Detectors, [83]

Developing solutions, [105], [122]

Diaphragm, movement of, [48], [52], [84], [87]

Dipping rods, [81], [83]

Distance of transmission, [33]

Duration of wave-trains, [22], [25]

Early experiments, [2]

Einthoven galvanometer, [32], [44], [45], [54], [113]

Electric clock, [93]

Electrolytic receiver, [4], [37], [54], [61], [64]