Submarine Telephoning
Charles Ward Raymond · Transactions of the American Society of Civil Engineers · 1878
A means of commnunication, direct and at the same time easy and reliable, is and has been a great desideratum by those engages in submarine work. The method of signaling now employed, by jerking upon the life-line, although, perhaps, sufficiont for ordinary work, is, at the best, deficient in rapidity and reliability; and where the work is of such a nature, that a word cannot express that which the diver would report to those above, it becomes necessary, in order to facilitate the work, that some other means be adopted.