young inventor, gravely.

"I have got my servant trained to look after those chickens," declared Mr. Damon. "And this invention of yours is really more important than even my buff Orpingtons."

"Just the same," remarked Tom to his eccentric friend, when Rad had left the room,. "I've got to fix it so that Eradicate stays at home with father. He doesn't really know how old and broken he is--poor fellow."

"His heart is green, Tom. That's what is the matter with Rad."

"He is a loyal old fellow. But I shall take Koku with me, not Rad," and the young inventor spoke decidedly. "And that is going to trouble poor Rad a lot."

The prospect of going West, however, was not the main subject of Tom's thoughts at this time. As the weeks passed and the end of the six months of experiment came nearer, the inventor was more and more troubled by the principal difficulty which had from the first confronted him. Speed.

That was the mark he had set himself. A maximum speed of two miles a minute on a level track for the Hercules 0001. With the speed already attained by both steam and electric locomotives in the more recent past, this was by no means an impossible attainment, as Tom quite well knew.

But he became convinced that the conditions under which he labored made it impossible for him to be positive of just how great a speed on a straight, level track his invention would attain.

There was no electrified stretch of railroad near Shopton on which the Hercules 0001 might be tested. The track inside the Swift Company's enclosure did not offer the conditions the inventor needed. He felt balked.

"I believe I have hit the right idea in my improvements on the Jandel patents," he told Ned Newton when they were discussing the matter. "But believing is one thing. Knowing is another!"

"Theoretically it works out all right, I suppose?" questioned Ned.

"Quite. I can prove on paper that I've got the speed. But that isn't enough. You can see that."

"Impossible to be sure on the trackage already built here, Tom?"

"I haven't dared give her all she'll take," grumbled Tom. "If I did, I fear she'd jump the rails and I'd have a wreck on my hands."

"And maybe kill yourself!" exclaimed Ned. "You want to have a care."

"Oh, that's all right! I've taken risks before. I don't want to risk the safety of the locomotive, which is more important. That machine has cost us a lot of money."

"I'll say so!" agreed Ned. "You'll have to wait till you can get the locomotive out there on the H. & P. A. tracks before you get a fair speed-test."

"And suppose instead of a triumph it is a fiasco?" Tom said, doubtfully. "I tell you straight, Ned: I never was so uncertain about the outcome of one of my inventions since I began dabbling with motiveÄpower."

"We could build several miles of straight track in the waste ground behind the works," Ned said, thoughtfully.

"Not a chance! There is neither time nor money for such work. Besides, I should have to rebuild my transforming station if I supplied longer conduit wires with current."

"You don't really consider that you have failed, do you, Tom?" and Ned's anxiety made his voice sound very woeful indeed.

"I tell you that my belief doesn't satisfy me. I hate to go West without being sure--positive. I want to know! I have tried the locomotive out in the yard half a dozen times. It runs like a fine watch. There doesn't seem to be a thing the matter with it now. But what speed can I attain?"

"I don't see but you'll have to risk it, Tom."

"I mean to give her one more test. I'll run her out tonight when there is nobody about but the watchmen--and you, if you want to come. I'll arrange with the Electric Company for all the current they can spare. By ginger! I've got to take some risk."

"By the way, Tom," said his chum, "did it ever strike you as odd that that private detective agency never got any trace of O'Malley?"

"Well, he's gone away. We needn't worry about him. Maybe the detective wasn't very smart, at that."

"And yet he was here in town after you put the inquiry on foot. I saw him in the bank. He came there occasionally. And either he, or somebody he hired, placed that bomb in the locomotive."

"All those being facts, what of it?"

"Besides, there was that other fellow--the man with the Vandyke beard. Might be a shyster lawyer, or something of the kind. He wasn't spotted, either."

"To tell the truth, I didn't bother to give the Detective Agency the description of that fellow, although you gave it to me," and Tom laughed. "I must confess that I depend more upon my man-trap electric wires to protect the invention than I do on the private inquiry agent."

"It's funny, just the same. If I had another job for a detective I should not submit it to the Blatz Agency," grumbled Ned.

"I fancy Montagne Lewis and his crowd called off their Wild West gunman," said Tom. "In any case, every attempt he made to bother us turned out a fizzle. I am not, however, forgetting precautions, my boy."

Ned Newton realized that his chum had determined to make this night test of the electric locomotive the pivotal trial of the whole affair. He came back to the works after dinner and was let in by the office watchman at about nine o'clock.

"Mr. Tom here yet?" he asked the man.

"Yes, Mr. Newton. The young boss didn't go home to supper, even. That colored man brought something down for him, and he's in the shed yet."

"Rad is here, you mean?"

"Yes, sir. At least, he didn't go out this way, and we watchmen have instructions to let nobody in or out by the yard gates at night."

"I'll say Tom is being careful," thought Ned, as he stepped out through the runway toward the erection shed.

Before he reached the entrance to the huge shed, however, Ned chanced to look down the enclosure. There were several arc lights burning, but even these only furnished a dim illumination for the whole yard.

He supposed that four watchmen were tramping their several beats along the inside of the stockade and close to the trolley- track. But when he saw an instant gleam of light down there, close to the ground, Ned did not believe that it was the flash of a torch in the hand of any sentry.

"Funny," he muttered. "That's outside the fence, or I'm much mistaken. I wonder now--"

He turned from the door of the shed, left the runway, and began walking toward the distant point at which he had seen the mysterious flash of light.