First attempt to establish a transatlantic link between Ireland and Newfoundland. The mighty HMS Agamemnon and the American frigate Niagara, with a flotilla of support vessels, set out from Valentia, an island just off the coast of Ireland, with 1,200 two-mile-long copper cable sections, pre-spliced into eight 300-mile sections. The cable weighs one ton per nautical mile (of which, however, only 50 kg of copper per mile). Thomson is aboard the Agamemnon while Samuel Morse is aboard the Niagara, struggling with seasickness and a leg injury. The cable breaks 600 km from Valentia, and work is interrupted in anticipation of winter. The following summer, two more attempts are made: the first fails immediately, while the second works for about a month, after which it fails due to excessive voltage passed through the cable in an attempt to strengthen the signal.
