We had heard the guns distinctly in the early forenoon, and again, less distinctly, about noontime. Thereafter, for a while, there had been a lull in the firing; but now it was constant--a steady, sustained boom- boom-boom, so far away that it fell on the eardrums as a gentle concussion; as a throb of air, rather than as a real sound. For three days now we had been following that distant voice of the cannon, trying to catch up with it as it advanced, always southward, toward the French frontier. Therefore we flogged the belly of our tired horse with the lash of a long whip, and hurried along. There were five of us, all Americans. The two who rode on bicycles pedaled ahead as outriders, and the remaining three followed on behind with the horse and the dogcart. We had bought the outfit that morning and we were to lose it that night. The horse was an aged mare, with high withers, and galls on her shoulders and fetlocks unshorn, after the fashion of Belgian horses; and the dogcart was a venerable ruin, which creaked a great protest at every turn of the warped wheels on the axle. We had been able to buy the two-- the mare and the cart--only because the German soldiers had not thought them worth the taking. In this order, then, we proceeded. Pretty soon the mare grew so weary she could hardly lift her shaggy old legs; so, footsore as we were, we who rode dismounted and trudged on, taking turns at dragging her forward by the bit. I presume we went ahead thus for an hour or more, along an interminable straight road and past miles of the checkered light and dark green fields which in harvest time make a great backgammon board of this whole country of Belgium. The road was empty of natives--empty, too, of German wagon trains; and these seemed to us curious things, because there had until then been hardly a minute of the day when we were not passing soldiers or meeting refugees.