How did William Thomson’s engineering consulting firms contribute to global telegraph communication?

Following the successful laying of the transatlantic cable, William Thomson became a partner in two engineering consulting firms that were instrumental in the planning and construction of submarine cables. These firms played a major role during the rapid expansion of the 19th century, which ultimately resulted in the creation of a global network of telegraph communication.1

Thomson’s contributions were rooted in his earlier theoretical work, where he applied mathematical equations—originally developed to describe heat flow—to solve problems regarding the velocity of electric currents in long-distance cables. His practical inventions, such as the mirror galvanometer and the later siphon recorder, were widely adopted and utilized across this worldwide network of submarine cables.2