"You must know what this means to me!" I cried. "It is the blasting of all my hopes and the ruin of my life! You surely will not inflict such a punishment upon me unheard. You will let me know what is the matter. Consider how impossible it would be for me, under any circumstances, to treat you so. For God's sake, Agatha, let me know what I have done!" She walked past me without a word and opened the door. "It is quite useless, Austin," said she. "You must consider our engagement at an end." An instant later she was gone, and, before I could recover myself sufficiently to follow her, I heard the hall-door close behind her. I rushed into my room to change my coat, with the idea of hurrying round to Mrs. Marden's to learn from her what the cause of my misfortune might be. So shaken was I that I could hardly lace my boots. Never shall I forget those horrible ten minutes. I had just pulled on my overcoat when the clock upon the mantel-piece struck ten. Ten! I associated the idea with Miss Penclosa's note. It was lying before me on the table, and I tore it open. It was scribbled in pencil in a peculiarly angular handwriting. "MY DEAR PROFESSOR GILROY [it said]: Pray excuse the personal nature of the test which I am giving you. Professor Wilson happened to mention the relations between you and my subject of this evening, and it struck me that nothing could be more convincing to you than if I were to suggest to Miss Marden that she should call upon you at half-past nine to-morrow morning and suspend your engagement for half an hour or so. Science is so exacting that it is difficult to give a satisfying test, but I am convinced that this at least will be an action which she would be most unlikely to do of her own free will. Forget any thing that she may have said, as she has really nothing whatever to do with it, and will certainly not recollect any thing about it. I write this note to shorten your anxiety, and to beg you to forgive me for the momentary unhappiness which my suggestion must have caused you. "Yours faithfully; "HELEN PENCLOSA. Really, when I had read the note, I was too relieved to be angry. It was a liberty. Certainly it was a very great liberty indeed on the part of a lady whom I had only met once. But, after all, I had challenged her by my scepticism. It may have been, as she said, a little difficult to devise a test which would satisfy me.