"All right, Joe," he said soothingly, putting on his overcoat to shield his tunic from grease and coal. "Just you do the best you can, and don't worry. I guess you'll feel well enough once you're started. There goes your signal!"

With a loud clang of the engine bell the train moved out of the station, slowly at first, but gathering speed as it left the little town with its flour mills and grain elevators behind.

Silk seated himself on the box and continued smoking his cigar. He was not long in discovering that his judgment of the locomotive had been accurate. She was certainly cranky. Her rods moved jerkily, and there was a constant rattling of loose bolts. The wheel tyres were so badly ground down in parts by the use of brakes that you might almost have believed that she had square wheels. With every revolution as the flat spots hit the metals, she dropped with a noisy thud, and then when she went over them she would raise herself bodily again, while the tender rammed her so spitefully that the worn coupling bolts were strained almost to breaking-point.

"Say, Joe," said the sergeant, "this is about as comfortable as riding a bucking broncho. How long have your wheels been like this?"

Joe Halkett looked round at him blankly, stupidly, and answered in a mazed way—

"Ever since last winter. They was ground down wrestlin' with the snow-plough in Crow's Nest Pass."

Silk glanced at the gauge.

"You're not getting much speed out of her," he said, "considering the amount of steam you're using."

"She's just obstinate," said Joe. "Obstinate an' wilful. You can't coax her nohow. I'm sick and tired of tinkerin' with her."

"She's wuss to-night than usual," declared Dick. "Reckon it's that heavy private car as takes it out of her. We've got all we c'n do ter fetch Three Moose siding 'fore the limited hustles along."

It was not a stopping train and it was only necessary to watch that the signals were shown for clear at the few stations that came at infrequent intervals along the line.

Joe Halkett appeared to be working very well. He had got the train adjusted to its gait, and the cars were thumping over the frogs and switches at a reasonable pace, labouring, panting, and grunting when mounting a steep gradient, but settling down again when there was a stretch of good running ground ahead. It was mostly cultivated prairie land, but now and again the track was through gloomy pine forests or deep mountain defiles.

Dusk had already deepened into darkness when they were rattling along the track across the Piegan Indian Reservation, and Halkett had somehow worked up his engine to such easy going that Sergeant Silk began to believe that he had exaggerated the disabilities of both locomotive and engineer, and that he might just as well have been enjoying the greater comfort of one of the passenger cars, or been seated luxuriously in the private Pullman spinning yarns with the Colonel and Sir George.

In the darkness Silk did not perceive the change that had come upon Halkett's face. It was only when Joe chanced to lean over into the light from the open fire-box that he saw the look of terror that had come into it. It was a look like that of a man who had got some terrible secret on his soul and was driven half mad by it.

"Joe? What's the matter?" Silk cried, starting to his feet. He glanced round at the fireman.

Dick had just come back from the water tank.

"Say, Sergeant," he gasped, "the water's runnin' low, an' we've passed the plug. We've got ter go back!"

Silk was alarmed. He knew well that one of the important things for an engine-driver to do is to figure out at what plugs he can fill his tank most advantageously, and that it is a high crime to run short of water.

"Are you certain sure we've passed it?" he asked sharply. He had leapt to the lever to stop the train, and whistle for brakes.

The fireman nodded.

"Yes," he answered. "We've got ter push back. It's a good three mile."

"But we can't push back," Silk protested. "There's not time, and we shall not have enough steam. There's the limited express to think of. How far on is the next water plug?"

"'Bout the same distance," Dick told him. "We're half ways between."

"Then we'll pull ahead," decided the sergeant.

"She'll bust, sure, if we do," declared Joe Halkett, rousing himself to a realisation of the situation. "Thar' ain't enough power ter carry her through, draggin' such a weight, and, say, thar's no switch near hand, where we kin side-track ter let the limited run past."

The train had stopped. Sergeant Silk stood still, hardly daring to take the responsibility. But even in the matter of managing an engine he proved himself to be a person of ready resource. He whistled for the conductor.

"Jump down and cut the engine loose, Dick," he ordered. And without questioning the motive, Dick obeyed.

By the time that the engine and tender had been uncoupled from the foremost car, the guard had come through the corridors from the brake van to know what had happened.

"All right; don't alarm the passengers," cried Silk. "We're short of water. We've run past the plug. I'm going on with the engine alone to the next plug to get some. Climb up to the roof of the head car with a lamp and signal us back, see?"

Leaving the conductor to guess how it chanced that the locomotive was in charge of a sergeant of police, he opened the throttle valve and started off along the line at the highest speed that he could get out of the cranky old kettle, arriving at the hydrant with an empty tank and a dangerously exhausted boiler.

Halkett and Dick helped him, and almost before the tank was filled they had started on the back journey. Many precious minutes had been lost, but the engine had returned to the waiting train with a quarter of an hour to spare in which to reach Three Moose siding and get out of the way of the express.

"D'you reckon we can do it, Joe?" Silk asked with a quick glance at the engineer.

Halkett had abandoned his duty. He sat on a corner of the tool-box and was staring about him like a man in a fever, with a sort of wild gleam in his eyes, as if some mortal terror had taken hold of him and was tormenting him. He held a long-spouted oilcan in his hand, and the oil was dripping to his feet.

"Can we do it?" Silk repeated. And looking at Joe more attentively he began to realise that the man's strange agitation of mind was due to something quite apart from the danger of being run into by the express.

"We can't get to the switch on time," Joe roused himself to say in a voice that was hoarse and unnatural. "You c'n try as you like; but, clever as you are, you'll never get this yer engine to pass Three Moose Crossing. Thar's blood on the track, see? The place is haunted—haunted by the ghost of a dead man."

"He's sure mad, now," muttered Dick. "Say, Sergeant, you'd best leave him and take charge. We might git inter the siding if we start right now."

Sergeant Silk snatched the oilcan from Joe Halkett's grip and handed it to the fireman.

"Look here, Dick," he commanded, "take this can and run back to the tail of the train and grease the metals. Oil first one rail and then the other. D'you understand? It's our only chance. Let the oil run about a car's length on the top of each rail, and come back again quick as you can."

Before Dick returned, panting and perspiring, with the empty can, Silk was ready to start, with his hand on the throttle valve. He blew the whistle, and with a snort, a grunt, and a noisy rattle, the engine moved on, now wholly under the sergeant's control.

"It's no use," Joe Halkett muttered with an insane laugh. "She'll never go past that crossin'."

"What do you mean?" Silk demanded. "Three Moose Crossing?" he repeated. And then, as if suddenly recollecting something, he looked down at Joe's face in the light from the fire-box; looked at it searchingly, wonderingly. "What do you know about Three Moose Crossing?" he asked with curious directness. "You were not on your engine that night—the night that Steve Bagshott was killed. What has it got to do with you?"

Halkett laughed—a ghastly, hollow laugh—then dropped into silence, while Silk forced the engine to fuller speed. But as the train dashed through the darkness, Halkett became more and more excited.

"The ghost'll be there, sure!" he repeated again and again.

"Well, and if it is," returned Silk, with his eye watchfully on the gauge, "I don't care for any of your ghosts. I don't care if there's a hundred of them so long as this train goes safe."

"But it can't go safe," cried Halkett, rising to his feet and laying a trembling hand on the sergeant's arm.

The train was covering the miles at terrific speed now as it went down the gradient. But it was not the speed that made Halkett shake like a reed and drove the blood from his cheeks.

"Sergeant," he said in a thick whisper as he clutched more tightly at Silk's arm, "that man who was run over—Steve Bagshott—wasn't killed by accident."

"What do you mean?" Silk cried. "What has come over you to-night?"

Joe bent his face forward. His hot breath was on the sergeant's cheek.

"He wasn't killed by accident," he repeated hoarsely. "He was murdered! That's why he haunts the crossing. He can't rest."

"Murdered?"

"Yes," Joe nodded grimly. Then, loosening his grip, he went to the side of the cab and peered forward into the darkness. "We're gettin' near," he muttered. "We're gettin' near the place, but we can't go on. She can't go safe over the crossing to-night."

Sergeant Silk blew the whistle, asking for a signal. He did not know that he was still many miles from the siding. He turned to speak to the fireman, who was at work among the coals. When he looked back again, Joe Halkett had slipped forward and had raised his hand to shut off steam.

"Stop!" shouted Silk, seizing his arm. "Do you think you can play with this train? She's going on, and at the same speed, until I get a signal, though there were a score of haunted crossings in the way. Stand back!"

He thrust the man aside. But Joe renewed his grip. His hard face was working with terror and his eyes were starting out of his head.

"I murdered him!" he panted. And by the light of the fireman's lamp Silk could see great beads of agony on his forehead. He went on jerkily, his voice rising sharp and wild as he told his fearful story of a brutal vengeance.

But Sergeant Silk flung him aside, not heeding him, thinking only that the fate of the racing train and the lives of scores of human beings depended upon what happened in the next few minutes.

"I dragged him to the crossing," Joe went on. "I laid him across the line. There was a train due in three minutes. This train—this engine. They thought it was accident. You—you—thought so, too. But it wasn't. I did it—I!"

His voice rose to a shriek. Then he crept to Silk's side.

"Sergeant, there's death ahead and death behind," he cried, and with a leap forward he seized the lever.

"Let go!" Silk shouted, flinging him backward among the coals. "Lay hold of him, Dick," he ordered. "The express must be coming on behind. But that oil has delayed her, sure."

Once again he whistled for a signal, and this time one came, telling him that the switch was open. He slowed down cautiously. He had passed the crossing, and now with a sudden turn from the straight track, the engine panted into the siding, safe from all possible harm.

"Oh, stopping again, are we?" said the millionaire in the private car. "We've run short of water again, I suppose. I wonder that your railway companies don't introduce those water troughs on the permanent way, such as we have in England."

"We do, on some lines," returned the Colonel. "But I don't fancy it's water this time. Listen! Yes, I thought so. We've gone into a side track to let the limited express go past. Dear me, she must have been exceedingly close on our heels! But our engine-driver—a man named Halkett, is a magnificent fellow. Quite the best driver on the line, I believe."

When the express had rushed by, he lowered the window and looked out. Some one was walking along the line towards the rear of the train.

"I say, there!" the Colonel called out. "Are we going to stop here very long?"

"No, Colonel; no!" came the answer. "We're changing engines, that's all. I'm going along to have a word with my mare. I reckon she's missing me."

"Oh, it's you, Silk, is it?" laughed the Colonel. "I didn't know you with your overcoat on. Won't you come in along with us here? Sir George is anxious to have a yarn with you, and I'm sure you'll be more comfortable here than in that third-class."

"Thank you, Colonel," returned Silk, "but I've changed my plans. I've got to go back to Macleod with a man who is rather ill. Good-night!"

He said nothing of who the man was, and no one on the train knew then or even afterwards anything of the danger that they had escaped. But that was Sergeant Silk's way.