FIRST EDITION. 8vo. (8.4 x 5.3 inches). iv, 67pp. Illustrated with four small diagrams in the text. Publisher dark green paper wraps, printed in black to the front panel. Some pages with spotting to the outer margins. The last few leaves have a stain to the bottom outer corner of the pages, but well away from the text. Corners bumped. In the publishers original wrappers with most of the spine missing and the whole booklet held together with two strips of dark green tape, extending onto the front and rear panels. Overall just a good copy of this scarce work. A philosophical essay, Leger's work details experiments and observations related to the Magnetoscope, an apparatus designed to detect subtle bodily or magnetic emanations, and delves into topics such as human magnetism, animal magnetism (mesmerism), and the nature of the magnetoid force. Theodore Léger, a French physician, had been a member of the faculty of the Paris medical school, a member of the Medical College of Mexico, a professor of midwifery, and a vice president of the Medical Society of New Orleans