At this juncture there came a knock at the door, and C--, with the slate in his hand, went to see who it was. It proved to be the pale-faced assistant. A few words in a low-tone of voice were exchanged between them, and the conjurer returned to the table, excusing the interruption by remarking, "Some one to see me, that is all, but don't hurry, for I have another test to show you." After thoroughly washing both sides of the slate he placed it, with a slate pencil, under a chafing-dish cover in the center of the table. We joined hands and awaited developments. Being tolerably well acquainted with conjuring devices, I manifested but little surprise in the first test when the spirit message was written, because the magician _had his fingers on the slate_. But in this test the slate was not in his possession; how then could the writing be accomplished? [Illustration: FIG. 3. THE HOLDING OF THE SLATE.] "Hush!" said C--, "is there a spirit present?" A responsive rap resounded on the table, and after a few minutes' silence, the mysterious scratching of the slate-pencil began. I was nonplussed. "Turn over the slate," said the juggler. I complied with his request and found a long message to me, covering the entire side of the slate. It was signed "Cagliostro." "What do you think of Dr. Slade's slate tests?" inquired C--. "Splendid!" I replied, "but how are they done?" His explanations made the seeming marvel perfectly plain. While the slate is being examined in the first test, the medium slips on a thimble with a piece of slate pencil attached or else has a tiny bit of pencil under his finger nail. In the act of holding the slate under the table, he writes the short message backwards on its under side. It becomes necessary, however, to turn the slate over before exhibiting it to the sitter, so that the writing may appear to have been written on its upper surface--the side that has been pressed to the table. To accomplish this the medium pretends to go into a sort of neurotic convulsion, during which state the slate is jerked away from the sitter, presumably by spirit power, and is turned over in the required position. It is not immediately brought up for examination but is held for a few seconds underneath the table top, and then produced with a certain amount of deliberation. The special difficulty of this trick consists in the medium's ability to write in reverse upon the under surface of the slate. If he wrote from left to right, in the ordinary method, it would, of course, reverse the message when the slate is examined, and give a decided clue to the mystery. This inscribing in reverse, or mirror writing, as it is often called, is exceedingly difficult to do, but nothing is impossible to a Slade.