Reconstruction of a Roman "Pertica", or measuring rod, 1st century A.D. Reconstruction of a Roman "Pertica"
One large bar for Colby's Compensation bar, as used on the Lough Foyle Base, 1827-1828. These are 10 feet in length but will change with temperature change. A bar for Colby's compensation bars
Box containing Mechanical Programme Finder (a type of planisphere) consisting of duralumin alloy disc and ten celluloid quadrants; ‘Star Catalogue for 45° Prismatic Astrolabe’; and diagram of ‘45° Astrolabe Value of Coefficient “A”, made by Cooke, Troughton & Simms, York, England, UK, 1930-1940. Designed as an accessory for use with the 45° Prismatic Astrolabe, also manufactured by Cooke, Troughton and Simms. Diagram corresponds to Diagram No. 5072 in the Star Catalogue. Mechanical Programme Finder for use with 45 degree Prismatic Astrolabe, by Cooke, Troughton and Simms