/ DE / . . . / F. W. EICHENS CONSTR / E. BERTAUX, ÉDITEUR / PARIS"
diameter 8.5 inches
The NavisphPre was designed to be "a nautical instrument of extremely simple construction and easily handled, by means of which nearly all the complex nautical problems may be solved in a few minutes, and without calculation, or, at least, with very little calculation." It consists of a celestial globe that shows only the
brightest stars, with a brass superstructure (the Metrosphere) that represents
the horizon and two meridians. Henri DeMagnac, a captain in the French navy who was interested in the problems of navigation, probably came up with the original design. Frederic William Eichens, an instrument maker in Paris, obtained a French patent for it in 1878, an American patent in 1881, and other patents in England and Germany.
Ref: F. W. Eichens, "Celestial Globe," U.S. patent #247,811.
H. De Magnac, "Le navisphPre - instrument nautique," Revue Maritime et Coloniale 61 (1879): 598-616.
H. De Magnac, Le NavisphPre: instrument nautique, instruction pour son usage (Paris, 1881); and The Navisphere (England, 1881).