This splendid volume has a tragic story. Dedicated to Lord Kelvin, it opens with an introduction by Silvanus Thompson and a preface by the distinguished author who himself passed from us before the book containing the fruit of many years of toil was ready for issue. And what toil! A Bibliographical History of Electricity and Magnetism covering 4458 years, from 2637 B.C., when Hoang-Ti, Emperor of China, is said to have directed the pursuit of his troops after a rebellious subject by the aid of the compass, up to Christmas Day, A.D. 1821, when Faraday first caused a wire carrying a current to rotate in a magnetic field. The early centuries are passed over quickly. Homer’s name occurs with quotations from the _Odyssey_: “In wondrous ships self-mov’d, instinct with mind, No helm secures their course, no pilot guides; Like men intelligent, they plough the tides.” Does this mean that the Greeks knew of the compass? The author is doubtful. Thales, 600–580 B.C., the discoverer of frictional electricity, follows. The Crusaders wrote of the magnet. A facsimile page is given of Vincent de Beauvais’ _Speculum Naturale_, and Gauthier d’Espinois, who lived about A.D. 1250, sang to his mistress: “Tout autresi (ainsi) comme l’aimant deçoit (detourne) L’aigulette pas force de vertu A ma dame tot le mont (monde) retennue Qui sa beauté connoit et aperçoit.” And when one passes to more recent years, there is not a name one knows omitted from the list. There are also many included who all contributed in some way to the growth of natural knowledge, but who can only be known to the few, the very few, who have burrowed in past records scattered far and wide with the perseverance, the patience, and the skill of Dr. Mottelay. And he has discovered interesting facts without number, and at the same time has supported his case with full references to original works. To the question, How can I find out what--some unknown writer--has written about Electricity? there can in future be but one answer: Look him up in Dr. Mottelay’s _Bibliographical History_. Our debt to the author is no small one; our regrets that he is not here to be gratified by the reception his book must meet with are deep and sincere. The Great War delayed the issue of the book. The public are indebted to Messrs. C. Griffin & Co., Ltd., for bringing out a work of the kind under the difficulties which all scientific publications have met with since 1918, and Dr. Mottelay realized to the full the value of the assistance they gave him. I trust with confidence that electricians throughout the world (for the interest of the book is world-wide) will not be slow to show their appreciation of the work of all those who have combined to render them so marked a service. R. T. GLAZEBROOK.