Chung Ling Soo. (1898). Spirit Slate Writing and Kindred Phenomena. Munn & Company. pp. 105-106. "Dr. Henry Slade was, of course, identified and recognized as the principal slate-writing medium, but at various times he presented other phenomena, one of which was the playing of an accordion while held in one hand under the table. The accordion was taken by him from the table with his right hand, at the end containing the strap, the keys or notes at the other end being away from him. He thus held the accordion beneath the table, and his left hand was laid on top of the table, where it was always in plain view. Nevertheless, the accordion was heard to give forth melodious tunes, and at the conclusion was brought up on top of the table as held originally; the whole dodge consisting in turning the accordion end for end as it went under the table. The strap end being now downward, and held between the legs, the medium's hand grasped the keyboard end, and worked the bellows and keys, holding the accordion firmly with the legs and working the hand, not with an arm movement, but mostly by a simple wrist movement. Of course, at the conclusion, the hand grasped the accordion at the strap end, and brought it up in this condition. Sometimes an accordion is tied with strings and sealed so the bellows cannot be worked. This is for the dark séance. Even in this condition the accordion is played by inserting a tube in the air-hole or valve and by the medium's using his lungs as bellows."
