“Who can have written this scoundrelly thing?” continued Marcus, turning over the letter, and then the envelope, for the twentieth time each, and minutely examining them.

The note was written on a half sheet of common letter paper.  The manufacturer’s stamp in the corner had been cut off, and the size of the half sheet further diminished by paring down one of the sides.  The writing was what is known as “backhanded,” in strokes which appeared at first sight to be of a uniform lightness.  On inspecting it very closely, Marcus discovered a tendency, in this backhanded penmanship, to ascend from the line; and also that, in a few instances, the downward strokes on certain long letters were a trifle thicker than on others.  That the writing was a man’s, Marcus had no doubt, though he would have been puzzled to give the reasons which led him to that conclusion.  The envelope was the ordinary prepaid-stamped one issued by the Government, and therefore could not contribute to the identification of the anonymous writer.  The superscription was in the same backhand, and was peculiar in nothing but a small curved nourish, like Hogarth’s line of beauty, beneath the words, “New York.  City.”

“The rascal has carefully disguised his hand,” said Marcus, “and does not mean to be found out.  I can say nothing more positive, than that it is written by somebody who has never corresponded with me.  My memory of autographs happens to be pretty tenacious.”

“And I am positive that it is written by no acquaintance of mine, or of my daughter’s, for we have none—­except you.  As the case now stands, it is a mystery, not worth the exploring.”

“Again I differ with you,” said Marcus.  “Whoever wrote this false letter, has powerful motives of hostility to me or you, or, perhaps—­worse still—­to your daughter.  I must try to smoke him out of his hiding place.  Meanwhile, I trust, sir, you will see the propriety of concealing this unpleasant matter from Miss Minford.”

“Certainly, Mr. Wilkeson, certainly.  As for myself, it is forever dismissed from my mind; and I cannot blame myself sufficiently for having troubled you with it.”  Mr. Minford here proffered his hand, which Marcus cordially shook, rejoicing to observe no trace of suspicion in the inventor’s clear gray eyes.

“Allow me to retain this letter for the present,” asked Marcus.  “It may serve as a clue to the detection of the concealed scoundrel.  I also beg that you will show me any other anonymous letters of the same character that may reach you.”

Mr. Minford laughed.  “The stove door is the pigeonhole where all such nonsense ought to be filed away.  But just as you please.  If any more come to hand, you shall see them.  They may amuse you, as they do me.  Ha! ha!”

Marcus echoed the laugh, but feebly.  Then it occurred to him that Pet would soon be home, and he felt a strange aversion to meeting her, after what had happened.  He therefore pleaded a pressing engagement at eleven o’clock (which it then was), and took his departure from the inventor’s roof, but not without a warm and seemingly sincere invitation to “call soon.”