Audio recording of a lecture given by tutor emeritus Howard Fisher on February 18, 2026 as part of the Dean's Lecture & Concert Series. The Dean's Office has provided this description of the event: "Overland telegraph technology implicitly embodied a familiar image of electricity as being a mobile substance confined to conductors. But phenomena encountered in undersea telegraph cables presented a competing image, one far more suggestive of Faraday’s image of tension in a dielectric. Subsequent production of electromagnetic waves could be seen as the ultimate practical expression of Faraday’s 'tension' image. But if they were to serve as a communications medium, electromagnetic waves had not only to be produced but be detected; and although various detecting mechanisms were developed, their operation was mysterious: the received images of electric current appeared to provide little clarity."