She paused, and the stranger turned to the princ.i.p.al. "If you will allow me--"

The princ.i.p.al smiled and he came up to Agatha, holding out his hand for the chalk.

"Suppose we alter the formula this way?" he said and wiped out the letters and figures.

Agatha studied him as he wrote fresh symbols. He was plainly dressed and about sixty years of age. There was nothing else worth noting, but he obviously knew his subject and she liked his face. She saw that the girls could follow his explanation, but while suited to their understanding, it was, in one respect, not quite accurate.

"I don't know if I've made it much plainer," he said deprecatingly when he stopped.

Agatha indicated a group of letters. "It is plainer, thank you! But does the combination of the two elements take place exactly as you have shown? At a normal temperature, the metal's affinity for oxygen--"

"Ah," he said, "you know that? It looks as if you had studied the new Austrian theory. But perhaps one may make a small concession, for the sake of clearness."

"Science is exact," Agatha replied.

"It's a bold claim for us to make," he rejoined, smiling. "Our symbols are guess measures; our elements split up into two or three. But I gather that you refuse to compromise about what, in the meantime, we think is the truth?"

"I think one must adhere to it, as far as one knows."

"Well, no doubt, that is the proper line. But I've stopped your lecture and perhaps bored your pupils."

"No," said Agatha. "You have helped me over awkward ground, and I expect they would sooner listen to a stranger."

He went away with the princ.i.p.al, and Agatha wondered about him as she resumed her task. It was plain that he knew something about science, but this was not strange, since geologists and chemists sometimes visited the school. After she dismissed her cla.s.s the princ.i.p.al sent for her.

"I suppose you don't know who that man is?" she asked.

Agatha admitted that she did not know and colored when the other told her. The man was a famous scientist who had recently simplified the smelting of some refractory British Columbian ores, and was now understood to be occupied with the problem of utilizing certain barren alkali belts in the West.

"Oh!" she said, "I talked to him as if he were one of the girls. In fact, I believe I was gently patronizing."

"I don't think he was much hurt."

"Then he must have been amused and that is nearly as bad. After he had gone I imagined I'd seen his portrait somewhere."

"He hasn't gone yet," the princ.i.p.al answered with a twinkle. "He's waiting to see you in the managers' room, and I must confess to something of a plot when I brought him in quietly to hear your lecture."

"But what does he want?" Agatha asked with excited curiosity.

"I imagine he wants to offer you a post, but he will tell you about this. You have half an hour before the next cla.s.s."

Agatha went out, trying to preserve her calm. The man had made his mark by the application of science to industry and the thought that she might help him gave her a thrill. This was different work from teaching beginners; taking them so far and then going over the ground again. If she got the post, she could go on, farther perhaps than she had hoped, and when she had learned enough embark on a career of independent research. She thought she had the necessary tenacity and brains. There was an obstacle, but she would not hurry to meet it and it might be removed.

When she entered the room the man got up and indicated a chair. He asked a few questions, rather carelessly, and afterwards remarked: "Miss Southern had already told me what I most wanted to know. You may have heard about the work in which I am engaged."

"Yes," said Agatha, with a touch of color, "I know what it is now."

He smiled. "Perhaps it would have been better had I asked Miss Southern to present me, but I'm not very formal. Well, I was asked by the Provincial Government and the railroad to find the best way of developing the alkali wastes, and the subject is extraordinarily interesting. If I can solve the problem, it will make important changes in our irrigation system and enable us to cultivate wide belts of barren soil. However, I must have help and want a lady who can take the charge of my correspondence with scientific people and a.s.sist in my experiments. After talking to Miss Southern, I feel I can offer you the post."

Agatha thrilled, but used some self-control.

"But you might not need me long, and I must give up the school."

He smiled. "If you wished to resume teaching, I daresay your having helped in my investigations would be an advantage."

"Then do you expect me to help much in that way?" Agatha asked with growing excitement.

"Yes; as far as you are able. I am told that you are used to laboratory work. Would this suit you?"

Agatha's eyes sparkled. "It would realize my pet ambition."

"Very well. We had better talk about the salary. My notion is--"

Agatha thought the offer generous. She would be richer than she had been yet and there was an object for which she needed money. She felt flattered and almost overjoyed. The work she was asked to do might start her well on the road she had long wished to take.

"There is another matter," the man resumed when she declared that she was satisfied. "It will be necessary for you to come to Europe. My wife will take care of you."

"Then you are going to Europe?" Agatha said with a curious sinking of her heart.

"Yes. I must consult an eminent Frenchman and two or three Austrians.

They have studied some of the problems I am up against."

"When do you start?" Agatha asked with forced quietness.

"In about three weeks, if I can get ready."

Agatha tried to brace herself. The disappointment was hard to bear, and for a few moments she engaged in a bitter struggle. If she took the post and went to Europe, she could not go North for a year, and Thirlwell might not be able to help her then. She knew that she had counted on his help, and that without it she could not penetrate far into the wilds.

Indeed, it was possible that she could not start at all.

Yet, if she went North, she must refuse an alluring offer and throw away an opportunity for making her mark. Her ambition must be abandoned, and if she failed to find the silver, she would have to resume her monotonous duties at the school. She was beginning to find them strangely dreary. Then George had warned her against sacrificing her youth, and perhaps all her life, to the pursuit of a shadow. Her friends did not believe in the silver, and she doubted if she could find the vein. Failure might leave her sour and the hardships break her health; she would come back with her savings exhausted to toil and deny herself again. Yet the lode was waiting to be found somewhere in the North, and the duty she had accepted long since must come first.

"Then I'm sorry I cannot go," she said with an effort.

The man looked surprised. "The voyage is short and comfortable if one travels by a big, fast boat. I expect to work hard, but you would have some leisure and opportunities for seeing famous pictures, statues, and laboratories. Then you would meet eminent chemists and learn something from their talk. In fact, the visit ought to be of help in many ways, and, if you afterwards left my employment, make it easy for you to get another post."

Agatha struggled for calm. He had rather understated than exaggerated the reasons why she ought to go. Then Toronto and Montreal were the only cities she knew, and she was offered a chance of seeing some of the capitals of Europe, with their treasures of art, and meeting men who had made famous scientific discoveries. It would help her more than many certificates if later on she resumed her work of teaching.

"Ah," she said in a strained voice, "please don't try to show me all that I shall miss! I want to go so very much, but it's impossible. If I went, I should neglect a duty that has a stronger claim."

He bowed. "Then, although I'm sorry, there's nothing to be said. Would it be an impertinence if I asked about the duty?"

Agatha was silent for a moment or two. Her refusal had cost her much; indeed, she was afraid to think what she had lost and felt she must do something to banish the crushing sense of disappointment.

"No," she said impulsively; "I cannot resent anything you ask. I must start North soon to look for a vein of ore my father told me about, I'm forced to make the search, but it would be a long story if I told you why." She hesitated and then went on: "I wonder whether you would look at this a.n.a.lysis and tell me what you think--I mean if you think there is ore of that kind on the Northern slope of the Ontario watershed."

He took the paper she had long carried about and studied it for a time.

Then he said: "It is not the ore a practical miner would expect to strike, but practical miners are sometimes deceived. As a rule, they know more about shafts and adits than scientific geology."

"Would _you_ expect to find the ore where I have told you?"