Near the entrance to Poperinge a British Major came over to our car as we were showing our passes to a military policeman. "Are you Canadian officers?" he said. "We are," I answered. "Then would you mind telling your Canadian transport drivers to stop going up and down this road; they insist on doing it, and I can't stop them." "There is a big battle up in the salient," I said. "Shells and many other things are needed; our men have been sent for them and know what they want; I wouldn't interfere with them if I were you." He looked at us as though we were hopeless idiots, and we drove on. The motor ambulance convoy, which we had been asked to have sent forward, had already gone, and our last errand was done. Putting on our headlights and opening the throttle, we tore homeward, reaching Merville at eleven o'clock. When we arrived at the Mess, Captain Ellis, who had been anxiously waiting, said that we looked grey, drawn and ghastly, partly perhaps from the effects of the poisonous gas. We had an intensely interested listener as we recounted our experiences and drew plans of the line as we thought it probably existed at the moment. Whether the Germans could get through or not was the dominant question. Nothing lay between them and Calais but the Canadian Division, and whether the Canadians could hang on long enough in face of this new terror of poison gas until new troops arrived, no one could even venture to guess. We felt that they would do all that men could do under the circumstances, but without means of combating the poison it was doubtful what any troops could do. Supposing the Germans just kept on discharging gas? Nothing under heaven apparently could stop them from walking over the dead bodies of our soldiers, choked to death like drowned men. We could not decide the question that time alone could answer, and we went to bed to spend a long sleepless night longing for the day, when we would get news of the battle. The next afternoon I was sent for by General Sir Henry Rawlinson, commanding the corps in our area. He had heard that I had seen the gas discharged the day before and wanted to know what the gas was, what the effect had been, how it could be combated and, in fact, all about it. When I had finished my narrative he placed a large map in front of me and asked me to sketch out the part of the line where the gas had been discharged, and how I thought the line should be at the present moment. I did my best, tyro as I was. It was one of the satisfactory moments of my life when the General drew the map to one side and showed me a map of the line as it really was, given him by General Foch that very morning. The maps were identical, and the General smiled a smile of appreciation as he thanked me for the assistance that our laboratory had given in helping to diagnose and combat this new mode of warfare, and I left his office feeling that we had been of some real use in the war even if we never did anything else. CHAPTER VIII.