Bruce J. Hunt is Associate Professor at the University of Texas, Austin.

Prologue. 'An imperial science'; 1. 'An ill-understood effect of induction': telegraphy and field theory in Victorian Britain; 2. Wildman Whitehouse, William Thomson, and the first Atlantic cable; 3. Redeeming failure: the joint committee investigation; 4. Units and standards: the ohm is where the art is; 5. The ohm, the speed of light, and Maxwell's theory of the electromagnetic field; 6. To rule the waves: Britain's cable empire and the making of 'Maxwell's equations'; Epilogue. Full circle.