About the year 1856 it occurred to me that an instrument for solving spherical triangles by inspection might be useful in navigation. But after some conversation on the subject with Professor Chauvenet, and others, I concluded that the saving of labor, effected by it, would not be sufficient to make it readily saleable, among navigators. The invention was therefore remanded to forgetfulness until 1873, when a paper, by Prof. Wm. A. Rogers, upon "The coefficient of safety in navigation," and an encouraging word from Prof. Benj. Peirce, led me to make a model, and show it to Mr. Cyrus H. Farley, of Portland, Me. He agreed with me in thinking that a ship with such an instrument on board, in the hand of one knowing how to use it, would in certain circumstances be safer; and after mature deliberation undertook the manufacture of what he calls The Nautrigon.
I had called it the Sumner, because I had received the first suggestion of its utility from T. H. Sumner's methods of using single altitudes.