The mechanical equipment of the new locomotive was now complete and Tom was establishing the electrical equipment as rapidly as possible. He not only acted as overseer of this work, but in overalls and jumper he was doing a good share of the work himself.

The weight of the electrical equipment when it was finally set up was not far from two hundred thousand pounds. Altogether, when the oil, sand, and water tanks were filled, the great machine would weigh two hundred and eighty-five tons--a monster indeed!

"She is going to take a lot of current to run her," said Tom to his father, who was standing by. "When I come to arrange with the Shopton Electric Company for power, it's a question if they can give me all I need. And I must have plenty of current to make sure that my motors till the bill."

"As your tests will be made in the daytime, the company should be able to furnish the power you need," rejoined Mr. Swift. "At night, of course, when they must furnish so much light as well as power, it might be difficult for them to give you the proper current."

"Forty-four hundred horsepower is a big demand," went on Tom. "I've got to have at least a three-thousand-volt direct-current to feed my motors. I will soon have to take up the matter with the Electric Company."

The heavy work of setting the electrical parts of the locomotive had been finished the day previous, and the track- derrick was removed. Tom was engaged in adjusting the more delicate parts of the equipment and had merely stepped down from the cab to speak to Mr. Swift.

Now he climbed back into the interior of the great machine which, in a general way, looked like a box car. An electric locomotive has not much of the appearance of a steam engine. The machinery is all boxed in and the entire floor of the locomotive is above even the drivers.

These six pairs of driving wheels were about seventy inches in diameter, while the diameter of the leading and following truck- wheels was but half that number of inches.

Mr. Swift had turned away from the locomotive when Tom put his head out of the door again.

"Do you hear that, father?" he demanded in a puzzled tone.

"Hear what, Tom?" asked the old inventor, looking up.

"That ticking sound? I declare, I'd think it was one of those death-watch beetles had got in here. Sounds like a big watch ticking. I can't make it out."

"Where is it? What is it?" repeated Mr. Swift. "I hear nothing down here on the floor of the shed."

"Well, it gets me," muttered Tom, and disappeared again. In a moment he called out: "Say, you fellows! who left his bundle of overalls in here? Better take 'em out to be manicured. Whose are these?"

Two or three of the mechanics working near looked up from their tasks. Mr. Swift turned back to the door of the cab again.

"What is the matter now, Tom?" he asked, in added curiosity.

"That bundle, Dad."

Tom once more appeared and addressed the workmen: "Whose bundle of dirty overalls is this in here? Come and take 'em away. They shouldn't have been left here."

"Why, Mr. Tom," said the foreman who was near, "I didn't see any soiled overalls in there when I left last evening. Any of you fellows," he asked the group of hands, "know anything about any overalls?"

"The bundle is here all right. Pushed back against the third series motors. Come up here, one of you fellows

Suddenly there was a noise at the end of the shed where the door to the offices lay. Two figures burst through from the glass doors and charged down the lanes between the lathes and cranes. Ned Newton led, Rad Sampson, his face a mouse-gray with fear, followed.

"Massa Tom! Massa Tom!" shouted the colored man. "Look out fo' de bomb! Look out fo' de bomb!"

The foreman sprang toward the high door of the locomotive where Tom stood, staring out. The young inventor, quick as his mind usually functioned, did not understand at all what Eradicate meant.

"There's something wrong in there, Mr. Tom!" shouted the foreman. "Come down, sir, and let me get up there and see what it is."

But Mr. Barton Swift grasped the meaning of what was going on more quickly than anybody else. Tom's father, Tom frequently said, had spent so many years investigating chemical and mechanical mysteries that he saw more clearly and more exactly into and through most problems than other people.

His raised voice now cut through the rumble of machinery and all the other noises of the shop. Even Rad Sampson's delirious cry was dwarfed by Mr. Swift's sharp tone:

"Tom! The ticking of that watch! That means danger!"

The declaration seemed to rip away a curtain from Tom's thoughts. Perhaps Rad's cry about "de bomb" aided the young inventor to understand the peril that threatened.

The faint ticking sound that had begun to annoy him during the past few minutes betrayed the nature of the threatening peril. Tom swung back from the open doorway of the locomotive cab, reached in to the space between the motors, and seized the bundle of overall stuff that he had previously spied.

He knew instantly that the rapid ticking came from that bundle. It could be nothing but a time bomb. He had heard of such things and, indeed, had seen one before, an infernal machine which, set like an alarm clock, would go off at a certain time. That indicated time might be an hour hence, or might be within a few seconds! Ned Newton, almost at the spot, shouted to Tom when the latter reappeared with the bundle in his hands:

"Get down out of that, Tom Swift! Quick! For your life!"

But Tom was cool enough now. He saw his father's white, strained face at one side and the young inventor could even smile at him. Behind the foreman was set a barrel of water in which tools were cooled and tempered.

"Stoop, McAvoy!" Tom shouted, and tossed the bundle from him.

Had the infernal machine exploded in midair Tom would not have been surprised. But McAvoy dodged, Rad clapped his hands over his ears, and, even Ned Newton halted like a bird-dog at point.

The bundle splashed into the barrel of water. It sank to the bottom. There was no explosion. When a few seconds had passed the group of excited men began to relax. The barrel was carried carefully to a neighboring field.

"Fo' de lawsy sake!" gasped Rad, and got a full breath again.

"That was touch and go, sure enough," muttered Ned Newton.

"Those overalls sure went to the wash, Boss," declared the foreman. "What was in 'em? And who put 'em in the cab up there?"

But Tom dropped down the ladder and went to his father. Their hands sought each other and gripped, hard.

"Better not tell Mary about this," whispered Tom. "She's worried enough as it is."

"Right, Tom," agreed the old inventor. "From this time on we cannot be too careful. If there proves to be an infernal machine in that package we may be sure that we are dealing with desperate men. We've got to keep our eyes open."

"Wide open," added Ned.

"I'll say we have," said Tom.