It’s the act of a traitor !” Tlie major did not agree with this hasty deduction, though lie was bound to recognise in it a piece of strongly circumstantial evidence of a negative character. He took up the letter again and pondered on its possibilities. Like a, flash he saw through it all. Tin 1 let ter was addressed, not to the Intelli gence Department, bnt to that of Mr Charles Tyson. This error had been committed deliberately. Clearly it was intended that it should pass into the hands of Tyson. ■Major Long became excited as the conviction grew upon him that he had struck the right path. "Well, we'll have Tyson here. Per sonally, I'm not sanguine.'’ was the eommeiit of the commanding officer. "This goto is in ordinary handwriting, and not in stenography. In what ca pacity Tyson can lie of service I fail to see.'' The request to Tyson was urgent. He came half asleep and half-dressed. “Can you suggest any reason why your name is affixed to so important a document r” inquired the general. "None, whatever,'' was the answer. "I ■ca.l say this for Dawson, however —he is trustworthy, he is patriotic to the linger-tips." "What wc cannot understand," said the major, "is this. He is a steno grapher like yourself. It this were not written under compulsion, lie might have done it more safely, well knowing you would lie aide to read it. And lie addresses it to your department, instead of the Intelligence Department. Please !..•.!: over it eareliillv. Don't miss any lliing. A great deal hangs on it."

Tyson was more awake by this time. He bent over the letter and traced every curve with his finger, line by line, down to tho signature. Not till he got to the flourishes did he find anything. These absorbed his whole attention for a few seconds. "It is there, general—right under his name,” he said. "What's there?” “Two shorthand words. It’s not a flourish; it’s shorthand.” “‘lnvisible ink.’ Those are the words. It’s oil of vitriol. He carries some with him very much diluted. Writes to his prospective father-in-law in ordinary ink, and adds a few lines in sympathet ic ink for tho daughter. His love-let ters arc a standing joke with his pal.'i. 