“For heaven’s sake, don’t waste your ammunition!” he whispered.  “One of them has gone up to the powder-house after dynamite.  I heard the creaking of the iron door.”

Adair whistled softly.  “Dynamite!  That will bring things to a focus beautifully, won’t it?  When they have blown us up, I wonder how they will account to Uncle Sidney for the loss of his car?”

Brissac had come running in at the sound of the firing.  He missed the grim humor in Adair’s query.

“Car, nothing!” he retorted.  “Better say the entire camp and everything in it!  There’s a whole box-car load of dynamite and caps out here in the yard—­sub-contractors’ supplies waiting for the freighters’ teams from the west end.  If they smash us, the chances are ten to one that there’ll be a sympathetic explosion out yonder in the yard somewhere that will leave nothing but a hole in the ground!”

“No,” said Ford.  “I gave orders myself to have that car set down below the junction when the Nadia came in.”

“So you did; and so it was,” Brissac cut in.  “But afterward it got mixed in the shifting, and it’s back in the yard—­I don’t know just where.”

Adair turned to the cowering porter.

“Have you any more cartridges for this cannon of yours, Williams?” he asked.

“N-n-no, sah.”

“Then we have three more chances in the hat.  Much obliged for the dynamite hint, Stuart.  I’ll herd these three cartridges pretty carefully.  Back to your sentry-boxes, you two, and make a noise if you need the artillery.”

Another interval of suspense followed, thickly scored with pricklings of anxiety for the besieged.  Then an attempt was made from the rear.  Ford saw a dodging shadow working its way from car to car in the yard and signaled softly to Adair.

“Hold low on him,” he cautioned, when the New Yorker was at his elbow, “those cheap guns jump like a scared cow-pony.”  Then he added:  “And pray God you don’t hit what he’s carrying.”

Adair held low and bided his time.  There was another musket-like roar, and an instant though harmless reply from two rifles on the other side of the Nadia.  But the dodging shadow was no longer advancing.

“I’ve stopped him for the time being, anyhow,” said Adair, exulting like a boy.  “If we only had a decent weapon we could get them all, one at a time.”

“This was crude,” Ford commented.  “Eckstein will think up something better for the next attempt.”

It was a prophecy which found its fulfilment after another sweating interval of watchfulness.  This time it was Brissac who made the discovery, from the forward end of the Nadia.  The nearest of the material cars was a box, lying broadside to the private car on the next side-track but one.  From behind the trucks of the box-car a slender pole, headed with what appeared to be an empty oyster tin, and trailing a black line of fuse, was projecting itself along the ground by slow inchings, creeping across the lighted space between the two cars.  Brissac promptly gave the alarm.