with his daughter and me, by leading him back to his work-a-day thoughts.  If I referred to his own experiments in particular he always made a joke about being afraid of my chemical knowledge, and of my wishing to anticipate him in his discoveries.  In brief, after a week’s run of the lower regions, the upper part of the red-brick house and the actual nature of its owner’s occupations still remained impenetrable mysteries to me, pry, ponder, and question as I might.

Thinking of this on the river-bank, in connection with the distressing scene which I had just had with Alicia, I found that the mysterious obstacle at which she had hinted, the mysterious life led by her father, and the mysterious top of the house that had hitherto defied my curiosity, all three connected themselves in my mind as links of the same chain.  The obstacle to my marrying Alicia was the thing that most troubled me.  If I only found out what it was, and if I made light of it (which I was resolved beforehand to do, let it be what it might), I should most probably end by overcoming her scruples, and taking her away from the ominous red-brick house in the character of my wife.  But how was I to make the all-important discovery?

Cudgeling my brains for an answer to this question, I fell at last into reasoning upon it, by a process of natural logic, something after this fashion:  The mysterious top of the house is connected with the doctor, and the doctor is connected with the obstacle which has made wretchedness between Alicia and me.  If I can only get to the top of the house, I may get also to the root of the obstacle.  It is a dangerous and an uncertain experiment; but, come what may of it, I will try and find out, if human ingenuity can compass the means, what Doctor Dulcifer’s occupation really is, on the other side of that iron door.

Having come to this resolution (and deriving, let me add, parenthetically, great consolation from it), the next subject of consideration was the best method of getting safely into the top regions of the house.

Picking the lock of the iron door was out of the question, from the exposed nature of the situation which that mysterious iron barrier occupied.  My only possible way to the second floor lay by the back of the house.  I had looked up at it two or three times, while walking in the garden after dinner with Alicia.  What had I brought away in my memory as the result of that casual inspection of my host’s back premises?  Several fragments of useful information.

In the first place, one of the most magnificent vines I had ever seen grew against the back wall of the house, trained carefully on a strong trellis-work.  In the second place, the middle first-floor back window looked out on a little stone balcony, built on the top of the porch over the garden door.  In the third place, the back windows of the second floor had been open, on each occasion when I had seen them—­most probably to air the house, which could not be ventilated