In January 1889, in the wake of Heinrich Hertz’s dramatic discovery of electromagnetic waves, the British physicist Oliver Lodge declared that with this experimental confirmation of James Clerk Maxwell’s electromagnetic theory of light, “the whole domain of Optics is annexed to Electricity, which has thus become an imperial science.” Lodge had hit on a very up-to-date way to express the preeminence electrical science had achieved by the last decades of the nineteenth century. But in 1889 electricity was an imperial science in a less metaphorical sense as well: it lay at the scientific heart of submarine telegraphy, one of the characteristic technologies of the Victorian British Empire.