Two nights after this, as Captain Buxton was sulkily going the rounds of the sentries he made a discovery which greatly enlivened an otherwise uneventful tour as officer of the day. It had been his general custom on such occasions to take the shortest way across the parade to the guard-house, make brief and perfunctory inspection there, then go on down the hill to the creek valley and successively visit the sentries around the stables. If the night were wet or cold, he went back the same way, ignoring the sentries at the coal-and store-sheds along Prairie Avenue. This was a sharply cold night, and very dark, but equally still. It was between twelve and one o'clock--nearer one than twelve--as he climbed the hill on his homeward way, and, instead of taking the short cut, turned northward and struck for the gloomy mass of sheds dimly discernible some forty yards from the crest. He had heard other officers speak of the fact that Mr. Hayne's lights were burning until long after midnight, and that, dropping in there, they had found him seated at his desk with a green shade over his eyes, studying by the aid of two student-lamps; "boning to be a general, probably," was the comment of captains of Buxton's calibre, who, having grown old in the service and in their own ignorance, were fiercely intolerant of lieutenants who strove to improve in professional reading instead of spending their time making out the company muster-rolls and clothing-accounts, as they should do. Buxton wanted to see for himself what the night-lights meant, and was plunging heavily ahead through the darkness, when suddenly brought to a stand by the sharp challenge of the sentry at the coal-shed. He whispered the mystic countersign over the levelled bayonet of the infantryman, swearing to himself at the regulation which puts an officer in such a "stand-and-deliver" attitude for the time being, and then, by way of getting square with the soldier for the sharply military way in which his duty as sentry had been performed, the captain proceeded to catechise him as to his orders. The soldier had been well taught, and knew all his "responses" by rote,--far better than Buxton, for that matter, as the latter was anything but an exemplar of perfection in tactics or sentry duty; but this did not prevent Buxton's snappishly telling him he was wrong in several points and contemptuously inquiring where he had learned such trash. The soldier promptly but respectfully responded that those were the exact instructions he had received at the adjutant's school, and Buxton knew from experience that he was getting on dangerous ground. He would have stuck to his point, however, in default of something else to find fault with, but that the crack of a whip, the crunching of hoofs, and a rattle of wheels out in the darkness quickly diverted his attention. "What's that, sentry?" he sharply inquired. "A carriage, sir. Leastwise, I think it must be."