Maury first began in November, 1853 to correspond with Cyrus W. Field, one of the prime movers in the enterprise, and soon thereafter he met him personally. In the following year, Field invited Maury to become financially connected with the submarine telegraph, but this was declined on the grounds that he could not then be a disinterested adviser of the company. Field came to Maury often, sometimes every day for weeks at a time, to consult as to the size and material for the cable, which according to Field’s first estimate was large enough, Maury playfully said, for the young whales to amuse themselves romping over it. Maury also devised a plan for making, coiling, and laying down the cable; and when somewhat later Field wrote asking on behalf of the company in regard to the best route and time for laying it, Maury with the help of his assistants consulted the results of 260,000 days of observations at sea and replied that the most propitious time for their undertaking would be either the last of July or the first of August, and that the steamer with the western end of the telegraphic cord on board would be less liable than the other to encounter a gale. Field greatly appreciated Maury’s advice, and invited him and his wife and two daughters to go on an excursion in the summer of 1855 to witness the laying of that part of the cable between Newfoundland and Cape Breton. He also gave permission that the National Observatory should be the first to use the telegraph to determine longitude across the Atlantic. In giving this assurance, Field wrote of the great help which Maury was rendering in “illuminating the path for the lightning”. In the year 1856, Lieutenant Berryman in the _Arctic_ made soundings from St. Johns, Newfoundland to Queenstown, Ireland, both on the outward and homeward passages. But these soundings were very carelessly made, and finally had to be declared worthless by Maury. In the summer of the following year Lieutenant Dayman, Royal Navy went over the same course in the _Cyclops_ and made satisfactory soundings, which confirmed Maury’s earlier statements as to the existence of the telegraphic plateau.