a draught of cold air , desperately welcome , came into their faces as they ran ; and they emerged from a small marble cloister into an open-air quadrangle , all the windows blazing around them ; granby at once dropped to one knee and fired up his signal-flares : one and the next refused to go , too wet to fire , and cursing he flung the inert cylinders to the ground , but the third , which had been tucked more deeply into his shirt , at last went off , and the blue glittering trail went smoking up into the black sky .