Digitising historic datasets : Greenwich Magnetic Yearbooks 1841-1925

This report describes a BGS project to begin digitising the collection of scanned yearbooks we have on record. This report covers the Greenwich yearbooks from 1841 to 1925. We recorded the declination, inclination, horizontal force and vertical force in the same format that they are published in. Furthermore, the report also details the steps taken to convert the inclination and declination, from various published units to standardised units (arcminutes). It also outlines the attempts to convert the horizontal and vertical force values published from 1868 to 1911 from British, and Gauss units to nanoTeslas, however due to inconsistencies in the scaling factors, and time constraints we have had limited success. Post-1911 the horizontal and vertical force data has successfully been converted into nanoTesla. Finally, we cover the data format that this data is now stored it to make it easier to extract and use.