Robertson, an English optician who was settled in Paris some fifty years since, was one of the first to exhibit the phantasmagoria with success. In order to obtain the best results he used a room some sixty or eighty feet long, and twenty-four wide, which he hung entirely with black. Of this a strip twenty-five feet long was cut off and devoted to the manipulation of the phantasmagoria. This portion of the apartment was separated from the spectators by a white calico screen, tightly strained from side to side, and at first concealed from view by a black curtain. The calico screen, which was about twenty feet square, was well soaked in a mixture of starch and fine gum arabic, in order to render it semi-transparent. The floor was raised about four or five feet at one end in order that the whole of the spectators might have a free and uninterrupted view of what was going on. It is undoubtedly to Robertson that we owe most of the improvements in the phantasmagoria. The success of his performances in Paris during the first Revolution has never been equalled by any similar exhibition. The enthusiasm excited amongst the Parisian public at the time surpassed that awakened even by Cagliostro and Mesmer. The spirit which guided Robertson in exhibiting these wonders was totally opposed to that which animated the two charlatans just mentioned. Robertson, unlike them, sought to spread the notion that there was nothing occult or supernatural in the marvels he exhibited, but that they resulted simply from the application of a few simple laws of optics. We shall presently give an account of one these famous _séances_, which were powerful enough to distract the attention of the people of that day from the stormy events that were going on around them; but we will first allow our author to tell the story of his experiments in optics in his own words.