ten kilometers by the military road."
He nodded and counted the ships. There were three.
"Is there more than one road which runs to Rosières-sous-Bois?" he asked.
"Yes. One may go by this road, or cross the bridge by the quarries and go by the river road, or there is still a better and shorter highway which runs west of Saïs."
"Then there are three main roads to Rosières-sous-Bois?"
"Yes. The road to the west is shorter. It is not more than seven miles that way."
Halkett casually counted the sea gulls. Seven gulls were flying around one of the ships; thirteen around another.
"And the river road, Sister?" he inquired.
"By the quarry bridge? Oh, that is longer – perhaps twelve or thirteen kilometers."
"I see… Rosières-sous-Bois is not a garrison town?"
"No. There are only a few gendarmes there."
Halkett examined the picture attentively. The sun appeared to be about three hours high above the horizon.
"The nearest military post must be about three hours' journey from here," he ventured.
Sister Eila thought a moment, then nodded:
"Yes, about three hours. You mean the fort above the Pass of the Falcons? That is the nearest."
He counted the rays of the sun. There were three long ones and two short ones.
"I suppose there are three or four battalions garrisoned there," he remarked.
"Three, I think. And a company of engineers and one company of Alpine chasseurs."
All the time, with a detached air, the young Englishman was examining the colored poster, searching it minutely for variations from other posters of the same sort which he had recently investigated.
There remained in his mind little or no doubt that the number and position of the groups of pointed wavelets signified something important; that the number of sails set on the ships, which varied in every poster, contained further information; that the sky, cloudless in some posters, dotted with clouds in others, was destined to convey topographical particulars to somebody.
These colored advertisements of a soap made in Cologne by Bauermann and Company, and plastered over the landscape of Northern and Eastern Belgium and France, concealed a wealth of secret information for anybody who possessed the key to the messages so clearly and craftily expressed in pictograph and cipher code.
The sinister significance of the sheet in his hand was becoming more apparent every minute. He had made a study of these posters – was just beginning to find them interesting, when he had been ordered to America. Now, all his interest in them returned.
Sister Eila had seated herself at her desk, and, while he was still examining the poster, she continued serenely to correct the pile of inky copybooks.
He watched her for a while, where she bent above the scrawled pages, her pen poised, her lovely face framed in the snowy wimple under the pale shadow of her wide-winged coiffe.
"Sister Eila?"
She turned her head tranquilly.
"You are English, you tell me?"
"Irish." She smiled.
"It's the same. Tell me, have you had enough experience in your world of duty and of unhappiness to know an honest man when you encounter him?"
Sister Eila laid aside her pen and turned toward him.
"I don't think I understand," she said.
"I mean, could you make up your mind about – well – about such a man as I am – merely by inspecting me and hearing me speak?"
Sister Eila laughed:
"I think I could very easily."
"Have you already done so?"
"Why, yes, I suppose so."
"Do you think I am honest enough to be trusted?"
Sister Eila laughed again, deliciously.
"Yes, I think so," she said.
He remained silent and his face, already grave, grew more serious. Sister Eila's smile faded as she watched him. It was becoming very plain to her that here was a man in trouble.
Silent there together in the cool stillness of the schoolroom, they heard the distant clatter of little feet, the vigorous voice of command from Sister Félicité; and a moment later a double file of chattering children passed in the sunshine outside the window, led toward their noonday playground by Sister Félicité accompanied by Warner.
"What is on your mind, Mr. Halkett?" asked Sister Eila, still watching him.
"If I tell you," he said, "will you ask me no more than I offer to tell you?"
She flushed:
"Naturally, Monsieur – "
"You don't quite understand, Sister. What I have to say I wish you to write down for me in the form of a letter of information to the French Government."
"You wish me to write it?"
"Please. And that is what I mean. Naturally, you might ask me why I do not write it myself… Don't ask me, Sister… If you really do trust me."
He turned, met her gaze, saw two clear, sweet eyes unspoiled and unsaddened by the wisdom she had learned in dark and wretched places; saw in them only a little wonder, a faintly questioning surprise.
"What is your answer, Sister?" he asked.
"My answer is – I – I do trust you… What am I to write?"
She took a few loose leaves of paper from the desk, and sat looking at him, pen lifted.
He said:
"Write to the chief of the general staff at the Ministry of War in Paris."
And when she had properly addressed the personage in question, he dictated his letter very slowly in English; and Sister Eila, her expressionless young face bent above the letter paper, translated into French as he dictated, and wrote down the exact meaning of every word he uttered:
"Information has come to me that the advertisements of Bauermann and Company, of Cologne, Prussia, which are posted everywhere throughout Belgium and Northern and Eastern France, conceal military and topographical details concerning the vicinity where these advertisements are displayed.
"Such information could be of use only to a prowling spy or an invading enemy.
"Therefore, acting upon the incomplete information offered me, I deem it my duty to bring this matter to the notice of the Government.
"It would appear that:
"1st. Secret information is contained in the details of the picture which embellishes this advertisement, a sample of which I inclose herewith.
"2nd. These details vary in every poster. Presumably their number, color, groupings, and general distribution constitute a secret code which is calculated to convey information to the enemies of France.
"3rd. In the sample which is inclosed with this letter, the number of ships probably represents the number of highways leading from Saïs to Rosières-sous-Bois; the sea gulls flying above two of the ships give the distance in kilometers; the ten white flowers give the distance by the military road.
"The sun, in the picture, appears to be about three hours high above the horizon; and it is three hours' journey from here to the nearest French fortified post, the Pass of the Falcons in the Vosges.
"The rays of the sun are five in number, three long ones and two short ones; and there are three battalions of the line guarding the fort at the pass, and two companies, one of engineers, one of Alpine infantry.
"My informant, who desires to remain anonymous, further declares it to be his belief that an exhaustive study of this and similar posters would reveal perfectly clear messages in every detail of color, drawing, and letter-press;