Abstract :
Professor William Thomson (later Lord Kelvin) contributed to submarine telegraphy in many ways. Same of these involved his active participation at the time, whilst other later contributions derived from these early experiences. They comprise almost every aspect of the subject: he became a shareholder and director of the Atlantic Cable Company; he derived a mathematical model for transmission through a cable giving the inverse distance-squared law for speed of signalling; he took an active part in testing the cable whilst laying and in improving the paying-out system to prevent excessive strain; he designed instruments for detecting and recording signals and later with CF Varley and Fleeming Jenkin in tailoring the generated signal to increase speed of signalling; he instigated the systematic testing of the conductivity of copper; he chaired a Board of Trade committee looking into the failures of early cables and a British Association committee to specify the definition and standardisation of electrical units; finally his seafaring experiences led him to devise many navigational aids which would prove invaluable in future cable laying including redesign of the magnetic compass and methods of compensation, a greatly improved depth sounder, analysis of tides and a calculator for their exact prediction, a code to identify lighthouses, and a simplified method for plotting position at sea.
