Demonstration polariscope, rosewood and ivory frame and handle a with rotating mount containing six mineral crystals samples and oval red leather and wood case with velvet and silk lining, unsigned, British, 1830-1880. Once the property of Sylvanus P Thompson (1851-1916), professor of physics at the City and Guilds Technical College in Finsbury, England. Demonstration polariscope with red leather case. 1830-1880