The heavy howitzers make far less noise, and the report cannot always be detected, but the sound of the shell in the air is unmistakable. It is a curious, intermittent, hollow, rushing sound, with an ever-deepening note which dies away, if it is not coming near you, just before the rending ‘crump’ of the explosion. This ‘crump’ is a sound-phenomenon which I am unable to explain. Whereas the lighter shell goes off with an ordinary ‘bang,’ the 15-centimetre and larger projectiles sound like a whole family of explosions going off not quite at the same instant. The German light field-howitzer in its acoustic effects is much like a smaller edition of its larger brothers. Of the huge 42-centimetre shells I have had, I am glad to say, no experience so far. Another sound that one gets to know with experience is the report of the trench mortar. This is not distinguishable if there is much noise going on, and is best likened to the ‘clap’ of a pigeon-trap. My ear has been somewhat trained by much _shikar_ in Ceylon jungles, and this has held me in good stead on at least one occasion, when, after blowing a mine, the Germans fired four trench mortars at a group of miners and myself in a front-line sap. I distinctly heard the ‘clap’ of the report and was able to give the warning to disperse. There was not much cover, but we had good luck and no one was hit. A pleasant ‘drawing-room’ voice is that of our beautiful little field-howitzer. It goes off with more of a puff than a bang, and the shell sails away with a soft whirring note which is lost in the distance long before the formidable crash of the burst is wafted back from the German lines. An alarming sound that one used to hear earlier in the war, when ammunition was of a lower quality than it is now, was that of a shell with a ‘stripped’ driving band. Such a shell will whirl through the air at any angle and will land, possibly base first, a mile or two short of its mark. One of the most encouraging of sounds is the dull thud of a German ‘blind’ shell, especially if, as often happens, they are coming over in appreciable numbers. We are sometimes treated to furious ‘strafes’ with shells of the ‘toy-shop’ quality, of which only a small percentage detonate properly, while a somewhat larger proportion go off with an impotent pop, and the majority fail to explode at all. ‘Smoky Bill’ used to fire such shells. ‘Smoky Bill’ was a funny old thing dating back from the ’seventies. A vast column of smoke rising from behind a certain wood in the German lines was the first signal that he had fired, and this was followed by a fearsome whirr in the air, and then, five times out of six, by a dull thud and nothing more! We knew where ‘Smoky Bill’ was, but nobody ever fired at him—he was one of the side-shows of that sector and never did anyone any harm.