This is a book that contains letters written during and shortly after the First World War from physicists and other scientists working on the location of German artillery using sound ranging. They have never before seen the light of day and now, a century on, provide a remarkable insight into a relatively unknown aspect of warfare. They were sent to William Lawrence Bragg, Nobel Prizewinner at 25, soon to be Professor of Physics in Manchester, who was in charge of sound ranging during WW1. They lay hidden and lost for a century until now, and reveal the daily lives of other physicists in the war zones of France, Salonika and Egypt, handwritten to the sound of bursting shells. In between all the technical stuff, there are flashes of the grim reality, the diversions, the stoicism and the remarkable spread of feelings as the war came to an end as these snippets “Luckily we saw the Pyramids from the train as we were approaching Cairo which relieved us of any further responsibility in that direction." “The ladies in those parts all wear the harem skirt – and look rather fetching." “You heard about our being arrested as spies out here?" “We buried the dead this afternoon." “All the outdoor people have had malaria." ”Well, Bragg, I think thats all for the moment – hoping all is well with you and that you aren’t getting too many bombs." “Poor old Simms, I was sorry to hear that he was gone. He was ‘one of the best’." “Well, cheerio oh! old man & best chin chin. I am looking forward to a good bust up in Blighty quite soon." “I have finally got rid of this damn flu." “I have been declared unfit for any duty at present." “I’m not a bit serious – bit of shell through right forearm." “Like you, we are applauding the events of recent days, and our only regret is not being able to take part in chasing the Boche in this triumphant chivy." “I hope you are not too sorry that the war is over."