The Bronx was slowly approaching the steamer in the fog, which appeared to have stopped her propeller, and to be resting motionless on the long swells, hardly disturbed by a breath of air. By this time the smokestack of the Bronx was vomiting forth dense clouds of black smoke. The steamers of the navy used anthracite coal, which burns without any great volume of smoke, and blockade runners had already begun to lay in whatever stock of it they were able to procure to be used as they approached the coast where they were to steal through the national fleet. The attention of the naval department of the United States had already been given to this subject, and the first steps had been taken to prevent the sale of this comparatively smokeless coal where it could be obtained by the blockade runners.  
Christy had been on the blockade; and he had 148 been in action with a steamer from the other side of the ocean; and he knew that this black smoke of the soft coal, exclusively used by English steamers, was a telltale in regard to such vessels. It had been an idea of his own to take in a supply of this kind of fuel, for while its smoke betrayed the character of vessels intending to run the blockade, the absence of it betrayed the loyalty of the national steamers to the blockade runners. It was a poor rule that would not work both ways, and the commander of the Bronx had determined to adopt the scheme he had now put in force on board of his vessel. Although the craft on the starboard bow could hardly be distinguished in the fog, Christy had sent a trusty seaman aloft to report on the color of the smoke that issued from her funnel.
 
This man had reported by swinging his cap in the air, as the captain had instructed him to do if he found that the smoke was that of soft coal. If there was no black smoke, he was to return to the deck without making any sign. The moment therefore that the man had been able to see the quality of the smoke, the commander was made as wise as though he had seen it himself. The information 149 left him no doubt that the steamer was intended to run the blockade; but whether or not she was one of the expected pair, of course he could form no opinion, for already this part of the ocean had begun to swarm with vessels in this service.
 
"I am beginning to make her out a little better," said Flint, who had been straining his eyes to the utmost capacity, as everybody else on board was doing, to obtain the best and earliest information in regard to the stranger on the starboard bow.
 
"What do you make out, Mr. Flint?" asked Christy, who was too busily employed in watching the movements of the officers and seamen on his own deck to give especial attention to the character of the other steamer.
 
"I can't see well enough yet to say anything in regard to details," replied the first lieutenant. "I can only make out her form and size; and she seems to be as nearly like the Bronx as one pea is like another, though I should say that she was longer."
 
"Is she in motion?" asked the captain with interest.
 
"She appears to be at rest, though it is possible 150 that she is moving very slowly; but if she has not stopped her screw, she is not going more than four knots."
 
"You say that she is built like the Bronx, Mr. Flint?" asked Christy anxiously.
 
"Just like her; I should say that both hulls came out of the same mould."
 
"That very nearly settles the question in my mind. Probably she was designed by the same naval architect, and constructed by the same builders, as the Bronx," replied Christy, gazing intently at the dim outlines of the steamer in the fog. "When a designer has made a great reputation for fast ships, men with piles of money, like the former owners of the Bronx, the Scotian, and the Arran, employ him to furnish the plans for their steam yachts. From what we have learned so far, though it is very little indeed, I feel reasonably sure that this steamer ahead of us is the Scotian or the Arran, and I don't care much which it is. But why has she stopped her screw, or reduced her speed to four knots?"
 
"That is a question that can only be answered an hour or two hence, if ever," replied the first lieutenant.
 
151 "But it is a very important question all the same," added Christy.
 
"I doubt if the Bronx is making four knots at the present moment," said Flint, as he went to the end of the bridge, and looked down into the water.
 
"In changing the fires in the furnaces, Mr. Sampson had been obliged to clear them out in part, and that has reduced the pressure of steam; but we shall soon have the usual head," said Christy, as he went to the speaking tube and communicated with the chief engineer.
 
He was informed that his explanation was correct in regard to the coal, and that in a very short time the boilers would have a full head of steam. Christy spent the next few minutes in an earnest study of the scarcely perceptible outline of the steamer in the fog. He was hardly wiser when he had finished his examination than before. The hull and lower masts of the vessel could be indistinctly made out, and that was all. Sampson informed him that he had not been using all the steam he had, and that the screw was hardly turning at all. He ordered him to stop it entirely.
 
Impatient as he was to follow up the discovery 152 that had been made, he realized that it would be very imprudent to expose his ship to possible danger when he had not steam enough to work her to the best advantage. He could only wait; but he was satisfied that he had done the best possible thing in changing the coal, for the black smoke would effectually blind the officers of the other vessel. They were not engaged in a chase, and the exciting question could be settled a few hours hence as well as at the present time.
 
"If the steamer ahead is the Scotian or the Arran, as I fully believe she is, probably her consort is somewhere in these water............