Collection of black and white WW I aerial reconnaissance photos by the Royal Flying Corps (RFC) , possibly associated to Map 36C (Lens) - Vimy, Lens, and other small communes and hamlets in the area. Title: 16AD 365.16.8.17:-5.30pm. 36c N2co8.8 The white cross indicates north On rear: "Printed by Army Printing and Stationery Services - No. 1 Advanced Section". The Army’s Printing and Stationery Service produced a series of technical appreciations and training manual pamphlets that were crucial to the development of military methods during the Great War. Map Sheet Numbers for 1:40,000 Maps It was decided to base the British Army Map Sheet numbering system on the existing numbering system of the Belgian map sheets. The 1:40,000 scale map sheets were, therefore, given a number. The map sheets covering the battlefield areas of the Western Front in Belgium were numbered as: Map 4: Belgian coast (northern section) Map 12: Belgian coast (southern section) Map 20: Dixmude area Map 28: Ypres area Map 36: Armentières-Lille area The new map sheets for France, to the south of the Belgian border were initially assigned numbers following on from the Belgian sheet of Map 36 as 36A, 36B and 36C from west to east. The the maps to the south of these number 36 map sheets were referenced with C to A, D to A, E to A, or F to A from west to east.