What man, unless he be entirely devoid of imagination, has not been profoundly impressed when, for the first time, he hears the distant roll of the guns? How many a soldier makes it the theme of his first letter home? It is the first intimation his relatives get that he is really at the front. And yet, from the sound alone, he will get very little idea as to how far off the line really is. The conformation of the ground, the wind and possibly other climatic conditions affect the transmission of sound in an extraordinary way. One can often hear the guns from very far back, whereas from closer up nothing can be heard at all. If there is a bombardment on, the noise is continuous but varies in intensity either with the wind or according to the number of heavy pieces that are firing at the same instant. Later on, if he is observant, the soldier may get to know the individual voices of some of these guns and recognise the bursts of their shell. On first coming into the line he is unable to distinguish the meaning of the various sounds, and the report of one of our own field-guns firing behind him is likely to cause him more alarm than a Boche rifleman sniping at his unwittingly exposed head. The 18-pounder field-gun makes a most ear-splitting crack for those who stand in front of the battery, and, moreover, the sound seems to come from only a few yards away. The sniper’s bullet will strike the parapet with a resounding crack, followed by the whirr of its passage through the air, and a new-comer might easily imagine that one of our own men had fired from the next traverse. The German field-gun, in common with our own 18-pounder, and, in fact, all high-velocity guns, always sounds a good deal nearer than it really is, and as the shell travels very fast and reaches the front-line trenches very shortly after, or, sometimes, even before, the whizz of its approach, it gives the infantry the impression that the battery is in some impossible position just behind the German support line. The ‘whizz-bang’ and the ‘pip-squeak’ are terms applied to the same German field-gun by people who are shot at by him at different ranges. In the first case there is a warning whirr of approach, but the shell reaches the man who is ‘pip-squeaked’ while it is still travelling faster than sound, and he gets the ‘pip’ of the explosion first and the whizz afterwards—if there is enough of him left to hear it! The voice of the German 77-millimetre field-gun can usually be distinguished from the various other guns, trench mortars, bombs and shells that are continually heard along the line. It sounds like two planks being banged together in a courtyard where there is some echo from the walls.