One morning, soon after Fuller and his daughter had gone home, Dick stood at a table in the testing house behind the mixing sheds. The small, galvanized iron building shook with the throb of engines and rattle of machinery, and now and then a shower of cinders pattered upon the roof; for the big mill that ground up the concrete was working across the road. The lattice shutters were closed, for the sake of privacy, and kept out the glare, though they could not keep out the heat, which soaked through the thin, iron walls, and Dick’s face was wet with perspiration as he arranged a number of small concrete blocks. Some of these were broken, and some partly crushed. Delicate scales and glass measures occupied a neighboring shelf, and a big steel apparatus that looked rather like a lever weighing machine stood in the shadow.

Where the draught that came through the lattices flowed across the room, Bethune lounged in a canvas chair, and another man, with a quiet, sunburned face, sat behind him. This was Stuyvesant, whose authority was only second to Fuller’s.

“Brandon seems to have taken a good deal of trouble, but this kind of investigation needs the strictest accuracy, and we haven’t the best of testing apparatus,” Bethune remarked. “I expect he’ll allow that the results he has got may be to some extent misleading, and I doubt if it’s worth while to go on with the matter. Are you sure you have made no mistakes, Dick?”

Dick pondered for a few moments. If he were right, as he thought he was, the statements he had to make would lead to the discharge of the sub-contractor. Remembering his own disgrace, he shrank from condemning another. He knew what he had suffered, and the man might be innocent although his guilt seemed plain. It was a hateful situation, but his duty was to protect his master’s interests and he could not see him robbed.

“You can check my calculations,” he answered quietly.

“That’s so,” agreed Stuyvesant, who added with a dry smile as he noted Bethune’s disapproving look: “We can decide about going on with the thing when we have heard Brandon.”

“Very well,” said Dick, giving him some papers, and then indicated two different rows of the small concrete blocks. “These marked A were made from cement in our store; the lot B from some I took from Oliva’s stock on the mole. They were subjected to the same compressive, shearing, and absorbent tests, and you’ll see that there’s very little difference in the results. The quality of standard makes of cement is, no doubt, much alike, but you wouldn’t expect to find that of two different brands identical. My contention is that the blocks were made from the same stuff.”

Stuyvesant crossed the floor and measured the blocks with a micrometer gage, after which he filled two of the graduated glass measures and then weighed the water.

“Well?” he said to Bethune, who had picked up Dick’s calculations.

“The figures are right; he’s only out in a small decimal.”

Stuyvesant took the papers and compared them with a printed form he produced from his pocket.

“They correspond with the tests the maker claims his stuff will stand, and we can take it that they’re accurate. Still, this doesn’t prove that Oliva stole the cement from us. The particular make is popular on this coast, and he may have bought a quantity from somebody else. Did you examine the bags on the mole, Brandon?”

“No,” said Dick, “I had to get my samples in the dark. If Oliva bought the cement, he must have kept it for some time, because the only man in the town who stocks it sold the last he had three months ago. The next thing is our storekeeper’s tally showing the number of bags delivered to him. I sat up half the night trying to balance this against what he handed out and could make nothing of the entries.”

“Let me see,” said Bethune, and lighted a cigarette when Dick handed him a book, and a bundle of small, numbered forms. “You can talk, if you like,” he added as he sharpened a pencil.

Dick moved restlessly up and down the floor, examining the testing apparatus, but he said nothing, and Stuyvesant did not speak. He was a reserved and thoughtful man. After a time, Bethune threw the papers on the table.

“FranÇois isn’t much of a bookkeeper,” he remarked. “One or two of the delivery slips have been entered twice, and at first I suspected he might have conspired with Oliva. Still, that’s against my notion of his character, and I find he’s missed booking stuff that had been given out, which, of course, wouldn’t have suited the other’s plans.”

“You can generally count on a Frenchman’s honesty,” Stuyvesant observed. “But do you make the deliveries ex-store tally with what went in?”

“I don’t,” said Bethune dryly. “Here’s the balance I struck. It shows the storekeeper is a good many bags short.”

He passed the paper across, and Dick examined it with surprise.

“You have worked this out already from the muddled and blotted entries! Do you think you’ve got it right?”

“I’m sure,” said Bethune, smiling. “I’ll prove it if you like. We know how much cement went into stock. How many molded blocks of the top course have we put down at the dam?”

Dick told him, and after a few minutes’ calculation Bethune looked up. “Then here you are! Our concrete’s a standard density; we know the weight of water and sand and what to allow for evaporation. You see my figures agree very closely with the total delivery ex-store.”

They did so, and Dick no longer wondered how Bethune, who ostentatiously declined to let his work interfere with his comfort, held his post. The man thought in numbers, using the figures, as one used words, to express his knowledge rather than as a means of obtaining it by calculation. Dick imagined this was genius.

“Well,” said Stuyvesant, “I guess we had better send for the storekeeper next.”

“Get it over,” agreed Bethune. “It’s an unpleasant job.”

Dick sent a half-naked peon to look for the man, and was sensible of some nervous strain as he waited for his return. He hated the task he had undertaken, but it must be carried out. Bethune, who had at first tried to discourage him, now looked interested, and Dick saw that Stuyvesant was resolute. In the meanwhile, the shed had grown suffocatingly hot, his face and hands were wet with perspiration, and the rumble of machinery made his head ache. He lighted a cigarette, but the tobacco tasted bitter and he threw it away. Then there were footsteps outside and Stuyvesant turned to him.

“We leave you to put the thing through. You’re prosecutor.”

Dick braced himself as a man came in and stood by the table, looking at the others suspiciously. He was an American, but his face was heavy and rather sullen, and his white clothes were smeared with dust.

“We have been examining your stock-book,” said Dick. “It’s badly kept.”

The fellow gave him a quick glance. “Mr. Fuller knows I’m not smart at figuring, and if you want the books neat, you’ll have to get me a better clerk. Anyhow, I’ve my own tally and allow I can tell you what stuff I get and where it goes.”

“That is satisfactory. Look at this list and tell me where the cement you’re short of has gone.”

“Into the mixing shed, I guess,” said the other with a half-defiant frown.

“Then it didn’t come out. We haven’t got the concrete at the dam. Are there any full bags not accounted for in the shed?”

“No, sir. You ought to know the bags are skipped right into the tank as the mill grinds up the mush.”

“Very well. Perhaps you’d better consult your private tally and see if it throws any light upon the matter.”

The man took out a note-book and while he studied it Bethune asked, “Will you let me have the book?”

“I guess not,” said the other, who shut the book with a snap, and then turned and confronted Dick.

“I want to know why you’re getting after me!”

“It’s fairly plain. You’re responsible for the stores and can’t tell us what has become of a quantity of the goods.”

“Suppose I own up that my tally’s got mixed?”

“Then you’d show yourself unfit for your job; but that is not the worst. If you had made a mistake the bags wouldn’t vanish. You had the cement, it isn’t in the store and hasn’t reached us in the form of concrete. It must have gone somewhere.”

“Where do you reckon it went, if it wasn’t into the mixing shed?”

“To the Santa Brigida mole,” Dick answered quietly, and noting the man’s abrupt movement, went on: “What were you talking to Ramon Oliva about at the Hotel Magellan?”

The storekeeper did not reply, but the anger and confusion in his face were plain, and Dick turned to the others.

“I think we’ll send for Oliva,” said Stuyvesant. “Keep this fellow here until he comes.”

Oliva entered tranquilly, though his black eyes got very keen when he glanced at his sullen accomplice. He was picturesquely dressed, with a black silk sash round his waist and a big Mexican sombrero. Taking out a cigarette, he remarked that it was unusually hot.

“You are doing some work on the town mole,” Dick said to him. “Where did you get the cement?”

“I bought it,” Oliva answered, with a surprised look.

“From whom?”

“A merchant at Anagas, down the coast. But, seÑores, my contract on the mole is a matter for the port officials. I do not see the object of these questions.”

“You had better answer them,” Stuyvesant remarked, and signed Dick to go on.

Dick paused for a moment or two, remembering how he had confronted his judges in a tent in an English valley. The scene came back with poignant distinctness.

He could hear the river brawling among the stones, and feel his Colonel’s stern, condemning gaze fixed upon his face. For all that, his tone was resolute as he asked: “What was the brand of the cement you bought?”

“The Tenax, seÑor,” Oliva answered with a defiant smile.

Then Dick turned to the others with a gesture which implied that there was no more to be said, and quietly sat down. Tenax was not the brand that Fuller used, and its different properties would have appeared in the tests. The sub-contractor had betrayed himself by the lie, and his accomplice looked at him with disgust.

“You’ve given the thing away,” he growled. “Think they don’t know what cement is? Now they have you fixed!”

There was silence for the next minute while Stuyvesant studied some figures in his pocket-book. Then he wrote upon a leaf, which he tore out and told Dick to give it to Oliva.

“Here’s a rough statement of your account up to the end of last month, Don Ramon,” he said. “You can check it and afterwards hand the pay-clerk a formal bill, brought up to date, but you’ll notice I have charged you with a quantity of cement that’s missing from our store. Your engagement with Mr. Fuller ends to-day.”

Oliva spread out his hands with a dramatic gesture. “SeÑores, this is a scandal, a grand injustice! You understand it will ruin me? It is impossible that I submit.”

“Very well. We’ll put the matter into the hands of the Justicia.”

“It is equal,” Oliva declared with passion. “You have me marked as a thief. The port officials give me no more work and my friends talk. At the Justicia all the world hears my defense.”

“As you like,” said Stuyvesant, but the storekeeper turned to Oliva with a contemptuous grin.

“I allow you’re not such a blamed fool,” he remarked. “Take the chance they’ve given you and get from under before the roof falls in.”

Oliva pondered for a few moments, his eyes fixed on Stuyvesant’s unmoved face, and then shrugged with an air of injured resignation.

“It is a grand scandal, but I make my bill.”

He moved slowly to the door, but paused as he reached it, and gave Dick a quick, malignant glance. Then he went out and the storekeeper asked Stuyvesant: “What are you going to do with me?”

“Fire you right now. Go along to the pay-clerk and give him your time. I don’t know if that’s all we ought to do; but we’ll be satisfied if you and your partner get off this camp.”

“I’ll quit,” said the storekeeper, who turned to Dick. “You’re a smart kid, but we’d have bluffed you all right if the fool had allowed he used the same cement.”

Then he followed Oliva, and Stuyvesant got up.

“That was Oliva’s mistake,” he remarked. “I saw where you were leading him and you put the questions well. Now, however, you’ll have to take on his duties until we get another man.”

They left the testing-house, and as Bethune and Dick walked up the valley the former said: “It’s my opinion that you were imprudent in one respect. You showed the fellows that it was you who found them out. It might have been better if you had, so to speak, divided the responsibility.”

“They’ve gone, and that’s the most important thing,” Dick rejoined.

“From the works. It doesn’t follow that they’ll quit Santa Brigida. Payne, the storekeeper, is of course an American tough, but I don’t think he’ll make trouble. He’d have robbed us cheerfully, but I expect he’ll take his being found out as a risk of the game; besides, Stuyvesant will have to ship him home if he asks for his passage. But I didn’t like the look Oliva gave you. These dago half-breeds are a revengeful lot.”

“I’m not in the town often and I’ll be careful if I go there after dark. To tell the truth, I didn’t want to interfere, but I couldn’t let the rogues go on with their stealing.”

“I suppose not,” Bethune agreed. “The trouble about doing your duty is that it often costs you something.”