Between Union Square and Second Avenue there are several blocks of dwelling-houses--a once fashionable and still highly respectable residential neighborhood. The particular street does not matter, but I was proceeding in the general direction of Stuyvesant Square and had crossed Third Avenue. Being on the lower or shady side it was something of a surprise to receive a flash of sunlight directly in the eye. I stepped back. On the pavement at my feet there floated a blot of quivering yellow light; it danced directly towards me, and again I was blinded by its dazzle. The reflection from a mirror, of course, but it took me several minutes to determine its location. Ah, there it was--a peculiar combination, in polished copper, of triple glasses fixed to the sill of a second-story window in the house directly opposite. The device is in common use in Philadelphia and Baltimore, but here in New York it must be classed as an exotic. Its very name is unfamiliar, and I dub it the "Philadelphia Quizzing-Glass" for want of a better term. You understand, of course, that the mirrors are hinged together and adjustable to any angle. It is consequently possible for an observer sitting in the room to remain entirely out of sight and yet command a view of all that passes in the street below. An ingenious contrivance, then, for keeping one's self informed upon the business of the neighborhood. But New-Yorkers, if not less inquisitive, are more energetic than their Quaker cousins, and prefer the direct method of leaning out of the window, or, if need be, going down into the street itself. Still, there is something to be said for the "quizzing-glass," for we may look upon it as the range-finder of the domestic fortress, forewarning us of the approach of the bore and the process-server. Obviously, the ability to look round a corner may save us from many of the minor complications that embitter modern life. I was under surveillance--that was certain. Now, should I submit to the impertinence? It was easy to put an end to it by walking away. But I had aspired to be a disciple of Esper Indiman, gentleman adventurer, and here was a chance to take out a letter of marque on my own account--one must look Fortune in the face to catch her smile. And so I stood there immovable, until the dazzle in my eyes cleared away signifying that the ordeal was at an end. Then I lifted my hat and walked on, taking note of the house number--23l. The next day, Wednesday, it rained, but Thursday was clear, and it was inevitable that I should pay a second visit to the house of the quizzing-glass, as I had mentally christened it. Again I submitted to a long scrutiny. Evidently the result was satisfactory, for the door of the house was opened and a man ran quickly down the steps and came towards me. He was a small man with an Oriental cast of features and he wore a red fez. It sounds incredible, I admit, but such was the fact. He addressed me civilly, but in somewhat imperfect English.