1768697 Aerial photograph with WWI trenches, 1917 (b/w photo) by English Photographer, (20th century); The Royal Institution, London, UK; (add.info.: Aerial photograph from an album belonging to Nobel Prize-winning physicist William Lawrence Bragg (31 March 1890 ??1 July 1971) showing the cross roads at St Helene to the north west side of the village of Pontruet (marked in ruins), 27 December 1917. The lines of trenches and tracks can be picked out including the major Trench Fourmi on the left and Trench Forgans on the right. The photograph has been marked with an arrow pointing north and a small white cross, possibly related to sound ranging.); 穢 Royal Institution ; English, out of copyright.