The Compass Museum, Article 21 Aralık 2008 tarihinde Wayback Machine sitesinde arşivlendi.: Though the Creagh-Osborne was offered in a wrist-mount model, it proved too heavy and bulky in this form.
ritchienavigation.com
E.S. Ritchie & Sons Company, Inc. About Us, Article 11 Ekim 2008 tarihinde Wayback Machine sitesinde arşivlendi.: 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.
E.S. Ritchie & Sons Company, Inc. About Us, Article 11 Ekim 2008 tarihinde Wayback Machine sitesinde arşivlendi.: 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.
The Compass Museum, Article 21 Aralık 2008 tarihinde Wayback Machine sitesinde arşivlendi.: Though the Creagh-Osborne was offered in a wrist-mount model, it proved too heavy and bulky in this form.
