(EN) The Compass Museum, ArticleArchiviato il 21 dicembre 2008 in Internet Archive.: Though the Creagh-Osborne was offered in a wrist-mount model, it proved too heavy and bulky in this form.
(EN) E.S. Ritchie & Sons Company, Inc. About Us, ArticleArchiviato l'11 ottobre 2008 in Internet Archive.: In 1860, Edward Samuel Ritchie, an American physicist and instrument maker, received a U.S. patent for the first liquid-damped marine compass adopted for general use aboard ships and boats.
(EN) E.S. Ritchie & Sons Company, Inc. About Us, ArticleArchiviato l'11 ottobre 2008 in Internet Archive.: In 1860, Edward Samuel Ritchie, an American physicist and instrument maker, received a U.S. patent for the first liquid-damped marine compass adopted for general use aboard ships and boats.
(EN) The Compass Museum, ArticleArchiviato il 21 dicembre 2008 in Internet Archive.: Though the Creagh-Osborne was offered in a wrist-mount model, it proved too heavy and bulky in this form.
