Brandis and Sons Bubble Sextant (A19570637000); basic instrument is “U.S. Navy High Grade Sextant, 7 inch radius” made ca. 1914-1916. This example has a Willson bubble telescope (the bubble is missing), drum micrometer and rapid release lever; may be a Mark I, Mod 3, ca. 1922. Studio photograph on dark blue background made January 18, 2013, at the Smithsonian National Air and Space Museum, Washington, D.C., in support of the exhibit “Time and Navigation” (opening March 2013).