A method is described of locating cable faults by means of a pair of towed electrodes, the cable section between fault and shore being energized by alternating or interrupted current. The limitations and difficulties of the method are discussed and remedies are indicated.Two practical trials of the gear are briefly described.Simple approximate formulae are derived for the range of the gear, and numerical values are calculated for three typical cables. It is shown that the device should be sufficiently sensitive to locate an earthed break in a modern cable up to 360 nauts from shore and an insulated break up to 100 nauts, though on account of the difficulty of handling the gear in deep water the useful ranges would often be much less.