A discoverer’s own account of his work is always of interest, and when it is an epoch-making work and the account so clear and well described as to be intelligible to all, it deserves the most careful attention, and should be studied by all who feel any interest in the subject. Dr. Hertz’s account of his discovery of the propagation of electric energy is eminently a work of this kind. The subject is of immense importance; the work described is of the highest order of experimental investigation; the results attained have contributed more than any other recent results to revolutionize the view taken by the majority of scientific workers as to the nature of electromagnetic waves. It is to be hoped that a translation 2 of this account of one of the greatest advances in our knowledge of nature will soon be in the hands of all who care to learn how the functions of the ether have been raised from obscurity into light, from being in the opinion of many a pious belief to be the momentous question of the hour.